Max wrote: ↑Fri Mar 26, 2021 6:48 am
Thanks a lot for the link. Interesting discussion.
In regard to the picture of SSS #004 posted and commented by talbany in his most previous post (Thanks!):
As this might not be self explanatory for all members here (at least not for me): Wouldn't it perhaps be fine, if in the context of this thread's topic someone might explain in perhaps some more detail the more subtle similarities and differences between the reverb circuits of SSS #004 (and/or some other SSS version) vs. ODSR #0013 (pre OD reverb) and vs. ODR #0060 (post OD reverb) and/or perhaps vs. ODR #0058 etc.?
Thanks a lot again and all the best,
Max
Max
You already sent me this a long time ago so it sounds like you are familiar with #13 and you basically already know where these circuits sit in the amp it sounds like?
Reverb:
This is what I know
2nd generation Overdrive Reverb:
3 tubes (driver, return amp, mix amp,). Mix is done before the OD circuit. So you have ìoverdriven reverbî. By this the reverb gets the more prominent, the more the OD decays. It is a bit like with a Deluxe Reverb in power amp saturation mode. When the note decays, the reverb gets more prominent. These amps have less gain AFAIR than the usual 2nd generation ODS.
4th generation Overdrive Reverb:
3 tubes (driver, return amp, mix amp). Reverb send is behind volume and ratio, mix before master volume. By this the reverb is a bit like an effect in the loop.
SSS:
Some with 3 tubes, some with 2 (2: mix is done by recovery after filters AFAIR)
DL 300SL:
2 tubes. Mix is done by recovery after filters AFAIR
DL 150W with reverb and without filters:
Similar to the 4th generation ìeffect in the loopî structure.
Here is what I know
#004/3 tube reverb
Reverb Signal
In the case of the SSS and ODSR The dry (or input) signal to the reverb input is usually taken from the wiper of the volume pot or just after the tone stack (a clean low level signal)..it's then sent to a reverb send amp to be amplified then to the 12AT7 to drive the tank. Then to the return or recovery amp to recover the signal lost with the tank, then off to the mixer amp
Filter Signal
Output signal coming off the Hi/Lo filters goes to the Mixer amp where the filter signal is recovered. It's then mixed at the plates (or output) of the mixer amp with the reverb mixer, usually with a pair of whats called mixing resistors then this mixed signal is finally sent back off the P.I and as you would put it like an effects loop.
002/Tweed Mixer/4 tube
The main difference with the tweed mixer is the signals are mixed at the cathodes of the mixer tubes instead of the plates, this becomes a low impedance buffer/mixer and not an amplifier,so this method of mixing is not really considered a "gain stage" (vs mixing at the plates).So you need to add an extra tube to amplify both reverb recovery and filter recovery before the mixer. This low impedance mixer circuit has less of a loading effect so it tends to have a more natural sound and a slightly wider bandwidth and a stronger sounding reverb..The wet/dry signals are basically treated the same as 004 (Mixed and sent to PI)
005 mixes the signal before the filter recovery amp. This way you are using this filter recovery amp to recover both reverb and filter signals already mixed saving you an extra tube,however adding some loading effects giving you a weaker less natural sounding reverb.IMO
IMO..The Tweed mixer is by far the best sounding.To best describe the sound would be clear with plenty of treble and does not seem to suffer from the boomey-ness most other reverbs have..These reverbs have plenty of drive so the reverb decays more naturally and the notes seem unaffected by adding more reverb no doubt due to the less of a loading effect on the low impedance mixer
I hope this makes some sense
Tony