Control the 6dB gain = THAT & AD Balanced Line Drivers - OUTSMARTS

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khstudio

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Any opinions on the best way to control the 6dB gain of the THAT & AD Balanced Line Drivers?
The Analog Devices ssm2142 & THAT Semi Corp 1606 & 1646 IC's ALL have a 6dB boost... I'd like to add a variable control of that gain.
I was wondering about the best way to do this? I had 2 ideas:

10k POT = Signal in pin 1, Output from Wiper & pin 3 to GND
OR
Variable L-Pad = signal into a series POT/Rheostat maybe 10-50k,
then a 10k shunt to GND (between the Pot & input of the IC.

Any ideas?

Thanks
 
Those chips need a low impedance source, like the output of an opamp.

I usually use an inverting amp, you can control the gain with a simple rheostat
connected pot from off to whatever.

Just reverse the output connections of the driver for correct polarity.
 
Dan Kennedy said:
Those chips need a low impedance source, like the output of an opamp.

I usually use an inverting amp, you can control the gain with a simple rheostat
connected pot from off to whatever.

Just reverse the output connections of the driver for correct polarity.

Thanks Dan!
The more I checked the data sheet I noticed the "need for a low impedance source, like the output of an opamp."

Question,
how or should I say where would you put the volume pot & can you recommend a value for the pot?


 
I drew up a ruff idea... not sure if it's overkill but what I'm trying to do is design a somewhat "universal" balanced output drive circuit with the added gain control of the 6dB boost of these output driver IC's. At the same time try to keep all the stages/loading happy.

Any thoughts?
 

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jensenmann said:
If the 6dB boost is your only problem you could swap to something lika DRV137 (IIRC), it's the same like a DRV134 without boost.

Thanks man... that's good to know...  2 things I was thinking:
the THAT IC's are a little cheaper & the 6dB of gain could be useful.

I'm just trying to make a universal output stage to use for testing on a few circuits but at the same time I want them to work & sound right.

I don't know if I'm looking for too much out of these things but will they drive a "Single-Ended LOAD" OK?
...the data-sheet seems to say it will but I have no experience doing that with them... like shorting pin 1 to 3 for Un-Bal.

*Also, on the schematic I posted, I added some optional components to the 1st amp stage so it can be a buffer or have gain.

 

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