Show Posts

This section allows you to view all posts made by this member. Note that you can only see posts made in areas you currently have access to.


Messages - alessandro_gfdp

Pages: [1]
1
Amplifier Discussion / Re: Marshall Mosfet Grounding Issue
« on: March 20, 2020, 04:25:47 AM »
the basic concept is that the whole circuit,preamp and output is referenced to the center tap of the transformer secondary,and probably connected to chassis at some point,maybe the input,or the power amp,sometimes through a loop breaker,that can be a resistor,with a combination of cap and diodes.
In the schematic this arrangement doesn't appear,but i guess there should be some kind of connection.

2
insert in series with R2  a 500k pot and wire in parallel a couple red leds,move VR1 on the output.
Mid pot is not really necessary,those are boost and cut bass and treble pots,so if you want to scoop the mids just raise them above 5,mid boost under 5.

3
Amplifier Discussion / Re: Vox TB35C2 repair advice
« on: July 28, 2019, 08:22:16 AM »
I have the schematic, but before thinking about replacing a transformer I would perform some voltage measurements without tubes,that will tell me more if something is bad.

Inviato dal mio Redmi Note 5 utilizzando Tapatalk


4
Amplifier Discussion / Re: Fuse or resistor?
« on: June 18, 2019, 05:37:48 AM »
Looks like a fuse,blown

Inviato dal mio Redmi Note 5 utilizzando Tapatalk


5
Tubes and Hybrids / Re: ENGL Fireball E625 Head white noise issue
« on: June 01, 2019, 03:10:45 AM »
no,the ultra channel uses 4 stages,the clean 3.
I had the same exact problem in the same amp,from a friend.
It developes over years,its not related to new or old tubes,in fact the old tubes were pretty good.Not related to anode or cathode resistors,changed all of them
I was running out of time and ended applying a coring circuit for noise reduction,but to me that is not the best solution.
Its all in the first 4 triodes,one thing i didn't do and maybe has value is to remove any trace of glue on the flat cables and the caps,and maybe substitute the filter caps,and wash the board and sockets with isoprop alcohol.

Pages: [1]