N810 Sound Output Fidelity [Archive] - maemo.org

TenSpeed

11-30-2007, 10:23 PM

Well, if nobody else is going to chime in, I will. I don't have an IT at the moment (waiting for the 810 developer device moment), but I believe the tablets can play 44.1/48k files just fine (I'd be HUGELY surprised if they can't). The challenge will be to achieve "crystal quality, low distortion sound" through the headphone jack, as almost all such devices have significant hiss at the headphone jack. It's not usually a problem when listening through crappy headphones while riding the bus, but audiophile territory, it's not (YES iPOD, I'M LOOKING AT YOU!!!). And depending on the volume you'll need to adequately drive your preamp, the distortion might also be a big issue. So even assuming the N810 can play those files, they'll probably sound lousy if connected through the audio out. So...

I've been looking at various UPnP devices today, thinking about streaming the music to my audio equipment. Assuming the media bridge/player is of decent quality, it should sound good. Perhaps you could even find one with digital outputs for your audio equipment (assuming you have digital inputs available). Maybe this would work in your (as yet unannounced) situation? C'mon, say what you want to use it for!!! :)

Capt'n Corrupt

12-01-2007, 12:17 AM

Well, if nobody else is going to chime in, I will. I don't have an IT at the moment (waiting for the 810 developer device moment), but I believe the tablets can play 44.1/48k files just fine (I'd be HUGELY surprised if they can't).

A safe assumption, to be sure. It seems that most modern sound hardware have very standardized specification.

I extracted this from the TI site regarding the OMAP 2420's TSC2301 Touch Screen Controller w/ (?) Stereo Audio Codec (http://focus.ti.com/docs/prod/folders/print/tsc2301.html).

Stereo Audio Codec
* 20-Bit Delta-Sigma ADC/DAC
* Dynamic Range: 98 dB
* Sampling Rate Up to 48 kHz
* I2S Serial Interface
* Stereo 16(Omega -- Ohms) Headphone Driver
...

The TSC2301 features a high-performance 20-bit, 48-ksps stereo audio codec with highly integrated analog functionality. The audio portion of the TSC2301 contains microphone input with built-in pre-amp and microphone bias circuit, an auxiliary stereo analog input, a stereo line-level output, a differential mono line-level output, and a stereo headphone amplifier output. The digital audio data is transferred through a standard I2S interface. A fully programmable PLL for generating audio clocks from a wide variety of system clocks is also included.

It would appear that the TSC2301 is quite capable of reproducing these ranges faithfully. Quite strange (to this outsider) that it's bundled with the touch screen controller. Perhaps the two share more technology than their functions would suggest.

The challenge will be to achieve "crystal quality, low distortion sound" through the headphone jack, as almost all such devices have significant hiss at the headphone jack. It's not usually a problem when listening through crappy headphones while riding the bus, but audiophile territory, it's not (YES iPOD, I'M LOOKING AT YOU!!!). And depending on the volume you'll need to adequately drive your preamp, the distortion might also be a big issue. So even assuming the N810 can play those files, they'll probably sound lousy if connected through the audio out. So...

I agree 100%. I confess, that I'm not an audiophile, but I do appreciate good sound quality and have a tuned ear to such.

That said, hooking the N810 to a speaker system would be an ad-hoc solution for playing music over a loudspeaker, and not my regular setup. Even in this situation, it would be nice to maximize on the quality.

I've been looking at various UPnP devices today, thinking about streaming the music to my audio equipment. Assuming the media bridge/player is of decent quality, it should sound good. Perhaps you could even find one with digital outputs for your audio equipment (assuming you have digital inputs available). Maybe this would work in your (as yet unannounced) situation?

I would be tremendously interested in your solution for this. Finding the hardware is likely the easy part: the components for constructing a media PC with an optical outs are abundant. The hard part is an effective interface. Ideally one would want something that's very easy: Just select the file on the N810 and it starts playing over the stereo with little fuss.

The easiest way I can see this being done is to share the N810 files via the network (NFS mount?), and have the media PC play the mounted file. In other words, stream the file *from* the N810 rather than *to* the media PC. Does the N810 recognize Samba (SMB) file shares? Are there any media streaming apps available for maemo?

Another solution, would be simply to use the N810 as a remote to select the files that already exist on the server. A nice web interface may work well. I wouldn't be surprised if this software already existed in the wild.

I wish I had a unit so that I could help devise a solution for this! It would be a great way to play audiophile quality music from the N810.

C'mon, say what you want to use it for!!! :)

Ok, Tenner, you yanked it out of me!

I'm planning on using the N810 as a portable player of Binaural Beats. They are quite simply, two similar sinusoidal waveforms of various frequency and amplitude, played simultaneously into each ear. This stimulates the brain into different states and is scientifically documented; no, I'm not crazy :D. Generally the carrier frequencies of such waves are quite low ~140Hz, though they can get much lower ~6Hz. Of course, high quality HiFi headphones would be required to effectively produce sounds at this frequency. Extraneous noise (eg. Hiss) isn't an issue, so long as the actual frequency is wholly reproduced. I want to know if the N810 is capable of outputting (via the headphone jack) such waves.

The difference between theoretical output and actual output can be quite significant. Although I'll buy an N810 either way, it would be great if it could fill this function for me.

}:^)~
YARR!

Capt'n Corrupt

bexley

12-01-2007, 12:30 AM

I'm not sure how to test the fidelity cheaply. Perhaps generate a WAV file of various sound frequencies, use a male-male jack to output it directly into a PC mic (or line in) jack, record the resultant sound to a WAV, and analyze the range of the newly saved WAV file. Not perfect, as you'd lose quality over the connection, but at least it would provide some insight.

This would provide no insight.

What I think you're saying is that you want to measure frequency response, which is a question that's just off the mark in many ways. First of all, frequency response is a product of everything in the chain, definately not just the source. Besides, plugging a source directly into a recording device is nonsensical; think about it: it's the equivalent of trying to judge a camera's colour reproduction while looking through a filter of random colours. Measuring frequency response is not something you can really do well at home, even with high-end recording equipment. But all that is moot, since no piece of consumer technology aims to give flat/balanced frequency response (that is, not boosting some frequencies over others). This is the chief concern for audio recording and mastering, for which unembellished reproduction is needed, but it absolutely is not for consumer products--even the very high end.

Lastly, you shouldn't be worried about the sound quality if what you're doing is plugging a portable device into a stereo via 1/8" for two reasons. First, this is the worst way to transmit an audio signal, but it's all relative so if you consider sound you've heard over 1/8" to be "crystal clear" then we've just got different standards. Second, almost every MP3 player or PDA out there has very similar specs for their amps, which are by no means sophisticated or great. Maybe a few devices have noticeably better quality and a few noticeably worse, but this is again completely subjective since it's not the aim of consumer audio to give balanced frequency response. Play around with your EQ on any device, and you'll probably find something that sounds "better," but it's certainly not more accurate.

bexley

12-01-2007, 12:44 AM

I just saw your explanation of what you want to use it for.

I wouldn't count on the N810 for that. I wouldn't count on whatever headphones you pick up that claim to go down to 6Hz either though. I can't help but think that, if something like this can be effective, it would need to be done through speakers since the inaudible frequencies can only affect you through your bones (up to half of your hearing is from reverberations through your bones).

Or are headphones supposed to be fine for this stuff?

