José modded amps and internal transformers (VAI DLR head)

[Amp_chaser]

Hello Guys,

i've tried to record every kind of mods josé made to amps and there is one which is very interesting and which is out of my reach.

Apparently José used small transformers inside the chassis to boost voltages. Dave Friedman told us that he used it on the low voltage amps like the jcm 800.

However he seems to have used it too on high voltages amps like jmp and plexis.

Interestingly enough the VAI dlr era josé has a transformer after the output jacks :

I've been looking for pictures of josé amps and it seems that very few heads had this mod :

here is a Friedman modded amp with a transformer mod :

Does anyone have any kind of information about how this mod works and what's its impact on tone ?

It will be kind to share it with the community.

gut shots will be appreciated.

 

[shar-vell Dan]

Isnt that for DC heaters ?

 

[shar-vell Dan]

I have a Friedman Kitchen Sink JMP and have no such thing.

 

[Ben Waylin]

Pretty sure Jose did that to create a power supply for DC heaters to the preamp tubes (noise reduction).

 

[Amp_chaser]

Pretty sure Jose did that to create a power supply for DC heaters to the preamp tubes (noise reduction).

oh if that's the case thx. I didn't know why he did use those. It never came to my mind that it would be for this reason.

 

[Amp_chaser]

I have a Friedman Kitchen Sink JMP and have no such thing.

those gut shots are so good, thanks man !

 

[Amp_chaser]

I currently have some shots of this one which was owned by David Lee Roth.

 

[shar-vell Dan]

View attachment 318849

I currently have some shots of this one which was owned by David Lee Roth.

Those push / pull pots on the left they don't make anymore or so im told.
IDK why that would be so hard to make nowdays.
If that has a remote standby on the back and it looks like it does thats a Jose Arrendondo hallmark signature feature.
Almost every Jose made amp has that.
There was a local Blues player got a nice Jose. He didn't know what he had and had a guy put the amp back to stock.
I know the Tech that did the work. But thats what the guy wanted.
Jose liked the B+ in excess of 500vdc. > Hot tubes.

 

[Ben Waylin]

oh if that's the case thx. I didn't know why he did use those. It never came to my mind that it would be for this reason.

Yeah, my Ceriatone BE-50 clone has a 14VAC tap off the PT and that goes into this circuit here, using a Rectifier chip, a voltage regulator chip, and smoothing caps to provide a clean, stable 12VDC to the preamp tube heaters.

 

[Amp_chaser]

Yeah, my Ceriatone BE-50 clone has a 14VAC tap off the PT and that goes into this circuit here, using a Rectifier chip, a voltage regulator chip, and smoothing caps to provide a clean, stable 12VDC to the preamp tube heaters.

It’s true that It could be the use too.

On the picture with Dave’s modded amp the wire seems to go the cathode caps of v1 or over the 820r at v3.

Perhaps that shar-vell Dan is also right to keep the b+ over 500v. I always thought that if you wanted more distortion you wanted lower b+ voltages x). I’m lost.

 

[shar-vell Dan]

It’s true that It could be the use too.

On the picture with Dave’s modded amp the wire seems to go the cathode caps of v1 or over the 820r at v3.

Perhaps that shar-vell Dan is also right to keep the b+ over 500v. I always thought that if you wanted more distortion you wanted lower b+ voltages x). I’m lost.

There's a dude named David Hopkins aka : New Religeon over at Marshall forum he know alot of Jose stuff and builds amps give him a shout.
Somebody here prolly knows too.



I just ran across this today. Daves production amps are PCB hybrids.

 

[SpiderWars]

It’s true that It could be the use too.

On the picture with Dave’s modded amp the wire seems to go the cathode caps of v1 or over the 820r at v3.

Perhaps that shar-vell Dan is also right to keep the b+ over 500v. I always thought that if you wanted more distortion you wanted lower b+ voltages x). I’m lost.

I havent looked at any of those pics but what you are describing could be a boost. Also, added transformers could also be for adding footswitching options (channels, dual masters, boost, etc). Those would also draw from the heater supply.

 

[SpiderWars]

I havent looked at any of those pics but what you are describing could be a boost. Also, added transformers could also be for adding footswitching options (channels, dual masters, boost, etc). Those would also draw from the heater supply.

I should also mention that those extra lugs on the input jacks can also be used to 'switch' things...such that when you plug into that particular jack it switches things around just for that input jack. I had a Super PA that had been modded so one side (channels 1&2) was a plexi and the other was a 2203 (channel 3 with channel 4 disabled). When you plugged into the 2203 'Hi' (channel 3 Hi) jack it activated switching to make the circuit happen and also to cut off the plexi circuit from loading it down. Unplug and it's back to channels 1&2 being a Super Lead.

 

[mixn4him]

Those small transformers are to power the relay, follow the red wire across the board..

 

[ChuggNorris]

I have a Friedman Kitchen Sink JMP and have no such thing.

Clips?

 

[Amp_chaser]

Those small transformers are to power the relay, follow the red wire across the board..

Yes but is their purpose only to switch comps and channels ? I mean Dave said he also used them to boost voltages which is probably true. The question is did he try to get higher b+ or higher filament voltages ?