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Brief Odac impressions - Page 2

post #16 of 1962
Thread Starter 
Quote:
Originally Posted by maverickronin View Post

It's set and forget unless you actually have stuff above 44.1 since it won't resample stuff at the SR you set the shared mode to.  If you have a mix of 44.1 and 96 (the USB chip won't do 88.2) then you can just let foobar/WASAPI take care of the SR.  If you've got stuff at 88.2 then you'll need a good resampler like SoX but something like 99.9% of digital music is in 16/44 so it shouldn't be that big of a deal to most people.

 

Also disabling the volume control would be a waste since the whole point of a 24 bit DAC chip was to allow headroom for digital volume control.  The Win7 SRC does still suck but the 32 bit FP volume doesn't hurt anything.

 

The sample rate conversion is not the issue, it's the bit depth. Windows defaults to 16 bit, foobar defaults to 24 bit, so it will resample from  24/44.1 to 16/44.1 and it go's though the sucky windows SRC at that point. It's audible.

post #17 of 1962
Quote:
Originally Posted by MikeW View Post

 

The sample rate conversion is not the issue, it's the bit depth. Windows defaults to 16 bit, foobar defaults to 24 bit, so it will resample from  24/44.1 to 16/44.1 and it go's though the sucky windows SRC at that point. It's audible.

 

Q: My E10 is 44/16 on Windows shared mode because of your results. Should that be the same for the ODAC with Pandora, Spotify, MOG?...In the exclusive mode... should the foobar WASAPI be 16 or 24 bits resolution to play files some of which are FLAC and 96/24 WMA?

 

A: If possible, just leave the ODAC at 24 bits even playing 16 bit material.

 

He said that online if it helps.


Edited by hamburgerladdy - 5/30/12 at 5:26pm
post #18 of 1962
Thread Starter 

you need to have the program you play music with aligned with the windows setting. If you use Foobar, then windows should be set the same as foobar. if you use something else, then it should bet set the same, this is if you have a very resolving setup, and are trying to achieve top sound quality, if it's just youtube video's who cares.

 

For example, i use foobar for all my quality listening, so i want it to be the same as windows mode, they are both set to 24/44.1

even though foobar plays back 16-bit files, I leave it set to 24 bit, as foobar just pad's with 000's. It's the windows resampler we are trying to avoid.

 

if you set windows to 24/44.1 and then use a program to output 16 bit audio, again we will possibly see windows resampling things. Keep them aligned for critical listening.

post #19 of 1962
Quote:
Originally Posted by MikeW View Post

The sample rate conversion is not the issue, it's the bit depth. Windows defaults to 16 bit, foobar defaults to 24 bit, so it will resample from  24/44.1 to 16/44.1 and it go's though the sucky windows SRC at that point. It's audible.

 

It's not SRC if the SR is the same...

post #20 of 1962
Thread Starter 

i guess i need to spell it out for you.

 

Foobar spits out 24 bit, windows converts it to 16 bit. so no, it's not sample rate conversion, it's some kind of bit-depth conversion, the point is the same. windows is working it's nasty voodoo. enough to be audible.


Edited by MikeW - 5/30/12 at 6:27pm
post #21 of 1962

I just ordered an ODAC last night.  MikeW, when you say I need to set Windows to use 24-bit, that is set in the ODAC properties in device manager?  Thanks.

post #22 of 1962
Quote:
Originally Posted by MikeW View Post

i guess i need to spell it out for you.

 

Foobar spits out 24 bit, windows converts it to 16 bit. so no, it's not sample rate conversion, it's some kind of bit-depth conversion, the point is the same. windows is working it's nasty voodoo. enough to be audible.

 

By padding it with zeros...

post #23 of 1962
Quote:
Originally Posted by maverickronin View Post

Quote: Originally Posted by MikeW  i guess i need to spell it out for you.   Foobar spits out 24 bit, windows converts it to 16 bit. so no, it's not sample rate conversion, it's some kind of bit-depth conversion, the point is the same. windows is working it's nasty voodoo. enough to be audible.   By padding it with zeros...

No by using a lossy algorithm to drop bits. 24(foobar)->16(windows+ final output)
Ie make sure foobar and windows are set to 24bit.

Sent from my HTC HD2 using Tapatalk 2
Edited by WiR3D - 5/31/12 at 12:09am
post #24 of 1962

Isn't the WASAPI option in foobar just WASAPI exclusive mode?  It lets you set the bit depth because it's bypassing all OS audio processing modules.  Note that the bit depth/sample rate option in the Control Panel is for shared mode.

 

btw 24 bit -> 16 bit is truncating (with or without dithering...or is it rounding?), not zero-padding.

post #25 of 1962
Quote:
Originally Posted by mikeaj View Post

Isn't the WASAPI option in foobar just WASAPI exclusive mode?  It lets you set the bit depth because it's bypassing all OS audio processing modules.  Note that the bit depth/sample rate option in the Control Panel is for shared mode.

 

 

Yes, that is correct. When I use WASAPI in foobar with the E10 and then open chrome and play a youtube video my laptop speakers play the audio.

