Tube Amp Archive

Hi, I'm surprised that noone has mentioned forming filter caps. I've been told that it takes some time to fully form the electrolytic in the filter caps and this has a pretty big effect on tone. I have seen amps that sounded like a** at first that got much better after a couple days of burning-in. I...

Hi All, 1st; Thanx for all the help and tips!! I did get that amp to mellow out and it turned into a real sweetie. I wound up making some changes in the power supply resistor string. That tightened up the amp real nice and got rid of the ghost notes. Since then I've done 3 or 4 of these D-Type thing...

I've been fooling with cabinet design also and I came across this freebie cabinet design program called WinISD. I think you can find/download it at linearteam.org It lets you design a cabinet with T/S parameters for a bunch of speakers and/or you can enter your own speaker specs. You can also mess w...

Hi, I've done a couple of these things now, a 20w non-HRM, and a 50w HRM. Both came out great! Now I've been asked to do a 80w HRM. I'm thinkin' I'll use a TwinReverb PT and a DualShowman OT. Are these good choices for this design or is there something better suited, tranny-wise? Any changes needed ...

Hi All, I've built lots of amps, but am a newbie to the "Dumble Culture";-) I'm working on a layout for a HRM. I've done many amps with the power supply/filter caps laid over the main board and these have worked well for me. See attached drawing. Neater layout, shorter wire runs, distributed filteri...

Thank you all for all the tips! I tried reversing the OT primarys, it screamed like hell, so I put 'em back. Tried the 47pf across the PI plates, no change. I'm fixin' to head out for the weekend (Arlington, TX Guitar Show!) I'll order some new filter caps and get back to it next week. Thanx again!!...

lower resistor values means more neg feedback. Have you tried changing the leads of the ot to the plates?. I had an amp with that problem, and it turned out that i have some positive feedback...but don't know why it didn't scream as usual, but did the problem you have...if it goes away by going up ...

You might be onto something with that - f/b-thing. I changed the f/b resistor to 10k (was 4.7k), now note-buzzing goes away when presence knob is turned up. A bit better now. Question: to get "more negative feedback" should the f/b resistor be higher or lower in value? I put in the 390pf caps across...

Here's a pic of what I'm up to. I've got the filter section layed over the amp section, all on one board. All the grounds from the PI forward are on a buss, grounded on a screw near the input (preamp ground.) The relay is on this board also. The relay is powered by a bridge rec/cap board on one end ...

Thanx for the tips! I've checked grounds and they seem real good (0 ohms.) Tha amp is really quiet when nothing is played, no hums. The relay is really quiet too, no pops or hums in either mode (clean or OD.) I've tried moving some grounds around (relay power supply, switching) to no avail. Still bu...

Hi, Well I've finished my first D-type, based on the '97 Overdraft Specimen schem. It's not exactly a "clone", different layout, dual bias adjust w/ test points, 6V6 tubes. The biggest change I made was to use a dual 50-50uf cap for the plate and screen filters, 50uf for each. The amp works fine for...

Cool, that's what I wanted to know. It sounds like the dropping resistor is the way to go.
Thanx!

Howdy,
Newbie here! Built lots of amps, workin' on 1st D-type. What's up with the FET input-thingy? I've seen this in several of the clones & layouts, but not in any of the schems. What's it do? How crucial is it to the D-tone? Do I really need one?
Thanx!
Ace Pepper

Hi All, 1st post here. I've done a couple amps w/O'Connor/TUT FX loop. They've worked great for me. I really like the series/parallel option. In series, with no FX plugged in, you can dial in some "fatness" (extra tube stages) but it doesn't really change/color the tone to speak of. Just more of wha...