Matching USB Phono Preamp to Audacity (sampling rate & bit depth)

the mix tape forum
NewOldVinyl
senior member
senior member
Posts: 368
Joined: 22 Nov 2006 19:42
Location: Oregon

Matching USB Phono Preamp to Audacity (sampling rate & bit depth)

Post by NewOldVinyl » 27 Mar 2019 18:02

I got a Music Hall pa2.2 phono preamp which has a “premium” analog to digital converter and USB interface. It appears to always operate at 24/96.

https://musichallaudio.com/product/pa2- ... amplifier/

I’m using Audacity to rip vinyl with it. Audacity has no trouble connecting to the USB preamp and everything sounds good.

Of course Audacity supports many different sampling rates and 16, 24, and 32-float.

Here’s what I don’t understand: If I configure Audacity to use 24/96, same as the pa2.2, is that the optimal choice for the master recording? Or does Audacity resample or otherwise manipulate the incoming data stream, regardless of what bit depth and sampling rate it’s set for? I don’t see how to tell Audacity to “Use the data exactly as the USB device is providing it, without any manipulation”.

What if I configure Audacity to use 16/44.1? Does it tell the USB device to use that as well? Or does Audacity convert the incoming 24/96 to 16/44.1?

My question isn’t about the merits (or lack of) of using higher-than-CD bit depth or sampling rates. My question is about getting Audacity to accept what the pa2.2 sends it without changing it. I can later export it from Audacity however I want. But I want the “master recording” to be exactly as the pa2.2 provides it.

When I read up on this on Audacity forums, the threads always devolve into debates about oversampling etc. I can’t find anything that directly addresses how to perfectly match Audacity to the USB device.

Anyone know how this works?

zlartibartfast
senior member
senior member
United States of America
Posts: 304
Joined: 20 Feb 2019 02:11
Location: 45th parallel

Re: Matching USB Phono Preamp to Audacity (sampling rate & bit depth)

Post by zlartibartfast » 27 Mar 2019 18:28

My experience is with Sound Forge 7, Sonar 4, and Logic X (not really using Sonar any longer).
In each case, the best approach is to set the software to match the hardware. Sound Forge and Sonar are for Windows only; Logic is for Mac only.

Of those 3, only Logic can actually change the hardware setting for resolution, and then only if using the built-in hardware of the Mac. I expect the same of Audacity - it will not be able to set the hardware sample rate and bit depth. So best to set your hardware first.

Now, in the case of hardware that has only one setting, you would want to set the software to match that. If I were to set my hardware to 16/44.1 and try to run Sound Forge with 24/96, Sound Forge would tell me there is no compatible interface available, which would be true. I would expect the same from Audacity.

So - you want to configure Audacity to match your interface, at least in terms of sample rate. This is imperative. If the clock rate (sample rate) doesn't match you get no signal path. You don't necessarily have to match the bit depth - your interface can provide 24 bits / word and your software can simply write 16 bits, or it can write 32 bits (in memory - this is 32bit float) then save as 24 bits. As long as you are saving the file with 24 bit depth you are getting the best you can achieve.

I think you are doing it right and you don't need to be concerned about changing your setup.

AFAIK Audacity does all of it's operations in 32 bit mode (while in memory) and only when the file is written to disk does the bit depth get truncated (probably dithered). This is true for Logic.

JoeE SP9
vinyl addict
vinyl addict
United States of America
Posts: 5029
Joined: 23 Feb 2009 19:20
Location: Phildelphia, Pennsylvania

Re: Matching USB Phono Preamp to Audacity (sampling rate & bit depth)

Post by JoeE SP9 » 29 Mar 2019 17:10

Good answer!

NewOldVinyl
senior member
senior member
Posts: 368
Joined: 22 Nov 2006 19:42
Location: Oregon

Re: Matching USB Phono Preamp to Audacity (sampling rate & bit depth)

Post by NewOldVinyl » 29 Mar 2019 17:23

I contacted Music Hall to see if they could shed any light on this. I got a very terse reply from Roy Hall stating that they don’t support Audacity and I should visit an Audacity forum.

