Ampeg Reverberocket GS 12

[Stevem]

Sorry, I should have posted to place a rap of tape on one section of each of the two long springs!

[goldenmonkeycolor]

You can buy a driver online as the post says above. It's called a "clutch head" screw.

As far as brightness, some of these had a bright cap, which can be snipped. The RWB Is a pretty warm speaker, so I'm a little surprised if the amp is bright with that.
I would check through the circuit carefully. They are bright amps, but not painfully so.

i found a100pf cap coming off pin 6 of v3 (12ax7) on the schemacitc that was missing from my amp so far. is that the bright cap? I added it back on but havent listened to the change yet

what else would be a bright cap on this schematic? I'm not seeing anything extra in my amp from the schematic- but there may still be things missing i suppose

http://el34world.com/charts/Schematics/ ... _gs12r.pdf

[goldenmonkeycolor]

Sorry, I should have posted to place a rap of tape on one section of each of the two long springs!

So put a 1/2" wide piece of tape like wrapped around each of the springs near the input? just one single wrap? how far down the spring from the start of the spring at the input side?

[Stevem]

It depends on how it sounds to your ear!
It seems to me like tape placed on the input transducer tames highs but does not deaden the depth of the verb as much as tape placed at the output side of the pan.

Just be very careful as I posted when removing tape as yanking on the springs too hard can snap that small hard wire locator at each end!

[FUCHSAUDIO]

Honestly, I silicone the wires at the jacks and transducers to extend pan life. I would tweak the reverb send and return electronically before I would mess with the springs in any way. You can’t undo a screw up, and I’ve never ever heard of this. I’m only doing this stuff for 40 years, so......

[goldenmonkeycolor]

Honestly, I silicone the wires at the jacks and transducers to extend pan life. I would tweak the reverb send and return electronically before I would mess with the springs in any way. You can’t undo a screw up, and I’ve never ever heard of this. I’m only doing this stuff for 40 years, so......

It actually worked really well lol. either the tape or the 100pf cap I keep mentioning that comes off pin 6 of v3 12ax7 and goes to ground. I realized that cap wasnt in my amp because it wasnt ever in there- the schematic (thats mostly ripped up) pasted on the inside of the cabinet definitely does not show this capacitor. Excuse my very limited knowledge but this is a high end snubber is it not? I put a 120pf in there- which would give me even more high end cut right? Or maybe I'm completely wrong and all of the treble reduction is from the tape on the springs.

I would much rather mess with it electronically. I thought I understood amps a little tiny bit when I worked with a bunch of fender blackfaces. I'm really not sure how I would mess with the reverb input gain on this amp because It does seem like the everb gets hit way too hard- I've never had an amp have the reverb react so much to turning up the volume. and its all this treble. I suppose I need to read up on exactly how this reverb circuit works. I know how to tame a fender's send and return. I really feel like lowering the gain going to the reverb would help me a lot- maybe something to do with a resistor (or variable resistor) in front of the reverb tank around the .47uf blocking cap there?

The amp is sounding TONS better now- thanks for all the help. just need to get that tremolo module.

I've taken out most of the ceramic caps and am waiting on some .005 poly film high voltage caps to finish the job of completely removing every ceramic cap from the amp.

Would it be wise to lower even more noise by using matched dale metal film resistors for the pairs of 1k and 270k at the power tubes? what are those called again... ugh i cant remember? maybe matching the .1uf caps too? if anyone wants to help?

are the plate resistors all the resistors coming off pin 1 or 6 of the 12ax7 (2 and 10 of 6u10?) preamp tubes? and the slope resistor is the 270k in the tone stack. I've had good luck using carbon comps in those positions to get warmth out of the amp (as opposed to a fender I tried mil spec metal films there and swear I could hear a difference- the metal films made it sound to sterile and sharp or something)

I'd really like to add a reverb tone control or dwell control to this amp. i think that would be so useful for me. Any ideas on that one?

[FUCHSAUDIO]

Pin 3 V4. The cathode cap can be removed and/or value reduced. You could also add a pot to the ground end 10-k (?) and it would allow variable dwell. You could also reduce the drive from the prior triode into v4.

