Capt'n Corrupt | # 1 | 2007-11-30, 12:58 | Report

Does anyone know of the acoustic range of the N810? What are the bounding ranges that can be reliably output via the stereo headphone port using raw wave data? Does it support the theoretical 44.1KHz sampling rate "standard"? What are the lowest frequencies it can effectively output?

Any insight would be swimming.


}:^)~
YARR!

Capt'n Corrupt

kilmar | # 2 | 2007-11-30, 14:28 | Report

Uh...it sounds real good? Sorry, that's as much as I know.

Capt'n Corrupt | # 3 | 2007-11-30, 17:41 | Report

Haha. Thanks... It's a start!

I have a couple of applications that would require High Fidelity. One of which is hooking the unit up to my in-home stereo system and getting crystal quality, low distortion sound.

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.

If this is too complicated a procedure, perhaps we can start with the sound chipset. Does anyone have any insight on the N810 sound system?


}:^)~
YARR!

Capt'n Corrupt

TenSpeed | # 4 | 2007-12-01, 02:23 | Report

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 | # 5 | 2007-12-01, 04:17 | Report

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.

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.

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 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.

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 . 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 | # 6 | 2007-12-01, 04:30 | Report

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.

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Last edited by bexley; 2007-12-01 at 04:40.

bexley | # 7 | 2007-12-01, 04:44 | Report

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 | # 8 | 2007-12-01, 05:14 | Report

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.

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

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Last edited by Capt'n Corrupt; 2007-12-01 at 05:17.

torx | # 9 | 2007-12-01, 05:28 | Report

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 | # 10 | 2007-12-01, 06:14 | Report

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.