Hi I came in the possession of a very nice tube amplifier, used previously in a nearby church, I have painstakingly reversed engineered the circuit, see attachment. It has been beautifully built, top quality components, all wiring neatly twisted and bound, the guy must have been a semi-professional.
I want to give it to my son so he can use it as a guitar amplifier. Yes I am aware of the differences, this amp has been built for low distortion, not what you need from a guitar amp. I have seen circuits where they create a parallel signal path with a reverb tank. Maybe I could do that after the EF86? Or ‘do something’ withe the feedback loop? Suggestions and advice are very welcome.
I want to give it to my son so he can use it as a guitar amplifier. Yes I am aware of the differences, this amp has been built for low distortion, not what you need from a guitar amp. I have seen circuits where they create a parallel signal path with a reverb tank. Maybe I could do that after the EF86? Or ‘do something’ withe the feedback loop? Suggestions and advice are very welcome.
Attachments
moved to Instruments & AmpsA good thing to ask is the style of music he plays. The gain structure are different for different amps. Also it seems you want to keep the amp mainly intact. I would change the two triodes preceding the outputs into a Long Tail Pair. The preceding one into a Cathode Follower. Tone stack behind it. First two stages normal gain stages, Marshall or Fender Bassman inspired. Not too much rewiring required, some part changes. May have to so a filter cap change also, three prong cord.
Fender had a champ style amp amp that tapped the reverb tank off the speaker out and fed the output of the tank back to an early stage. The likelihood of feedback or oscillation is higher but it doesn’t require any added gain stages
Yes, you can cut the heck out of a well-built amplifier. Or merely change the first stage to pentode for more gain.
Reverb is really a whole nother set of preamps and tiny power amp. For the time being, K.I.S.S.
The 10 best reverb pedals 2020: the best guitar effects for your pedalboard | MusicRadar
Reverb is really a whole nother set of preamps and tiny power amp. For the time being, K.I.S.S.
The 10 best reverb pedals 2020: the best guitar effects for your pedalboard | MusicRadar
That sounds really interesting, especially because the output transformer has multiple impedances, 3-5-7-15-400ohms where the last one is intended for the so called 100v output which will be transformed back at the other end in order to lose less signal in a big space like a church. But how to I find the right reverb tank? Any suggestions?
The best example of the reverb I could find.
YouTube
http://ampwares.com/schematics/champ_12.pdf
025934 tank number.
YouTube
I watched most of the vids out there to find one that uses the reverb on more than a light touch, Seems no one uses much. It gets annoying after a while so people don't use much.
YouTube
YouTube
http://ampwares.com/schematics/champ_12.pdf
025934 tank number.
YouTube
I watched most of the vids out there to find one that uses the reverb on more than a light touch, Seems no one uses much. It gets annoying after a while so people don't use much.
YouTube
You don’t need anywhere near that much power. I made an outboard reverb that was driven directly from the output of a 100W amp and it had 220 resistor in series. The tank was a standard fender style tank.
No sorry my text was misleading, I just mentioned the 400ohms/100V output option for completeness, I will select the output impedance which corresponds best to the reverb tank input impedance, so probably not the 400ohms one
Here's my 2 cents on a fold back reverb driven from the power amp(based on a champ12 schem)..........It doesn't sound anything like a std Fender(black/silverface) reverb setup. I fooled with it for a while but was ultimately disappointed, removed it,. and bought a rev xfmr and added some tubes for the blackface design. That presupposes you have the room and current capacity in your power xfmr. A Rev pedal is so much easier.....
I agree, I tried the reverb fed by the amp, unless you get creative in your filtering the resonances re-enforcer themselves in the loop and you get an unpleasant sound. If you want an integral reverb I would get a little chip amp and feed the signal through it and reamplify it to be sent back to the amp.
I used this one in a still-ongoing small solid-state guitar amp project. It's under fifty bucks (American), small, appears to be solidly built, and I think it sounds good: Amazon.com: Donner Digital Reverb Guitar Effect Pedal Verb Square 7 Modes: Musical Instruments
Here's an online review from Shane "InTheBlues" : YouTube
IMO this pedal is better sounding, more versatile, and cheaper than a typical DIY spring reverb implementation...
-Gnobuddy
I think Gnobuddy is on to something there---that Donner reverb is pretty good! And lots of variations available. I highly doubt you can build a better one for anywhere close to $45!!