Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: Jonas on July 21, 2024, 04:00:10 pm
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I'm looking for ideas, suggestions, help with splicing in the attached Ampeg reverb circuit. I plan on spicing in immediately before the phase inverter, but not sure how to do this....
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Something like this:
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… spicing in immediately before the phase inverter…
How much gain does your preamp circuit produce?
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thanks Merlin, I'll start with 270K / 150K and adjust from there.
tubeswell the amp has 2 inputs; (V1) 5879 and (V2) 5751 for preamps. The 5879 and V2A mix into V2B with 470K resistors then out to PI.
I don't plan on implementing trem, so the second half of V7 will be available if I need more recovery gain for the reverb. I plan on trying out a few different tanks (2 spring / 3 spring, short decay / long decay, etc.) to see what works best for me - so for a capacitance driven style reverb I'm needing a type "C" tank?
The Ampeg reverb tube (V6) 6CG7 is powered from different nodes. My power rail is more like the attached Marshall so not exactly like the Ampeg original, but if looks like node F would be similar to the Marshall phase inverter node v3?
I don't plan on implementing trem, so the second half of V7 will be available if I need more recovery gain for the reverb. I plan on trying out a few different tanks (2 spring / 3 spring, short decay / long decay, etc.) to see what works best for me - so for a capacitance driven style reverb I'm needing a type "C" tank?
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Jonas, I hope you will post your progress and results.
I have been puttering with cap driven reverb recently (https://el34world.com/Forum/index.php?topic=31634.0), and looked at a bunch of Ampeg reverb circuits. Many if not all use a 2.2Meg reverb isolation resistor. I have the reverb isolation resistor at 1 Meg with my 12DW7 one-tube cap driven reverb after trying lower and higher values.
As far as the return circuit, in the Ampeg GU-12 and some other Ampeg schematics, their return circuit uses 470K plate and 3k cathode resistors. I had started with 100K/1.5k and found that the 470K/3k gave noticeably more reverb. Not sure how much difference there would be compared to the 270k/1k as shown in your schematic. But it might be worth a try.
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pullshocks - thanks for the link, there is a lot of great information in there that I'm looking forward to reading through...
I plan on getting a few different tanks ordered up and get it going, I will post progress and results during the process.
I will probably have more questions at first....
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Hello, I plan to move forward and experimenting with capacitance driven reverb - I plan to follow the AMPEG version; have a question regarding reverb tank codes; 5th alpha-numeric (input and output grounding)
XXXX(X)XX where
A = grounded input / grounded output
B = grounded input / insulated output
C = insulated input / grounded output
D = insulated input / insulated output
Not sure which one I need, or can feature be modified on-hand?
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Grounded output is ideal; grounded input doesn't really matter. I'd go for isolated input, grounded output