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Restoring a 1964 AC30 Super Twin

yeatzee

Member
Joined
Jul 21, 2016
Messages
70
Decided to dive into the world of AC30's and go after my dream rig, the AC30 Super Twin (head and cab)! Long story short these don't come up often in the states so when one popped up locally I jumped at it. Was listed as all original but upon further inspection of the blurry photo's it had a few standout issues. Eventually settled on a price that gave me a buffer in case the issues were really bad and went to pick it up. Amp did not function well, no sound out of the trem channel, normal barely worked. Also had lots of pops/crackles, a weird cutout on the back of the head cab that wasn't disclosed, non-original celestion alnico silvers with one recone, etc. A slight basketcase, and that was without really seeing what was what on the inside.

Then as luck would have it, a second 60's copper top popped up locally, this time a combo which appeared to be much more original... so I bought that too. Here they are:

tqGkXZA.jpg



The end goal is to restore the super twin and make it gig-able, and potentially grab the original alnico blue speakers from the combo to complete the set in the ST. I've been dabbling with working on amps this past year, recently restored a '65 Vibrolux Reverb so I've got some reps under my belt but nothing with a vintage vox. Exciting project for sure! I decided to document the whole process on YT showing step by step, and fingers crossed when it's all done I've got a beautiful vintage AC30 of my dreams ready to go for another decade!

Here's the video kicking off the series, in it I open up the ST and show everything:

And if you can't be bothered, here are some gut shots:

ZDvl8IH.jpg

YXGocPD.jpg


Good news, mostly original and doesn't look too messed with. Bad news, replaced Power Transformer with a 70's AC30 Lemark. OT is an original albion. Top Boost appears to be a homebrew kit. According to the previous owner this was Mark Sampson of Matchless fame's amp. Who knows, but I wouldn't say the work done looks thatttt great.

The hardest part has been deciphering what is what, to me the amp is not laid out intuitively like a fender is. The grounds jump between both sides of the tag board, the tube order is bizarre, etc. And unlike a fender, there isn't a readily available layout to reference and the schematics are quite complicated due to the very crazy trem circuit which takes up like 65% of the tag boards. Eventually I found a home-drawn layout by some legend from years ago that I was able to use to cross reference and determine what's been changed and what is different on mine vs that guy's (also worth noting mine is a treble model, vs the normal model the layout is based on). I took diligent notes after reviewing everything very carefully and built out a game plan.

8Q6dzCc.png

Direct link for zooming in

Circled in teal = replacing / questions. Black/yellow obviously notes for what is different with mine vs the layout or just general notes as I learn more about what I'm looking at. I recorded a video detailing my findings in the layout vs mine here:


After that I started my first soldering attempts. The tag boards are extraordinarily fragile so no solder sucker, the recoil will break them so lots of braid and patience.


Next up it's installing carbon comps where the resistors were swapped to carbon film to keep it as it was from the factory, and then also replacing the trim pot since it was the wrong value and the bypass caps since it's best practice to do so.


After that I tackled the screen and grid stopper resistors off the power tubes, very important on vintage AC30's as the stock values don't work well with modern voltages and modern glass. Also a very tedious job to do it right.


Been a massive project so far, not too far to go until it's done but wanted to share if there are any amp geeks on here :)
 

yeatzee

Member
Joined
Jul 21, 2016
Messages
70
Installed the last of the major electrolytics the amp requires with a dual 8uF F&T and a 30uF F&T for the top boost circuit. Not a lot of space to mount them, but pretty happy with how it came out overall.

 

yeatzee

Member
Joined
Jul 21, 2016
Messages
70

Next video up, all about checking the bias in the amp at a couple different voltages from the wall as well as show the PT buzz I'm getting for some reason.
 

TM1

Well-known member
Joined
Jun 27, 2003
Messages
8,382
I helped Jim Elyea with his 864 page "Vox Amps-The JMI Years". Jim had about 300+ Amps, mostly AC-30's, But got to work on some of his 7120's and other "7" Series amps(which were made by Triumph Electronics). I only own 2 Vox amps these days. I had about a dozen at one time. I wish I'd kept the other AC30 I had, it was a 1960, early 6 input and had been owned by "The Shadows". The one I have now is covered in smooth Gray Rexiene with a Candy coloured control panel and brown Grill with 2 of the early Silver Alnico T1088's. We figured the T-1088's came in around April 1964. Great Amps!
 

yeatzee

Member
Joined
Jul 21, 2016
Messages
70
I helped Jim Elyea with his 864 page "Vox Amps-The JMI Years". Jim had about 300+ Amps, mostly AC-30's, But got to work on some of his 7120's and other "7" Series amps(which were made by Triumph Electronics). I only own 2 Vox amps these days. I had about a dozen at one time. I wish I'd kept the other AC30 I had, it was a 1960, early 6 input and had been owned by "The Shadows". The one I have now is covered in smooth Gray Rexiene with a Candy coloured control panel and brown Grill with 2 of the early Silver Alnico T1088's. We figured the T-1088's came in around April 1964. Great Amps!
That's awesome! That book was so fun to read through when I was borrowing it. As for this amp, I'm happy to report it passed it's first big test with flying colors. 3hr gig cranked up, no problems was rock solid!