After thanking him for going to such lengths to assist me as a Music Hall customer, he did volunteer that the Music Hall pa2.2 can be configured via software to use a higher sample rate. But no info as to how.

zlartibartfast
senior member
senior member
United States of America
Posts: 304
Joined: 20 Feb 2019 02:11
Location: 45th parallel

Re: Matching USB Phono Preamp to Audacity (sampling rate & bit depth)

Post by zlartibartfast » 29 Mar 2019 18:13

Well I learned something new that may be of help. Things have hanged a bit in the world of USB since I was supporting PC's in the previous century.

Some of the new hardware that uses the USB Class 2 driver standard will allow the software to change it's sample rate.

My new Pro-Ject Phonobox DS2 USB can run at sample rates other than what the front panel buttons allow. All I have to do is open Sound Forge (this is running under XP/SP3, which is the oldest OS supported) and select a sample rate in the Options menu (it could be a different menu in Audacity; I'm not sure) and BAM! the Phonobox goes to that sample rate. It will stay on that setting until you make a change either in software or on the front panel.

I would not be surprised if the Music Hall box will do the same thing. I took a look at the user's guide, which doesn't cover this topic, but it looks as though MH box is using the same class 2 driver standard (I say this because it doesn't support Vista, which is also true for the Pro-Ject box). So- try it out! The worst thing would be that Audacity would lose connection to the unit, which might force you to restart it.

Let me add this - the MH box is optimized for 24/96, which (by no coincidence) has become the de-facto "standard" resolution for digital audio today. I suggest just stick with that for your initial recordings, and if you need to lower the resolution (say maybe you want to burn a CD, or save as MP3), just do that in Audacity.

NewOldVinyl
senior member
senior member
Posts: 368
Joined: 22 Nov 2006 19:42
Location: Oregon

Re: Matching USB Phono Preamp to Audacity (sampling rate & bit depth)

Post by NewOldVinyl » 29 Mar 2019 21:34

Interesting stuff.

I've been playing around with this some more today. Moved everything back to Windows 10. Windows and Audacity correctly identify the USB audio source as a "Music Hall PA2.2". In the advanced sound properties for the device, I can set the default sample rate and bit depth to "2 channel, 24 bit, 96000 Hz (Studio Quality)". I also checked the box "Allow applications to take exclusive control of this device".

After doing that, in Audacity I can now change the Audio Host from the default of MME, to Windows WASAPI. Previously I couldn't select WASAPI in Audacity, got an error about a sample rate mismatch. I'm pretty confident now that Audacity is grabbing the data exactly as the PA2.2 sends it, without any resampling etc. So from that I can then export it in any format I want.

Another observation: After changing Audacity to WASAPI mode, the no-signal noise floor from the USB input device as displayed by Audacity was significantly reduced. If Audacity's dB scale is to be believed, the background noise dropped at least 5dB, down to the -70s range. That would be about the s/n ratio of the MM phono section of the PA2.2 (connected to an Ortofon 2M Blue).

zlartibartfast
senior member
senior member
United States of America
Posts: 304
Joined: 20 Feb 2019 02:11
Location: 45th parallel

Re: Matching USB Phono Preamp to Audacity (sampling rate & bit depth)

Post by zlartibartfast » 29 Mar 2019 22:54

Yes I believe all of that - no doubt the WASAPI mode is better then MME - MME was made for PC gaming back in 1998!

Honestly I didn't know about WASAPI (Waaass Uuuuup Ee!) I thought you'd be offered ASIO but that's not important.

You got it figured out, despite the "No help Whatsover" Desk!

NewOldVinyl
senior member
senior member
Posts: 368
Joined: 22 Nov 2006 19:42
Location: Oregon

Re: Matching USB Phono Preamp to Audacity (sampling rate & bit depth)

Post by NewOldVinyl » 29 Mar 2019 23:17

I had no idea what WASAPI was until today. ;)

According to Audacity, ASIO capability cannot be built-in to Audacity for public distribution due to ASIO being proprietary. However, individuals may compile Audacity from source code, with the ASIO functionality incorporated, but only for their own private use. You can’t distribute the compiled version containing ASIO.

https://manual.audacityteam.org/man/asi ... rface.html

zlartibartfast
senior member
senior member
United States of America
Posts: 304
Joined: 20 Feb 2019 02:11
Location: 45th parallel

