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Digital recording on the cheap

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Anonymous
December 20, 2004 11:46:20 AM

Archived from groups: rec.audio.pro (More info?)

We have an Allen & Heath 32-channel board and other good analog
equipment in our church. We wanted to capture some audio in digital
format for post processing and CD production.

Being short on funds (as always) a multi-track digital recorder was not
an option, so I bought a Sound Blaster Live! USB external for $49.
This, connected to a laptop is an easy and inexpensive solution.

The problem: The SB works fine when connected to a portable CD player
or home stereo. When connected to the Allen & Heath (via Aux outputs)
it is full of computer-generated noise. The noise level runs about -45
dB and varies in frequency and level based on what is going on in the
laptop (e.g. disk access, loading applications, even moving the mouse
around are clearly audible in the noise).

I don't understand how the computer is coupling into the analog signal.
It is converted from A to D in the external SB box -- the only
computer connection is the USB cable. This noise does not feed back
into the board. Disconnecting the SB box from the console at the AUX
outputs silences the noise, so I conclude it is not RF broadcast, but
something about the physical connection.

I even purchased another similar USB device ("Instant Music" by ADS
Tech). Same problem.

I can over-drive the AUX outputs and get a better S/N ratio, but it is
still way too much noise (and if I push too hard I drive the AUX
outputs to analog distortion).

Does anyone have experience with using one of these computer-based
digital capture USB devices with a mixer?

Thanks,
-Mark
Anonymous
December 20, 2004 1:39:06 PM

Archived from groups: rec.audio.pro (More info?)

I ran it that way for an event last night. The S/N is much better (but
the noise is still audible). The real problem is knowing when the
analog is clipping -- that does not show up on the (digital) VU meters.
I listened to the headphone output of SB box but because of all the
ambiant sound in the room could not hear it clearly. This morning I
find the recording is (analog) clipped and distored in several of the
loud passages. Ugh.

Sounds like you did not find a solution to the root of this problem...

I assume if we bought a Tascam US-122 (about $200, 2 channel) or the
US-428 ($300, 4 channel) we would not have this problem? E.g. I
assume a Tascam problem would work well in a professional audio
environment. Any experience with those?
Anonymous
December 20, 2004 3:00:30 PM

Archived from groups: rec.audio.pro (More info?)

<mcmillan@engineous.com> wrote in message
news:1103561179.969927.226230@f14g2000cwb.googlegroups.com
> We have an Allen & Heath 32-channel board and other good analog
> equipment in our church. We wanted to capture some audio in digital
> format for post processing and CD production.
>
> Being short on funds (as always) a multi-track digital recorder was
> not an option, so I bought a Sound Blaster Live! USB external for $49.
> This, connected to a laptop is an easy and inexpensive solution.
>
> The problem: The SB works fine when connected to a portable CD player
> or home stereo. When connected to the Allen & Heath (via Aux outputs)
> it is full of computer-generated noise. The noise level runs about
> -45 dB and varies in frequency and level based on what is going on in
> the laptop (e.g. disk access, loading applications, even moving the
> mouse around are clearly audible in the noise).

Been there, done that.

Turn the input gain on the Sound Blaster Live! USB as far down as you can,
and still have a signal.

Then increase the signal voltage from the console to just below clipping.

Let me know how this works.
Related resources
Anonymous
December 20, 2004 5:26:18 PM

Archived from groups: rec.audio.pro (More info?)

Sounds like you have a classic earth look. The noise is being injected
into the desk or the A to D Converter via the earth connection or mains
power. The suggestion about running the computer fromm battery may
help, setting the gain to max on the desk improved the signal to noise
ratio. I suggest you check the desk output and make sure you are not
mixing a balanceds output with an unbaliances input, in which case a
modificed cable may help.

I suggest you play around with lifting the earth connections, and see
if you can locate the noise path.