Capt'n Corrupt

12-01-2007, 01:14 AM

This would provide no insight.

What I think you're saying is that you want to measure frequency response, which is a question that's just off the mark in many ways. First of all, frequency response is a product of everything in the chain, definately not just the source. Besides, plugging a source directly into a recording device is nonsensical; think about it: it's the equivalent of trying to judge a camera's colour reproduction while looking through a filter of random colours. Measuring frequency response is not something you can really do well at home, even with high-end recording equipment. But all that is moot, since no piece of consumer technology aims to give flat/balanced frequency response (that is, not boosting some frequencies over others). This is the chief concern for audio recording and mastering, for which unembellished reproduction is needed, but it absolutely is not for consumer products--even the very high end.

Lastly, you shouldn't be worried about the sound quality if what you're doing is plugging a portable device into a stereo via 1/8" for two reasons. First, this is the worst way to transmit an audio signal, but it's all relative so if you consider sound you've heard over 1/8" to be "crystal clear" then we've just got different standards. Second, almost every MP3 player or PDA out there has very similar specs for their amps, which are by no means sophisticated or great. Maybe a few devices have noticeably better quality and a few noticeably worse, but this is again completely subjective since it's not the aim of consumer audio to give balanced frequency response. Play around with your EQ on any device, and you'll probably find something that sounds "better," but it's certainly not more accurate.

Great information! Thank you very much. As you surmised in your last post, you are correct, good frequency response isn't really what I'm after (I just read up on it using wikipedia :)), but rather the frequency spectrum (am I using the correct terminology?). I didn't, however, know the difference between the two, so your post shed much light on this fascinating subject.

I wouldn't count on the N810 for that. I wouldn't count on whatever headphones you pick up that claim to go down to 6Hz either though. I can't help but think that, if something like this can be effective, it would need to be done through speakers since the inaudible frequencies can only affect you through your bones (up to half of your hearing is from reverberations through your bones).

Or are headphones supposed to be fine for this stuff?

Actually headphones are a requirement as they are the only way to guarantee that each ear receives the proper output. Speakers would muddle the frequencies together eliminating the effectiveness of the recording.

The ~6Hz is an absolute minimum I've read about and probably far exaggerated. I'd have to do more research. Suffice it to say, low frequencies are the name of the game for this type of audio.

I've researched some headphones that claimed <10Hz. They tend to be expensive "audiophile-grade" headphones. Do you think that these specs are not achievable at home?

How would one test the various audio output properties of the N810?

}:^)~
YARR!

Capt'n Corrupt

torx

12-01-2007, 01:28 AM

In terms of frequency response accuracy, it's likely not an issue, in fact, I would safely assume it as flat. Even cheap china-made imitation mp3 players can achieve a flat freq response.

The real issue with portable players is the internal amp. Most mp3 player have an undersized amp, and hence is unable to produce a proper sine or square wave. Yes, even iPod is guilty of this. If you tried to square wave with an iPod, you'll get something which looks like a shark fin instead. So to TenSpeed, iPod is really far from audiophile-quality.

Anyway, you just need a square wave file, and your ears and you'll get a good idea how the N810's amp fare.

However, just from the hiss alone, I can pretty much guess that it's an undersized amp too.

bexley

12-01-2007, 02:14 AM

Ah, your explanation for headphones makes sense. If you're really into it, you should invest in a headphone amp and headphones meant to be driven by a dedicated amp. However, the value of this is questionable when you're plugging a souce that's already amplifying the signal somewhat into the dedicated headphone amp. It's still an improvement, but the relationship is complex and subjective. Any 'phones can be plugged into a headphone amp, but the better types meant to be driven by a dedicated amp have different electrical properties, mostly impedance.

Check www.headphone.com for an excellent and well-priced portable headphone amp, the HeadRoom Total AirHead ($99).

Ah, I thought of a solution that is actually getting me excited! I think the N810 would be able to drive the cousin of the AirHead called the BitHead, which is basically an outboard DAC (soundcard) too: that would clean up the audio quality greatly since the N810 would be supplying a perfect digital signal to the amp--as good as plugging an optical cable into your amp.

The only question is if the USB device would work, but I think the probability is high. Has anyone tested tested a USB soundcard with OS2008 and/or the N810 yet? If it doesn't work already, it should be feasible since it's a very simple and standard device. The Bithead takes batteries, so it shouldn't have any issues with a lack of USB power either.

bexley

12-01-2007, 02:20 AM

torx, of course a square wave throws off an amp like one on an iPod or probably most other portable devices. They're not really made to reproduce that. Square waves don't occur naturally. Well, as someone who listens to real electronic music (read: not dance), I should say they exist in some types of electronic music, but nothing that's recorded.

Anyway, you're judging things through a screen again: whatever set of headphones you used. You have no way of knowing where the inaccuracies were produced without doing exclusive testing.

Even cheap china-made imitation mp3 players can achieve a flat freq response.

I'm having trouble imagining a standard that would call any MP3 player's frequency response flat. What do you mean by "china-made imitation" anywhere? Everything, even the iPod (why people consider it some holy grail, I have no idea), is made in China.

However, just from the hiss alone, I can pretty much guess that it's an undersized amp too.

High frequency noise is inherent in any amp and comes from a few things; an underpowered amp is not one of them. Are you just talking about how you have to jack up the volume to a much higher level than you would with an amp that matches your speakers? Raising the volume on any amp will increase the noise floor. The essential relationship between an amplifier and its speaker is impedance (ohms). An amp's power or lack thereof isn't so important, and watt ratings in consumer products are neither significant nor even close to accurate.

TenSpeed

12-01-2007, 11:47 AM

Hey, look at all the people here - that's better! :)

I agree with everyone above regarding the precious iPod and its many bastard cousins - frankly, they all sound pretty bad to my ears. Of course, that's only when listening through nice studio headphones in a quiet environment - add a noisy toddler or two, and frankly, they sound decent.

As far as flat v. non-flat frequency response, it all depends on what you're measuring, or (more critically), whether you're measuring at all. I've been doing recordings for about a dozen years (mostly classical music - also lots of electroacoustics), and I have never had a listener key in on "non-flat frequency response" as a problem with a recording. Yes, it's a nice way to measure electronics (and even better, to market them), but it has very little to do with how we listen. Besides, there are too many other variables - non-linearities in the amplifier stage(s), different transducers (speakers/headphones), different listening environments, and the hearing of the listener. Not to mention the listener's preferences, mood, etc...

Okay, I'm drifting WAY off topic. Sorry...

As far as listening to binaural recordings while on the move, check out the Etymotic ER-4B in-ear headphones <http://www.etymotic.com/ephp/er4.aspx>. The 4B model is specifically designed to reproduce binaural recordings, and they all have excellent sound isolation characteristics (in case your listening environment is less than ideal) - typically 35-40 dB isolation. Price is about $250-300, and you'll certainly have to order the 4B, as stores tend to focus on the 4P.

As far as UPnP, I'm leaning toward a dedicated NAS device with all my media on it, and with the option (?) of using the N810 as a remote of some sort. This is well beyond my areas of expertise, and as I said, I only started looking at it yesterday, so I don't have much to add just yet. Maybe in a few weeks.

Perhaps Canola could be used as a UPnP source/controller?