And yes: a cap from pin 6 to ground would certainly be a snubber.

[goldenmonkeycolor]

Pin 3 V4. The cathode cap can be removed and/or value reduced. You could also add a pot to the ground end 10-k (?) and it would allow variable dwell. You could also reduce the drive from the prior triode into v4.

And yes: a cap from pin 6 to ground would certainly be a snubber.

so youre saying reducing the cathode cap on the 6u10 would reduce brightness or reduce gain? and thats putting a pot on the resistor in parallel to the cathode cap would be a dwell control?

Let me preface by saying I'm sure you know more than me, so maybe you can just help explain.

I was under the notion that decreasing the cathode bypass cap does decrease gain but it also causes the signal to be much brighter, as in you decrease the gain a lot more in the low end so the disparity between say 100hz and 10khz is much bigger.

Also I thought you had to have a cathode bypass cap and you woldnt get any signal without one?

I did a little research and wouldnt I be able to reduce the gain by reducing the plate resistor (again I'm not sure) or the 10k resistor coming off v4 pin 2?

Or is this all completely different because its a 6u10- or do i just not understand anything.... ughhhh

Thanks so much for the help guys

[sluckey]

If I was gonna put a dwell control in this amp I'd replace that 220K on V4-11 with a 250K pot, wired as a common volume control.

[FUCHSAUDIO]

If I was gonna put a dwell control in this amp I'd replace that 220K on V4-11 with a 250K pot, wired as a common volume control.

That would work fine. Perhaps a small tail resistor so the reverb won’t go completely off.

You can certainly run a circuit without a cathode cap, you simply get less gain. You could safely disconnect it and see if you like the reverb better.

Compactron tubes behave just like normal 9-pin tubes, just three sections in one bottle.

[goldenmonkeycolor]

If I was gonna put a dwell control in this amp I'd replace that 220K on V4-11 with a 250K pot, wired as a common volume control.

That would work fine. Perhaps a small tail resistor so the reverb won’t go completely off.

You can certainly run a circuit without a cathode cap, you simply get less gain. You could safely disconnect it and see if you like the reverb better.

Compactron tubes behave just like normal 9-pin tubes, just three sections in one bottle.

Well back to my original point- the reverb is too bright for me. so reducing the cathode capacitor wouldnt that cause a large jump in brightness. I put it in duncans tone stack calculator and it would be wayyyy brighter. What about reducing the plate resistor on the gain stage? that would reduce gain without changing the frequency response nearly as much, right?

[goldenmonkeycolor]

If I was gonna put a dwell control in this amp I'd replace that 220K on V4-11 with a 250K pot, wired as a common volume control.

Just to clarify-
a common volume pot? doesnt that use all three lugs- input, output, ground.

so a wire from the junction of the .1uf and 2.2m junction goes to lug 3, lug 1 goes to ground and lug 2 goes to pin 11 on the tube.

should I use shielded wire on the input or output?

Thanks so much cant wait to try this out!!!

I know i could just audition- but if you got an idea of what taper pot may work best let me know!

[M Fowler]

Add a 1MA tone pot with your mix pot.

[goldenmonkeycolor]

Add a 1MA tone pot with your mix pot.

Yeh! Okay!

[goldenmonkeycolor]

Pin 3 V4. The cathode cap can be removed and/or value reduced. You could also add a pot to the ground end 10-k (?) and it would allow variable dwell. You could also reduce the drive from the prior triode into v4.

And yes: a cap from pin 6 to ground would certainly be a snubber.

i've been trying to private message you about the tremolo module you contacted me about.

And i've been trying to ask you about your idea to reduce the cathode cap to help the problem with my reverb being much too bright (has too much treble content in the decay of the reverb)

Everything that I've read shows that reducing the cathode cap causes less lows and more highs to be passed through- while yes it will reduce the gain, it will also mostly reduce the low end content while the treble content hardly gets reduced at all.

I could be totally wrong. But wouldnt this make my reverb even brighter? Again maybe I dont know what i'm talking about at all, so please forgive me.