Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: Diverted on July 26, 2018, 09:39:27 pm
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Hi all,
I'm kind of interested in trying to build an Ampeg Reverbrocket2. This amp seems really interesting to me and I've been reading some great things about it. The ability to have tremolo and reverb with only five tubes including outputs is pretty amazing (one of them is a triple triode 6U10 which I have no experience in, which is partly what interests me).
I have a correct output transformer for a pair of 7591s, the right tubes in stock to make it work (except for the6U10 which is cheap), etc.
Here's the schematic:
https://el34world.com/charts/Schematics/files/Ampeg/Ampeg_gs12reverbrocket2.pdf
I do have a few questions:
1. Am I right in seeing that there is no reverb transformer on this amp?
2. What is TM-10, at lower center of schematic. And the X and Y points are confusing to me. I don't see where the connections go to unless I'm just missing them.
3. What type of reverb spring would I need for this amp?
I would love to hear from anyone who has worked on one of these, owns one or built a clone. This seems like it might be a really fun build but want to make sure I'll be able to find the parts and be able to follow through with it.
Thanks!
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I do have a few questions:
1. Am I right in seeing that there is no reverb transformer on this amp? yes
2. What is TM-10, at lower center of schematic. And the X and Y points are confusing to me. I don't see where the connections go to unless I'm just missing them. That's the tremolo optocoupler. X and Y connect to the Intensity pot . Look at the upper left.
3. What type of reverb spring would I need for this amp? Hi-Z input and Hi-Z output
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I have been a fan of the amp for years. During the early 70s the stones recorded exile and sticky fingers. In reading, Ronnie was not happy with the verb, so they used studio verb which is common.
I am sure you played the amp, right.?
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Thanks for all the help. Ah yes, I overlooked those connections. I figured that was the optocoupler but was not sure, since it would need one with the cathode bias.
Nope, I haven't played it. Have never even seen one actually. I'm going into this strictly because a friend and I were talking and he mentioned how he used to have a 60s Ampeg Rocket (not sure if reverb or not) and I'd never seen a schematic, so I looked it up. Couldn't figure out what was going on with the layout/schematic until I looked up the 6U10. So it's kind of an intriguing thing and I may build him one as a surprise birthday gift (birthday in about a month). I have everything I need except for the octocoupler and reverb spring.
Can anyone tell me where I could source the correct spring? And can I use the optocoupler found on the Hoffman page?
Thanks!
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I think the fender tremolo bug will work, but no guarantee. Here's the spring...
https://www.tubesandmore.com/products/reverb-tank-mod-9fb2a1c
or
https://www.fliptops.net/catalog/p-100453/reverb-tank-type-c-most-vintage-ampegs
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Beautiful. Thanks! This should be fun. I have a Fender Princeton chassis laying around so it's going in that.
Once I get going will post some photos. Maybe a week or so.
The only change I think I'm going to make is tube rectification. I don't have a power transformer laying around that has voltages low enough for solid state so I think it'll have a 5U4 but we'll see.
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7199 is pretty much mined-out. $80-$100. Gah! $24 for an adapter to use a more common type in a 7199 hole!
I too admire low bottle count. But when an amp needs three un-common types (7199, 6U10, 7591) it gets a bit risky for long-term playing.
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Yes, this is true. Luckily I have a decent stock of 7199s, and Ampeg also made another version of this amp with a 12ax7 so I may build that one instead. And while I’m not too familiar with 7591s, I hear they are quite durable. Looking at the voltages it doesn’t look like they will be driven super hard so hopefully they will last. Could always modify output stage for 6L6s, though I hope not to do that.
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If you have not played the amp, take a hard look at Sluckey's Hampeg. It is absolutely wonderful, responsive, quick. If you really want to know what your guitar sounds like try this amp.
Now Sluckey was proud of his Supro and loads of folks built his TDR, and I did too. Didn't pay much attention to his conversion of the AO-63, but the tremolo is great. The Celestion loaded SUNN cabinet goes very will with it.
He called it a Hampeg, because he used a Hammond amp to build an ampeg gemini. I am planning one, but I am not in a hurry. Soon as Sluckey gets enough Icehouse in him and decides to play Cream at concert volumes with it and they haul him off to jail, I will just get that one.
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Hey! I resemble that remark!