The Ampegs

[Greg_L]

I'm gonna use this thread to document the Ampegs @Lt. Bob gave me.

I've been working on them pretty steady. I've got one of them totally restored.

The Ampeg V2. 60w head. Two channels (which are seemingly identical), crazy active tone stack with tube driven midrange...how insane is that? Very. Really nice spring reverb and a very usable master volume. The head by itself weighs more than most combos. This is a very nice amp.



First thing I did...visual inspection. Gotta wrap my head around these weirdo amps. They're very unique and interesting.


The reverb tank is bolted to the top chassis shield.


The schematic is actually affixed to the top shield. So awesome. Ampeg cared about their amps being serviceable.


First thing I see is some blown out capacitors. They gotta go.




The two little blue caps were the bias caps. They were leaking DC onto the power tube grids which if left unchecked would kill those tubes in short order. They got yanked fast, among others.



More caps. These are cathode bypass caps. The dark ones are supposed to be light blue like the others. But they been cooked. They all got changed out for freshies.


Finally the main filter caps. These are huge multi-section can caps that cost a lot and are hard to get. These are nearly 50 years old and have drifted out of spec and have to go away. These things filter and stabilize the massive DC voltage cruising through this amp.


I'm not buying expensive humongous multi-section can caps just to keep it original looking. They're just capacitors. So I devised my own plan to use discreet but correct value components that will do the exact same job at about 1/10 the cost. We've made some advancements since 1977. Capacitors are better and smaller now.




Same scenario with the preamp filter cap.






My scribblings to trace out how to convert the old caps and wiring to new caps and wiring.


This weird little 6K11 tube is just for the midrange control lol. Nuts!


And here it is all back together ready to rock. Really good voltages everywhere, bias set, good to go.


And I have used the amp a lot so far. It's working great.


Hear it HERE!

[Lt. Bob]

Awesome!!

This makes me so freakin' HAPPY !!

[JD01]

Excellent, well done, Greg. I'd love a nice bass amp.

[Greg_L]

Excellent, well done, Greg. I'd love a nice bass amp.

This one's actually a guitar amp. It does do bass pretty good though.

[Greg_L]

Awesome!!

This makes me so freakin' HAPPY !!

And with those tubes you sent I can get back to work on the VT-22 now. It's needed a lot more work. I've got it passing signal but I need some healthy tubes in it.

[Farview]

I had a V4 a lifetime ago. It was the loudest Amp I ever had. Especially when paired with its 4x12 cabinets. Those cabs had xlr inputs.

[Greg_L]

I had a V4 a lifetime ago. It was the loudest Amp I ever had. Especially when paired with its 4x12 cabinets. Those cabs had xlr inputs.

Yup. The VT-22 I have is the V4 but in a 2x12 combo configuration. Besides being crazy loud, it's also probably the heaviest combo on earth too.

[Tadpui]

Awesome job man! I'll mosey over to the other thread tonight and have a listen to this tank in action.

[rayc]

Excellent.
Will the other one be a journey thread?

[Greg_L]

Awesome job man! I'll mosey over to the other thread tonight and have a listen to this tank in action.

Thanks I think it's pretty cool!

Excellent.
Will the other one be a journey thread?

The other one has a lot more to do...much of which I've already done. I don't expect the VT-22 to sound much different. They are the same exact amp, the 22 being 120w watts with two extra power tubes. The rest of the circuit is identical. Same tube layout and everything. Not unlike a 50w vs 100 watt Marshall. They're basically the same amp and sound almost identical. I'll just post about it in here when it's done. The VT-40 is a little weirder.

Nice stuff.

Have you just worked all the electrical stuff you know and do out on the journey, or do have a background in it?

Thanks. I've just taught myself because it's something that interests me. It started with just basic maintenance on my own amps because I don't trust "amp techs", that led to simple mods, that led to repairs, and that led to full builds and restorations. I have no electrical engineering background. I am a "handy" person though. I'm naturally good with tools and parts and fixing things.

[Lt. Bob]

The VT-40 is a little weirder.

of the three, that's my favorite .... that thing thrui its 4x10s is magical ..... I gigged that thing for some years before it just got too heavy to deal with.
What's weirder about it?

