USB digital input

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Vince
Posts: 17
Joined: Fri Dec 07, 2007 5:02 pm

USB digital input

Post by Vince »

I've just switched to Windows 7 on a new PC. I own a phono pre-amp with both analogue line and digital USB output.
When I plug the pre-amp into the PC it installs as a "Microphone (USB Audio Codec)". Clicking Record starts at an absurdly high level, almost as if line input was plugged into a mic socket. So the Input Device volume has to be reduced to about 20% to get a sensible recording level.
With my previous PC (Windows XP), Goldwave recognized the USB device as a digital input and (I assume) took the bit stream straight into recording; there was no input volume level available, as I would expect.
But now it looks as if the USB input is being put through the PC sound card, converted to analogue and delivered to Goldwave like that.
If this is so it makes a mockery of trying to use a USB digital source. Should I be finding a different codec somewhere?
I'd appreciate any comments / ideas about this.

Many thanks

DougDbug
Posts: 2062
Joined: Wed Feb 16, 2005 3:33 pm
Location: Silicon Valley

Re: USB digital input

Post by DougDbug »

I'm pretty sure the audio isn't going through your soundcard/soundchip... The only that should happen is if you are recording "What-U-Hear".

And, this is a driver issue, not a CODEC issue. (CODECs are for encoding/compressing and decoding/decompressing files or streamed-compressed audio/video). Does the manufacturer of the USB device offer Win7 drivers? Sometimes, when you upgrade your operating system, you have to upgrade your hardware too. (I just bought a laptop with Win7, and I have to get a new printer because there are no Win7 drivers for my old printer.)

But, if reducing the volume to 20% works and you're not getting distortion, that doesn't seem like a big problem.

Vince
Posts: 17
Joined: Fri Dec 07, 2007 5:02 pm

Re: USB digital input

Post by Vince »

Thanks for the reply. I happen (temporarily) to have a dual boot set up with XP and W7 on my old PC and want to avoid that on the new one, and the OS's work differently on the one machine.

1. XP doesn't give any sort of message about installing hardware when the pre-amp is plugged in. Goldwave recording properties (via F11) just show the device as USB audio codec with no volume or other options. So I assume the bit stream is just going straight through.

2. W7 installs the pre-amp as I described, with all the usual properties for microphone input including volume. This is made me think the sound card was being used as I was under the impression that a digital stream from device to Goldwave cannot be altered like an analogue signal.

Regarding your printer comment, I have a photo scanner for which there is no W7 64-bit driver so I had to plump for 32-bit.
I'm afraid W7 is proving a retrograde step in many ways. If I hadn't bought the retail version with 32 and 64 bit options I'd probably go back to XP.
I still might........

DewDude420
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Re: USB digital input

Post by DewDude420 »

those "usual properties" you're talking about on the headset USB....those are totally normal. Even the most basic sound chip these days has basic processing and mixing, which is basically volume control....is in just about EVERYTHING. The reason the levels are so dramatically different is because Windows7 does sound differently. I can't explain a volume control not being there in XP....it's not normal and probably is there...just in a location you can't see it. Windows7 moved it to a move visible location.

BTW, from my understanding...when you have a Windows 7 license...it's valid for both 32 and 64-bit versions...if you thnink you bought a special license, you're wrong. You can SOMETIMES get SOME 32-bit drivers to work in 64-bit. I had to fudge my scanner drivers but they worked.

DougDbug
Posts: 2062
Joined: Wed Feb 16, 2005 3:33 pm
Location: Silicon Valley

Re: USB digital input

Post by DougDbug »

This is made me think the sound card was being used as I was under the impression that a digital stream from device to Goldwave cannot be altered like an analogue signal.
GoldWave won't alter the sound, but I really don't know what the drivers are doing... Somewhere I read that the recording volume was "always" adjusted in the digital domain. If this is true, it means that most of the time you're not getting all 16 bits of resolution. And, if the analog-to-digital converter is clipping (distorting), it means that reducing the recording volume (in software) will not prevent the distortion!

When you play-back audio, volume control (and mixing) is done digitally, and typically it's re-sampled during playback.

Vince
Posts: 17
Joined: Fri Dec 07, 2007 5:02 pm

Re: USB digital input

Post by Vince »

I contacted ARTcessories who make the USB Phono pre-amp I use. I received this reply:
------------------------------------
"We have heard complaints (and a web search shows this is across the board, not just ART models) with noise / too much gain when USB audio devices are used with Windows7. Here are some things you need to change some of the "Control Panel > Sound Settings" to get Windows 7 to work with any USB audio product.

1) The default setting for the input is 1 channel / 16bit/44.1K. The properties need to changed to: 2 channel/16bit/44.1K.
2)Windows also sets the Mic input gain high by default, so this needs to be reset.
3).Use the Configure button in the Sound window to access the Speech Recognition section and selected Set up Microphone:
Select Other under the input type.
4). Run a signal into the USB device and run the Windows 7 Speech Level Program.

After this, the Mic input level gain will be corrected and you will be able to use the USB Audio CODEC without a problem."
--------------------------------
I went through this and seems to solve the problem. Using the Speech Recognition section automatically sets the recording volume; to my surprise it finished up at 3.
A very brief recording seems OK, but as the Windows audio processing of the USB signal is unclear I've no idea if the input quality is dimished. In due course I run a comparison with recording from a turntable on a Marantz CD recorder via a Denon amp and from the USB pre-amp direct to PC.

DewDude420
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Re: USB digital input

Post by DewDude420 »

ust as I suspected; from the steps you described it was just the default volume settings for the card under Windows 7 was less than optimal (too much gain).
very brief recording seems OK, but as the Windows audio processing of the USB signal is unclear I've no idea if the input quality is dimished.
Windows 7's internal mixer shouldn't be touching the audio stream at all since it's able to run everything at native resolutions...whatever the card says it supports is what it does. Volume mixing is done in hardware on the card...so no, you shouldn't be losing any quality.

cdeamaze
Posts: 87
Joined: Thu Oct 05, 2006 3:19 pm

Re: USB digital input

Post by cdeamaze »

DougDbug wrote:Sometimes, when you upgrade your operating system, you have to upgrade your hardware too. (I just bought a laptop with Win7, and I have to get a new printer because there are no Win7 drivers for my old printer.)
That's just one way to do it. You don't have to buy a new hardware just because you upgrade your operating system if you know the trick. Instead of buying a new printer, you can also install a dual(or even triple) boot operating system with Windows 7 preinstalled and install a second operating system either Vista or XP. The beauty of this approach is that you got to keep your old printer and will not cost you a dime (assume you still have Vista or XP somewhere and printer driver for either one is available) .

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