Square peak at very low end

[Diaultra]

Hello everyone

Hope you can help me. I changed the Output Transformers in one of my tube compressors. I used a LL7903 wired inverse 4:1.
The point is that I am getting a square wave peak at the very low end. No idea if it is resonance. The load impedance is 9K6 (tube output with decoupling cap [1.5uf]).
Do you know if a RC Network at the OT primary can help with this or is better to use another OT?

Thanks in advance.

 

[JonSnell Electronic]

Distortion as described could be down to not enough iron or the inductance of the transformer is too low to pass lower frequencies.
R C networks may help with higher frequencies but at lower frequencies destroy the high frequency response.

 

[Diaultra]

Distortion as described could be down to not enough iron or the inductance of the transformer is too low to pass lower frequencies.
R C networks may help with higher frequencies but at lower frequencies destroy the high frequency response.

Thanks for your input Jon. What is the option then? Choke?

 

[Diaultra]

Anyone?

 

[jan.didden]

Bigger transformer. Iron does matter ;-)

Jan

 

[pieter t]

LL7903 is more a microphone step up transformer.
It is specified for +10 dbU 0.1% distortion at 50 Hz when all primaries are in series; that is some 2.5 VRMS.
Used inversed the transformer should accept some 5 VRMS at 50 Hz for low distortion; for 20 Hz no more than some 2 VRMS.
Likely your tube compressor puts out too much; you would need a bigger transformer.