husky wrote:paulster wrote:Clapton's Twins are nothing like standard ones.
They are solid state rectified with 4x output tubes from what I remember.
John Suhr mentioned over at HugeRacksInc broadly how they'd been modified sometime before (since he did them) and the only resemblance to a stock Tweed Twin is the cabinet really!
True they are different but not terribly so.
Primarily the removal of the Tube rectifiers and replaced with 2 more 5881's
Solid state rectifier, bigger filtering and flipped phase on the speakers. He did start playing it with only two power tubes after I convinced him it would be better. It was the stock Triad OT and a replacement power transformer. The voltages were stock but the transformer had more VA.
The other key that was a tough nut to crack on the repro amps I made was the tone of the cabinet. Baffle being VERY important. Oh yeah also Oxford reconed speakers.
The basic circuit of the preamp was stock 5E8A
This is the impression that I was under. Thanks for the great info. I still hold that I built the 5E8A out of curiosity about the dual rectifier setup more than anything. I didn't know about the Clapton connection until somebody else pointed it out to me on here.
I can't see the amp needing more power TBH, part of why I really dig this amp is how well it sings when cranked without killing me volume-wise and how amazing the cleans are when dialed back. I use all NOS 6072's in the first few tube sockets as I find that swapping in 12AX7's make this amp unbearably gainy. Any comment on the tube choice that Clapton uses? (tube type, brands, etc..).
It's a fun circuit with lots of versatility on those few knobs. I also prefer the dual rectifier setup, it gets way too spongy and flabby with a single rectifier. The trick IMO is finding a PT that can
easily handle the dual rectifier setup. I think the Triad PT I ended up using was close to 12 lbs with solid copper leads coming out of the transformer. A nice little note: rating the current capacity of each winding on a transformer with solid copper leads is a lot easier than that of a stranded lead PT. You can get out your calipers, measure the diameter, convert this to circular mils (google can do this for you!) and use the 700 circular mils/Amp rule. Mine ended up being rated for about 5.8 Amps (ish, don't remember the exact number) but this is more than close enough in my book.
I'm interested as well on the baffle issue as well as what are "appropriate" speaker choices for the amp. I've heard it sound amazing on an old Fender open back 2x10 with whatever stock speakers were in it (might have been Oxfarts) but it also sounds very good on my 1x12 closed-back/front-port alnico SRO loaded cab. Then again, that 1x12 sounds good with anything
.
Cliff Schecht - Circuit P.I.