Just joined looking for tech help

[camarofreak]

Hey everyone. just joined your group because I want to learn about building my own amps( with my brother). I am a huge fan of the Dumble and Two Rock amps, but cannot afford either one. So I figured build one and see how close I can get to that style tone. I am not starting from scratch, rather modding an existing schematic to what I think it should be. My brother knows schematics and electronics way better than I do and we are learning tube amps together.

My plan is to take the Fender Excelsior schematic dump the tremolo and add a third preamp tube. The signal path would then be v1a gain stage/D-style tone stack/v1b tone stack recovery. v2a possible switched gain stage not sure yet how to accomplish. v2b/v3a single tube reverb circuit drive/recovery, v3b phase inverter. Into mostly stock Excelsior cathode bias dual 6v6 power section with an added NFB loop to help smooth everything out. Am i missing anything important? Any insights to make things go smoother? This will be a few months before it happens, I'm trying to do my homework before hand. I really don't want hear "you can't do that" or "that won't work" either. This is a learning experience for me and if I am missing something, explain it to me and me find a solution. Thanks everyone! I look forward to sharing this journey with you!

[rock_mumbles]

What kind of Dumble amp are you thinking about?

I don't see the Excelsior a good starting point for a D-style amp ... Excelsior to Princeton ... yes!

A low wattage Small Special would work ... but the cathodyne phase inverter in the Excelsior will be something you'll have to work around

For an ODS, Overdrive Special amp you need three 12AX7's for the preamp and phase inverter ... an ODS amp has 8 knobs and at least three switches

[camarofreak]

Oh sorry! It will probably be a simplified SSS#002 tone stack. no switches, just T/M/B controls with Dumble values. The Excelsior is a fixed tone stack with bright/dark switch. I want full controls for flexibility and to reduce the drive a bit for a cleaner sound. And if I am going to add a full tone stack, why not try something a bit different?

I also forgot to explain the unused v2a. I am not sure how to do it yet, but I want to put it on a switch. So it can be added as an extra gain stage in case I want more dirt. The end result I'm going for is a 10-15 watt non-master clean-ish kinda thing. I like the Excelsior, but want more out of it. I know it won't be an Excelsior anymore. As a learning experience I thought modding an existing design would be a good start. And transformers and such can all be sourced from D. Allen for fair prices.

[ToneMerc]

Hey everyone. just joined your group because I want to learn about building my own amps( with my brother). I am a huge fan of the Dumble and Two Rock amps, but cannot afford either one. So I figured build one and see how close I can get to that style tone. I am not starting from scratch, rather modding an existing schematic to what I think it should be. My brother knows schematics and electronics way better than I do and we are learning tube amps together.

My plan is to take the Fender Excelsior schematic dump the tremolo and add a third preamp tube. The signal path would then be v1a gain stage/D-style tone stack/v1b tone stack recovery. v2a possible switched gain stage not sure yet how to accomplish. v2b/v3a single tube reverb circuit drive/recovery, v3b phase inverter. Into mostly stock Excelsior cathode bias dual 6v6 power section with an added NFB loop to help smooth everything out. Am i missing anything important? Any insights to make things go smoother? This will be a few months before it happens, I'm trying to do my homework before hand. I really don't want hear "you can't do that" or "that won't work" either. This is a learning experience for me and if I am missing something, explain it to me and me find a solution. Thanks everyone! I look forward to sharing this journey with you!

I'm going to be the elephant in the room and give you my 2 cents about pissing into the wind uphill.

You want a Corvette, but can't afford a Corvette, but there's a junker Chevette nearby. Thus, you are going to take this junker 4 door Chevette and waste your time trying to super mod it into a Corvette nevertheless. You don't want anyone to tell you what can or can't be done or what won't work. However, you are open to folks finding you a solution to turn this junker Chevette into Corvette.

Why piss into the wind when there are documented Dumble circuits and layouts on this forum? Use the search function you will find scaled down 6V6 Dumble based circuit (D'lite or visit Brownnote Amps website) and there are even some single ended Dumble based circuits scattered around this forum as well.

IMHO, you will be much better served by at least starting from this point. Now you have a nickel, carry on and good luck.