Capt'n Corrupt

12-01-2007, 03:27 PM

Check www.headphone.com for an excellent and well-priced portable headphone amp, the HeadRoom Total AirHead ($99).

When you provided that link, it was like the earth cracked beneath me, and a whole new world opened up before me. I had no idea that such devices existed, and the tantalizingly complex relationships that bind the various concepts of audio together, are just too mysterious to leave uncharted. I simply need to know more. It reminds me of the joy I felt when introduced to my first programming language. There was a world, so vast and mysterious, that I just couldn't leave it alone!

Needless to say, thanks for the recommend! I'm looking forward to buying a good amp (likely portable) and high quality cans/buds. I simply can't consider purchasing sound products based on wattage spec and marketing hyperbole anymore! That's a good thing!

Moving on....

One thing of interest that I pulled from the TI OMAP page that may give us some insight on what N810 facilities can be used

The audio portion of the TSC2301 contains microphone input with built-in pre-amp and microphone bias circuit, an auxiliary stereo analog input, a stereo line-level output, a differential mono line-level output, and a stereo headphone amplifier output. The digital audio data is transferred through a standard I2S interface. A fully programmable PLL for generating audio clocks from a wide variety of system clocks is also included.

Notice that the TSC2301 has "stereo line-level output." Could this be line-out functionality? If so, I wonder if this capability needs to be hardwired as a distinct port on the device that uses the OMAP, *or* if it is somehow a mode that can be turned on via some programmable interface. Certainly the picture of the 2420 suggest that there is only one out-port and one in-port on the device. Line out capability and headphone capability may suggest that the same port is used for amp and no-amp. In the interest of limiting pre-amp as much as possible for external amplification via the headphone jack, this would be interesting to explore. Certainly for portable Binaurals, but also for a quick-and-dirty 3.5mm connection to a HIFI stereo.

Ah, I thought of a solution that is actually getting me excited! I think the N810 would be able to drive the cousin of the AirHead called the BitHead, which is basically an outboard DAC (soundcard) too: that would clean up the audio quality greatly since the N810 would be supplying a perfect digital signal to the amp--as good as plugging an optical cable into your amp.

Me too! I know that the linux ALSA sound framework is a complex beast with many capabilities. If only I had an N810, I could run a couple of tests. :confused:

The only question is if the USB device would work, but I think the probability is high. Has anyone tested tested a USB soundcard with OS2008 and/or the N810 yet? If it doesn't work already, it should be feasible since it's a very simple and standard device. The Bithead takes batteries, so it shouldn't have any issues with a lack of USB power either.

I'm 99% sure that something like this will work. As far as I can tell, the potential problems are:

1) The format for the data. In the case of the BitHead device, it seems to require proprietary drivers to control the USB output. Is it streaming straight wav data, or some other format only recognized by its closed device? This would have to be investigated.

2) The amount of data. I'm assuming that any connectivity would have to be implemented a user-level application (not a driver built into the linux kernel). If the data requires conversion, this could potentially be computationally expensive. If it's beyond the requirements of the N810, choppy sound could be the result. Somehow, I doubt that this will be a hindrance.

Can anyone else shed a little insight?

}:^)~
YARR!

Capt'n Corrupt

Capt'n Corrupt

12-01-2007, 03:46 PM

As far as listening to binaural recordings while on the move, check out the Etymotic ER-4B in-ear headphones http://www.etymotic.com/ephp/er4.aspx. The 4B model is specifically designed to reproduce binaural recordings, and they all have excellent sound isolation characteristics (in case your listening environment is less than ideal) - typically 35-40 dB isolation. Price is about $250-300, and you'll certainly have to order the 4B, as stores tend to focus on the 4P.

Great recommend! Do you have experience with this product?

As far as UPnP, I'm leaning toward a dedicated NAS device with all my media on it, and with the option (?) of using the N810 as a remote of some sort. This is well beyond my areas of expertise, and as I said, I only started looking at it yesterday, so I don't have much to add just yet. Maybe in a few weeks.

Perhaps Canola could be used as a UPnP source/controller?

It's worth looking into. This would be a great use for the N8xx: controlling the audio around the house. Ideally, this concept could extend to a home theatre as well. One only needs to be able to start/stop audio.

I came across this behemoth article on linux devices: Building the Ultimate Linux based Music Servier (http://www.linuxdevices.com/articles/AT6488801276.html). This is a system that is similar to the Sonos (http://www.sonos.com/) based home server, only with far more flexibility (and configuration, I might add :D). Interestingly enough, the article's author uses the Nokia N800 as the system remote! It's worth a look and a bookmark.

If you are really serious about using the N8xx as a media centre remote (and I mean really interested; my time is every so limited these days), I can whip up a slick flash 9 interface, and some perl scripts that will allow just that, on any modern linux installation with a web server. Maybe I'll throw in fancy-schmancy inertial scrolling (if it performs well). We'd have to work out the system capabilities and spec before hand, though. I don't like wasting time engineering shoddy software.

For a quick and easy solution, I'm sure there exist simple to install Windows apps out there. They just need to be found.

}:^)~
YARR!

Capt'n Corrupt

bexley

12-01-2007, 04:27 PM

Yes, it's a nice way to measure electronics (and even better, to market them), but it has very little to do with how we listen.

That's exactly what I was saying, though I'm not sure if you're trying to refute anything I said. Flat response is indeed a BS form of marketing for high-end audio equipment. People who buy low end like to hear that it is "a lot of base!"--ugh.

But, as I mentioned, flat response is essential for mixing and mastering. For very well mastered music that's not made for the radio or extremely wide consumption, relatively flat response is very nice to have--but it's by no means close to the balance of a great set of studio monitors, which aren't geared for listening to music for enjoyment but are great for analyzing what's actually there.

Great recommend! Do you have experience with this product?

I own the ER-4P's and they're very good. Of all the earphones out there (in-ear and regular earbuds) they are at the topic for balanced response. To get the best out of these, as with any high-end ear/headphones, you should listen to them through an amp. The ER4-P's need a small adapter that changes the impedance, or ohms, to make them match the amp--the ER-4S are made for an amp without that tiny adapter, but don't work as well with a self-amped device like an iPod.

I would not go for the 4B or anything made for binaural recordings, unless you already have a collection of binaural recordings that's amongst your favourite music. Very little is recorded for binaural reproduction, it's more expensive and it's harder to come by. Canalphones like the ER-4P's already reproduce a stereo soundstage incredibly well and create a mild effect that you're listening to a binaural recording from having the sound aimed so directly into your ear. Soundstage can be described as the virtual space that's created by a recording with more than one channel (stereo=2). Good soundstage has to do with how cohesive, convincing and accurate the virtual space is. Stereo fields can appear too "far apart" or "close together," and this is bad soundstage--almost entirely from the speakers or headphones as opposed to the amp. The ER4-P's have excellent soundstage, noteably for solo instruments. Simply amazing with a solo cello or guitar.

I can't believe I referred to wiki, but it does tend to have good and concise descriptions of things that are tricky to describe, like soundstage:

"According to audiophiles, the quality of the playback is very much dependent on how one is able to pick out different instruments, voices, vocal parts, etc. exactly where they are located on an imaginary 2D or 3D field. This can enhance not only the listener's involvement in the recording but also their overall perception of the stage."

