Thanks for all the help I really appreciate it, Sorry I am just responding I was attempting to make a video of my recorded sounds to share but kept losing the files somehow but ill post it on here soon. Also its music festival season so ive been enjoying that. I have ordered a variety of I0 watt wire wound resisters from multiple sources and they almost all are on back order 'i think I have at least one 470 R coming today.
First, I added a VVR. It works much better now. I added It right after the choke. It has definitly made the amp more usable and sometimes it sounds great. The clean channel almost always sounds great. I think i have a solid grasp on the way the amp works now. The advice to treat it like a clean amp and the OD channel like a pedal is great advice and helped me a lot. Once I get home and tweak a few things ill take my voltages and post them.
The OD channel is usually somehow too dark and at the same time too shrill and its always lacking in bottom end. The Voltage is a little better now but still too high. I placed two 5 watt wire wounds in parallel and then those in series with a ten watt but i forget the exact values, i think i am somewhere around 470R. Once i get some more 10 watts finally ill experiment. Another problem i had was with the fx loop jacks. I almost always have a delay and reverb hooked up while playing. Last night i unplugged all my pedals and the amp sounded 1000 times better but slowly started to make a sound as if the speaker in my cab was lose or blown. I checked and one of the switch terminals on my jack was bent and hopefully once i replace that jack it will be fixed. I tried my pedals in true bypass vs buffered ect… but it never sounded as good as it did without anything in the loop.
dorrisant wrote: ↑Fri Jun 09, 2023 5:03 am
I don't know if anyone else already stated it, but it looks like your PI tail resistor is 100k and should be 10k. That may solve your PI voltage issues. I see brown black black orange brown... It should be brown black black RED brown
When you wired all of your pots backwards you taught yourself a huge lesson. You'll probably not do that much anymore. And don't worry... There aren't many members here who haven't made mistakes like that. If they haven't, they will if they build enough, and then they'll learn. Keep going. You will learn more with every build. Your attitude will get you almost all of the answers around here.
As far as bepone's comments... He is absolutely right. But you can worry about that after you get it to function without the voltage issues and with better tone/less unwanted noise. What he is telling you is what you will learn is best. You can always rework it later and hear for yourself. I used to build with a bunch of metal film resistors, I learned to build differently. Keep reading and that stuff will come to you.
The topology of this amp is very much like a Dumble... You have to think of it as a clean amp, and when you change channels, it is much like kicking in an OD pedal. Except it is tube (much better). Look at the switch and realize that it functions much like a stomp switch in a pedal. That makes it easier to wrap your head around it.
Nice to meet you,
Tony
Thanks for the kind words and also all the work you have done in this community! It is nice to meet you as well! The PI resistor was a 10k, I replaced it anyway but i appreciate you looking at everything so closely. I am all for learning and try and take in as much as possible. I really want to design an amp myself at some point but that will be a good while from now. The advice you give to treat the OD channel as a pedal is great advice and really helped me approach the amp in a much better way. Again, thank you!!
10thTx wrote: ↑Fri Jun 09, 2023 1:13 am
A few thoughts about the Tweed Overdrive Special ...............
I've always thought of this as an amp to build and then change to personal taste in tone. So if you experiment I would do small changes and do them ONE at a time. Then play it that way for a few hrs or days and then decide what to keep or change.
I have built amps with VVR and I do think the VVR preserves a good tone at a lower volume than the PPIMV. I think the PPIMV dialed in between 5-7 sounds excellent but I agree that the PPIMV dialed down below 5 loses some good tone. I think the VVR helps in recording an OD tone at low volumes.
Having said that, I found the PPIMV to be more reliable. I had a VVR develop some hum after using it a few yrs and removed it.
IF I were experimenting these would be some changes I might try. I would definitely add the 220p "enhance cap" on that LTPI plate resistor. It seems to smooth out the high end harshness that amps sometimes will have.
I always thought the design going into the first gain stage of the OD channel was sort of convoluted. IIRC, I think I eventually removed a bunch of parts there and put in a 100ka pot instead? Not sure if I'm remembering correctly but that's what I think I did? However, I sure don't think it's necessary to remove those parts. It's simply more convenient.
I might also try a .01 coupling cap into the LTPI instead of the .02 simply to see what sounded the better to me.
You might want to try a 12AT7 in V4 (the LTPI)?
None of these ideas are things you "should" do. They're simply a starting place to tweak stuff IF you're inclined to do things that way.
It's critical in my thinking that the changes are small and done one at a time.
With respect, 10thtx
I will Try a few of your suggestions, one at a time of course. I like the idea of removing those parts and once i get everything working properly ill see if i can find a way to remove them but only if i can easily reverse it.
I have tried an 12aT7 in the PI, it sounds good but the best setup i have gotten so far has been
V1 - EH12AX7
V2 - TAD12AY7
V3 - 5879
V4 - JJ12AX7
V5 - Sovtek 5881
V6 - Sovtek 5881
V7 - 5Y3* I prefer the SS rectifier but The 5Y3 drops the voltage so thats how ive been running it to keep it as low as possible.
Thanks again for your time man! Even with it not working perfectly i have managed to get some amazing tones from this design. Its the best clean/slightly overdriven tone ive ever gotten from any amp so i really thank you sir!