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Bumping Up Unbalanced/Balanced Signal

Last response: in Home Audio
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October 24, 2004 3:28:06 PM

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

I am recording a studio-sized grand piano with the following set-up:
Two MXL 603's
Symetrix 203 mic preamp
Consumer grade MD &/or CD recorders
Since the preamp is Balanced and the recorders are Unbalanced the
output is about 6-7dB low
Here are my questions:
Should I turn up ONLY the gain on the preamp or ONLY the recording
levels of the recorders to compensate? SPLIT the difference?
Symetrix also makes the 303 Interface Amplifier "A Stereo Level
Matching Amplifier that accepts balanced or unbalanced inputs and
converts them to balanced or unbalanced outputs"
http://www.symetrixaudio.com/Products/303.htm
If I am NOT getting any interference due to the unbalance cables, is
the $200 worth spending to bump-up the signal this way instead.
Thanks,
Paul
Anonymous
October 24, 2004 3:46:54 PM

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

Paul wrote:
> I am recording a studio-sized grand piano with the following set-up:
> Two MXL 603's
> Symetrix 203 mic preamp
> Consumer grade MD &/or CD recorders
> Since the preamp is Balanced and the recorders are Unbalanced the
> output is about 6-7dB low

Since the preamp is +4 and the recorders are -10 there should be no problem.

How do you define "6-7dB low?" Are you expecting peaks to hit digital zero?




> Here are my questions:
> Should I turn up ONLY the gain on the preamp or ONLY the recording
> levels of the recorders to compensate? SPLIT the difference?

Find out at what gain setting your recorder has its best SNR. Set the preamp so the digital signal is where you want it to be (assuming that's less than wide open.)



> Symetrix also makes the 303 Interface Amplifier "A Stereo Level
> Matching Amplifier that accepts balanced or unbalanced inputs and
> converts them to balanced or unbalanced outputs"
> http://www.symetrixaudio.com/Products/303.htm
> If I am NOT getting any interference due to the unbalance cables, is
> the $200 worth spending to bump-up the signal this way instead.

I seriously doubt it.
Anonymous
October 25, 2004 12:49:08 AM

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

In article <e1850e8c.0410241028.906ce58@posting.google.com> pgruodis@yahoo.com writes:

> I am recording a studio-sized grand piano with the following set-up:
> Two MXL 603's
> Symetrix 203 mic preamp
> Consumer grade MD &/or CD recorders
> Since the preamp is Balanced and the recorders are Unbalanced the
> output is about 6-7dB low

You have something wired wierd, or else you just have the gain set low
on the preamp. The preamp has a nominal +4 dBu output and should have
plenty of output to drive your consumer grade recorders. If anything,
you would want to DROP the level out of the preamp rather than raise
it.

> Should I turn up ONLY the gain on the preamp or ONLY the recording
> levels of the recorders to compensate? SPLIT the difference?

Neither. Set the record level on the recorders to about where you
normally set it. (Turn the knobs to 7). Then use the preamp gain to
adjust the record level, watching the meters on the recorder. If you
see the overload light on the preamp flashing on peaks (unlikely) then
reduce the gain of the preamp and increase the gain of the recorder.

> http://www.symetrixaudio.com/Products/303.htm
> If I am NOT getting any interference due to the unbalance cables, is
> the $200 worth spending to bump-up the signal this way instead.

No. You just need to get the gains set correctly and you'll have
plenty of level. But make sure that you're wiring the output of the
preamp to the unbalanced recorder inputs correctly. Symetrix has an
application note in their "library" that has several different
configurations that work best with different combinations of input and
output circuitry. There's probably something in the manual for your
preamp about how a cable to an unbalanced device should be wired.
Check it out.


--
I'm really Mike Rivers (mrivers@d-and-d.com)
However, until the spam goes away or Hell freezes over,
lots of IP addresses are blocked from this system. If
you e-mail me and it bounces, use your secret decoder ring
and reach me here: double-m-eleven-double-zero at yahoo
Anonymous
October 25, 2004 11:02:08 AM

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

"Paul" <pgruodis@yahoo.com> wrote in message
news:e1850e8c.0410241028.906ce58@posting.google.com
> I am recording a studio-sized grand piano with the following set-up:
> Two MXL 603's
> Symetrix 203 mic preamp
> Consumer grade MD &/or CD recorders
> Since the preamp is Balanced and the recorders are Unbalanced the
> output is about 6-7dB low

Not necessarily. MXL-603 mics have plenty of output, and the Symetrix preamp
has plenty of gain for just about any reasonable use.

> Here are my questions:
> Should I turn up ONLY the gain on the preamp or ONLY the recording
> levels of the recorders to compensate?

If anything, the gain on the recorders and the mic preamp will have to be
turned down.

> SPLIT the difference?

For optimum SNR you might consider using passive attenuators to reduce the
+4 output of the preamps to match the -10 inputs of the recorders.

> Symetrix also makes the 303 Interface Amplifier "A Stereo Level
> Matching Amplifier that accepts balanced or unbalanced inputs and
> converts them to balanced or unbalanced outputs"
> http://www.symetrixaudio.com/Products/303.htm

You don't need it for this application.

> If I am NOT getting any interference due to the unbalance cables, is
> the $200 worth spending to bump-up the signal this way instead.

IME you just need to do some intelligent level setting. Start out with the
gain controls on both the preamp and the recorders set to 12 o'clock, and
work from there in equal-sized steps to suit.
!