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Old November 29th 19, 03:46 AM posted to
Scott Dorsey
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Posts: 16,730
Default Input transformer for Spectra Sonics 101 preamp

Rick Ruskin > wrote:
>Are you saying that a step-up transformer on the input simply will not
>work or just that it will alter the performance of the card?

The step-up transformer doesn't give you free gain.... power is conserved
so there is no way to get power out of nowhere.

What the step-up transformer can do is to match a low-impedance load to
a high impedance load, so you lose less power in the process. This works
well if the load is severely mismatched (say, a microphone that wants to
see 600 ohms going into a 1M tube stage) but if the load is already matched it
doesn't help any.

>Would adding a resistor to the feedback loop along with the 502 eq
>that is already there do anything to increase gain?

Dunno, I'd have to sit down and do the math.

>As far as I know, the 101 was used as the front end on all
>Spectra sonics consoles until the 110 came along.

It was. It was also used as make-up gain for all kinds of other things.
It was a handy general-purpose gain module.

"C'est un Nagra. C'est suisse, et tres, tres precis."