Peter.


mcmillan@engineous.com wrote:
> We have an Allen & Heath 32-channel board and other good analog
> equipment in our church. We wanted to capture some audio in digital
> format for post processing and CD production.
>
> Being short on funds (as always) a multi-track digital recorder was
not
> an option, so I bought a Sound Blaster Live! USB external for $49.
> This, connected to a laptop is an easy and inexpensive solution.
>
> The problem: The SB works fine when connected to a portable CD player
> or home stereo. When connected to the Allen & Heath (via Aux
outputs)
> it is full of computer-generated noise. The noise level runs about
-45
> dB and varies in frequency and level based on what is going on in the
> laptop (e.g. disk access, loading applications, even moving the mouse
> around are clearly audible in the noise).
>
> I don't understand how the computer is coupling into the analog
signal.
> It is converted from A to D in the external SB box -- the only
> computer connection is the USB cable. This noise does not feed back
> into the board. Disconnecting the SB box from the console at the AUX
> outputs silences the noise, so I conclude it is not RF broadcast, but
> something about the physical connection.
>
Anonymous
December 20, 2004 8:19:00 PM

Archived from groups: rec.audio.pro (More info?)

"Arny Krueger" <arnyk@hotpop.com> wrote in
news:kcydnQhxZ961mFrcRVn-1A@comcast.com:

> <mcmillan@engineous.com> wrote in message
> news:1103561179.969927.226230@f14g2000cwb.googlegroups.com
>> We have an Allen & Heath 32-channel board and other good analog
>> equipment in our church. We wanted to capture some audio in digital
>> format for post processing and CD production.
>>
>> Being short on funds (as always) a multi-track digital recorder was
>> not an option, so I bought a Sound Blaster Live! USB external for
>> $49. This, connected to a laptop is an easy and inexpensive solution.
>>
>> The problem: The SB works fine when connected to a portable CD player
>> or home stereo. When connected to the Allen & Heath (via Aux
>> outputs) it is full of computer-generated noise. The noise level
>> runs about -45 dB and varies in frequency and level based on what is
>> going on in the laptop (e.g. disk access, loading applications, even
>> moving the mouse around are clearly audible in the noise).
>
> Been there, done that.
>
> Turn the input gain on the Sound Blaster Live! USB as far down as you
> can, and still have a signal.
>
> Then increase the signal voltage from the console to just below
> clipping.
>
> Let me know how this works.
>
>
>

Try the laptop on battery (with the AC adaptor disconected)
December 20, 2004 11:18:54 PM

Archived from groups: rec.audio.pro (More info?)

I have the Tascam US122, and I still get noise from the power supply brick.
Works great without it though... I still have it but I mostly use a
MOTU828mkii with the laptop now. (Dell Inspiron 4150).


<mcmillan@engineous.com> wrote in message
news:1103567946.761056.25260@f14g2000cwb.googlegroups.com...
>I ran it that way for an event last night. The S/N is much better (but
> the noise is still audible). The real problem is knowing when the
> analog is clipping -- that does not show up on the (digital) VU meters.
> I listened to the headphone output of SB box but because of all the
> ambiant sound in the room could not hear it clearly. This morning I
> find the recording is (analog) clipped and distored in several of the
> loud passages. Ugh.
>
> Sounds like you did not find a solution to the root of this problem...
>
> I assume if we bought a Tascam US-122 (about $200, 2 channel) or the
> US-428 ($300, 4 channel) we would not have this problem? E.g. I
> assume a Tascam problem would work well in a professional audio
> environment. Any experience with those?
>
Anonymous
December 21, 2004 11:00:57 PM

Archived from groups: rec.audio.pro (More info?)

>mcmillan@engineous.com wrote:
>> We have an Allen & Heath 32-channel board and other good analog
>> equipment in our church. We wanted to capture some audio in digital
>> format for post processing and CD production.
>>
>> Being short on funds (as always) a multi-track digital recorder was
>not
>> an option, so I bought a Sound Blaster Live! USB external for $49.
>> This, connected to a laptop is an easy and inexpensive solution.
>>
>> The problem: The SB works fine when connected to a portable CD player
>> or home stereo. When connected to the Allen & Heath (via Aux
>outputs)
>> it is full of computer-generated noise. The noise level runs about
>-45
>> dB and varies in frequency and level based on what is going on in the
>> laptop (e.g. disk access, loading applications, even moving the mouse
>> around are clearly audible in the noise).
>>
>> I don't understand how the computer is coupling into the analog
>signal.
>> It is converted from A to D in the external SB box -- the only
>> computer connection is the USB cable. This noise does not feed back
>> into the board. Disconnecting the SB box from the console at the AUX
>> outputs silences the noise, so I conclude it is not RF broadcast, but
>> something about the physical connection.
>>

It sounds as you have something strange going on, I would hire a qualified tech
to have a look at just what you have and how you are running it. It'll cost you
atleast $100.00 or so but it will get rid of your noise.
!