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vintage vox ac4

TM1

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Joined
Jun 27, 2003
Messages
8,349
Other than the Filter caps/smoothing caps are in dire need of being replaced, the amp looks good! I've been inside many of these and after the filters are replaced they're good for another 50 years.
Filter/smoothing caps/cans are only good for around 10 years before they start to deteriorate. It's like changing the oil in your auto, some things need routine maintenance.
I disagree with their opinion on the front baffle having been changed. The cloth, when new, was as dark as a Hershey Bar and the fawn Rexiene used could have been from a different roll than the outside shell. Vox/JMI used 3 different cabinet makers for their amps. I've worked on hundreds of JMI-era Vox Amps and each one can be slightly different from the next. They sure want alot for this amp. I have a 1965 JMI "Domino Bass" amp/cab and it's basically the same amp as this minus the Vibrato circuit. Anyway, these keep going up in price and I'd grab it as the early ones are fairly hard to find.
Cheers!
 

riscado

Active member
Joined
Jul 6, 2006
Messages
1,460
Other than the Filter caps/smoothing caps are in dire need of being replaced, the amp looks good! I've been inside many of these and after the filters are replaced they're good for another 50 years.
Filter/smoothing caps/cans are only good for around 10 years before they start to deteriorate. It's like changing the oil in your auto, some things need routine maintenance.
I disagree with their opinion on the front baffle having been changed. The cloth, when new, was as dark as a Hershey Bar and the fawn Rexiene used could have been from a different roll than the outside shell. Vox/JMI used 3 different cabinet makers for their amps. I've worked on hundreds of JMI-era Vox Amps and each one can be slightly different from the next. They sure want alot for this amp. I have a 1965 JMI "Domino Bass" amp/cab and it's basically the same amp as this minus the Vibrato circuit. Anyway, these keep going up in price and I'd grab it as the early ones are fairly hard to find.
Cheers!

Thanks, I've been able to spot a local one, not fawn tolex, for a significantly lower price. Might give it a try.
 

F-Hole

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Sep 2, 2015
Messages
2,171
I'd be very wary of this seller. And this amp has had lots of changes, may of which are undisclosed.
 

TM1

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Jun 27, 2003
Messages
8,349
Charlie Chandler has had one for sale for a while...I saw it the last time I was at the shop.

Replacement speaker, but maybe worth looking at?

http://www.guitarexperience.co.uk/amps/second-hand/vox-ac4.html

:)

That's a `64 made between April & late August since it has the charcoal gray Rexiene. I have an AC-30 from the period. I'd have to check my friend Jim Elyea's book: "Vox Amps-The JMI Years" to be exact on the date range.
The only changes I see on the first one is that someone added a large smoothing can at the bottom right. Probably cause they couldn't get the right can that chassis mounts and the caps from the volume pot is a different one than the stock cap. Should have either a Wima Tropyfol or a Phillips/Iskra mustard cap. But all those blue "Hunts" caps need to be replaced if you're going to play it.
 

F-Hole

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Sep 2, 2015
Messages
2,171
There's more going on with this seller (and his "accomplice") than it would be appropriate to post here.

And I don't get the "change all caps" mentality. If drifted or leaking, then yes, but otherwise leave them if they work fine. I've got dozens of old amps that work perfectly well with old caps.
 

TM1

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Jun 27, 2003
Messages
8,349
I just don't trust 50+ year old electrolytic caps. I've seen too many that have damaged amps. The worse thing anyone can do to an amp is not turn it on for a few hours a month and keep those electrolytics liquid inside. I've seen them take out output trannys when they've gone simply because someone was to lazy to either not turn their amp on or just let them sit for months/years at a time. If there's little dimples poking out on top you should change them out. Cheap insurance for your amp I think. Personally I do look at them and check the value compared to what the casing says. I once had an 8ufx8uf/450v cap in an AC-30 read 27uf on each side....They can also suck your B+ voltages down. I know everyone has their own method for determining if they need to be replaced and there's not one hard and fast rule.
The worse offender are the caps Fender uses now. There are plenty of "newer" Fender amps that develop bad hum because they use cheap Asian made electrolytics. Most say Illinois on them. I've had alot of customers bring me newer Hot rots, Blues Jr.'s, etc with hums. As soon as I clip lead in a new F&T cap and start going thru the B+ supply, I'll find one or two that as soo as I touch the lead to a cap the hum's gone..
I know the people who manufacture F & T and Sprague say they start to loose their effectiveness after 7-10 years(Personally I think it's more like 15 years) cause they want to sell more caps/cans.
 

66SuperTremMKIV

New member
Joined
Oct 4, 2015
Messages
405
I think John's referring to coupling caps more so than mains filter caps. Too many non vintage sympathetic techs love to replace all regardless of need.

Never had an issue with original caps unless visibly ruptured or in the process of, or audible tell tale signs.
 
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