Anyway, I went off track. But the biggest reason to not spend money on binaural earphones is that they are not made for regular recordings, ie. 99.99% of what's out there. Unless you have tons of cash and want to throw down a few hundred to try out something new (which you can do just as well with regular headphones), go with earphones made for regular recordings. Binaural recordings already sound very convincing on regular earphones, especially accurate ones like the ER-4P's, so any improvement from the ER-4B's is highly unnecessary unless you're a big binaural recording afficionado with cash to spare.

Also, binaural recording is very interesting and worth a listen, but it'll never replace your regular listening or the music you already like. At most, it'll expand what you listen to by 5% or so and give you a new kind of listening experience, which is very neat but hard to justify a big expenditure over.

Google "binaural recording" or something and give some of the free samples out there a listen with whatever set of headphones you have lying around. Find some music suitable for binaural recording (big bands/anything electronic or amplified = not very suitable, but solo instrument = wow) and close your eyes. It's fun.

bexley

12-01-2007, 04:39 PM

That's interesting about the TSC2301, but every portable device I've seen that's able to provide both an amplified signal an a line-out (the iPod and many other DAP's) have seperate outputs, so it could be that the N810 simply isn't set up for it. Without a crazy proprietary connector that somehow packs in 5 or more contacts onto a 1/8" (something like the stupid iPhone jack, but worse), I think that the only way to provide line-out in addition to an amped signal is with a seperate jack. I don't know if I read your post carefully, but if you suggested some kind of switch mechanism that would let the output switch between amped and line--well, that would be awesome.

About the Bithead, it really shouldn't need proprietary drivers on any modern system. It's just an outboard DAC (digital-to-analogue converter), which is one of the most simple and standard kinds of chips out there. It doesn't need a signal sent to it in any special way; it just receives the audio stream digitally over USB and the DAC converts it to an analogue signal. Done.

This is what the somewhat vague description on the site says:

Then the computer looks at the Total BitHead, and if it doesn’t recognize it, the computer will download the driver stored on the Total BitHead and quickly install it.

I just learned about the choice it gives you of using USB power or running of battery power for a cleaner signal. Great! It also happens to solve the problem that the N810 would probably not supply enough power.

Then the computer will begin to use the Total BitHead as an audio playback device. No batteries are required; simply leave the power switch off and the Total BitHead filters, re-regulates, and runs of the computers USB power bus. If, however, you are of an audiophile mind, turn the power switch on and the Total BitHead’s digital-to-analog converter (DAC) and power amp section will run off the internal batteries for ultra-clean performance and lower power drain on your computer.

It's an efficient amp, too. They claim 30-35hrs of 4 AAA's.

TenSpeed

12-01-2007, 05:45 PM

Hi Bexley - I'm not trying to refute anything you've said - it sounds great to me! I also agree with you on the ER-4P, which, for my money, is fantastic. The 4B is great as well, but as you've mentioned, it's for a very specific application. So for the vast majority of people, I also head towards the 4P.

And Captain, I'm very interested in this idea, but want to wait for the next version of Canola to be released. It sounds as though there might be a way to add this sort of capability as a plug-in in Canola, using their interface etc. I'm planning to hold off for a few weeks until that situation becomes more clear.

By the way, a HUGE thanks for the Linux audio server article - that's just the sort of thing I needed to read.

dsmudger

12-02-2007, 02:37 PM

Just skimmed through arriving quite late to this thread - saw a few things mentioned there that I've got to hand though, so if anyone wants me to run any kind of test and report back let me know..

770, N810, Headroom Total Bithead, various Grado/Shure/Sennheiser headphones..

oh, and speaking of USB sound cards; Hercules DJ controller MkII - connecting that up might be fun and it's a generic MIDI controller so all sorts of potential there... would be awesome if something like the monome project could be set up with a Nokia tablet (even just with the touchscreen...) :)

Don't have a USB mini-A-to-micro-A cable though - I guess that's what you'd need to connect them?

Capt'n Corrupt

12-02-2007, 04:16 PM

I own the ER-4P's and they're very good. Of all the earphones out there (in-ear and regular earbuds) they are at the topic for balanced response. To get the best out of these, as with any high-end ear/headphones, you should listen to them through an amp. The ER4-P's need a small adapter that changes the impedance, or ohms, to make them match the amp--the ER-4S are made for an amp without that tiny adapter, but don't work as well with a self-amped device like an iPod.

Thanks for the recommend and solid review. I think I'm leaning towards the ER4Ps as well. The majority of recordings I listen to will indeed not be binaural, and the response for these earbuds will more than allow for accurate binaural and normal listening. After taking a look at the frequency response graph, it's quite astonishing how flat it is for frequencies up to and around ~2000Hz. After comparing, many graphs of audiophile grade speakers, the ER4Ps offer tremendous bang for the buck. The online reviews are all very positive as well.

What type of adapter is required for matching the impedance of the amp? Does this come with the ER4Ps, or is it a piece of equipment that needs to be purchased separately? Does the Bithead have this functionality?

[QUOTE=bexley;103211]Google "binaural recording" or something and give some of the free samples out there a listen with whatever set of headphones you have lying around. Find some music suitable for binaural recording (big bands/anything electronic or amplified = not very suitable, but solo instrument = wow) and close your eyes. It's fun.

This will be at the top of my list of things to try! As a person that's only used earphones that have been pre-packaged with portable players (Cassette and CD), I can't wait to experience the difference that only good headphones/speakers can deliver. It's funny, but I've always known the craptacular quality of the headphones that I've been using, even with no other frame of reference. Audiophalea is in my blood :).

I don't know if I read your post carefully, but if you suggested some kind of switch mechanism that would let the output switch between amped and line--well, that would be awesome.

This is precisely what I'm suggesting, and yes, it would be awesome :). I'll be looking investigating this quite diligently when I actually get the N810. For the time being, though there's too little documentation lying around, so it makes investigating quite difficult. However, if the Total Bithead can indeed take audio from the N810 easily over the USB , and other home-stereo devices can take audio from the N810 via USB, the difficulty in discovering line-out and getting it to work would not be as large a priority. I would likely just ignore discovering the potential line-out functionality altogether.

About the Bithead, it really shouldn't need proprietary drivers on any modern system. It's just an outboard DAC (digital-to-analogue converter), which is one of the most simple and standard kinds of chips out there. It doesn't need a signal sent to it in any special way; it just receives the audio stream digitally over USB and the DAC converts it to an analogue signal. Done.

This is an exciting revelation! It's even more exciting considering that the Bithead has it's own power supply, increasing plug-free listening longevity, and making it more likely to actually work in the first place.

It would be interesting to pipe a wav file through the raw USB device and listen what comes out the other end. Since I'm planning on getting the Bithead (or similar mobile amp), I'll be able to test out a couple of configurations. Additionally, it would be great for home audio as well, as the N810 could not only be a remote, but also the device actually supplying the audio.

I'm sure there would be a bevy of people that would appreciate any solutions we could come up with. Great work Bex!

Of course, after USB connectivity, comes WiFi streaming of audio to a capable server attached to the stereo. The only thing better than hooking into and playing your tunes from the N810, is doing it without hooking in! This solution should also be possible (and quite easy). I *think* that MPlayer can pipe wav data out, meaning that a socket connection to a media server that pipes it's data to the systems audio device, *should* allow fairly simple wireless audio streaming from the N810. A nice interface (possibly a configuration of existing media players), and you can play crystal-quality tunes from your N810 just as easily as playing them on the actual device; something well worth getting working! This is something I would like to work on.

