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View Full Version : I totally destroy a good amp...

samtheman
10-18-2008, 05:32 AM
...But in a good way :crazyguy

It was a late 60 Marshall *clone* from best maker.

Upgraded:

- Sozo Vintage Premium tone caps
- Hoffman Hotswitch
- Lar Mar PPIMV
- SS rectifier plug

Now its what I like, old Marshall crunch i.e. OD100 CL+ ch2.

That hotswitch is so good, no reason to switch back to the stock mode.

I tweaked a bit first cathodes also...

http://www.vilo.net/ppimv/hs1.jpg

http://www.vilo.net/ppimv/hs2.jpg

http://www.vilo.net/ppimv/hs3.jpg

http://www.vilo.net/ppimv/master1.jpg

http://www.vilo.net/ppimv/master2.jpg

http://www.vilo.net/ppimv/master3.jpg

*If It Works, Don't Fix It!* :roll:roll

cheers

/sam
M@tt C
10-18-2008, 06:27 AM
Should sound killer!!

Ya gots some clips??
topbrent
10-18-2008, 10:10 PM
Could you describe the Hot Switch vs. no Hot Switch sound?
jerrydyer
10-18-2008, 11:16 PM
good call. does everyone here know the Metro termonolgies? Lar Mar etc? cool. Hoffman hot switch. His schems were the first that I pondered over for hours.
samtheman
10-19-2008, 12:14 AM
Could you describe the Hot Switch vs. no Hot Switch sound?

w/o Hotswitch amp has stock preamp, here is a hotswitch (http://www.el34world.com/projects/hotswitch.htm)info and schem.

Lar / Mar PPIMV (http://www.vilo.net/ppimv/ppimv.jpg)

/sam
Unabender
10-19-2008, 05:41 AM
I have serious doubt about the lar/mar type PPIMV... I mean, when you turn the master down, doesn't it affect the bias :huh ? The reasoning being the amp actually runs hotter when master volume is turned down, as the bias voltage drops towards zero. I haven't implemented lar/mar type PPIMV, so I haven't measured this myself, though.

In my opinion, this should be the proper way to implement PPIMV on a fixed bias amp:

http://blueguitar.org//new/schem/misc_mod/pi-m-vol.pdf

The bias circuit is separated from the master volume.
samtheman
10-19-2008, 05:52 AM
I have serious doubt about the lar/mar type PPIMV... I mean, when you turn the master down, doesn't it affect the bias :huh ? The reasoning being the amp actually runs hotter when master volume is turned down, as the bias voltage drops towards zero. I haven't implemented lar/mar type PPIMV, so I haven't measured this myself, though.

In my opinion, this should be the proper way to implement PPIMV on a fixed bias amp:

http://blueguitar.org//new/schem/misc_mod/pi-m-vol.pdf

The bias circuit is separated from the master volume.


Its *mastervolume type 2* from TUT books, but added 2 safety resistors

/sam