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"Custom" Vibrolux Reverb Mods

8/22/1999 9:34 PM
Mark Moyer	"Custom" Vibrolux Reverb Mods Just wanted to post some mods that significantly upgraded my Lux. I always thought that the Reverb on my Lux was lacking. I compared the Lux schematic to my copy of the Vibroverb 6G16 Schematic, I do not have a copy of the '63 Vibroverb re-issue, and I noticed three differences. First is that the Verb runs a 12AX7. Second the 12AX7's cathode resistor is a 1K1W where as the Lux's 12AT7's cathode resistor is a 2.2K1W. I therefore changed resistor #26 to a 1k and installed a 12AX7. Finally, and in mind most importantly, the Verbs coupling cap from pin #1 of the recovery 12AX7 to the 100K pot is a .003uf whereas the Lux's cap value was 500pf. I changed C16 from a 500pf to a .003. Now I have full deep Reverb. This change made all of the difference in the world. Before the change I was running the Reverb level at 7 and still not satisfied. Now I am running the reverb level at 3 where it sounds full, rich and beautiful. I also feel that the dwell is a bit longer most likely in response to the 12AX7. One last change that I made was to remove the diodes from pins 3 of the 6L6GCs. I tried it both ways and I like the tone of the amp without the diodes. It may be in my mind but I find the amp to have a bit more sparkle without the diodes. Besides, I have played through Fender amps for years and years and none of them had the diodes on the power tubes. To stop the hissing I installed the feed back loop as found on the Verb re-issue. I also added the 100pf-shunting cap across the PI and lowered the cathode resistor from 39k to 6.8k. This stops most of the hissing. I further installed a 10k pot in series with a 5k resister in place of the fixed 18k resister for a bias pot. Boys, let me say that after you take to boards out of the Lux it is no harder to work on the any other amp and the results were stunning! I am very pleased with my Custom "Custom" Vibrolux Reverb amp. Mark

8/22/1999 9:34 PM

Mark Moyer

"Custom" Vibrolux Reverb Mods

Just wanted to post some mods that significantly upgraded my Lux. I always thought that the Reverb on my Lux was lacking. I compared the Lux schematic to my copy of the Vibroverb 6G16 Schematic, I do not have a copy of the '63 Vibroverb re-issue, and I noticed three differences. First is that the Verb runs a 12AX7. Second the 12AX7's cathode resistor is a 1K1W where as the Lux's 12AT7's cathode resistor is a

2.2K1W. I therefore changed resistor #26 to a 1k and installed a 12AX7. Finally, and in mind most importantly, the Verbs coupling cap from pin #1 of the recovery 12AX7 to the 100K pot is a .003uf whereas the Lux's cap value was 500pf. I changed C16 from a 500pf to a .003. Now I have full deep Reverb. This change made all of the difference in the

world. Before the change I was running the Reverb level at 7 and still not satisfied. Now I am running the reverb level at 3 where it sounds full, rich and beautiful. I also feel that the dwell is a bit longer most likely in response to the 12AX7. One last change that I made was to remove the diodes from pins 3 of the 6L6GCs. I tried it both ways and I like the tone of the amp without the diodes. It may be in my mind but I find the amp to have a bit more sparkle without the diodes. Besides, I have played through Fender amps for years and years and none of them had the diodes on the power tubes. To stop the hissing I installed the feed back loop as found on the Verb re-issue. I also added the 100pf-shunting cap across the PI and lowered the cathode resistor from 39k to 6.8k. This stops most of the hissing. I further installed a 10k pot in series with a 5k resister in place of the fixed 18k resister for a bias pot. Boys, let me say that after you take to boards out of the Lux it is no harder to work on the any other amp and the results were stunning! I am very pleased with my Custom "Custom" Vibrolux Reverb amp. Mark