}:^)~
YARR!

Capt'n Corrupt

Capt'n Corrupt

12-02-2007, 04:28 PM

And Captain, I'm very interested in this idea, but want to wait for the next version of Canola to be released. It sounds as though there might be a way to add this sort of capability as a plug-in in Canola, using their interface etc. I'm planning to hold off for a few weeks until that situation becomes more clear.

I'm also really interested in using the N810 as a media center remote. As the owner of a projector (not that great, but a great value), I've been spoiled by the Home Theater setup. The ability to use the N810 as a remote to control tv, movies, and music, is one of my many planned uses for the device. Of course, it would have to be simple to use and highly effective making accessing the media a pleasurable experience.

You raise a good point and I will also look into Canola. Certainly if a plugin can be created to serve this purpose, then there's no need to re-invent the wheel (for the nth time). If however, the systems isn't flexible enough to handle this complex control, I would likely write a nice interface to accomplish this.

By the way, a HUGE thanks for the Linux audio server article - that's just the sort of thing I needed to read.

Haha. No problem. The document is LONG, but I think it concerns itself with configuring the server from the ground up. I'm pretty sure that any modern linux installation would eliminate a great portion of the recommended setup, especially things like kernel config, etc.

}:^)~
YARR!

Capt'n Corrupt

Capt'n Corrupt

12-02-2007, 04:42 PM

Just skimmed through arriving quite late to this thread - saw a few things mentioned there that I've got to hand though, so if anyone wants me to run any kind of test and report back let me know..

This would be AMAZING. I'm very eager to find out what can be done with the N810. Keep us posted!

I wish I had information to contribute, but alas, I'm N810-less...

}:^)~
YARR!

Capt'n Corrupt

Capt'n Corrupt

12-02-2007, 05:24 PM

For those interested in wireless streaming from a computer check this out:

http://labs.morpheuz.eng.br/blog/24/02/2007/n800-video-streaming-with-netcat/

It would just as easily work in reverse, to digitally (and wirelessly) stream audio/video to a media server.

It needs a nice interface, though. Hopefully Canola can handle this!

}:^)~
YARR!

Capt'n Corrupt

ArnimS

12-03-2007, 07:57 AM

dsmudger

12-03-2007, 08:34 AM

This would be AMAZING. I'm very eager to find out what can be done with the N810. Keep us posted!

I wish I had information to contribute, but alas, I'm N810-less...

}:^)~
YARR!

Capt'n Corrupt

Sure - just someone who knows what they're doing let me know what to do, e.g. "buy this cable from here (or better buy one for me ;)), run this command/post this log file output" etc and I'll be happy to oblige :)

Incidentally - the low-end in-ear earphones by Sennheiser (about £30-40 high street price, the ones with the black rubber domes) are a great match for the N810.

If you haven't already replaced the total-waste-of-time Nokia freebies, I'd recommends these as the ones to go for as to my taste, this combo sounds great at all volumes with no need for any EQ (which is good because none is available in any of the maemo media players AFAIK?)

(fair enough, including throwaway headphones increases the manufacture cost by only a few cents, so you might as well, but why-oh-why didn't they make them interchangeable at the mic/remote?? what a waste... :()

Just like the 770 though, plug in something a bit more serious like a Shure e5c and the sound all goes into the midrange with harsh/overly bright treble - much like a clock-radio kind of speaker - but the Senn's fat/quite uncontrolled bass-iness offsets the tight-but-light bass of the N810, and kind of reigns in the harsh treble - end result is very nicely balanced sound IMO, especially for the price (better than the same phones driven by for example iTunes+iMac internal sound card, which sounds excessively boom-y to me).

Been listening to a lot of last.fm in Vagalume at work with this setup - very happy with it this way - and so much easier to untangle myself (than something like the e5c) when someone comes over with a question or something :)

Capt'n Corrupt

12-03-2007, 09:37 AM

Beat frequencies are generated by two overlaid waves at different frequencies. If for e.g. you play back a 400hz wave and a 406hz wave, your ear will hear a wave at 6 hz.

For the ear to hear a beat frequency does not require a playback mechanism capable of reproducing a carrier at that frequency. Specifically, to hear a 6hz (cycles per second) frequency using ~400hz carrier waves, any speaker or headphone will suffice. Here, i show yuu.

http://pupnik.de/beat_frequency_6hz_at_400hz.mp3

The insight is much appreciated! However, it is the carrier frequencies are in question. With certain binaurals, the carriers themselves can drop to the sub 10Hz level (6Hz with beats at ~0.2, I've read). I would imagine that regular headphones would butcher sound at this level especially given the standard amplifiers in most (not excluding the N810) portable listening devices. Though the beat frequencies are likely inaudible, there is apparently a very real psychological effect that the recordings have. I would imagine, that at this ultra-low level, its likely that special binaural headphones would have to be purchased.

For the time being, though, it doesn't hurt to have a good pair of headphones to take advantage of a wider and more consistent frequency spectrum for normal listening! :) The ability to use the N810 for this task further broadens its usefulness.

}:^)~
YARR!

Capt'n Corrupt

Capt'n Corrupt

12-03-2007, 09:47 AM

Sure - just someone who knows what they're doing let me know what to do, e.g. "buy this cable from here (or better buy one for me ;)), run this command/post this log file output" etc and I'll be happy to oblige :)

I wish I could help, but I don't know enough, and would hate for you to waste money on equipment for something that may work.

Does anyone have any ideas/experience that could lend a hand?

Incidentally - the low-end in-ear earphones by Sennheiser (about £30-40 high street price, the ones with the black rubber domes) are a great match for the N810.

Good recommend! I'll look into this, as I'd like a nice (almost dispensable) pair of headphones to take with me on the road when I'm walking about. I could stand to lose ~$60 headphones, but losing/damaging $200+ would be devastating. Additionally, carrying an additional 4"x3" amp to take advantage of the headphones whilst out and about, is less than appealing.

I'll take a closer look at the 'casual' Sennheiser headphones! Thanks!

}:^)~
YARR!

Capt'n Corrupt

Mara

12-03-2007, 09:56 AM

Mara

12-03-2007, 08:11 PM

I just ordered myself Shure e2c in-ear headphones. Those go now around $60-70 in the US... and should be relatively decent in sound quality. (And do block background noise quite effectively.)

I'll post back about my experience once I receive them.

Just got them today. Overall I'm very pleased with them.

Sound quality is very good. (That shouldn't be a surprise... since we are talking Shure... :D) The volume, while can not be adjusted to insane levels, is loud enough, especially when you know that background noise is almost completely sealed outside.

Some reviews I read some people said that these may not be comfortable to wear for everybody. I didn't wear them very long yet, but initially they do not feel bad at all. Much better than my other cheap earplugs I bought few months back...

So, if you are thinking about spending about $50-$100 range in headphones you should not forget to try these... :)

speculatrix

12-04-2007, 08:00 PM

one issue with really low frequencies will be how the output from the A-D converters is coupled - chances are it's capacitively coupled and will thus effectively be a high-pass filter.

Benson

12-04-2007, 09:11 PM

Measuring frequency response is not something you can really do well at home, even with high-end recording equipment.
Well, as an EE, or at least a recent EE graduate, I think it's something I can really do well at home. :p
I have a couple scopes, signal generator, counter, and the like sitting around, and know how to use them.

