Reverberocket II GS-12R sounds, mods, reverb etc

[claytushaywood]

I have a mid 60's gs12r reverberocket ii. I've post about the tremolo being broken before, but I have some more questions regarding the circuit and tone. I can solder and I know a bit about electronics (and how to not shcok myself on an amp), but not nearly enough to look at a schematic and go yeh this is what I can do.

First- I cant get very much low end bass out of the amp- The bass pot works and adds bass, But I usually have it maxed with the treble at noon or less (i do play a strat) I thought these amps were known for having some serious warmth- is this how its supposed to sound- is the warmth description just mean its mostly mids? I cant get anywhere close to a princeton reverbs bass levels. Any mods I could do or maybe I need to replace the original caps in this part of the circuit? It should be noted that I even have a newer eminence red white and blues speaker in this amp now- maybe not the best choice but its definitely capable of putting out some low end.

Reverb is super bright- I know this is how these amps are, and I think my friend got on here a while back and posted about taking some of the highs out of the reverb decay, but I still think the reverb is way too shrill. Anyone know a quick way to tame the icepick reverb decay?

The multi cap can--- Someone soldered 2 extra 20uf caps to the lugs of the can cap at some point- they look old, but not 50 years old- more like 15. I'd like to replace them though- would I be better to buy the super expensive cap can and try to rewire it, or should I just replace these caps as they are- amp seems to be working pretty solidly- (except my lack o bass)

and someone sell me a tremolo module plz!!!

Thanks a bunch- Any info on mods and I will report back my subjective findings on how they sound.

[claytushaywood]

Also- anyone tell me what bit size the clutch screws are on these old ampegs? is it 5/32"? Trying to get a bit

[jjmt]

First, I wouldn't think about modding the amp until it is working right. A lack of bass could easily mean that the electrolytics are bad, and since you're already looking at that, I would suggest replacing them. Don't forget all the cathode bypass caps.

Second, if you don't want to spend the money for a cap can (and yes, they are rather pricey) you might consider restuffing it. I did that recent with my Ampeg 835. You can find the thread in the 50s forum on this site. It's not really hard, but you'll need a Dremel or something to cut the can open. There are suggestions there for caps that will fit inside the can.

[claytushaywood]

First, I wouldn't think about modding the amp until it is working right. A lack of bass could easily mean that the electrolytics are bad, and since you're already looking at that, I would suggest replacing them. Don't forget all the cathode bypass caps.

Second, if you don't want to spend the money for a cap can (and yes, they are rather pricey) you might consider restuffing it. I did that recent with my Ampeg 835. You can find the thread in the 50s forum on this site. It's not really hard, but you'll need a Dremel or something to cut the can open. There are suggestions there for caps that will fit inside the can.

Yeh youre probably right. I read through your thread and followed your links but I didnt find any info about restuffing a cap can besides you saying that you might do it. Maybe I'm missing something? one of the links you posted doesnt exist anymore.

[jjmt]

Yeh youre probably right. I read through your thread and followed your links but I didnt find any info about restuffing a cap can besides you saying that you might do it. Maybe I'm missing something? one of the links you posted doesnt exist anymore.

Look at post #7. There are some pictures as well, you just have to follow the links.

[jjmt]

I concur with slider on this one. Given the existence of a drop-in replacement can, doing anything else would be a less desirable plan-B.

I usually get frustrated with cans when there are only 55 degree cans available, or when the correct values are not available, or (as in the case of my 835) when I am on a budget and need to buy more than one.

[claytushaywood]

Well-.....

I had already ordered the regular caps when I saw your guys posts. unfortunately. I've had bad experiences with can caps- and I've heard bad experiences. and I got some F&T caps for cheap.

I probably would have ordered the cap if I could have just dropped it in- but somebody has already messed with the cap wiring so I'm gonna have to spend some time on it anyways.

On that note- the schematic pasted to the inside of my cabinet has had the bottom portion torn away.

I've found a few pictures of a schematic that looks like mine, but they are severely poor quality and I cant even really read the values on a lot of parts.

DOes anybody have a decent resolution of the 1966 GS-12R reverberocket ii.

It has the 7591 power tubes, 6u10, and 12ax7's.

Mine has a single 40uf cap on the board (instead of the 2x20uf thing I've seen on others)

You all think I should use some terminal strips to wire these up? I'd appreciate some help during this process- but I'll probably report back in a week.

Thanks for the advice, sorry I missed it- I gotta get my email notifications worked out.

[jjmt]

Well-.....

I had already ordered the regular caps when I saw your guys posts. unfortunately. I've had bad experiences with can caps- and I've heard bad experiences. and I got some F&T caps for cheap.

I probably would have ordered the cap if I could have just dropped it in- but somebody has already messed with the cap wiring so I'm gonna have to spend some time on it anyways.

