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soundcheck 10th August 2010 12:15 PM

Transformer based voltage gain + unity gain stage?
Hi folks.

I am planing to do a bit of reengineering on my system.

Currently I am running a Sabre 32 (Buffalo) passive SE into a Tripath 2021B
feeding my 98db/W SPL speakers. All SLA driven. Sounds quite nice.

What's causing me headaches is the questionable performance of the opamp on the input and the losses associated to the outputfilter-inductors.

I am now thinking of using an output transformer of e.g. 1:4 (6,4V) on the DAC to go out differential. Voltage gain would be done by the transformer.

On 8R speakers I'd end up with approx. 5,2W if using an unity-gain-amp.
I think that should be OK.
A 2nd secondary on the transformer I could even use for feeding my subwoofer crossovers.

What I can think of for amplifcation is a nice differential unity gain amp
with a high input impedance and dc-coupled replacing my Tripath amp.
The amp should work on +-12V supply rails and be of highest quality.
Feedback should be avoided if possible. It should not be too complicated to build. ;)

I'd really appreciate any hints or advise on above idea. ( I don't have too much background on amp-design ;) ).



AndrewT 10th August 2010 12:21 PM

have a look through the thread

DF96 10th August 2010 02:44 PM

It is difficult to avoid feedback if you want a unity gain amp. The obvious circuit, source/emitter follower, has very high levels of feedback although all within one stage.

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