Let's build an amp! Greg's journey to electrocution

[Greg_L]

Thanks guys. I really appreciate your support and encouragement and following along with this monster task that I'd never done before. I've been thinking about this for years. It's finally come to fruition. It has consumed me for the past month. My mind has never been too far off of what I've got to do next on this build and how I'd do it.

But we're not really done yet. I've still got to do lots of tone clips and put this thing to work. We may need to go back in for some touch-ups or something. I do still want to add the bias test points, and new power tubes are coming soon. But the bones are done. This thing is a functioning amp.

JD, I think this amp would definitely do SRV tones with the right player and, of course, a Strat. I can't do SRV tones. I don't know any of that shit. But this amp has that DNA in it.

The controls....
The amp has two channels. Normal and Vibrato. The Normal channel has one less gain stage and no reverb/tremolo. You could think of it like a clean channel. The Vibrato channel has an extra gain stage and the reverb/tremolo functions. It is actually "TREMOLO". There is no Vibrato on this amp. It's Tremolo. Anyway...the two channels are typical "Blackface" Fender circuits. This amp is a clone of the classic AB763 Blackface circuit that you'd find in mid 60s Fender amps. The inputs are kind of like Marshall inputs, but this amp cannot be be channel-jumped. The two channels run out of phase with each other. There are tweaks that can be done to give the Normal channel the reverb and tremolo effects, but I'm not doing that. The input jacks, 1 and 2, for each channel are different sensitivities. The 1 jack is a little "hotter" than the 2 jack....like a Marshall....which is actually copied off a Fender. Neither channel has a Mid control. The Mid control is fixed in the tone stack. Ummmmmm, what else......typical bright switches for each channel that you might find on any amp. They're just a little bypass cap to shelve off some lows if you want. Reverb is reverb. It's obviously got a real spring reverb tank and I love that. The reverb actually runs in parallel with the guitar signal. The signal is split after the second gain stage, some of it goes to the reverb circuit, and it gets blended back into the dry signal later. The tremolo works sort of the same, but it comes much later in the circuit.

The thing that really opened my eyes on this amp is how complex it is when you think of it in regard to when it was designed. This is an early/mid 60s design. It's got a lot going on compared to other amps from that time period. And it does it all with tubes. No transistors, obviously no digital effects, it's all wires and tubes and caps and resistors. Pretty amazing.

[Lt. Bob]

I've missed this and don't want to go thru the whole thread to find it ...... what power tubes and wattage?

[Greg_L]

I've missed this and don't want to go thru the whole thread to find it ...... what power tubes and wattage?

6V6 - 22 watts

[WhiskeyJack]

That is impressive man. Hella impressive. I can only imagine the rewarding full fillment you must have right now man. Holy fuck.

For some reason i had it in my head it was going to be a combo amp but it's you. I should have known better. Looks awesome. purple tolex is deadly. It looks right at home with it's cousins.

Very stoked to hear what that rig can do Hombre.

[Bubba]

This has been an excellent thread to follow. What I'm most impressed with is your ethos during the build, Greg. The routing, the quality of soldering, the continuous testing and checking that everything is performing exactly to spec has left you with an amp build that is of professional quality. I suspect that somebody could throw this kit together without all your planning, meticulous testing and skill and they may even end up with it working if they're very lucky but it would not be a patch on what you've accomplished.

Very, very well done.

[JD01]

Cool. Not that id ever expect you to play SRV tunes, was just wondering what sort of thing it was. Looking forward to hearing it properly cranked.

[Greg_L]

That is impressive man. Hella impressive. I can only imagine the rewarding full fillment you must have right now man. Holy fuck.

For some reason i had it in my head it was going to be a combo amp but it's you. I should have known better. Looks awesome. purple tolex is deadly. It looks right at home with it's cousins.

Very stoked to hear what that rig can do Hombre.

