6V6 Screen-Grid resistor mod for DRII/PRII

[FuzzWas]

Not really a mod I guess but I would like to know more about the grid screens and how to impliment them into my Deluxe Reverb II.

Things I know..
The Grids on 6V6 are on pins 4 and 5.
Fender used 470Ω -1W resisters between pin 4 and pin 6.
Both 6V6's had the Pin 6 connected together.
Then the pin 6 was also connected to some High + Voltage that is labeled differently in the Blackface then it is in the Rivera Models.

The Rivera models don't even use pin 6 or pin 1 locations.

I am talking about the lugs on the back of the Tube sockets and yes, I know that 6V6's don't have an actual pin 6 or 1.

I assume they would control power to the screens and keep a ballance, making the amp tighter maybe?

 

[Minneapolis Slim]

Here's a link to a page about PR II modifications that describes fitting the screen grid resistors.

Pretty neat site, lots of the info also applies to the DR II.

http://www.geocities.com/princerev2/modifications.html

 

[FuzzWas]

Thanks Slim, I've got the .022 tone caps in and added a standby switch too. In another week when I really figure this amp out I think I will have Fender and Marshall in the same box with reverb. At leas as close as you can get.

However it turns out, its become a great learning experience for me. I used to just read the layouts, but this has forced me to try and read schematics more closely.

It's hard for me to figure exactly where the signal is switched to the clean or the overdrive tone section. V1 and V5 are done up kind of wierd I think.

All in all I should have started my serious modding on a single channel amp though. Rivera was really doing his job on these amps.

Happy 4th

 

[Minneapolis Slim]

Sounds great, FuzzWas! I'm really anxious to hear how your amp turns out. Think you'll be able to post any soundclips?

 

[Tim C.]

Fuzzwas,

Did you receive the package I sent you?

Tim C.

 

[FuzzWas]

Yup sure did Tim! You're sweet this 4th of July!

I am going to try and finish tonight. I was confused about a few things so instead I got the standby working and the tone caps in, along with a better 47ohm 1W resister.

I want to finish your marshall mod and set up the amp to have a bias pot too.

 

[FuzzWas]

I am mainly confused about how the signal is switched to from the clean sectoion or the overdrive section.

Does V1 still effect the Overdrive channel? I am sorry, I just never tried to work on a 2 channel amp before, and seeing the two extra bypass caps by V4 and V5 gets me lost.


I put the .022 tone caps on the overdrive channel instead of the clean one. I hope that was correct.



Okay happy 4th to all. Me and the family are off to the BBQ :2zone

 

[Minneapolis Slim]

Fuzz, these amps use what I've heard termed a parallel input circuit. It's not like a std blackface where V1 is the clean channel and V2 is the other channel. The tone stacks sit between V1 and V2 on these amps. Instead of the clean tone stack sitting between V1A and V1B, it sits between V1A and V2A. Same with the lead tone stack, between V1B and V2B. At least that's what I understood when an amp guy was explaining it to me.

 

[FuzzWas]

That's some interesting stuff Slim!

I got the Tim C. mods done. but left the bias and screens for a later date. I think I'm worn out on the mods for a couple days..most of this was kind of new to me and the Rivera layouts are a lot different than blackface when it comes to being simple and well documented.

BTW Tim, thanks so much for the mod and the parts. I changed everything out except for the Mids pot. I need to find a 25k push/pull but I might just leave it. It sounds pretty darn good but I have not yet played it loud yet, nor have I tried the reverb.

It almost seems to have the cleans of an 18watter and the gain of a soldano, but I'm not sure if it's just because I was playing too low on the master.

I would be pretty happy if it carried some of this sound up into the high volumes.

Cool mod Tim

Edit - and this place saved my life. http://www.electrician.com/resist_calc/resist_calc.htm

 

[Minneapolis Slim]

Wow, sounds like you've created a monster! When you say it has the cleans of an 18 watter, do you mean on the modded channel? An d then that channel can also get up to the gain you're talking about? I'd hate to lose the Fendery cleans on the normal channel.

You have one of the JBLs in there now? I'd really love to hear how this turned out.