And with those tubes you sent I can get back to work on the VT-22 now. It's needed a lot more work. I've got it passing signal but I need some healthy tubes in it.

you said the 6K11 drives the mids ..... where are mids usually handled, half a 12AX7?

[Greg_L]

of the three, that's my favorite .... that thing thrui its 4x10s is magical ..... I gigged that thing for some years before it just got too heavy to deal with.
What's weirder about it?

I haven't dug too far into that one yet but right off the bat the chassis and layout is different. It may be the same circuit, I'm not really sure yet, but how it's physically put together is much different. It's a top-facing combo so it's chassis is kind of narrow and cramped like the gnarliest beefiest heaviest Fender Tweed you've ever seen.

you said the 6K11 drives the mids ..... where are mids usually handled, half a 12AX7?

In most Fender/Marshall/Vox amps, if there even is a mid control, it's handled as part of a typical RC/CR low/high pass filter tonestack circuit. The bass, treble, and mids are all grouped into one part of the circuit and they interact with each other. And it's passive. It only removes...there is no boost. When you turn up the bass on one of these amps you're not really "adding bass". You're just letting more of the available bass through. On these amps there is no boosting of anything. If you put all the tone controls on 10 you're just letting the amp be what it already is. Technically there is no "turning up" bass, mids, or treble. When you turn up the treble you're really just turning it down less.

In the Ampeg the 6K11 is a triple-triode tube. It's like having a full 12AX7 and half a 12AT7 - two high gain triodes and one medium gain triode - in one single tube. It works with the active frequency-selectable midrange control. There's that 6K11 tube and it's last triode is set up as a cathode follower to drive a small toroidal transformer just for the selectable mids. And with all this shit happening the mids can actually be boosted. It's got active mids. I mean, dude the midrange control by itself takes up it's own pretty large section of the schematic. Bass and Treble happen before all that mid stuff and they're in a relatively standard tonestack circuit. It's cool because each tone control is truly it's own thing. None of them interact. There is no overlap like you'd have on a more standard cathode follower driven Fender/Marshall type tonestack.

If you were to build a clone or copy of this amp you could theoretically skip the weird 6K11 tube and just implement a single 12AX7 an use half of a 12AT7 and do the same thing.

[Lt. Bob]

It's cool because each tone control is truly it's own thing. None of them interact. There is no overlap like you'd have on a more standard cathode follower driven Fender/Marshall type tonestack.

That's what they mean when calling it a Baxandall tone stack ..... I'm guessing designed by some guy named baxandall.

And just out of curiosity I looked for 6K11 tubes ..... Antique Radio Supply has 'em ...... they're freakin' 45 bucks!! lol

[Greg_L]

That's what they mean when calling it a Baxandall tone stack ..... I'm guessing designed by some guy named baxandall.

And just out of curiosity I looked for 6K11 tubes ..... Antique Radio Supply has 'em ...... they're freakin' 45 bucks!! lol

Ha yeah they're available. I just don't wanna buy any.

[Farview]

Are the 7027a power tubes still available?

[Farview]

Are the 7027a power tubes still available?

[Greg_L]

Are the 7027a power tubes still available?

Yup. They're not anything special.

[Farview]

I remember them being hard to find, but that was pre-internet.
Tv repair shops did keep el34, el84, 6l6, 6550 and such on hand for us hippie weirdo types. But anything beyond that, they would act like they never heard of it.

One of the downsides of being stuck in a far flung suburb in the 80s...

[Lt. Bob]

I remember them being hard to find, but that was pre-internet.
Tv repair shops did keep el34, el84, 6l6, 6550 and such on hand for us hippie weirdo types. But anything beyond that, they would act like they never heard of it.

One of the downsides of being stuck in a far flung suburb in the 80s...

actually according to Ampeg sites you can use a 6L6 ... but Greg has a buncha 7027s I gave him because you can't use them in a 6L6 amp ...... I'm not sure you can use the 7027s in anything but an Ampeg currently.

I always wanted to stay true to the original and so, had bought a decent supply of 7027s thinking I would always use these amps.

[Greg_L]

7027s are pretty much 6L6GCs. You can use almost any high-power octal base power tube in the Ampegs. EL34s and 6550s need some minor tweaks but they can work. The B+ is a little much for 6V6s, but any other common-to-guitar amps big bottle tube can be used.