Thanks man. Yeah I have no use for a combo. The plan all along was to have this built as a head to be used with my Marshall cabs. That's why I had to use a different output transformer and finagle that impedance selector switch to work. Fender stack? Sure! I can do it now.

This has been an excellent thread to follow. What I'm most impressed with is your ethos during the build, Greg. The routing, the quality of soldering, the continuous testing and checking that everything is performing exactly to spec has left you with an amp build that is of professional quality. I suspect that somebody could throw this kit together without all your planning, meticulous testing and skill and they may even end up with it working if they're very lucky but it would not be a patch on what you've accomplished.

Very, very well done.

Thank you man, I appreciate that. Since I don't/didn't really know what I was up against I have to assume that my slow and steady attention to every little detail is why I have a working amp and not a pile of parts with problems. I can honestly say that I didn't let anything slide. I'm satisfied with my work on every single wire and blob of solder. Besides my one terribly boneheaded tube socket fuckup, it's ended up pretty much perfect. I expected to be chasing down bugs for weeks. But it seems that so far I've dodged that bullet. Maybe it's beginner's luck, maybe it's my careful attention to detail, but whatever it is I'll take it.

I've read many horror stories from people building these amps and then I see their pics and I'm like, no fucking wonder. It looks like a 5 year old built it. You CANNOT just throw these things together. But if you look at the guts of an original 60s Blackface Fender, they look like total hell inside, so who knows. Lol. Whatever.

Cool. Not that id ever expect you to play SRV tunes, was just wondering what sort of thing it was. Looking forward to hearing it properly cranked.

I can try some SRV, but that would be a massive LOL.

[Greg_L]

Hold the phone, I think I found a problem.

My #2 jacks seem to be hotter than my #1 jacks on each channel. That aint right. I did something goofy with my jack hookups. Dammit.

That stupid layout diagram bit me again. The schematic and diagram are different.

[JD01]

Shit a bollock! Easy fix?

[Greg_L]

Shit a bollock! Easy fix?

Shouldn't be too bad. I know what I need to do.

[JD01]

Shit a bollock! Easy fix?

Shouldn't be too bad. I know what I need to do.

That's alright then. I was worried (fuck, I'm worried about your project) that it would be something that you'd have to hunt for!

[Greg_L]

That's alright then. I was worried (fuck, I'm worried about your project) that it would be something that you'd have to hunt for!

No no, I'm just trying to decipher if my way of wiring it still functions as it should, but with the jack's roles just being reversed.

I'm okay with 2 being the high input and 1 being low. That's fine. But I need to know that the impedances are correct.

[Greg_L]

Okay so I measured across a guitar cable plugged into each jack. My 2s are measuring at 1M and my 1s are measuring around 118k....which is about right, but they are backwards to what I thought they should be.

So my 2 is indeed the high input, and 1 is the low input. No big deal, and I understand why now. I think I'll just leave it.

[rayc]

My 1st thought on thta fault was label & leave - just leave works too. Excellent journey with no hair tearing or tears on my part.

[jonny deep]

Nice work, Greg! Look forward to hearing it.

[Greg_L]

My 1st thought on thta fault was label & leave - just leave works too. Excellent journey with no hair tearing or tears on my part.

Nice work, Greg! Look forward to hearing it.

Thanks dudes. Tones coming today!

[JD01]

Thanks dudes. Tones coming today!

Cool - I imagine its a bit early in the morning there to go cranking amps. Looking forward to it though.

[Greg_L]

Cool - I imagine its a bit early in the morning there to go cranking amps. Looking forward to it though.

It's 6 am. Lol. I could do it. I can do whatever I want. But out of respect for the rest of the family, I'll wait a little while.

[JD01]

Cool - I imagine its a bit early in the morning there to go cranking amps. Looking forward to it though.

It's 6 am. Lol. I could do it. I can do whatever I want. But out of respect for the rest of the family, I'll wait a little while.

Would make an excellent alarm clock.

[liv_rong]

Excellent work man! Can’t wait to hear it.