 

The exclusive mode is independent of the shared mode because of this bypass and the computer defaults to the Conexant onboard audio. 

post #26 of 1962

Just ordered an O2+ODAC combo from JDS, looking forward to it. 

post #27 of 1962

Anyone know where I can get some ridiculously tall isolation cones for these two (got standalone units) on the cheap?  (Just for kicks)

post #28 of 1962
Quote:
Originally Posted by WiR3D View Post

No by using a lossy algorithm to drop bits. 24(foobar)->16(windows+ final output)
Ie make sure foobar and windows are set to 24bit.
Sent from my HTC HD2 using Tapatalk 2

 

Wait.  That's what he's talking about?  Playing from foobar and outputting 24 bit from foobar when shared mode is set at 16?

 

Ok, that's not padding but it still doesn't matter what Win7 is set to because you can't even set the output bit depth with the DS output which goes through the mixer.  AFIK you can only set it through foobar with WASAPI output (ASIO is set by the driver, IDK about KS) and foobar uses WASAPI exclusive which will bypass the mixer and sets the device to whatever sample rate your file is and whatever bit depth you set in foobar.

 

The bottom line is that if you use WASAPI exclusive mode like foobar's WASAPI plug in the music will never go though the windows mixer so it doesn't matter what the other settings are.  That's probably why I misunderstood what MikeW was saying.

 

Lets talk a little more about bit depth and the windows mixer while we're at it.  The Win7 runs internally at 32 bit FP.  A program can stream data to the mixer at any any bit depth up to that and any SR up to (I think) 192khz.  It then mixes and resamples the streams as necessary to output the bit depth and SR specified for shared mode.  Resampling can be messy and introduce audible artifacts.  The windows resampling algorithms are especially suspect because they have to be very CPU efficient.

 

Distortion is very easy to hear in pure tones and if I set my sine wave generator program to the wrong sample rate the mixer's SRC introduces clearly audible distortion.  I can't say that I've noticed it from other sounds that go though the mixer but since I do my "serious" listening though foobar/WASAPI that mostly just leaves games, youtube, and system sounds which should mostly match up with my usual 44.1khz shared mode SR.  In any case if you know that the distortion exists it's best avoided.

 

On to bit depth.  The mixer runs at 32 bit FP for precision in mixing and volume control.  In fact if you use the DS output foobar will output a 32bit FP stream.  If you're not using the volume control or any DSPs it will pad the bit stream with zeros.  Anything sent to the mixer at less than 32 bits will be padded as well.  In fact if there are no streams to mix, the windows volume is at 100%, and the shared mode SR and bit depth match what you're playing, then windows will give you bit perfect playback without any special output mode like WASAPI or something.  It will pad the word length with zeros, do no processing, and then truncate the extra zeros before sending the signal off to the device.

 

If you send a 24 bit signal to the mixer when shared mode is set to 16 bit it will just chop off those last 8 bits before sending it on to the device but that's not really all that bad.  Bit depth only determines the dynamic range and noise floor.  Nothing uses all of 16 bit's 96dB of dynamic range and you need to listen very loudly in a very quiet place to expose the signal's noise floor.  Basically, 99% of the time truncating 24 bits to 16 doesn't change anything because you couldn't hear the 16 bit noise floor to begin with.  At least if you're not using a digital volume control.  That's why the ODAC is 24 bit device.  It gives you headroom to lower the volume in either windows or your media player without raising the noise floor to an audible level.

 

If you don't have any hi-rez recordings then you can just set the ODAC's shared mode to 24/44.1 and not worry, even if you like the idea of bit perfect, because if you don't use the volume control it will be bit perfect whenever two things aren't playing once.  If you're not a purist, the 24 bit word length lets you use the volume control without raising the noise floor to audible levels.  If you want to use WASAPI exclusive mode to block system sounds and what not then set it to 24 bit as well.  WASAPI will error out if you try to play a sample rate (or bit depth) the device doesn't support (like 88.2 for the ODAC) since there are no provisions for SRC.  If you have such recordings you'll need to set up some kind of conditional resampler in your player or just make a separate copy and resample them.

 

That last part will be a pain for some people and probably disqualify the ODAC from their consideration but using a different USB chip that supported 88.2 would have raised the price for everyone even though 88.2 is a very uncommon format in the big picture.

post #29 of 1962

Can we get some more impressions of this thing? Also, a picture of the unit since all I can find on the web are renders. Finally, does this allow for system-wide volume control on OS X?

 

I'm also interested in a comparison between the ODAC and the HRT MSII, being at the same price range I'm considering getting one or the other.


Edited by Kayk - 6/2/12 at 9:24am
post #30 of 1962
Quote:
Originally Posted by Kayk View Post

Can we get some more impressions of this thing? Also, a picture of the unit since all I can find on the web are renders. Finally, does this allow for system-wide volume control on OS X?

I can't offer much in the way of impressions because my only other DAC is a boutique unit, a HotAudio DAC-Wow, that most people have never heard so comparisons are moot. And I haven't done extensive listening either. But the detail is very good.

The designer has plenty of recent images on his blog. Are you looking for something particular? If so, I'll try to help.

I'm surprised, but yes, it allows for system-wide volume control. With my SP/DIF HotAudio DAC, it was gone and I had to control volume via the amp or the individual apps.
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