Output some pure sine waves at various frequencies from the N800, into some appropriate load, and measure the voltage across the load. 20 log10(v/v0) is your friend!

That comment from speculatrix is dead on, of course. The low frequency reproduction of a DAC is perfect. But it is no doubt capacitively coupled, so it will roll off (probably 20dB/dec, not that it matters) at low frequency. I can hook up, say, the comes-with phones, and take some measurements to find the corner frequency.

Regarding the comes-with phones. :eek: They killed my ears! Until I took the rubber rings off. Now they fit OK, though the sound is still poor. But having the mic on there means I get to keep them for VoIP, and I'm not going to swap headphones all day. (Does that switch do anything, anyway?) I think, when I have too much time, I shall hack in a 1/8 jack in the mic unit, allowing me to use my Rio earbuds.

Capt'n Corrupt

12-04-2007, 09:50 PM

@mara

Thanks for the solid recommendation! Good isolation is a big plus. I'll look into these before my final purchase.

@speculatrix and Benson

Thank you kindly for your insight. The trouble is, I have only a very faint clue as to what you both are talking about! If it's not too much, do you mind giving me a frank explanation? It would help out tremendously, as it really does sound interesting.

}:^)~
YARR!

Capt'n Corrupt

Benson

12-04-2007, 10:50 PM

Well, I wasn't so much offering insight, as offering to take a couple measurements on my setup. Oh, and I was offering EE-jargon, too.

But if you think it's insightful, here's more:

Overview:
The sound hardware in the N800 has some stuff which generates a digital output.
This digital output gets run through a DAC (Digital -> Analog Converter). The DAC outputs a voltage corresponding to the numeric input.
This analog signal then goes through some filters, out the headphone jack, and presumably into a load.

So parameters of the system include:
Maximum output sample rate: This is how often the digital output gets updated. Probably 48kHz, but IDK. This is the most important factor in maximum frequency. (The highest output frequency is one-half the sample rate, since you need a positive and a negative peak in each cycle.)
DAC resolution: This is how many levels of voltage the DAC can output.
Probably 16 bits, maybe less. Highly unlikely to be more, though PC sound cards are readily available higher. This is the limiting factor on dynamic range.
Analog filtration stuff:
Since the DAC outputs a constant voltage for a given input, the output has stair-steps. This results in HF noise, at frequencies at and above the sample rate. Those are well above the range of human hearing in this case, but are still probably eliminated with a low-pass filter, which attenuates frequencies above about 24 kHz (sample rate / 2).
There could be more analog filters here; probably volume control is here (it definitely should be), and there may be circuits to compensate for the frequency-dependence of the load.

Finally, the output goes to the headphone jack. Now, if the outputs are directly connected, it'll work fine for headphones. But you could have trouble when connecting it to an amp, as the sound wave is riding on top of a DC level, and the amp may have its inputs referenced to ground. To avoid such trouble (which could cause anything from distortion to frying one of the components), the output is connected to the jack with a capacitor.

Brief discursion into capacitors and inductors:
Resistors have a given resistance value. It's constant for all frequencies of voltage/current you might care to apply. Capacitors and inductors (the ideal ones) have no resistance, but have impedance, which is like resistance. The distinction is that resistance doesn't change the phase; the voltage across it is in phase with the current through it. Impedance shows the same current-voltage relation (high impedance = low current for a given voltage, or high voltage for a given current), but also contains a phase difference between voltage and current. The interesting thing, for our purposes, is that the capacitor has an infinite impedance at DC, and a low impedance at HF. Inductors are the opposite.

So, our capacitor looks like an open circuit for DC -- no DC gets sent through, and if the load has a DC bias, it doesn't send any DC back to fry the N800. For high frequency, it looks like the jack is wired directly.
The only question is, at what frequency does the capacitor "start" conducting?

For the moment, we'll treat your load (earphones, external amp, speakers, whatever) as a resistor. It's not, of course, though the assumption is probably respectable for the amp. The others have strong inductance, but we'll ignore that in the interest of simplicity.

The output power will be one-half the pass-band power (-3dB) when the impedance of the capacitor is equivalent to the resistance of the load. This frequency (called the corner frequency) can be shown to be characterized as 1/(R*C), where R and C are the resistance and capacitance. This formula gives the ouput in radians/second, but we want Hz, so it's 1/(2*pi*R*C) Hz. Above this frequency, we can treat the capacitor as conducting, since the resistance of the load rapidly dominates. Below this, the capacitance dominates, so we can treat the response as falling off at 20 dB/decade. A decade is a power of 10, so if the corner frequency is 100 Hz, a 10 Hz signal would be attenuated by 20 dB, or have one-tenth the voltage, or one-hundredth the power, of a higher-frequency signal with the same amplitude. A graph of the output on a dB scale versus the frequency on a log scale looks like a straight line rising at 45 degrees up to the corner frequency, then level the rest of the way, hence the term corner frequency.

The corner frequency, then, is what we need to find. But it depends on the resistance of the load. So the only thing to do is hook the load (your earphones) up, and measure the voltage output while playing a bunch of sound files containing sine waves with the same amplitude (but a range of frequencies). Look for the point where the output really starts falling off as the frequency drops, and you know the corner frequency. (To best determine it, plot all points on a dB-log plot, giving you the entire frequency response, but if you just want the corner frequency, look for where the output amplitude is drops to 70.7%)
That is easiest with a scope, though you could do it with a good AC voltmeter.

HTH!

Capt'n Corrupt

12-05-2007, 07:55 AM

Benson, that was a tremendous post! Thank you kindly for your insight.

I think I understand most of it. The following confuses me a bit:
The output power will be one-half the pass-band power (-3dB) when the impedance of the capacitor is equivalent to the resistance of the load.

I'm not sure what this is. Are these assumptions made prior to the explanation? I think I understand the idea of corner frequency, even if my inchoate mental model is somewhat wobbly.

One more question: What is it that electrical engineers do exactly? I've always been interested in circuits, but have never taken the plunge to play around with some home brew electronics. I'm guessing that EEs do this, at a much higher level. Am I right in assuming that Computer Engineers, are like EEs only with a specialty involving the organization of circuits for computation (logic/arithmetic/etc)?

Thank you so much. Could you recommend a good book/author? I need to know more, and can't continue asking you questions directly!

}:^)~
YARR!

Capt'n Corrupt

muki

12-05-2007, 10:28 AM

What is it that electrical engineers do exactly?

We sell burgers for a living, lol. Just joking, I hope.

Assuming your interest is (or will be) electronics hooked up to a computer/microprocessor/system-on(-a)-chip, then I would recommend dev kits for the MSP430 or the very interesting Parallax "Propeller".

On subject (sort of): if anyone has the equipment I would be interested to know the frequency response of the inbuilt speakers for 770/800/810. Why? I have an idea, here's a hint: anyone remember principle of operation of early tv remotes?

Capt'n Corrupt

12-05-2007, 10:56 AM

We sell burgers for a living, lol. Just joking, I hope.

Nothing wrong with burgers! They're delicious, and fill a great human need. :D

Assuming your interest is (or will be) electronics hooked up to a computer/microprocessor/system-on(-a)-chip, then I would recommend dev kits for the MSP430 or the very interesting Parallax "Propeller".

