Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: TIMBO on May 10, 2010, 01:11:49 am
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Hi guys. just sorting out a few problems with the reverb in My Opus build . What is a good voltage for the 12AX7 to operate at and is a standard 12AX7 ok ?? Thanks
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What sort of problem with the reverb?
I run the one tube reverb with a very wide range of voltages on plate 1 and plate 6 and had all of them work. I personally have not found that to be very critical in getting the reverb to work to my liking. I think I've run plate 1 from around 200v all the way to 300v (IIRC).
With respect, Tubenit
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Thanks tubenit. I was confused as the schem of the Opus Amp showed the power supply for the reverb driver comming from "C" which was in the VVR circuit. The overall amp works but the EF86 section not so well ,it starts up ok but when playing a couple chords it quickly dies to nothing.I also think that by grounding the channel not being used is causing a hum? Thanks
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it starts up ok but when playing a couple chords it quickly dies to nothing
Sounds like it could be parasitic oscillation which is difficult to resolve at times.
Reverb volts need to NOT be on the VVR circuit. Use a different node.
With respect, Tubenit
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Hi Tubenit, just doing some checks before i fix the chassis into the cab.I moved the reverb driver to "F" node getting a 270v supply everything else is the same.But i'm thinking i should be getting a better respounce. Any thoughts Thanks
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i'm thinking i should be getting a better respounce
That is so vague, I don't know what it's doing or not doing?
IF .......... it means that you don't have enough reverb look at the reverb tweaks under one tube reverb in the ARCHIVES. The other thing that you can do to increase the reverb is add a 100k resistor after the master volume off the wiper.
With respect, Tubenit