Mesa Stiletto Deuce Low Output

[samgraysound]

Hi All,

I am trying to fix a Mesa Stiletto Deuce. It has low output, maxing out at 70w, when rated 100w. This is when driven from the effects return, so I'm pretty sure it's the power amp. schematic attached

Please help me troubleshoot. I have tried new power tubes. New V5. Checked tube voltages. Checked OT.

 

[Khron]

"Driven from the effects return"... With what amplitude of signal?

 

[samgraysound]

"Driven from the effects return"... With what amplitude of signal?

Just turning the oscillator up until the amp is at max output. Haven't measured the exact input amplitude for this. I can tomorrow.

 

[radardoug]

When you say maxing out, do you mean when the waveform starts to distort? A lot of guitar amps only produce rated power when producing at least 10% distortion.

 

[samgraysound]

When you say maxing out, do you mean when the waveform starts to distort? A lot of guitar amps only produce rated power when producing at least 10% distortion.

I mean i am driving the amp into a load, monitoring AC RMS level at the load. Turning the oscillator up until the level at the load won't go up any more.

 

[CJ]

what frequency?    try 500 Hz

make sure dummy load ohms = transformer tap

there appears to be a half power circuit in the cathodes, watch out for that,

 

[samgraysound]

I talked to Mesa.

They basically told me that the amp is probably not actually 100w and the marketing department just rounded up.



so cool.