2 X EL84 Reverb Rocket

[KT66]

Finally got around to starting my 15W Reverb Rocket this weekend. It's in a Callaham chassis I picked up on Ebay a few years ago. The iron is a custom set I ordered from Heyboer a while back - standard 18W OT, 18W PT with a lowered HT secondary : 250-0-250, and a 20H choke.

I'll post updates as it progresses. Thanks of of course go to the usual suspects - Norm, Mark, Allyn, Dana, RJ et al for sharing all the great info here.

[M Fowler]

Looking great, your going to confuse the pack with the PI in the back row

[KT66]

Looking great, your going to confuse the pack with the PI in the back row

Thanks Mark. Ya, I was going to drill out another hole for the PI to put it in the normal spot and plug the extra power tube hole, but I thought I would save myself the trouble of having to do any more metal work to the chassis since I already had to make the cutout for the PT, cap can and extra panel controls.

[surfsup]

I see your layout is straying quite a bit from the normal layout most use. I also see the cap can. I have acquired two old tube hifi stereos, a sansui and vector research (one is my dad's he's had and the other was mine) that were in my dad's basement I just noticed last weekend. One has capcans, didn't look in the other yet. Was thinking about repurposing as both stereos still work so the cap cans should be good still. Hmm....

Thanks for the pics! I plan to start drilling this weekend for everything except the PT/OT and choke. I want to do the headphone trick first.

[dcribbs1412]

Looks cool
I'm actually using your layout of Marks 2 hole rocket
for a 2 hole reverb rocket...thanks
wondering about the "edge" pot in your layout
if you thought it was worth adding?

Thanks again

Darin

[M Fowler]

I like using cap cans when I can and never have had a problem with their use, less space is used up as well.

Nice to see some builds are coming up guys!

[KT66]

I see your layout is straying quite a bit from the normal layout most use. I also see the cap can. I have acquired two old tube hifi stereos, a sansui and vector research (one is my dad's he's had and the other was mine) that were in my dad's basement I just noticed last weekend. One has capcans, didn't look in the other yet. Was thinking about repurposing as both stereos still work so the cap cans should be good still. Hmm....

Thanks for the pics! I plan to start drilling this weekend for everything except the PT/OT and choke. I want to do the headphone trick first.

Yes, the layout does stray somewhat, but the Rocket is not sensitive to straying like an Express or a Liverpool. The choices I made on where to put what were dictated by the fact that I'm mostly using parts I had on hand already - the chassis, transformers, cap can, and board material. I some times use the headphone trick myself but didn't bother with this one because there isn't much room to move stuff around with all the components that are topside. If you really want to get crazy, and you have a scope you can use that instead of headphones to find the optimal OT placement position.

Looks cool
I'm actually using your layout of Marks 2 hole rocket
for a 2 hole reverb rocket...thanks
wondering about the "edge" pot in your layout
if you thought it was worth adding?

I do think it's worth adding for the simple reason that both Mark and Colossal like it and that's good enough for me. I have not tried it before though but would like to know what it's all about. It's a simple mod and the circuit is stock when it's set at max, so I figure no harm no foul if it turns out I don't like it, which I doubt. I gave it the "Edge" name because I was trying to avoid ambiguity in control names because I also have an adjustable power control ( read - power scaling) and sometimes those 2 features use the same kind of name. If I was planning this build again, I just would have bought Dana's VVR - the few bucks I saved by DIYing it are resulting in it being a big PITA. I know it is overkill to have a master and the edge control and power scaling but I haven't tried scaling before either and I wanted to familiarize my self with it because people ask me about it sometimes - I don't really need any of those features personally because I have a Hotplate that I like just fine.

I ran out of the 20 gauge solid that I like to use in the preamp so I am stalled now waiting for the order I just placed with Apex Jr. to get here, here's a pic of where it is now :

[dcribbs1412]

Thanks KT66
Mine is up and running(no reverb not sure what the problem is)
haven't messed with it much...
it sounds good with a strat...clean and sparkly
I added a Mid pot as per RJ+MFowler and the dwell pot from your layout
I just have to figure out what the reverb problem is( i did add a 22uf node for it)
tried 2 different tanks..it might be wiring..not sure if the reverb part of the layout is correct
voltages are all pretty close el84's are around 325..a little high I think?(pt is 275-0-275)
any suggestions as far as the reverb goes?
will post pics ASAP

Thanks

Darin

[angelodp]

Ryan, looking good. So you are going for the PPIMV ?

A

[ampgeek]

Hey Darin,

RE: Reverb troubleshooting. Follow the link below to about 2/3rds of the way down the page. See amp stethoscope description/principle of operation.

Its a really easy build and is an invaluable tool for focusing in on the location of problems in the signal chain.

It may not always "tell" you exactly what the problem is. But...it will always very quickly narrow down the area of the problem.

http://www.el34world.com/Hoffman/tools.htm

Good luck,
Dave O.

[dcribbs1412]

Thanks ampgeek
very cool link will have to put a few of those "tools" on my to do list
KT66 sorry if this is hijacking your thread...here's the pics of the build
so far using your layout...again thanks to you Normster MFowler and everyone else that has helped make this place a cornucopia of knowledge...
(ya I wrote that) FYI limited woodworking skills here...
not sure about the knobs...and still have to figure out the reverb problem...
Next up....

[KT66]

Finished the amp this evening except for the power scaling. Too late to fire it up, will try tomorrow and post a clip or 2.

DCribbs : Not hijacking at all, no worries. I agree with ampgeek, a signal tracer will help you nail down quick where the problem is - I'll post a simple way to do it in the thread you started. I like your drawer cab, it looks good.

Ange : ya, I thought I would try a PPIMV to see how I like it with this circuit. Just a standard volume control voltage divider thing using a dual ganged pot to replace the power tube grid load resistors. I haven't had the panel made yet, so I am not committed to any of the extra controls . I installed the turret board for the power scaling, but I might just ditch that idea, I haven't decided yet.

[Cliff Schecht]

The PPIMV works beautifully on Rocket type builds. I use dual 500k pots paralleled with either 1M or 1.6M resistors (the slightly larger resistors give it a nice feel IMO).

[M Fowler]

Nice builds guys.

[dcribbs1412]

Looks great KT66
how's it sound? reverb working?
interested in what you think about the master
looking at your pic does the treble pot connect to the cut then to dwell pot?
which would be different than the layout

Congrats on the build

Darin