Gibson Falcon RVT-19

[andyjazz]

I've had this amp for quite awhile, '62 Falcon. Inherited it. It was the reason I started working on my own amps because the local guy I took it to years ago did such a half-assed job I figured I'd give it a try. The reverb has always been kinda lousy. I always figured it was because of the old 7199 pentode/triode misbehaving. Recently when I tried the reverb it just made an awful loud buzz-like something is just shorting to ground-figured the tube finally went (I have an old tube checker, but no clue as to how to set it for a 7199). Anyway I figured I'd just get a new 6u8 and change the tube pinout and be done with it. I open the thing up and there are no connections to the pins for the pentode at all! Pins 2,3,6, and 7, have nothing connected - well I guess that's why the reverb won't work! I'm trying to remember if I disconnected them awile back? -sucks to get old.

So anyway, as far as I can tell it looks like the triode half of this socket is connected but not the pentode. So I guess I'll wire up the missing half but I'm having a hard time tracking thru the schematic and then looking at the chassis to see what wires I'm looking at. For instance pin2, which is the plate for the pentode looks on the schematic like it comes from a 470k resistor thats in series with a 10k resistor which is in series with a bunch of other stuff and in parallel to a 1.5M resistor. It sure aint like having a printed board with labels and everything. How the hell do you guys do this stuff? Am I on the right track?

[ric]

Andy I have a GA15RVT and I can tell you how mine goes. I got the schematic from Gibson, but I imagine someone here can link you. The RVT15 has a cathode drive reverb send. It sounds very good and I use my variant of it for my builds. It didn't use a tranny. It resembles a concertina splitter in that a drive stage plate is coupled thru a cap to to the cathode follower. The CF has it's plate direct to B plus. The grid is tied thru a high value resistor(1M) to the junction of the cathode resistor and a 10k to ground. That junction feeds the reverb out to pan thru a cap. So low impedance/transformerless reverb. I have no idea if yours is the same, but the parts sound similar.

[andyjazz]

yeah, I have a schematic. One from the tube amp book. Just not very good at making the connection to what's on the schematic and the layout of the amp. I've worked on a few amps but this layout is really confusing.

[ric]

I see. Thought since the reverb on mine is nontraditional n yours mite b similar it mite help. One of the pros here can get you pointed in the rite direction, I'm sure. Best of luck with it.

[g1]

Without some high res. gut shots, not much help available "over the phone" so to speak.

[Leo_Gnardo]

Despite schematics there's all kinds of variations in this series of Gibson amps. They were made by job shops, and as long as the amp made sound and had working reverb & vibrato, it got sold. Looks like whoever built it used the pokey triode of the 7199 and didn't need the pentode side so didn't connect it. They could have used a 6C4 or one triode of a 12AU7. Can't say I've ever seen that one before but anything's possible.

[nsubulysses]

If you are able to view these pics this might help. Not sure if you have the same amp but let us know. The one I worked on did not match the schematic. I had to use a Maestro M-216 RVT schematic

Gibson GA 19 RVT

Edit: Actually I guess it seems like you have the later version. This thread may help. It has pics of all 3 versions. I believe version 1 and 2 are electronically identical but the 3rd version has the 7199 to drive the reverb. Anyway let us know and then these tech gurus will sort it out I'm sure. FWIW, my reverb problem was a bad reverb transformer. Once it was replaced it had a nice sound. Might be a good idea to check voltages on the 7199 and make sure they are correct.

http://forum.gibson.com/index.php?/t...-rvt-19-watts/

[andyjazz]

@Leo-gnardo
Upon further review I see that the "in" to the reverb tank comes from the triode side of the 7199 socket. The return from the tank goes to one side of V3. So whoever wired it I guess just used half of that 6eu7 (V3) to amp the recovery from the tank. I'll be doing some checking on whether that 6eu7 is ok before continuing. Since I have a brand new 6u8 I could always just rewire the 7199 socket for it and give a try. I've tried twice now to upload a photo but pc keeps freezing up.

[andyjazz]

After retouching some questionable looking solder joints I have got the existing circuit to function. The reverb tank is one I stole out of an old Conn organ. The original is long gone. Anyway the reverb is functioning in this wiring set up that I mentioned above - using half of the 7199 and half of the 6eu7 at V3. Not what the schematic says but.....oh well. The only problem is......it just sucks. Not a good reverb sound. I'm considering what to do at this point. Looking at the tube sockets on V1 and V2, they look old and crappy. I might consider putting new ones in and in the process rewiring the 7199 socket for this new 6u8 that I bought. Maybe a new tube would help? It could be that the original transformer in the reverb circuit is to blame for the shitty reverb sound? - I dunno. I might just put it back together and buy a Holy Grail pedal and be done with it. Thanks everyone for your interest and your input!

[Leo_Gnardo]

The only problem is......it just sucks. Not a good reverb sound. I'm considering what to do at this point. Looking at the tube sockets on V1 and V2, they look old and crappy. I might consider putting new ones in and in the process rewiring the 7199 socket for this new 6u8 that I bought. Maybe a new tube would help? It could be that the original transformer in the reverb circuit is to blame for the shitty reverb sound? - I dunno.

Some tanks just don't sound good - and you won't know until you swap in another and audition it. You can't panel-beat a lousy sounding tank into sounding good no matter what tubes, transformers etc. I used to buy a dozen at a time. Some sounded magnificent, some were just awful, same manufacturer same batch. And that was in the "glory days" of USA made Accutronics.

[davohilts]

I would buy a new MOD tank to match your amp. The cost about 18 bucks and with a new tank you will be surprised at the difference. I am not sure which tank will work for you, on my 19rvt the reverb transformer was doa so I bought a new fender style transformer and replaced both the transformer and tank. good luck!

[andyjazz]

@davohilts. Yeah this tank I robbed out of an old Conn organ. It sounded great in the organ but not so good in the Gibson. I'll probably buy a new one or screw around with some other tanks. I already replaced the output transformer with a Mercury Magnetic. This amp also has the original speaker-something some people think is the cats meow, I'm not that impressed. Thinking maybe get a new Jensen, get better low end and more headroom.