new amp project

[dearmond]

Hello!
I'm looking for your input on my new amp project. Attached is my rough draft schematic. The question marks are that I'm not sure. however, all components are open to change. I've got info about the OT from this forum (Thanks!). I'm a little grey on the PT. My sonic goals to keep under 50W, good touch response and get clean, acoustic like strumming to a tight rock distortion with just adjusting the guitar volume.
I would like to keep the signal simple as possible. However, open to your suggestions to acheive my goals.
Any input would be greatly appreciated!
Thanks.

[you_never_know]

What's the value in doubling up V1 and V2? Sure, you increase the current output, but given that the input impedance of the next tube is so high, there's really no need to decrease the output impedance of the previous stage like that. You're driving a grid, after all - not a reverb tank.

[Sir Cuitous]

I like the design (without being able to tell you that it will sound great). IOWs, It looks like something fun to try to get to work. I would add my $.02: You can get about 70% voltage gain from two paralleled triodes that you would if they were in series. For a two power tube output section your pre-amp might swing the signal voltage enough to drive both tubes, but possibly not enough to drive four power tubes. I'm not saying this is a fact, but it's something to check into. Why not think about wiring the second tube in series?

[dearmond]

Thanks guys.
As far as the reason for paralleling V1 and V2, I just thought I try it. Se what happens. It was kind of inspired from the Matchless Chieftan (same with the MV position). If you look at the Chieftan schematic, it does somewhat the same except for the tone control positions. Is this done because of the reverb circuit? If someone knows the reason please let me know. I had a Chieftan and loved it. Hence the reason for some of my circuit choices. Furthermore, as far as V1 is concerned, I've done this on my last two amp builds and liked it. The only difference between those two amps was the first one had seperate volumes that were voiced differently which I might try again on this project. As far has the power tubes are concerned, I don't plan on running all four at once. The switches you see on the cathode grounds is going to serve two purposes: switch between tube types and use as a standby. As far as making V2 in series, I'm very open to that. I may need to do that in order to achieve my sonic goal. This project is going to be open to changes.
With that said, PLEASE, PLEASE keep give me your opinions and suggestions! I'm still learning.
Thanks everybody!

[loudthud]

The slope resistor (usually 100K) is missing from the tone stack. It's basically the Vox tone stack but the 500pF is too big. Something like 200-300pF will work with the 250K treble pot. As drawn the amp will sound very dark. You'll need at least one good treble boost somewhere in the signal chain to brighten things up.

[Bruce / Mission Amps]

Originally Posted by Sir Cuitous

...You can get about 70% voltage gain from two paralleled triodes that you would if they were in series. ...

I think the general consensus is only about a +3dB boost with two parallel triodes but you can get tens (like +20 to +30dB) of dB gain with two triodes in series.

[dearmond]

Yeah, your right about the slope resistor. I forgot to add that. Also, I wasn't sure about that treble cap. That's why the question mark. I'll probably put an approx 250pf cap there.
Bruce, when you put it that way, I'm going to put it in series.
Thanks guys.

[dearmond]

What do guys think of my updated V2 design? I got this from a note on a Trainwreck Express cloner's version. Any idea on how this would sound? Would I be better off just splitting the V2 tubes into a cascaded gain stage? I also have other changes on the schematic in red.
Let me know what you think!

Thanks

[Sir Cuitous]

Bruce: with all respect, I don't think it's that much of a discrepancy. My source is Richard Kuehnel, but I can't find the reference. I'm sure that paralleled triodes will amplify much more than +3dB, but since I can't show the math, I will defer to your better judgement. However, I am pretty certain that parallel triodes offer greater amplification than a single triode. So two triodes in parallel will give at least 50% of the voltage amplification of two triodes in series. I believe it is closer to 70%.

[loudthud]

I think you'll have plenty of gain as is. One more stage and you'll be in the Trainwreck unstable zone. Heat up that soldering iron and build the thing! You can always change it later.

[dearmond]

Amen to that Loudthud!
This amp is going to be open to changes. That's for sure.
Thanks guys!

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