dda -2dbu (-10/+4 ref levels)

Posted: Fri Feb 16, 2007 1:34 pm

Davedog wrote:

I LOVE all you 'real' engineer types. This is great stuff here. GAFF STICKY THIS!

Did I mention that I LOVE you engineer folks?

Now what fun would it be, being an [electrical] engineer, if we can't nitpick at little things like adding 449.7 nanoVolts of thermal noise (making the cumulative AWGN a whopping (-116) to (-122) below +4dBu.

Somebody has to worry about a few nanoVolts or microVolts of noise Cool

Posted: Sun Feb 18, 2007 6:18 pm

Thank God I became a mathematician. Dimensionless variables. All constants set to one. Life is good - at least in my day job.

Posted: Sun Feb 18, 2007 10:01 pm

Awwwwwwwww That's sweet Dave. I love engineers too, especially good ones. Console size does matter. After all, I've had the best.

Throw that Dog a Microbone or maybe a Dogphone?
The Demure Ms. Remy Ann David

Posted: Sat Mar 31, 2007 1:23 pm

[quote="Mises"]

rambelam wrote:

Good transformers cost upwards of $120 - $200+ apiece (just from what I've seen)... so you couldn't realistically be putting one of those babies on every single channel on your board... though I suppose you could put it on just a few select channels... depends how many -2dBu outoputs you have.

Holy Cow! You looking in the wrong spot. We get $90 Jensens or $ 75 Cinemags without even trying.

Posted: Sat Mar 31, 2007 2:10 pm

Sorry have to bring the geek out on this one.
Check out:
http://www.sengpielaudio.com/calculator-db-volt.htm

Heres some numbers:
-2dBu = 1.74Vpp
+4dBu = 3.47Vpp

-10dBV = 0.89Vpp

You need a gain of 2 to go from -2dBu to +4dBu
or you need a gain of 1/2 to go from -2dBu to -10dBV

Are these short unbalanced lines?
If yes a resitive divider will work just fine provide you pay attention to the input impedence of the -10dBV inputs.

Or use a simple class A fet amp with a gain of 2, If you would rather go up +4dBu.

I can send you circuits for either solution if you like.

The class A fet design is cheap compared to xfmrs. Although I do love cinemag! I use them in all my Apex 460 mods.

Best of luck.

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