KBE5j5q.jpg


And a couple shots back at home for fun :)

jEJux9K.jpg

KWOyVAM.jpg
 

TM1

Well-known member
Joined
Jun 27, 2003
Messages
8,382
Excellent!! Have fun playing it! BTW...
Derek Underdown, who was Dick Denny's Boss, told me to never run a AC30 above 110v as the Mains tranny doesn't like it. 240v, 220v are fine on their selected voltages.
 

renderit

Well-known member
Joined
Jan 19, 2009
Messages
10,990
If'n I knowed half of the 'lectronics you do I'd be whackin' the voltage dissipators instead o' readin' aboot it!

Awesome documentation my friend!
 

Icandrive55

Active member
Joined
Oct 26, 2019
Messages
166
I just ordered a copper panel Super Twin with integrated Top Boost and the cab with original Blue's. You're not wrong that they're hard to come by in the US. I had to order it from Denmark! But as you know, these are so rare I had to go for it. I was originally just trying to find the 2x12 cab for my grey panel Super Twin. I hope you are loving yours! That's some impressive work you did. I love the videos. I'm very curious what you think of the Twin vs the combo.
 

yeatzee

Member
Joined
Jul 21, 2016
Messages
70
Excellent!! Have fun playing it! BTW...
Derek Underdown, who was Dick Denny's Boss, told me to never run a AC30 above 110v as the Mains tranny doesn't like it. 240v, 220v are fine on their selected voltages.
Yeah I'm sure it's not ideal but all of the voltages seemed within acceptable ranges at 120v heaters included.
I just ordered a copper panel Super Twin with integrated Top Boost and the cab with original Blue's. You're not wrong that they're hard to come by in the US. I had to order it from Denmark! But as you know, these are so rare I had to go for it. I was originally just trying to find the 2x12 cab for my grey panel Super Twin. I hope you are loving yours! That's some impressive work you did. I love the videos. I'm very curious what you think of the Twin vs the combo.
Saw your thread! Lovely looking amp, like I said I strongly considered buying that one.

I like the Twin a lot more so far, more punch and head and cab is just way cooler ;)
 

Icandrive55

Active member
Joined
Oct 26, 2019
Messages
166
I'm glad you found yours locally! It's so much more ideal to be able to see something in person. You're not wrong to be sketched out by overseas sellers. It's not my first bad experience.

I'm actually surprised you prefer the sound of the Twin! Since the open back cab is a big part of the traditional AC30 sound. I will tell you... I've never heard a neck pickup sound better than on that AC30 Twin. There's zero mud.

That's a beauty of a rig you have going there. Great guitar choices!
 

yeatzee

Member
Joined
Jul 21, 2016
Messages
70
I'm glad you found yours locally! It's so much more ideal to be able to see something in person. You're not wrong to be sketched out by overseas sellers. It's not my first bad experience.

I'm actually surprised you prefer the sound of the Twin! Since the open back cab is a big part of the traditional AC30 sound. I will tell you... I've never heard a neck pickup sound better than on that AC30 Twin. There's zero mud.

That's a beauty of a rig you have going there. Great guitar choices!
It just has so much more punch and beef to it with the closed back cab. More focused of a tone, feels more powerful and cuts better gigging imo. I did reach out to Mojotone about building a partial open back for the cab in case I ever want to get more "room" sound (and cut down on weight, that back plate is HEAVY) but I haven't felt the need yet.
 

Icandrive55

Active member
Joined
Oct 26, 2019
Messages
166
It just has so much more punch and beef to it with the closed back cab. More focused of a tone, feels more powerful and cuts better gigging imo. I did reach out to Mojotone about building a partial open back for the cab in case I ever want to get more "room" sound (and cut down on weight, that back plate is HEAVY) but I haven't felt the need yet.
I can see that being the case. The note definition is unbelievable. Super punchy, like you said. I'm sure it will record incredibly well too.

I thought about getting a custom open back as well. But it sounds so good I think I'm not going to bother messing with it. Especially, after hearing that you prefer the closed cabinet. You probably gig more than I do so I'm sure weight is more of an issue.
 

jimijam33

Member
Joined
Dec 29, 2015
Messages
58
I have an original 1963 AC-30 Super Twin in great condition. It had a factory added TB but is missing the original serial # plate. It came with Albion Transformers and sounds great but there is a bad cap that needs replacing (making strange noises at idle).
 

yeatzee

Member
Joined
Jul 21, 2016
Messages
70
I have an original 1963 AC-30 Super Twin in great condition. It had a factory added TB but is missing the original serial # plate. It came with Albion Transformers and sounds great but there is a bad cap that needs replacing (making strange noises at idle).
Popping crackling?


Some final details wrapped up before I got to do a string of gigs with the amp. So far so good, it's been rock solid and sounding great! I still plan to try the blues and I also need to lift the heater ground connection. It's noisy, but also that doesn't matter when you're playing so hasn't been a priority.
 
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