I wanted to build the Dumble Princeton 100w but decided to just go 50w in a JTM45 chassis and transformers (Heyboer).
Using EL34's it stays pretty clean but gets a good high volume tone kind of dark so engaged bright switch with 200pf and mids/treble at noon.
I think the answer to this experiment is to build the 100w version into a nice small Princeton combo, guys that like to get their grit from pedals would like this clean platform.
Well did that now onto other projects.
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Added effects loop between MV wiper and PI it works but this amp is a little different from others and not sure if that is the best way to add a simple effects loop here.
Changed to single input jack, SPST switch for bright cap, and two more cliff jacks for send/return in the front 4 jack holes. Knobs up mounting chassis Blues Breaker style into 1-12 combo cab.
I don't think the back panel of a combo is strong enough to hold a JTM45 what do you guys think? I actually have never mounted a chassis that way before.
Congrats Mark
nice looking build
FX loop in front is a cool idea.
You have me wondering the major differences between this
and the Small Special circuit?
Thanks guys, the amp wiring has changed in the past day. I've been busy trying different ways of wiring the volume, treble and MV but went back to original with series effect loop on the front panel.
I see that original BB chassis had 6 chassis mounting holes and I have 4 but I'll give it a try. Doesn't seem like a good way of mounting a chassis to me.
I like the front loaded style cabinets with chassis bolted to top of cabinet.
Should have internal bracing you bolt the chassis to and then cover with back wood piece. Oh well.
dcribbs1412 wrote:Congrats Mark
nice looking build
FX loop in front is a cool idea.
You have me wondering the major differences between this
and the Small Special circuit?
Darin
Darin, I wondering about that Small Special compared to what I built. This amp stays very clean and great pedal board amp.
Looking at it there's not a whole lot of difference (not considering the PT & OT probably). Few values here and there (NFB ratio, few caps, etc.).
I don't see what the PS filtering is with this one, but should be pretty close as well.
The overall topology is very much the same.
Niki
Is your tone stack still wired as in your pics? How is it with the Mid wired that way?
The mid control in the layout you linked to with the 250kA pot connected to the bottom of the bass pot as a variable resistor is like the raw control that one guy uses. It seems a more dumble oriented mid control would be separated from the bass.
Is this a real documented dumble mod or is it a "what if" kind of situation?
Looks *somewhat* close to a clean only 3rd generation...
EDIT: Ok I searched for the original thread and found the pics. It looks like there was a little confusion on the layout because the mid pot was added in the intensity spot to the right of the bass control (looking from the front)... Are the tone pot values a guess?
Yeah the pot values were all guess work by Greg. I would have to take a look at my amp to see if I used different values which I may have and I know I had to do some rewiring of the pots to get it to work properly. Probably better take a more current photo huh
EDIT: Mark, you ever have any ground loop issues using the 8AB2A1B with both the tank in and out grounded? On the mod tanks the grounds are easy to change.
Mark,
did you ever get this in a combo cab?
I'm looking at using the Mojo jtm45 chassis and their front load
1x12 combo cab for a 50 watt D style build.
EDIT: Mark, you ever have any ground loop issues using the 8AB2A1B with both the tank in and out grounded? On the mod tanks the grounds are easy to change.
Only on a 100w Rocket I had slight hum not on any other builds.
