Amps Fender Twin chassis project

[CapnDenny1]

I was looking at amps that need work to try and make some money off of.. and I ran across this on ebay. I am so sick of getting sniped at the last minute. this one had a buy it now, so that's what I did. It's a 10 year old Fender Twin chassis. He said the send receive quit working so he took it out? No word on what happened to the rest of it, like the cab, and speakers?

So the plan is to first fix it, and restore the send receive. Then I will build a cabinet out of some nice hardwood, maybe walnut? I will probably make a head version, and a matching speaker cab. So here is the amp chassis pics. I wish these people would leave the knobs on?

I can use my Fender Twin to get measurements of the cabinet. I may just do a combo? But even if I make a head it will help to have something to start from.

s-l1600 (1) by Dennis Kelley, on Flickr

s-l1600 (4) by Dennis Kelley, on Flickr

s-l1600 (3) by Dennis Kelley, on Flickr

s-l1600 (5) by Dennis Kelley, on Flickr

 

[Iheartbacon]

That looks like it is from a “68 Custom” in which case you aren’t missing much. Having the cabinet would be nice, but the speakers they came with were Celestion’s which were not a good match for what people normally want from a Fender BF/SF type of amp, especially a Twin.

With a better matching speaker set that is a decent amp. The vintage channel is just a circuit board version of the Twin Reverb, and the Custom channel has something like a 59 Bassman tone stack which sits in a funky space between a modern tweed vintage Marshall type voicing but with the Black Face power section.

Making it into a head will make it much easier to transport, but it still is a damn loud amp! If it were mine, I would remove the outer pair of output tubes and run it into an 8 ohm load for 40-50 watts of output. If you ever need to peel paint off the walls, just pop the extra power tubes back in and plug it into a 4 ohm cab and you are back to 85-100 watts. Having it in a head configuration would make it a lot easier to change the speaker load than a Combe where you would normally have to disable one of the two speakers when pulling tubes.

Good luck with the project, it should be a fun one.

 

[CapnDenny1]

Yes, I could do that. I like clean amps mostly, so all 4 tubes just increases the headroom. It doesn't make it louder, you just have to turn the volume down a bit.

I think perhaps 3 cabs would be the best. 1 head cab, then two speaker cabs, each with a 1x12 speaker. I would make them all stackable. That way for a small space you could use it 1x12. If you need more volume you would use both 1x12 cabs, so then it would be a Twin again.

There is a guy on ebay that makes a nice pine Twin cab for $200. I could do it for $50 in wood, but there's a lot of work involved.

I think pine is pretty boring for a guitar cab. Bubinga is over the top. But nice walnut, or mahogany, or even white oak, would look really nice.

I have about 4 amps that need cabs built, so I need to spend some time in the woodshop.

 

[CaptainMoto]

Looks like a worthwhile undertaking.

 

[Iheartbacon]

so all 4 tubes just increases the headroom. It doesn't make it louder, you just have to turn the volume down a bit.

Unfortunately the tone changes quite a bit on a Twin Reverb if you do that, more so the more you turn the volume pot down. They sound their best with the pre-amp (Channel) volume in the 4-6 range which goes from ear splitting loud to paint peeling loud with a bit of breakup. That is why they added the master volume in the mid 70’s, but that also sucked tone, especially if you used more than about 1/4 of the range.

I like to add a post PI MV to my twins which allows you to turn down a few DB before losing tone, pull a pair of tubes to lose 3 dB and add an attenuators that can pull a few dB without losing to much. All together they make a big difference, and on a couple I have also added a variable voltage B+ circuit which really tames it. All that is way too much for your project though unless you have a specific buyer who wants an amp that can cover a wide volume range and is willing to pay you for it.

One other mod I do that only costs a buck or two is to add a second bias pot or three more. Various Twin circuits either had a universal bias level adjustment or bias balance adjustment. With the universal level one you can at least buy 4 matched power tube sets for extra $$$ but the transformers are never perfectly balanced. The balance circuit sucks because you still need 2 matched pairs and then you can get them balanced including the impact of the transformer, but you cannot choose the absolute bias level. Adding a bias level pot for each tube frees you from matched tube sets, allows correction for the transformer imbalance, and allows you to set the idle current through all the tubes evenly and where you want it.

 

[CapnDenny1]

To each his own. I love how my twin sounds at moderate volume. I never drive it to distortion.

My Princeton sounds best at mid level. If I turn it up, it looses the sound I like from it.

 

[CapnDenny1]

UPS delivered the amp this afternoon. Hopefully I can unbox it tonight.

I just remembered that my tube tester is on the Fritz! I will need it for this one.

Still going back and forth on the head vs combo issue? Leaning towards the combo. Less cabinet work. It's as easy to build a combo as the head version. And then I have to build the speaker cabs too! More wood too.