samgraysound

Mesa Stiletto Deuce Low Output
« on: August 07, 2019, 02:22:17 PM »
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.
« Last Edit: August 07, 2019, 03:36:56 PM by samgraysound »
Sam Gray
Owner & Technician, Sound Audio Repair
www.soundaudiorepair.com

Recording Engineer, www.samgraysound.com


Khron

Re: Mesa Stiletto Deuce Low Output
« Reply #1 on: August 07, 2019, 08:45:43 PM »
"Driven from the effects return"... With what amplitude of signal?
Khron's Cave - Electronics - Audio - Teardowns - Mods - Repairs - Projects - Music - Rants - Shenanigans

samgraysound

Re: Mesa Stiletto Deuce Low Output
« Reply #2 on: August 07, 2019, 10:36:00 PM »
"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.
Sam Gray
Owner & Technician, Sound Audio Repair
www.soundaudiorepair.com

Recording Engineer, www.samgraysound.com

radardoug

Re: Mesa Stiletto Deuce Low Output
« Reply #3 on: August 08, 2019, 12:17:45 AM »
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

Re: Mesa Stiletto Deuce Low Output
« Reply #4 on: August 08, 2019, 12:22:00 PM »
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.
Sam Gray
Owner & Technician, Sound Audio Repair
www.soundaudiorepair.com

Recording Engineer, www.samgraysound.com

CJ

Re: Mesa Stiletto Deuce Low Output
« Reply #5 on: August 08, 2019, 09:19:25 PM »
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,

If I can't fix it, I can fix it so nobody else can!
Frank's Tube Page: www.mif.pg.gda.pl/homepages/frank/vs.html
Guitar Amps: http://bmamps.com/Tech_sch.html

samgraysound

Re: Mesa Stiletto Deuce Low Output
« Reply #6 on: August 12, 2019, 01:05:25 PM »
I talked to Mesa.

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

 :o

so cool.
Sam Gray
Owner & Technician, Sound Audio Repair
www.soundaudiorepair.com

Recording Engineer, www.samgraysound.com


 

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