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Mod suggestions for the 6G15 Reverb unit.

10/15/2000 9:58 AM
Mark Abbott
Mod suggestions for the 6G15 Reverb unit.
I have been screwing around with this for a while, (in between other projects) I have done a fews mods to it myself such as increasing filter cap size, changing the voltage divider to get maximum reverb from the unit (just the thing when the surfs up).  
As the bypass circuit is a cathode follower (which means a loss of signal voltage) is a problem, does anyone have any suggestions in overcoming this problem. I do have some ideas such as using a plate follower (regular cct), but I'm not sure if this is such a great idea, any thoughts?  
Thanks for your help.  
10/20/2000 3:35 PM
Scott Swartz

I built one of these and got a ground loop from the 3 prong power cords of the reverb unit and the amp.  
The original had a two prong cord, which eliminates this problem, but isn't as safe.  
Do you have any hum?  
If so, a good mod would be to rearrange the output cathode follower and mixer and add an output transformer for ground isolation. I did this and mine is dead silent.  
I used a full wave power supply, but I started from scratch and planned that all along. FW is a helluva lot better than the half wave used on the original.
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10/21/2000 3:06 AM
Mark Abbott

Thanks for the reply Scott. Regarding the hum I decided to go with the back to back diodes with a cap and 10 ohm resistor across the diodes this proved to be very quiet.  
I found if the circuit is above ground (a signal ground), and the chassis is earthed, this brought the quietest results.  
I also decided to use full wave rectification. I also decided to up the values of the caps around the choke in an effort to lift headroom. What I was curious about was the bypass stage, which is a cathode follower circuit, as most people complain about this stage, and Clark amps reverb unit has above unity gain, I was wondering if anyone else has gone down this path?  
Thanks for the assistance.  
Yours Sincerely  
Mark Abbott.
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