Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: Papa Jim on January 14, 2019, 04:06:19 pm

Title: Power up without reverb tank
Post by: Papa Jim on January 14, 2019, 04:06:19 pm: I would like to power up a Twin Reverb Amp without a reverb tank present. The output on the amp has a 12A shorting plug that shorts in the output to the reverb tank if it is not present. Is this too risky to do. If so I can wait until tomorrow when I can get my hands on a cable for connecting the tank
Title: Re: Power up without reverb tank
Post by: mresistor on January 14, 2019, 04:12:56 pm: I fire up Fender amps without the reverb tank all the time.. no harm done so far. What Twin do you have ? A reissue? Must be if there is a switchcraft 12A jack on it..

Guess you could always pull the 12AT7 driver if you are concerned..
Title: Re: Power up without reverb tank
Post by: Papa Jim on January 14, 2019, 04:55:26 pm: Yeah Reissue. I just found some cable and hardwired it up to the tank by soldering to the back side of the RCA Jack inside the tank just to be safe. Thanks
Title: Re: Power up without reverb tank
Post by: mresistor on January 14, 2019, 05:12:19 pm: I'm looking at the schematic of the twin reissue and I don't see any switchcraft 12a that goes to the reverb tank. The reverb tank is connected with rca jacks. I think the 12A jack you are describing is the footswitch jack. Seriously. there is no harm turning on a Fender amp with the reverb tank disconnected.. you didn't have to solder to anything..
Title: Re: Power up without reverb tank
Post by: mresistor on January 14, 2019, 05:14:00 pm: If you really have to have to reverb tank connected, like to trouble shoot the reverb circuit, then you need two double female ended rca adapters and some stereo rca cables.. like what you would use to hook up a stereo amplifier to a cd player
Title: Re: Power up without reverb tank
Post by: sluckey on January 14, 2019, 05:17:09 pm: Quote from: Papa Jim on January 14, 2019, 04:06:19 pm
I would like to power up a Twin Reverb Amp without a reverb tank present. The output on the amp has a 12A shorting plug that shorts in the output to the reverb tank if it is not present. Is this too risky to do. If so I can wait until tomorrow when I can get my hands on a cable for connecting the tank
Hmm. My TR Reissue has a funky looking dual RCA jack for the reverb tank. The jack is located on the top of the chassis rather than the back of the chassis like the old '60s Fender amps.
Title: Re: Power up without reverb tank
Post by: mresistor on January 14, 2019, 05:20:41 pm: Are you sure this amp has a 12A shorting jack in the reverb circuit ? Looks like a Switchraft 11 to me on the footswitch.

http://ampwares.com/schematics/65_twin_reverb_@20manual.pdf Mods is this in the library?
Title: Re: Power up without reverb tank
Post by: sluckey on January 14, 2019, 06:01:38 pm: The footswitch jack is a 1/4" stereo phone jack, similar to Switchcraft 12B stereo jack.
Title: Re: Power up without reverb tank
Post by: Papa Jim on January 14, 2019, 09:25:59 pm: Somebody modified it to have a 12a the tank that I can't get my hands on tonight has a cable with rca at one end for the tank and 1/4 phono plug at the other end. I got it powered on and no problems. Sorry I've been working and did not get back to post. All is fine. Thanks guys you are great help whenever I need it.