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    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

Interstage transformer for balanced amp question


2002-11-16 3:43 pm
I would like to use an interstage transformer (or line output transformer) between my tube preamp and a balanced mosfet power amp as a phase splitter.
The tube preamp has ca. Zout 100R and the Mosfet amp has Zin 90Kohm /+-channel.
What would be the ideal transformer parameters for this combination?? What imp or voltage ratios?
I thought on something like the Jense JT-10K61-1M with 4:1
or a toroid....

It really doesn't matter.

The transformer is merely a ratio device.
If you don't need any "voltage gain" then the ratio needs to be 1:1 wrt each part of the secondary that is going to be used separately, unless they are recombined and that sum = "one". Otherwise the full secondary is a step up.

If you have extra headroom/gain then the ratios don't matter much at all - but not sure why you want/need a "phase splitter"??

The only issue wrt the actual transformer is the driving impedance, if it is sufficiently low then the frequency response should be preserved when driving a low Z primary (not a lot of inductance) ... but the effective impedance will be the reflection of the secondary load... which in some instances will need to be loaded to maintain the transient response (prevent ringing) if the actual load (the amp) is high - Z.

If ur trying to use this to bridge two amps, beware that you may well exceed the current capability or even the voltage swing of the output stages on many amps when bridging... also beware of the possibility of grounds that do not want to be connected together.

_-_-bear :Pawprint: