Fender Super Twin.

[Hobastard]

Cool Score... Quad box is definitely the way to go...

[wazkelly]

You won't need a gym membership if you plan on lugging that thing around haha.

[Simon Barden]

I wouldn't worry too much about the maker, rather the specifications and frequency responses of any speaker you fit in them. Fender started with a mix of speakers, then settled on Jensen, but then used JBL for some of the higher powered amps and then swapped to Eminence or re-badged Eminences for a long time. Now they offer Jensen, Eminence and Celestion depending on the amp or special editions of their standard ones.

Some of those Eminence speakers are very heavy. I've recently bought a used turret post hardwired Fender 5E5-A (Tweed Pro) conversion of a Blues Deluxe (using only the cab, chassis and input and output transformers from the Fender). Whoever had it before me had fitted an Eminence Redcoat 'The Governor' speaker in it. Weighed 13lbs/5.9kg on my digital scales (it's supposed to weigh less). I replaced it with a Celestion Neo Creamback that weighed 4lbs/1.8kg. That's a lot less weight to lug around!

But any 4x12 cab that can handle 300W+ needs to be sturdy or it will add all sorts of resonances of its own. So the wood itself needs to be pretty solid and heavy, so going for light neodymium magnet speakers would be a good move (though expensive).

But you may find that the amp is just too loud for your needs. Most valve amps need to be turned up to a reasonable percentage of their output volume before they come to life. If you were a pedal steel or lap steel player then it might be ideal as you can get loads of clean volume from it, but unless you were touring stadiums, then it's probably too loud for rock use.

I'd look at renovating the head first and getting the woodwork looking nice, then trying it with a borrowed 4x12 cab (or two) to see whether you think it's your style of amp. You may be better off selling it on for a profit and getting something that's a bit more your style.

[wazkelly]

Good comments Simon.

In one of several band line ups about 35 years ago a lead guitarist had a Fender Twin Reverb, 100w from memory, and it sounded gutless until our sound guy pulled 2 of the valves out, not sure which ones, but that trick really transformed the amp and gave it the warmer bordering on crunchy valve sound it lacked before.

Hey Doc, I reckon you probably know more than that bloke and could figure out a way to load up the output valves without lifting the decibels. 180w is a massive overkill and could end up way too loud before it sounds any good. That was the problem I had with my JMP 100w Super Bass head as there was no master volume. Sounded great clean but needed a Boss OD-1 to bring out the true Marshall distorted tone.

[DrNomis_44]

Good comments Simon.

In one of several band line ups about 35 years ago a lead guitarist had a Fender Twin Reverb, 100w from memory, and it sounded gutless until our sound guy pulled 2 of the valves out, not sure which ones, but that trick really transformed the amp and gave it the warmer bordering on crunchy valve sound it lacked before.

Hey Doc, I reckon you probably know more than that bloke and could figure out a way to load up the output valves without lifting the decibels. 180w is a massive overkill and could end up way too loud before it sounds any good. That was the problem I had with my JMP 100w Super Bass head as there was no master volume. Sounded great clean but needed a Boss OD-1 to bring out the true Marshall distorted tone.

I guess I could mod it so that it only uses two 6L6 power Valves, and then just swap out the output transformer for one suitable for two 6L6 valves, that would bring the output power down to about 60 Watts max, but then again the HT from the power transformer might be a bit high, I know someone who I could consult for advice, he used to do a lot of tech work for Darwin musicians and fixed my Marshall amp so that it no longer blew fuses at random intervals.


If it turns out not to be very cost effective to restore the amp, I might use some of the parts to get my Soldano Amp head going.

[Simon Barden]

There will be some people interested in a working Super Twin amp in a head version. All the existing head needs is a new front panel and re-Tolexing to look good (though maybe some side handles would be a good idea as well!). It does look rather rusty, so it really needs to be looked over by an amp tech to make sure its safe to use. The existing knobs look rather dirty and faded, so worth seeing whether they clean up easily. If not, the knobs are easy to get on eBay, it's just knowing if you'll need to order one or twelve!

[Simon Barden]

While waiting for Windows to finish updating, I thought I would see what valves were installed in the chassis, here's what I found:


Three 12AX7 valves, one 7025 (basically a lower-noise version of the 12AX7), one 12AU7A, and six 6L6 power valves!!

OK, bad news. Looking on the web for a schematic of the amp, one thing is certain - it shouldn't have three 12AX7s in it! http://acruhl.freeshell.org/mga/sche.../supertwin.jpg

The valves should be:

V1 = 7052
V2 = 6CX8
V3 = 6C10
V4 = 12AX7A
V5 = 12AT7

The 6C10 is a triple triode valve, so certainly can't be replaced with a 12AX7 unless the amp has been seriously modified. Maybe by omitting the reverb unit they've been able to do this, but the amp certainly isn't standard, and you don't know how well any modifications have been made.

The 6CX8 and the 6C10 aren't made any more, so you have to rely on a dwindling supply of NOS valves (which aren't cheap if you can get them), so I can see why someone made some changes. However, it isn't a proper Super Twin amp any more, so is worth what someone is willing to pay for what it is now. The big question is, were the changes made by someone who knew what they were doing and all the supporting resistors for the valves were changed to the right values so they work properly? You can't simply change valve types and expect them to do the same job without changing the supporting circuitry. Even the 12A_7 range (12AX7, 12AT7 etc.) aren't 100% compatible and the bias resistors for them need to be tweaked to get the best from them.

In the light of this, I wouldn't advise even powering it up, but it needs to go straight to an amp specialist who should be able to tell if it's safe to use and whether the modifications have been done correctly. If not, it could be lethal.

Also note that it needs a 4 ohm load (no alternate tappings are available), so a standard 4x12" cab will need to be modified so that all four 16 ohm speakers are wired in parallel.

[DrNomis_44]

OK, bad news. Looking on the web for a schematic of the amp, one thing is certain - it shouldn't have three 12AX7s in it! http://acruhl.freeshell.org/mga/sche.../supertwin.jpg

The valves should be:

V1 = 7052
V2 = 6CX8
V3 = 6C10
V4 = 12AX7A
V5 = 12AT7

The 6C10 is a triple triode valve, so certainly can't be replaced with a 12AX7 unless the amp has been seriously modified. Maybe by omitting the reverb unit they've been able to do this, but the amp certainly isn't standard, and you don't know how well any modifications have been made.

The 6CX8 and the 6C10 aren't made any more, so you have to rely on a dwindling supply of NOS valves (which aren't cheap if you can get them), so I can see why someone made some changes. However, it isn't a proper Super Twin amp any more, so is worth what someone is willing to pay for what it is now. The big question is, were the changes made by someone who knew what they were doing and all the supporting resistors for the valves were changed to the right values so they work properly? You can't simply change valve types and expect them to do the same job without changing the supporting circuitry. Even the 12A_7 range (12AX7, 12AT7 etc.) aren't 100% compatible and the bias resistors for them need to be tweaked to get the best from them.

In the light of this, I wouldn't advise even powering it up, but it needs to go straight to an amp specialist who should be able to tell if it's safe to use and whether the modifications have been done correctly. If not, it could be lethal.

Also note that it needs a 4 ohm load (no alternate tappings are available), so a standard 4x12" cab will need to be modified so that all four 16 ohm speakers are wired in parallel.

The wood cabinet that the amp chassis is in needs replacing with a new one because I noticed that the corner-joints are starting to come apart, good call about the 6CX8 and 6C10 valves, I didn't notice that, I'm going to wait till I've paid the guy the money I owe him for the amp before I go and do anything with it, I'm familiar enough with the safety procedures for working on valve amplifiers so I'll see if I can do the work myself, I'll certainly give it a good check out electrically to make sure it's electrically safe beforehand, that's for sure, I don't think I will sell the amp once it's all sorted out, I think I will keep it.

One thing I have noticed is that the standby switch definitely needs replacing because it appears to be stuck in the on position, the power switch seems good though, but I might just replace both as a matter of course, I think I can get a new knob for it from Evatco.


On the back panel of the amp chassis, near the speaker output socket, it says that the minimum load impedance is 4 Ohms.

[billb]

Interesting, while I certainly don;t have the expertise of either of you two I do have an old Fender Studio Bass amp which is apparently pretty much the same basic amp as the super twin, minus a distortion control and at 8ohms - it certainly has the same valve set up as you found in yours so someone may have used it as the basis for refurb'ing yours?
If you can get it working properly, and if it sounds anything like the Studio Bass, you will NEVER sell it. (although to be fair you will also never actually move it as mine weighs well over 60kgs)
Here's some info you might find interesting for what you're doing:
https://www.talkbass.com/threads/fen...s-club.809269/
http://johnkvintageguitars.homestead...tudioBass.html
(last link has the schematic if you want it)

[DrNomis_44]

So if I wanted to, I could mod it so that I could use it as a Bass amplifier?, that's interesting to know, if so, then I'd have something I could play my Squire P-Bass through, I'm assuming that I'd have to go through and change the value of some of the components to get the amp working well for a bass guitar, going by the preamp valves installed in the chassis, that's probably what it's previous owner did.