Dartanion! Thanks for the suggestion - Richie brought that up to me as well, and I'll definitely keep it in my tool box as I go along with this amp and others.
Also, thanks for making the transformers available - hope your remaining order came in OK.
Cheers,
Greg T.
2-EL84 Rocket Tribute with reverb underway
Moderators: pompeiisneaks, Colossal
Re: 2-EL84 Rocket Tribute with reverb underway
Great looking amp and glad you are enjoying it. 
Mark
Mark
Re: 2-EL84 Rocket Tribute with reverb underway
After several days, I finally connected a footswitch to the back panel jack for the gain boost circuit and gave it a whirl - outstanding! Thanks, Mark.
This amp still sounds great, but needs a little fine tuning on the tone - think I might play with voltages, and will post my voltage chart to see if anyone has comments. Definitely not a huge amount of clean headroom, and not super loud, but I'm comparing it to my MK Rocket, which it turns out, was eating output tubes because it was running them at 15watts each plate dissipation! First set was new production, then it went through some '80s Russian tubes that sounded great and never red-plated, but were obviously torching out. But that's another thread...
On the down side, I have discovered that my cabinet, as beautiful as it turned out, does not have enough space for me to mount the reverb pan where it doesn't hum! OH NO! Right now I'm using it with the pan sitting outside the amp, and I'll either have to build a separate box, or a new, larger cab. The standard size cab as shown in the files section just didn't work with this reverb build.
This amp still sounds great, but needs a little fine tuning on the tone - think I might play with voltages, and will post my voltage chart to see if anyone has comments. Definitely not a huge amount of clean headroom, and not super loud, but I'm comparing it to my MK Rocket, which it turns out, was eating output tubes because it was running them at 15watts each plate dissipation! First set was new production, then it went through some '80s Russian tubes that sounded great and never red-plated, but were obviously torching out. But that's another thread...
On the down side, I have discovered that my cabinet, as beautiful as it turned out, does not have enough space for me to mount the reverb pan where it doesn't hum! OH NO! Right now I'm using it with the pan sitting outside the amp, and I'll either have to build a separate box, or a new, larger cab. The standard size cab as shown in the files section just didn't work with this reverb build.
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Re: 2-EL84 Rocket Tribute with reverb underway
For headroom change the 220k plate resistor V1 to 100k-150k range. Or use a trimmer.
Regarding the reverb pan did you use the short pan? Make sure it is all the way over towards the preamp tubes away from the PT/OT more. Not a lot of room but I built mine in a Dr Z Route 66 cab with 16x8x2 chassis so even smaller then what your using.
I'm running 6550 tubes and no noise. Maybe I got lucky?
Mark
Regarding the reverb pan did you use the short pan? Make sure it is all the way over towards the preamp tubes away from the PT/OT more. Not a lot of room but I built mine in a Dr Z Route 66 cab with 16x8x2 chassis so even smaller then what your using.
I'm running 6550 tubes and no noise. Maybe I got lucky?Mark
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Re: 2-EL84 Rocket Tribute with reverb underway
Thank you, Mark - I'll make that resistor change and check it out. I like the trimmer idea, too.
My pan is 9.5" long. I tried it pushed all the way forward away from the preamp tubes, then toward the back, and moved it around near the transformers (most noise). The choke seems to cause some hum in the pan. Wonder if a grounded shielding plate would work? I wonder if your cab is a bit taller, and that extra height is what did the trick.
By the way, I like that metal mesh you used for the rear!
Greg T.
My pan is 9.5" long. I tried it pushed all the way forward away from the preamp tubes, then toward the back, and moved it around near the transformers (most noise). The choke seems to cause some hum in the pan. Wonder if a grounded shielding plate would work? I wonder if your cab is a bit taller, and that extra height is what did the trick.
By the way, I like that metal mesh you used for the rear!
Greg T.
Re: 2-EL84 Rocket Tribute with reverb underway
It's a real Dr Z Route 66 cab I bought 4 blemished cabs from doc a few years ago for my home projects. They come with that mesh on back.By the way, I like that metal mesh you used for the rear!
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Update after tweaking
Almost a year later, I think I've got this amp where I want it. While I was very happy with the overall build, there was something missing with the tone that I was having a hard time tracking down. Basically, it lacked the punch, volume and clarity of my regular Rocket clone, sounded thin and reedy, and compressed with the reverb turned up even a little. I just couldn't dial in the tone with tube rolling, settings, or even the V1 plate resistor change or boost circuit mod.
On a hunch, based on the higher preamp voltages in a Liverpool and my recent 18watt K60 build that turned out so well, I tried it first with the reverb tube pulled, then the pan, and both. Found out the sound was improved when the tube was out, and more so when the pan was disconnected.
So, I decided to look at the preamp voltages more carefully, and though they were close to expected, they seemed a bit low. I realized that while the PT was supplying more B+ than a Rocket was designed for, preamp voltages further down the rail could be bumped up. A change from 18.2k to 17.3k brought the string up 1-2 volts.
Big difference in performance now. Gainier, but with much improved tonal character. The compressed sound with reverb turned up is much reduced, and with it turned down, the amp has the character more expected with a Rocket - good punch and clarity, with the right amount of sag or compression at high volume. Last change was to switch from RJ's suggested 5.6k bass resistor to the stock 10k.
A couple more hours of playing will tell me if this hits the mark, but it's so much improved now.
Thanks to you all for the education!
Greg
On a hunch, based on the higher preamp voltages in a Liverpool and my recent 18watt K60 build that turned out so well, I tried it first with the reverb tube pulled, then the pan, and both. Found out the sound was improved when the tube was out, and more so when the pan was disconnected.
So, I decided to look at the preamp voltages more carefully, and though they were close to expected, they seemed a bit low. I realized that while the PT was supplying more B+ than a Rocket was designed for, preamp voltages further down the rail could be bumped up. A change from 18.2k to 17.3k brought the string up 1-2 volts.
Big difference in performance now. Gainier, but with much improved tonal character. The compressed sound with reverb turned up is much reduced, and with it turned down, the amp has the character more expected with a Rocket - good punch and clarity, with the right amount of sag or compression at high volume. Last change was to switch from RJ's suggested 5.6k bass resistor to the stock 10k.
A couple more hours of playing will tell me if this hits the mark, but it's so much improved now.
Thanks to you all for the education!
Greg