TM

[M Fowler]

http://ampgarage.com/forum/viewtopic.php?t=17449

[Paultergeist]

........
Why piss into the wind when there are documented Dumble circuits and layouts on this forum? Use the search function you will find scaled down 6V6 Dumble based circuit (D'lite or visit Brownnote Amps website) and there are even some single ended Dumble based circuits scattered around this forum as well.
IMHO, you will be much better served by at least starting from this point. Now you have a nickel, carry on and good luck.
TM

I agree with TM. Why re-invent the wheel? There are a number of schematics out there, and I built a D'Lite (2 x 6V6) some time ago -- great Dumble-esc tone. The only thing that Fender would be good for would be the chassis and the transformers (based on what you describe). I suggest you listen to some YouTube clips of some well-vetted Dumble clone (inspired) schematics, and build something already known to get you close to where you want to go -- then just season to taste.

[rock_mumbles]

debug post

Sorry I didn't refresh so I didn't see that it had posted ...

[rock_mumbles]

...
I also forgot to explain the unused v2a. I am not sure how to do it yet, but I want to put it on a switch. So it can be added as an extra gain stage in case I want more dirt. The end result I'm going for is a 10-15 watt non-master clean-ish kinda thing. I like the Excelsior, but want more out of it. I know it won't be an Excelsior anymore. As a learning experience I thought modding an existing design would be a good start. ...

To do even the most simple D-style circuit there is no unused V2a triode ... you need two triodes for the clean preamp, if you are going to stick with the cathodyne a gain stage followed by the cathodyne ... that's four triodes. If you convert to a LTPI you need four triodes ...

How about putting a 12AY7 in for V1 to clean up the Excelsior ...

There is really no common circuitry between any D-style amp and the Excelsior ... and the stock transformers are going to be lacking

Your best bet would be to convert the Excelsior to a four tube Princeton
http://www.rh-tech.org/public/Tweed_5E3 ... ematic.png
The non-reveb Princeton is a pretty clean amp, you could add a mid control if you wanted ... or even a Dumble tone stack

The SSS is not an amp to look at for your mod

[camarofreak]

I am so sorry for ruffling any feathers everyone!!!!! I guess I didn't explain myself well.... I am not trying to clone anything. I like the Excelsior but feel it needs some tweaks to be more "me' and this stuff looks like fun. the cost of buying an Excelsior and then upgrading transformers is not much less than it will cost to build from scratch, I've already checked. That still leaves me with a fixed tone stack and tremolo instead of reverb. I get the point of polishing a turd, but i like soldering and problem solving. I have no expectation that anyone here would solve my problems for me, but the amount of information available is crazy and if someone could narrow the search, is all I meant. I really hope to be around here for awhile, lots of places don't appreciate Dumble talk . Talk to everyone soon.

[rock_mumbles]

I don't think it's so much you've ruffled feathers ... it's just being realistic.

Where are you planning on putting the reverb tank?
- I don't see any place in the cabinet where you could put in even a small reverb tank ... the top of the cabinet has the preamp/controls chassis and the bottom of the amp has the power supply power amp chassis.
- An internal Belton brick based reverb pedal would be a viable reverb option.

How are you planning to do the mod? Are you planning to rework the circuit using the pcb?

How much room do you have for controls on the chassis?
- Maybe move the LED indicator and cut back to just one input jack ???

[Paultergeist]

No ruffling over here......and I am sure you'll get plenty of advice along the path of whatever you decide to do. The consensus opinion seems to be that you may be taking a harder path to get to where you say you want to go, that's all.

But maybe this Excelsior thing has the look/vibe/color you really want -- if so, that's cool too.

Best of luck, however you decide to proceed.

[Jana]

Since I already pissed off one newb and scared him off, I might as well go for two.

You aren't ruffling any feathers. We just find it amusing (at least I do) when the newb of the day comes in and, as Tonemerc said so well, wants us to redesign the chevette into a corvette.

Next? Who's number three?

[matt h]

(deleted)

[armillary]

I built a 5C3 with a 15" Jensen in the last year and I felt like I was a tube amp god. (In my world, the tube amp god community is very large and includes all of you. It's polytheistic.) That was my best amp ever, although I really like the couple of SE amps I've built since then. It was the seventh or eighth tube amp I've built. I think a beginner building a 5c3 or a 5e3 for their first amp would be a prodigy.

I hope one comes along and does it.

[vibratoking]

+1 on a 5E3. What a great amp.