The Amp Garage

Robert ! I changed the 2 coupling caps(22nF).The lower distorted note is almost all gone.I can hear a slight hum on the drive channel still there when I play a note(again after the amp is warm;20-30 minutes)I will wait to see if the changing the smoothing caps will correct the problem. I did your 47...

Oh your amps !!Italian fit and finish !!They immediatly reminded me of Ducati motorcycles !!

Mario

Thanks again Roberto !
I can't wait to try your mods on the clean channel.I mis-typed the caps on V2.I meant to say I changed them from 22nF to 10nF

Mario

Roberto ! Glad to share with someone who has also reworked this amp ! substitute two 82µF 450V with two 220µF 300V (fi 22mm, pin distance 10mm) I did this. substitute all Rp with same value but 1W I did not do this,but will.I just ordered parts and will try to add them. [/quote]1st and 2nd OD channe...

Thanks Billy !

I will replace the the coupling cap(s) from V1A & V1B while I'm at it.I will also replace the three smoothing caps(20u,20u,40, and the bias circuit 47u).

I am waiting for the parts which should be in this week.

Mario

Generally speaking, if you have 60 or 50Hz hum the issue is with heater wiring and/or relative positions of power and output transformers. 120 or 100Hz buzzing hum is rectifier and smoothing capacitor related or caused by a ground loop. On this particular amp heater supply is grounded via winding c...

Nobody has had this problem before???

I have ordered smoothing caps.Any suggestions would be welcome.

Mario

Roberto, I could post pics.Keep in mind that this problem was there before mods,from the beginning.I know I should have addressed this first but oh well... The 4 caps in the power supply are new and bigger as per Mike and Bill at Soldano. Any suggestions from the info I mentioned? Does it make sense...

Hello all! I've been working/modding a yamaha t50c.When I got the amp,it would develop a hum/ringing after the amp is on for about 20 minutes.I did some mods and have gotten the sound pretty close to where I like it minus that ringing/hum.Here are some observations: 1)It sounds like a 60 cycle hum 2...

Thanks for sharing! Very helpful !
Mario

Roberto,

I read this quickly(too quickly) last night,and made a mistake.It is the grid leak that affects the gain at middle frequencies.Let me read some more and get back to you.

Mario

Roberto, Keep in mind that I am new at this hobby.I love these post because they motivate me to do some reading and speed up the learning process. I can't quote copyright material,but from what Richard K. shows that the gridstopper affects the gain at middle frequencies but does not have much effect...

Hi Roberto !
I just found what I think your looking for:

Guitar Amplifier Power Amps
Richard Kuehnel

Chapter 4(pages 47 to 55)
Chapter 8 also

Mario

Anybody build a Supercharger GTO ?

Mario

http://www.justradios.com/

Super service from Dave.

Mario