Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: mmrxcsr01 on November 06, 2013, 06:48:59 pm
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I found this on Steve's page, along with several other really cool things, and started to build one some time back. Upped the power supply parts to Super Reverb level, and have been double checking connections and testing voltages again today. Turns up several days worth of poking, prodding and Fluke-ing still gave me no joy, so I contacted Steve, whose suggestions led me to a bad socket for v1...never had a new socket be bad, but it shows there's first time for everything. Thanks to Steve, and a parts order is one the way, Doug...photos to follow when done.
http://home.comcast.net/~seluckey/amps/misc/AB763_Deluxe_Lite.pdf (http://home.comcast.net/~seluckey/amps/misc/AB763_Deluxe_Lite.pdf)
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Tubes and sockets on the way- no better service than Doug's...
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Well, let me start by saying how generous Sluckey has been with his time. I've exchanged several emails with him, and he has been very helpful in trying to talk me through a very frustrating period of troubleshooting. The amp (his ab763 lite, no reverb or trem) is now working. I did in fact replace the socket for V1; I still had issues. I use solid core wire, as I have through my other builds, and this evening reflowed all the connections to both ends of all the runs to the board, and lo and behold...success. Not sure which one was the culprit, but there you go...so, now the amp goes into a used Newell Deluxe Reverb cab, blonde Tolex with oxblood grill cloth, with a Weber 12...or maybe two 10's...I'll post some pics over the weekend. The chassis was from a dead Randall keyboard amp, cut to the correct length, and drilled for tube sockets and mounting the iron. It already had the Fender-style angle front. I used the original faceplate as a template for a local sports shop to make me a new one, with only the number of holes I needed, where I needed them, with the logo I chose. NOS 5U4, 6l6's, Hammond power, Mojo choke, and Allen output trannie...all items on the shelf when I found Steve's circuit. Added a 5k pot to the negative feedback circuit, the "Soul Control" mod Guitar Player mag ran years ago, which was very satisfying in the Super Reverb I had at the time. I need to tidy up some wiring , and we'll be good to go. This will be for outdoor/ larger rooms, with the 5E3 I built from Hoffman parts years ago for the smaller gigs. I think the Lite will be a nice addition, and again, want to thank Steve. And Doug, who, once again, got my sockets and tube order to me at light speed...
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this evening reflowed all the connections to both ends of all the runs to the board, and lo and behold...success.
All right!
Brad :bravo1:
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Glad it's finally working. Since you are using 6L6s with appropriate iron there are a couple changes you may need to make.
1. Change B+ dropping resistors R32 and R33 to 1K and 4.7K respectively. This may not be necessary. Super Reverb uses 1K/4.7K. Tremolux uses 10K/10K.
2. Change bias resistor R36 to 27K to increase bias voltage to proper 6L6 values. The 10K on my schematic gives a good bias range for 6V6s but will likely not give enough bias voltage for 6L6s.
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Well sorry folks, my friend who was to take pics didn't make it yesterday...but the amp is great. I've tried it with 1 single 12, two 10's, and a 15,
and just can't make it sound bad...if you need a blackface tone with no rev or trem, Steve has it for you. Thanks again...peace.