6L6GC usage in Princeton Reverb kit

[SuperSix]

I received a PR Mojotone kit for Christmas and have built some of their kits before with pleasing results. In this case, I wanted the PR so I would have a very light amp since I am 71. I have used a Blackstar 60 and Super Six Reverb converted to a head cab (Still massively heavy). I am used to having excellent clean headroom. I just recently sold a non-reverb Princeton from 64 I'd used since 1968 and realize how they are treasured for their breakup, but in my case, it was overdriven much too easily and I want only as much clean as I can get out of an amp. I want no breakup. (obviously the value of the vintage amp meant no mods since it was all original and mint beyond recap and AC cord).

As I've embarked on this build, I'm making changes to meet that need. The mods I'm doing are a solid state rectifier, an adjustable bias, and 6L6GCs. When I received this kit, I contacted Mojotone to see if I needed to upgrade the PT and OT. They stated that as long as I have the right bias, their transformers could handle this (these are Mojo760EX PT and Mojo722 OT. Thus I'm headed down this road. It's not necessarily to increase output wattage much, really just make the princeton as clean as possible with it's current power and possibly a little more.

My next research before putting it all together is involving using a speaker that matches the goals without being overly heavy. I've contacted Weber on that.

Is there anything else you can think of that I should be looking into for this configuration. I recognize that a common response to this would be to just get a Deluxe Reverb, but I really like the size of the PR so wanted to pursue this for the learning, and then potentially replace my monster (Super Six) in gigs.

BTW, the reason clean is so important, is I use Zoom G11 (amp and cab modeler off) into the clean amps, even for overdrive. It really sounds great and is so configurable, but the amp has to be clean like my two larger amps.

Thanks in advance for any ideas and warnings.

[Carlsoti]

The one thing that comes to mind is putting a sizeable grid-stop resistor on the phase splitter, which I don't think was stock. It might only matter if you crank the amp most of the way/all the way up.

[SuperSix]

Thanks for that. My brother (radio tech) had mentioned that but I forgot about. I'll check the Bassman schematics for a similar config.

[SuperSix]

I did think of something that might be necessary with this build to get the most out of it. If I were to place a choke inline between output transformer and screen supply, it sounds like it would reduce sag and possibly support more clean headroom better. Is this ill-advised or a good idea?

[SEL49]

You would need to replace that 1K 1W resistor with the choke.

[SuperSix]

Thanks for that. That was what I was thinking, and it appears that the standby switch would go right in there too. I have heard I need the Standby when using the SS Rectifier.

[SuperSix]

Here is the schematic with modifications to support increased clean headroom. I apologize for how hideous it looks, the drawing tool I used only allowed me to produce resistor and choke graphics that came from a Kindergarten electronics class ;-). The values on the 6L6GC resistors are just what I took from my other large fender. If possible please slaughter it so anyone coming along and seeing this will not think it's a valid prototype.

I borrowed much from the Hoffman and Robinette pages along with several others.

I put a giant disclaimer on it since some guitar player might browse it up in images and think he/she has found the brass ring

[DummyLoad]

Here is the schematic with modifications to support increased clean headroom. I apologize for how hideous it looks, the drawing tool I used only allowed me to produce resistor and choke graphics that came from a Kindergarten electronics class ;-). The values on the 6L6GC resistors are just what I took from my other large fender. If possible please slaughter it so anyone coming along and seeing this will not think it's a valid prototype.

I borrowed much from the Hoffman and Robinette pages along with several others.

I put a giant disclaimer on it since some guitar player might browse it up in images and think he/she has found the brass ring

100mA PT HV secondary won't last long. 200mA part would have best survivability. APD sells an upgrade Princeton PT (Heyboer part) that's rated at 150mA, taller but same mounting footprint. Link HERE. IMO a better choice than 100mA for 6L6 tubes. 
Vibroverb OT (Hammond 1760J or MOJO770) fits with minor mod. 

--Pete

[SuperSix]

The same mounting footprint sounds very good. I will check the link and probably buy one.

[SuperSix]

@dummyload.

Purchased. I had just purchased from them but didn't look at their transformers. I'd rather given up on trying to find something with the PR footprint that would be larger than the mojotone.

Really appreciate the input.