Re: Matching USB Phono Preamp to Audacity (sampling rate & bit depth)

Post by zlartibartfast » 30 Mar 2019 00:05

Well if it comes down to that, just use Linux
recompile indeed....
I should have reckoned ASIO was not open source, 'cause Apple uses it!

rkay5
senior member
senior member
United States of America
Posts: 817
Joined: 17 Nov 2003 22:05
Location: California,USA

Re: Matching USB Phono Preamp to Audacity (sampling rate & bit depth)

Post by rkay5 » 03 Apr 2019 06:31

ASIO has nothing to do with Apple.ASIO is only for windows os.I wouldn't use Audacity for recording with Windows as you will not get true 24bit recordings unless you can get to work with ASIO.Also Steinberg wrote the ASIO software.

NewOldVinyl
senior member
senior member
Posts: 368
Joined: 22 Nov 2006 19:42
Location: Oregon

Re: Matching USB Phono Preamp to Audacity (sampling rate & bit depth)

Post by NewOldVinyl » 04 Apr 2019 02:11

rkay5 wrote:
03 Apr 2019 06:31
ASIO has nothing to do with Apple.ASIO is only for windows os.I wouldn't use Audacity for recording with Windows as you will not get true 24bit recordings unless you can get to work with ASIO.Also Steinberg wrote the ASIO software.
Audacity is able to do 24-bit with WASAPI. I believe it stores 24-bit samples as 32-bit, padded with zeroes. Isn’t the end result is the same?

zlartibartfast
senior member
senior member
United States of America
Posts: 304
Joined: 20 Feb 2019 02:11
Location: 45th parallel

Re: Matching USB Phono Preamp to Audacity (sampling rate & bit depth)

Post by zlartibartfast » 04 Apr 2019 19:39

rkay5 wrote:
03 Apr 2019 06:31
ASIO has nothing to do with Apple.ASIO is only for windows os.I wouldn't use Audacity for recording with Windows as you will not get true 24bit recordings unless you can get to work with ASIO.Also Steinberg wrote the ASIO software.
Yes you're right I sit corrected - Apple is using Core Audio now. It's just Windows that needs additional support.
NewOldVinyl wrote:
04 Apr 2019 02:11
Audacity is able to do 24-bit with WASAPI. I believe it stores 24-bit samples as 32-bit, padded with zeroes. Isn’t the end result is the same?
Yes you will have a 24 bit path from the ADC to the file, so it should sound the same. Apparently WASAPI doesn't perform as well as ASIO in multitrack DAW setups but for stereo it's fine

https://xylio.com/wiki/index.php?title= ... PI_or_ASIO

balky
senior member
senior member
Belgium
Posts: 446
Joined: 28 Jun 2016 14:43
Location: Sint Niklaas

Re: Matching USB Phono Preamp to Audacity (sampling rate & bit depth)

Post by balky » 06 Apr 2019 06:45

rkay5 wrote:
03 Apr 2019 06:31
ASIO has nothing to do with Apple.ASIO is only for windows os.I wouldn't use Audacity for recording with Windows as you will not get true 24bit recordings unless you can get to work with ASIO.Also Steinberg wrote the ASIO software.
This is all there is to say... :D

Audacity on Windows won't deliver a true 24-bit recording...

There are a few $50 (or less) ASIO capable recording software out there that will get you what you want.

rkay5
senior member
senior member
United States of America
Posts: 817
Joined: 17 Nov 2003 22:05
Location: California,USA

Re: Matching USB Phono Preamp to Audacity (sampling rate & bit depth)

Post by rkay5 » 02 May 2019 04:54

If you are using Windows it is best to use recording software like Vinyl Studio that ASIO so you can record in true 24bit

Sunwire
long player
long player
United States of America
Posts: 2038
Joined: 07 Oct 2004 21:54
Location: New York

Re: Matching USB Phono Preamp to Audacity (sampling rate & bit depth)

Post by Sunwire » 02 May 2019 05:19

You can compile your own build of Audacity incorporating ASIO support, but you can't distribute it.
https://manual.audacityteam.org/man/asi ... rface.html

Post Reply