Amazing! This has turned out to be the best thread I've ever had the pleasure of contributing to. I'll check out the dev kit. I'm now seriously rethinking my desired Christmas gift; cologne was my first option. :rolleyes:

On subject (sort of): if anyone has the equipment I would be interested to know the frequency response of the inbuilt speakers for 770/800/810. Why? I have an idea, here's a hint: anyone remember principle of operation of early tv remotes?

Here's a guess: Using high pitched, nearly inaudible sound, one could control devices remotely. This post triggered a very old childhood memory I had, when I noticed that a very quiet high pitched noise came from the tip of the remote when I pushed buttons. I noticed that the pitch was different for each button pressed. I *never* would have remembered that, had it not been for this post!

}:^)~
YARR!

Capt'n Corrupt

Capt'n Corrupt

12-05-2007, 11:32 AM

For those interested in learning more, I've located a great resource of scientific texts online (by searching the ITT), SpringerLink (http://beta.springerlink.com/home/main.mpx). Together with the classical literature of sites like Manybooks.net (http://Manybooks.net), there's more free content than anyone could ever hope to read! Here's to hoping that I can additionally purchase the occasional book (DRM'd or not).

I very excited to get a N810 to call my own! It's going to be my e-book solution until e-ink based readers get better (colour e-ink is around the corner, and pixel density and refresh speed is bound to improve).

}:^)~
YARR!

Capt'n Corrupt

muki

12-05-2007, 11:54 AM

TA-t3

12-05-2007, 12:04 PM

Ah, early remotes.. I remember those. They used ultrasound. That didn't last long, because the ultrasound sometimes went through the walls and when you had just sat down to watch "Flipper" (which was popular back then.. ;) your TV would switch channels because the neighbour operated his own ultrasound remote. :)

Benson

12-05-2007, 12:36 PM

As for the bit that confused you, perhaps that wasn't the best way to put it. The -3dB point is the conventional place to define the "start" of the pass-band. In this sense, it is an assumption, of where we conventionally draw the line.
But the bit about the impedances being equivalent (by which I meant, have the same magnitude, but different phase), is not an assumption. It's simply that the output falls off to one-half the power at the point where the impedances are equivalent.

I should have thought of Wikipedia, and it's propensity for useful pictures: Corner frequency (http://en.wikipedia.org/wiki/Corner_frequency)

What is it that electrical engineers do exactly? I've always been interested in circuits, but have never taken the plunge to play around with some home brew electronics. I'm guessing that EEs do this, at a much higher level. Am I right in assuming that Computer Engineers, are like EEs only with a specialty involving the organization of circuits for computation (logic/arithmetic/etc)?
As for what EEs do, yes, that's more or less it. You can go into power, where you get to spend your life bored to death specing overhead transmission lines and the like, or you can go to typical electronics stuff (most EEs), which consists of designing all manner of circuits. Or, you could go to various minor specialties, like IC design and such. Wikipedia (http://en.wikipedia.org/wiki/Electrical_engineering) is helpful again.
CpEs are really more like EEs who know how to program better. (And, on the flip side, aren't as good with heavy-duty analog stuff, like super-heterodyne radios.) But both EEs and CpEs have basic skills in analog and digital electronics.
I have more of a CpE bent, but took the EE course due to difficulties scheduling some of the CpE classes. Sometimes CpE is considered a specialty within the EE field, sometimes as a separate, though closely related, field.

Here's a guess: Using high pitched, nearly inaudible sound, one could control devices remotely. This post triggered a very old childhood memory I had, when I noticed that a very quiet high pitched noise came from the tip of the remote when I pushed buttons. I noticed that the pitch was different for each button pressed. I *never* would have remembered that, had it not been for this post!

Well, I expect the design specs weren't for "high-pitched, nearly inaudible sound", but rather for ultrasound, i.e. high-pitched, totally inaudible sound. But kids tend to have higher range of hearing, so you could hear it anyway.
I have even heard of some cell-phone ringtones at the top end of human hearing, where most schoolkids can hear them, but their teachers can't!

Capt'n Corrupt

12-05-2007, 03:06 PM

@Capt'n Corrupt: you are giving away your age if you remember those types of remotes, lol. But spot on, I'm envisaging a matchbox sized device with a highly selective audio filter that converts audio pulse train to IR. It would have the advantage of being cheap and not requiring additional hw (such as some BT/networked device). All assuming the RC codes can be captured or dl'ed somewhere. I am not an audio engineer though and suspect some specialist equipment is needed to test if this idea would be feasible.

... which would explain why mention of infinite impedance made me nervous at first glance... :P

This would be an interesting project and a fun one. Your device has the advantage of being small and portable, and with bright IR LEDs, could easily drive remote devices.

A spin on this, would use a computer with an IR transmitter and a wireless network interface. Not as portable, but relatively easy to design.

Another neat alternative, would be to use the microUSB, a homebrew circuit (and code), and a small IR LED to drive devices remotely. It requires additional equipment used in conjunction with the N810, but it should work effectively.

Ah, early remotes.. I remember those. They used ultrasound. That didn't last long, because the ultrasound sometimes went through the walls and when you had just sat down to watch "Flipper" (which was popular back then.. ;) your TV would switch channels because the neighbour operated his own ultrasound remote. :)

Heh heh... The perfect platform for a few childish pranks...

}:^)~
YARR!

Capt'n Corrupt

Frank Banul

12-05-2007, 04:45 PM

For those on this thread that have asked about using the tablet to control a media center, a Roku Soundbridge can be controlled a couple different ways with the tablet.

Media Streamer can be used to control the music queue of the Soundbridge. The downside of this application is that if you stop it, the Soundbridge stops playing. This is a limitation of the Media Streamer application, not the Soundbridge (see Cidero).

Because of this limitation, I wrote my own application soon to be renamed TabletBridge. With this I can control and view the Soundbridge screen from the tablet via WiFi. The downside of this application is it's ugly :) and not very fault tolerant regarding the network connection although I improved that last night. http://www.kjainvestments.com/sb/

Frank

dfn_doe

12-05-2007, 05:57 PM

After a quick peek at the data sheet for the TI chip mentioned earlier in the thread it looks like the pins 51 and 52 (voutr and voutl) on the chip are the line level outputs, a few minutes with a soldering iron should easily move the connection for the 1/8" jack from one to the other and avoid the simple onboard amp outputs 55 and 56 (hpr and hpl).

Sorry if this is redundant to something else in the thread, I was getting a bit tired of the speculation as to how the chip worked and it's ins and outs without anybody actually just taking a peak at it's block diagram.

dblank

12-05-2007, 06:29 PM

After a quick peek at the data sheet for the TI chip mentioned earlier in the thread it looks like the pins 51 and 52 (voutr and voutl) on the chip are the line level outputs, a few minutes with a soldering iron should easily move the connection for the 1/8" jack from one to the other and avoid the simple onboard amp outputs 55 and 56 (hpr and hpl).

I wonder if there's a way to switch to line level output in software, I'd certainly prefer that to voiding my warranty.

Are those pins currently connected to anything?

wisp

12-06-2007, 11:40 AM

My personal experience is that the buitl-in speakers are not very good at all -- they would be fine for video conferencing, but suck for audio. What I was surprised by though is the headphone response -- bass is extremely limited (and I know these haedphones well, they reproduce bass fine) I would be vey surprised if these have anything approaching a "flat to 20Hz" response. Otherwise, quite listenable, just anemic in bass.