On that note- the schematic pasted to the inside of my cabinet has had the bottom portion torn away.

I've found a few pictures of a schematic that looks like mine, but they are severely poor quality and I cant even really read the values on a lot of parts.

DOes anybody have a decent resolution of the 1966 GS-12R reverberocket ii.

It has the 7591 power tubes, 6u10, and 12ax7's.

Mine has a single 40uf cap on the board (instead of the 2x20uf thing I've seen on others)

You all think I should use some terminal strips to wire these up? I'd appreciate some help during this process- but I'll probably report back in a week.

Thanks for the advice, sorry I missed it- I gotta get my email notifications worked out.

I've been looking at this schematic:

http://www.kbapps.com/audio/schematics/t.../gs12r.php

Without seeing into your chassis, it's hard to suggest a layout plan for individual caps. In the R12R it's typical to zip-tie a couple caps off to the side and then run wires to resters mounted on the board. Need to have space on the board for that, however.

[claytushaywood]

So. I put two terminal strips on the back side of the chassis. I left the can in place though for looks from the outside.

The amp sounds fantastic now! Reverb is still too bright despite my attempt to turn that .002 cap off the echo pot to .003uf

However I have some new noise. It gets louder when I turn up the treble knob. And the overall noise level of the amp is barely affected by going between single coil and humbucker pickups. I was thinking it may be a ground loop because I left the cap can on and some of the ground connections tom still go there but I’ve grounded most of the filter caps to the terminal strips that I bolted to chassis with star washers and whatnot.


Could the noise be from having filter caps too close to each other? Or maybe I screwed something up while replacing the ceramic caps in the tone stack (I took out a bunch of ceramic caps that looked bad). I also took out the 1 watt 470ohm resistor that connects to one of the filter caps. And replaced it with a 5 watt cement style resistor. Should I ground everything to chassis?

As I said it does get a bit louder when I turn up treble knob but not a ton. When the amp is cranked and I’m playing it’s really not terribly loud. But it’s definitley not right.


And again. Anyone have any ideas on taking he ultra bright reverb decay?

Thanks!!!!

[claytushaywood]

It's not a good idea having a power supply cap mounted right above the power tube. The heat given off by that tube will cause a problem. It also looks like that may be the original bias cap next to the 140 ohm bias resistor? If it is, it should be replaced. As for the reverb tone/decay, check the spec of the resistors in the reverb circuit and try a couple of different 6U10 tubes.

Its not right above the power tube- there are about a hundred amps with worse filter cap locations... i dont know why you think this is so bad- maybe repeating what someone else said? all electrolytics are new.

I was asking about noise and a potential lead dress problem or grounding problem- as well as reverb.... so you're telling me I should change the 6u10 to get less treble in the decay of the reverb??? I should just go buy a few 6u10's and try em and see if that helps?!? what kind of terrible advice is that? i'm sorry but I'm by no means an expert at this stuff, but you're posts are just pointless


so I had a few things going on- If you have noise in your reverberocket check out all those crazy lead wires- it has terrible lead dress and design but it can really stay pretty low noise as long as those leads are in the right place. I also had a ground loop. The amp is super quiet now and is definitely getting to where it needs to be.

I studied the schematic and I decided to try increasing the .022uf capacitor that goes to ground right after the .47uf cap (both right in front of the reverb tank on the schematic) I increased the .022uf to ,047uf and this does take some of the highs out of the reverb decay to make it not so ridiculously piercing. (i have an eminence red white and blues which is more like an older fender jensen style speaker rather than the piece of garbage that comes in a standard reverberocket- the OG speaker probably tames enough highs and upper mids to not make the trebley reverb a problem with most people.

so there's one option- something else I tried was adding another cap in parallel with the .002uf cap that comes off the echo potentiometer. I added a .003uf in parallel and it seems like it decreased the super long decay of the reverb. But it may also be cutting highs a bit... not really a bad thing either.

Anyone have any good recommendations for just taming the overall shrillness of this amp? I never put the treble knob over 40% of the way up- and I mostly crank the bass all the way with my strat or turn them both way down to try to get the mids up.

I still feel like the decay of the reverb is super intense and its super bright and ringy. I'm by no means smart enough to look at a schematic and do more than oh i think adding capacitance or lowering resistance here will decrease treble...

So if anyone has any ideas- like real ideas- id really appreciate it- even if they're guesses (just as long as they're beyond go buy a bunch of tubes and see if something changes)

Also- i've read pages and pages of terrible, terrible, terrible reviews of these CE brand and other Cap Cans. Do yourself a favor and replace cap cans with regular big boy electrolytics whenever you can. Putting them in the vicinity above a pair of tubes in a well ventilated cabinet is not a big deal. Have you ever seen a vox ac30? whoever is spreading the fear of heat in ampeg reverberockets has no idea what theyre talking about