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bexley is offline bexley
2007-12-01 , 06:20
Posts: 160 | Thanked: 7 times | Joined on Nov 2007
#11
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.
Last edited by bexley; 2007-12-01 at 06:33.
 
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TenSpeed is offline TenSpeed
2007-12-01 , 15:47
Posts: 139 | Thanked: 73 times | Joined on Oct 2007 @ Winnipeg, Canada
#12
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?
 

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Capt'n Corrupt is offline Capt'n Corrupt
2007-12-01 , 19:27
Posts: 3,524 | Thanked: 2,958 times | Joined on Oct 2007 @ Delta Quadrant
#13
Originally Posted by bexley View Post
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.


Originally Posted by bexley View Post
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.

Originally Posted by bexley View Post
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!

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Capt'n Corrupt is offline Capt'n Corrupt
2007-12-01 , 19:46
Posts: 3,524 | Thanked: 2,958 times | Joined on Oct 2007 @ Delta Quadrant
#14
Originally Posted by TenSpeed View Post
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?


Originally Posted by TenSpeed View Post
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. This is a system that is similar to the Sonos based home server, only with far more flexibility (and configuration, I might add ). 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!

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bexley is offline bexley
2007-12-01 , 20:27
Posts: 160 | Thanked: 7 times | Joined on Nov 2007
#15
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.
Last edited by bexley; 2007-12-01 at 20:33.
 
bexley is offline bexley
2007-12-01 , 20:39
Posts: 160 | Thanked: 7 times | Joined on Nov 2007
#16
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.
Last edited by bexley; 2007-12-01 at 20:46.
 
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TenSpeed is offline TenSpeed
2007-12-01 , 21:45
Posts: 139 | Thanked: 73 times | Joined on Oct 2007 @ Winnipeg, Canada
#17
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 is offline dsmudger
2007-12-02 , 18:37
Posts: 108 | Thanked: 6 times | Joined on Nov 2005 @ Central London
#18
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?
 
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Capt'n Corrupt is offline Capt'n Corrupt
2007-12-02 , 20:16
Posts: 3,524 | Thanked: 2,958 times | Joined on Oct 2007 @ Delta Quadrant
#19
Originally Posted by bexley View Post
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.

[QUOTE=bexley;103211]
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?

Originally Posted by bexley View Post
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 .

Originally Posted by bexley View Post
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!

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Capt'n Corrupt is offline Capt'n Corrupt
2007-12-02 , 20:28
Posts: 3,524 | Thanked: 2,958 times | Joined on Oct 2007 @ Delta Quadrant
#20
Originally Posted by TenSpeed View Post
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.


Originally Posted by TenSpeed View Post
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.


}:^)~
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