Hi,
once there were a number of either spring reverb drive and recovery amplifier circuitries at the ::::::::: Accu Bell Sound Inc ::::::::: site. But nowadays this site appears to be down. Is there any chance to find these circuits again?
Best regards!
once there were a number of either spring reverb drive and recovery amplifier circuitries at the ::::::::: Accu Bell Sound Inc ::::::::: site. But nowadays this site appears to be down. Is there any chance to find these circuits again?
Best regards!
not sure but it seems Accutronics may have been bought out or aquired.
there's also a battery tech company with the same name...so who knows
it may not contain the specific info your after but have a look here Spring Reverb Tanks Explained and Compared | Amplified Parts
or try Rob Robinette's site
there's also a battery tech company with the same name...so who knows
it may not contain the specific info your after but have a look here Spring Reverb Tanks Explained and Compared | Amplified Parts
or try Rob Robinette's site
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Thanks a lot! While the Amplified Parts site seems to concentrate on tube powered designs, the Robinette site basically gives me all the information I was after. It is not that difficult to design a suitable tube reverb driver and recovery amplifer, but a SS one requires some tricks to get it done satisfyingly.
Basically I could go either way, but as reverb just is a FX device that is out of the main signal path, as a SS amp requires significantly less power and space, and as I'm quite convinced that a thick guitarist without significant knowledge in science won't even notice a difference here if he's not been told that there might be one, I decided to go the SS way in my next project.
Best regards!
Basically I could go either way, but as reverb just is a FX device that is out of the main signal path, as a SS amp requires significantly less power and space, and as I'm quite convinced that a thick guitarist without significant knowledge in science won't even notice a difference here if he's not been told that there might be one, I decided to go the SS way in my next project.
Best regards!
99% of tube amps today go the SS route, period. 😳
That said, the typical "humble Op Amp does all" solution "works" , sort of, but is weak of its very nature; and paralleling 2 or 3 (as in Marshall) is not a real game changer.
Search for more powerful drivers, typically an Op Amp driving a couple transistors fed from a "good" supply, so they are mini power amps.
Think a Watt or two, not 100-200 milliwatts.
Pat of the Fender Blackface or Silverface magic is using parallel 12AT7 and driving tanks hard with 1 or 2 W RMS.
And even harder in their standalone Reverb unit.
Check, say, LAB Series L5 reverb for a killer circuit, adapt it to Tube amps.
In fact, LAB L5 was intended as a "Twin Killer" and was over engineered in all aspects ... including reverb 🙂
Their driver is king of kings, but there are some intermediate ones, basically 1 Op Amp driving 2 transistors, not more.
IF I find one of those, I´ll post it here for reference.
That said, the typical "humble Op Amp does all" solution "works" , sort of, but is weak of its very nature; and paralleling 2 or 3 (as in Marshall) is not a real game changer.
Search for more powerful drivers, typically an Op Amp driving a couple transistors fed from a "good" supply, so they are mini power amps.
Think a Watt or two, not 100-200 milliwatts.
Pat of the Fender Blackface or Silverface magic is using parallel 12AT7 and driving tanks hard with 1 or 2 W RMS.
And even harder in their standalone Reverb unit.
Check, say, LAB Series L5 reverb for a killer circuit, adapt it to Tube amps.
In fact, LAB L5 was intended as a "Twin Killer" and was over engineered in all aspects ... including reverb 🙂
Their driver is king of kings, but there are some intermediate ones, basically 1 Op Amp driving 2 transistors, not more.
IF I find one of those, I´ll post it here for reference.
Another thumbs up for the Rod Elliott article:
Spring Reverb
and note that he points out several mistakes and poor circuit designs on the Accutronics site. Better to use his design (for solid-state) or just copy the Fender stand-alone reverb unit for a tube design.
Spring Reverb
and note that he points out several mistakes and poor circuit designs on the Accutronics site. Better to use his design (for solid-state) or just copy the Fender stand-alone reverb unit for a tube design.
Some of the accutronics schematics are still available through the wayback machine:
https://web.archive.org/web/*/www.accutronicsreverb.com//*
https://web.archive.org/web/*/www.accutronicsreverb.com//*
Not sure if you are aware of the Surfybear spring reverb, which is a solid state version of the Fender 6G15 standalone unit. Uses JFets for the preamp/recovery circuits and the driver amp using a Mosfet in class A with current source. Very compelling sound and though a bit power hungry it uses a 12 VDC supply. They used to offer a DIY kit with stuffed PCB but I think they are only doing completed units now.
Man, I missed the boat when they had these as kits for sale. Now their prebuilt units are going for 300-400 bucks. Ugh!
Can´t edit above answer (weird) so separately posting.
This Pearce G1 reverb driver and recovery (same designer as Gibson/Lab L5 but much simpler and doable) drives springs HARD: 60Vpp 😱 from a couple TO220 mid power transistors
This Pearce G1 reverb driver and recovery (same designer as Gibson/Lab L5 but much simpler and doable) drives springs HARD: 60Vpp 😱 from a couple TO220 mid power transistors
JM,
your schematics might be intended to drive high input impedance reverb tanks 😉.
Thanks to you all for your suggestions. Highly appreciated 😀! I think I'll be going the current drive road with a small incandescent lamp as the current sensing resistor (for instance instead of or in series with R27 in the #13 example) to get some compression. Then I'll feed the reverb signal coming from the recovery amplifier into the cathode of the tube right before the main volume control. I know that Fender amps' designs are different from my idea as they feed the reverb into the last triode's grid, but they don't feature low output impedance recovery stages that allow to drive cathodes.
Best regards!
your schematics might be intended to drive high input impedance reverb tanks 😉.
Thanks to you all for your suggestions. Highly appreciated 😀! I think I'll be going the current drive road with a small incandescent lamp as the current sensing resistor (for instance instead of or in series with R27 in the #13 example) to get some compression. Then I'll feed the reverb signal coming from the recovery amplifier into the cathode of the tube right before the main volume control. I know that Fender amps' designs are different from my idea as they feed the reverb into the last triode's grid, but they don't feature low output impedance recovery stages that allow to drive cathodes.
Best regards!
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Why, of course!!!!
ALL modern reverb circuits use high impedance (>125 ohm) drive tanks.
Only ones using nominal 4-8 ohm drive coils are very expensive (by comparison) Tube driven ones (ideally 12AT7 , marginally 12AX7) transformer coupled ones.
You´ll only find those in Fender Black and Silverface re-editions (meaning 60´s designs) and some Boutique amps, in total comprising about 0.1% of Guitar amps out there.
If that many.
And high impedance/current drive is achieved by NFB
Did I say something that could be interpreted as the contrary?
Btw, I have quite some bunch of 8 ohms input reverb tanks that I've harvested from crappy transistor Hammond organs. I prefer to use them at first place over sourcing and buying - expensive - 125 ohms units.
Best regards!
Btw, I have quite some bunch of 8 ohms input reverb tanks that I've harvested from crappy transistor Hammond organs. I prefer to use them at first place over sourcing and buying - expensive - 125 ohms units.
Best regards!
I came to similar results as JMF and choosed Accutronics reverb springs with 8 Ohm primary driven by LM380 in current mode.