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

[Greg_L]

UNROOL.
Could be a return to your psych/surf/abilly days.
I will worry if you buy a tele.

Lol. That will not happen. Gretsch...probably. Jag....maybe. Tele...no way.

Nice man!

I know it’s not time yet, but any initial first impressions?

No, not really. Not yet. My first impression is that it makes sound, and that's good enough for right now. I can't tell much from a single speaker, not even in a cab, laying face down on a towel. Lol.

I did try the Tremolo real quick, and it works. So that's cool.

[einstein magoo]

Excellent!

[muttley]

Uber cool man.. I'm a confident guy when it comes to building stuff but I would never have done this so quick and cleanly. Respekt

We just gotta get a rebels build only tune out there some how.. Your amp, your tune, your style, with a muttpup or two and a nice mutt axe... Maybe some of them peddles Dan is building...

[Greg_L]

Uber cool man.. I'm a confident guy when it comes to building stuff but I would never have done this so quick and cleanly. Respekt

We just gotta get a rebels build only tune out there some how.. Your amp, your tune, your style, with a muttpup or two and a nice mutt axe... Maybe some of them peddles Dan is building...

Haha yeah. I've got the drums and bass laid out for a song using this amp and my G90. It's just waiting for me to finish it. I'll have to add more to it now.

[Tadpui]

Nice going Greg! What an accomplishment. I hope the rest of the amps circuits are as good too!

[einstein magoo]

Sweetly glowing tubes and low noise hiss = nearly time to "dime" it damnit!

[Greg_L]

Nice going Greg! What an accomplishment. I hope the rest of the amps circuits are as good too!

Sweetly glowing tubes and low noise hiss = nearly time to "dime" it damnit!

Ha yeah, thanks dudes. We're getting really close now.


Did a little more dicking around this morning. More bench testing. This is my test setup - an exposed reverb tank, a single speaker not in a cab, and the footswitch. Gibson SG with my Mutt G90 not pictured.


So just like this, as it sits in this goofy configuration, it all works. Reverb, tremolo, channels, everything. It works. And it sounds pretty fucking good even just sitting like this. I just sat there playing it for like 30 minutes.

Nothing blew up, nothing popped, nothing burned the house down, so I think I'll move on to recording all of my voltages. I need to make a chart of where everything is at and compare mine to known good AB763 readings. So I'm gonna do that now and then we'll start getting the cab ready for the chassis and reverb tank.

[Greg_L]

Okay you sumbitches....

With everything passing the voltage tests, I gotta put the cake pan over these filter caps. Cake pan and tube shields.





Time to do some work on the head cab. I'm shielding the top underside of this thing with shielding tape. The chassis sits in here with it's mouth wide open to every sort of electromagnetic radio nuclear cosmic interference there is, so this shielding tape should help "farady cage" the chassis. This is just the first strip. The whole thing will be shielded and the chassis will make contact with the shielding to complete the "cage".



Next up, I gotta find a way to mount this reverb tank. I don't have a "bag" for it, and I don't want to just screw it down to the chassis, so industrial strength velcro to the rescue. This shit worked great! The reverb tank is secure and sort of cushy insulated off the wood of the head box.







Backside all buttoned up with footswitch.



And.........here it is. Done!









IT'S FUCKING FINISHED!


And let me tell ya......this thing sounds awesome! I got it hooked up to a 16 ohm Marshall 4x12 cab just like the plan was all along, and this thing sounds fucking killer. The reverb and tremolo work flawlessly. The footswiching works perfectly. Every pot and switch performs perfectly. And it idles quieter than any of my Marshalls. This amp is silent. You can't even really tell it's on. All of my grounding and shielding weirdness seems to have paid off. Greg wins!!!!!

The only issue I'm having is the power tubes are not matched very well. They're drawing about 10mv difference in current, but that'll live for now. No big deal. The discrepancy follows the tubes when I move them around, so I know it's a tube issue and not something in the circuit. New tubes should cure it....if it even matters at all. And I stripped the set screw on one one of the tone knobs, so blah, whatever. This fucker works!

[einstein magoo]

Congrats! Well done! Looks great!

[Minerman]

Cool Gerg!!! I'm very impressed with your skills man, it looks great to say the least...

How gain-y is that thing??? I'm assuming it's basically like an old school Marshall where you have to crank it to get the goods...

Throw us some clips when you get time...

[Greg_L]

Congrats! Well done! Looks great!

Thanks!

Cool Gerg!!! I'm very impressed with your skills man, it looks great to say the least...

How gain-y is that thing??? I'm assuming it's basically like an old school Marshall where you have to crank it to get the goods...

Throw us some clips when you get time...

Thanks dude.

It's not very gainy. It'll get to a pretty mean crunch when cranked, but it doesn't go anywhere near the grinding roar of a full-tilt Marshall. I've only tried it with my SG with the G90s though....and that was mostly for testing to make sure it all works. I haven't really dug into it's tone options yet.

[Tadpui]

That's BAD ASS man! Seriously, that's some next-level guitar nerd bad assery. Looking forward to hearing it roar!

[Lt. Bob]

How gain-y is that thing??? I'm assuming it's basically like an old school Marshall where you have to crank it to get the goods...

No !

It's a Fender circuit ...... no Marshall tones lurk within.


Looks badass greg

[rayc]

I like the labeling - it is a nice counter to the everything perfectcness - and it's tidily done anyway.
Well done on the whole thing but most particularly on the inherent problem solving to solve unaddressed design flaws and prevent others.
Your brain is good man.

[JD01]

And.........here it is. Done!
[URL=http://s29.photobucket.com/user/whodat6 ... e.jpg.html]

That's really excellent, mate. Looking forward to hearing how this thing sounds.

Can you explain to us what all the inputs do too.

So this amp do the SRV thing if you stick a TS9 in front of it?

[muttley]

Ear protectors on standby here mate... Lets have some clips...

Frankly Id sooner have that than one of your Marshalls but I'm a Fender guy when it comes to amps... Nice work. Next one you build the cab too...

[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.