YMMV, all my subjective opinion. I have the equipment to measure the response, but doubt I will bother - would love an EQ though...

dblank

12-06-2007, 03:05 PM

YMMV, all my subjective opinion. I have the equipment to measure the response, but doubt I will bother - would love an EQ though...

There really should be a proper EQ!

For now, you could try xmms at least for audio, it has a software EQ.

dfn_doe

12-06-2007, 05:25 PM

I wonder if there's a way to switch to line level output in software, I'd certainly prefer that to voiding my warranty.

Are those pins currently connected to anything?

The block diagram doesn't show any switching circuitry between the line-level and the amplified pins, so if there were a way to do it in software it'd have to be specific to the n810 hardware external to the chip itself. As to current connectivity on those pins, I couldn't say as I'm waiting for my dev discount to be activated...

mdarnton

12-08-2007, 11:13 AM

There's a lot of not-too-good advice in this thread, mixed with good, in my opinion, relative to the quality of what comes out of the 810. The original poster needs to understand that he needs a system that fits HIS needs and HIS ears, not the theoretical prejudices of audiophiles and engineers. Lots of people find iPods satisfactory, which is why so many own them. Lots of audiophile types make iPods work for them under some circumstances, by various dodges. If, however, you run iTunes music through them, encoded at a very low rate, the result ain't too good. That is, garbage in, garbage out.

That said, my 810 doesn't sound horrible run into my good headphones, which cost twice what the 810 did (and aren't high-impedence, nor do they demand a lot of power), with good source files. Things could be better, but they could be a whole lot worse. I don't think the data specs of the thing are sub-CD quality--16/44.1--and probably the amp is about what you get in any mp3 player these days; that is, not audiophile, but adequate.

The real place to be finding out this stuff, if you want to know practical stuff about amps and headphones (rather than the specs of the 810) is at http://head-fi.org org
If you prefer to hang out at the other end, with the guys who think everything is inadequate garbage, check out http://www.head-case.org/
Your choice. :-)

bexley

12-13-2007, 01:00 PM

Any idea why the N810 isn't sending sound out via the headphone jack? I've just tried Vagalume (last.fm client) so far and it only plays from the speakers. WTF?

I'm probably going to sound like an idiot for some reason, but I shouldn't have to do anything to get sound from the headphone jack--or, even worse, I shouldn't have to listen through the speakers if it doesn't do headphone-out in some cases.

Edit: Okay, I could've checked easily before posting, but it seems like this is just something that Vagalume does. Why? No damned clue, but I'll take it to a Vagalume thread.

But on topic, my Grado SR-80's sounded great(o) powered by the N810--even for that crap that Nokia included on the tablet. This is a first-impression and nothing more, but I won't use the N810 for "serious" listening anyway and when I'm on the go surrounding noises will preclude really careful listening.

speculatrix

12-17-2007, 06:01 PM

IMHO, one of the biggest problem with consumer audio equipment is that the power supply cannot supply the peak power requirements of music when driving headphones at high levels, and as for transients there's insufficient energy storage in the power supply, and battery operated devices have insufficient voltage overhead to drive peaks cleanly.

Most cheap headphones are relatively insensitive, and can be quite high impedance, so need the volume cranked up to be useful making the problems worse. A good pair of sensitive headphones allows the volume to be kept down and thus give the audio amplifier and its power supply the best chance to provide a clean signal.

However, I've not done any analogue electronics for a while, and now it's all class D/PWM switching amps, I might be completely wrong :)

jdm

03-09-2008, 10:44 PM

Has anyone managed to connect a bithead or total bithead, yet?
(also posted on sister thread on N800 forum)
Speculation on the N800 forum is that it should be plug and play.
http://www.internettablettalk.com/forums/showthread.php?t=15452&highlight=bithead&page=4

hangster

03-10-2008, 04:13 AM

I've connected N810 headphone out to my C&C Box+ headphone amp which is connected to my Beyerdynamic DT770 Pro 80 Ohm. Sound quality improves drastically, and hiss is gone. very happy =). Note: volume on max is usually equivalent to a line out (on some players yes, some no).

edit: just tested with JBL Reference 410. Hiss reduced drastically as well, more punchy. I will try Crossroads MylarOne X3, JVC HA FX66 later on (sleepy).

An amp might help if you dislike the hiss. Not sure if all amps will do so though. For reference, I have a C&C Box+ headphone amp upgraded with an LTC6241HV op amp.

gutterboy

03-10-2008, 03:14 PM

Ok this thread is perfectly timed for what I am going through right now. I recently went from the Weston UM1 earphones (probably the best all around earphone for $100) to the fantastic Westone UM2 (pricey but worth it)
# Sensitivity: 119 dB/mW
# Frequency response: 20 Hz -18 kHz
# Impedance: 27 ohms
# Driver: Dual balanced armatures with a passive crossover

Anywho, I placed a bunch of FLAC files on my n810 and listened to a variety of albums the past week. Everything from Radiohead, Classical Music, Beatles, Primus , etc. Even with a lossless codec and audiophile grade earphones, the n810 always lacked low end and overall clarity of sound. I have done numerous comparisons between output from n810, ipod, ipod shuffle, and direct from pc. The ipod shuffle even sounds fuller than the n810. I am likely going to pick up a zune for my music needs since I can convert FLAC to WMA lossless easy enough and I hate apple, but that is a different thread all together.

So, I am devoid of any super technical data like most of you on this thread, but I do have some solid "ear time" with high quality earphones and the n810 and it doesn't seem like the ideal choice. Moreover, lossless audio libraries start piling on the gb's real quick and a larger hdd bases player would probably be a better choice.

PS- Anyone own a Zune 2 80gb and have some feedback? e.g. sound quality, usage, etc.

GeraldKo

03-10-2008, 03:34 PM

I don't know if this is responsive, but I'm sure impressed with OGG files on my tiny iAudio U3. (I'm using Shure E2c earphones, pretty high end but not the best.) The iAudio units also handle FLAC. The UI is rudimentary but everyone seems to regard their sound very highly.

bunanson

03-12-2008, 09:18 AM

scan thru the 1st 40 posts and get interested. The last thing I read was Shure e2c is the recommended one. I looked it up, it costs $125 from newegg.com! I want something better but do not want to pay that price (its like half of a N800!). Is anything like $50 price range and "sounded" better than the Nokia one? Just for you to help me, this is what I meant better. I compared the Nokia ear plug with the ipod, (just yanked it out from my kid for a test :)), the ipod sound has much more frequency and crispier. Please stop arguing that the ipod is a piece of $hit, the ipod ear plug sounded good to me. Can someone recommend something in that level? So, any suggestions, please? TIA,

Edit: Cant help but stir it up more....I routinely switched the original packaged ear plug with the ipod ear plugs just to test things out. I found the ipod ear plug has much better frequency response and crispier than most comealong packaged ear plugs. This included Dell Axim, eeePC, most mp3 player I played with, some HP small footprint notebooks, the Nokias tablets (770, N800 and N810). I supposed the average consumers like the ipod because they packaged the ipod with a slightly above average ear plug. So, even the ipod is a piece of $hit, because of the earplugs it 'sounded' a lot better. Has anybody tested the ipod earplugs and would like to shed some light on this?

bun