Tube Amps / Music Electronics
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|11/13/1997 6:46 AM|
||Ampeg Reverberocket 2|
I am having a terrible time trying to get the reverb in my Ampeg to work properly. I ordered a new (slightly used) tank, and have installed it. I am not getting enough reverb output from it. The tank has the proper impedence (I think!). I did notice the shield was not connected to the input (internal to the amp), and the tank I received had isolated shields on the inputs and outputs. I connected the shields internal to the reverb.
The schematics I found on the net were not the same as the damaged one on the back cover of the amp. There is a rather large hole drilled through the schematic which someone tried to install a speaker jack.
The re is some "residual" output coming from the tank, but the footswitch does not cancel the effect. I believe I am hearing some sort of acoustic coupling which results in a very small amount of reverb output. As I can see on the undamaged part of the schematic, the reverb input is pulled to ground when the footswitch is depressed. I have obviously checked the operation of the switch. When the reverb is installed vertically as the original, I get a feedback of about 1KHz, this is resolved by putting the amp on its side. Can anybody help me with this. I am a solid state kind of tech, and do not have much experience with tubes. BTW, the amp uses 2- 12AX7's, 1-6U10, and 2 7195A's. There is not 7199 in the circuit as the schematics posted on the net.
Thanks in Advance for any Suggestions,
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|11/13/1997 10:47 PM|
There are several variations on the Reverberocket 2. Aspen Pittman's book [The Tube Amp Book] has the correct schematic. Ampeg usually favored a capacitance driven reverb. The Reverberocket is one of these. The pan should have an "F" as the second or third letter of the model #.[9F..... or 9AF....] Perhaps your pan is one of the more common transformer driven styles.[9AB....] The correct replacement can be gotten at Mojo Musical Supply or Magic Parts or New Sensor. Concerning the residual noise issue, try fixing the shielded reverb pan cables against the cab and as far from the speaker as possible. Thats right, these tube reverbs are fickle. Hope I've helped some!
|11/14/1997 6:38 AM|
I did do my homework when ordering the reverb tank. 4FB2D1B is the model I ordered. I going to bring my scope home from work and really get into it this weekend and see what the heck is really going on. The cables from and to the tank are routed as the original and are retained against the side of the amp, as far away from the speaker as possible. I'll keep you posted as to what I find this weekend.
Thanks for the Reply,
|11/14/1997 9:11 AM|
I know you said you checked the switch, but did you check the cable to the switch? Make sure its not acting like a big resistor. Also, and I hesitate to be the devil's advocate, I have bought about 20 pans so far this year and one of them was defective and another only lasted a short time. Hang in there.
|11/15/1997 8:35 AM|
I don't need the reverb part of the switch, although I need the tremelo. Maybe I'll disconnect it an see what happens. I did check the switch at the terminating point in the amp and it reads about .2ohms. Looks OK to me. Hopefully my family will be understanding and let me fool around with it this weekend. I just have to train my dog to keep his nose out of the circuitry .
|11/15/1997 11:04 AM|
I'm guilty of the misinformation over the net faux pas. There is only one known Reverberocket II. It's possible that you are holding a Reverbojet model J-12-R.[two 12ax7,one 6u10, and two 7591 tubes]
I am also a failed home dog schooler.
|11/16/1997 9:55 AM|
I too, am guilty of spread undeliberate misinformation over the net on occation also. The circuit you are describing sounds like my amp, however the schematic on the back of the panel calls the model GS-12-R, and the amp's front panel clearly calls itself a Reverberocket 2.
I used to work for MCI (not the phone company, but the recording equipment company). These guys were consistantly guilty of changing circuits without documenting things in manuals. It made it very confusing trying to help customers deal with technical problems over the phone. This was esspecially true if the product predated my employment there.
I bought this amp from an 75 year old man about 4 or 5 years ago, for $80. I am a keyboardist by trade, so I didn't use it much. I sold my guitar to pay some IRS bills a few years back. Now I bought a new guitar and am trying to get the amp in original working condition. The ouput tubes are still in real good shape. I guess the guy played accordian or something through it and never really pushed it (or hardly used it). The speaker (Jensen) was damaged in a recent move to CA. The braided leads to the voice coil were pulled out. I replaced it with a Celestion and it really sounds much better. The only thing left is the reverb issue, however, I recently ordered a back copy of Glass Audio with a mod to use 5881 or 6L6's with the amp. I hope the output xformer can handle this mod.
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