I've been thinking about building an EL84 Tremolux. I just put together a 2x12 cab with some really nice old Jensen 12" speakers. The cab sounds fantastic with a Champ but I'm afraid to throw anything more than a Deluxe at it because I'm not sure the Jensen PM12C in there can handle more than 10W or so. I figured the EL84 Tremolox would be a good compromise but 84's can kick out a lot of sound from that small envelope. I really don't want to blow this speaker!
I'll keep an eye on this thread and I look forward to seeing the results. I've built most of the tweed circuits and am just starting to dig into the brown era Fender stuff (just finished a few 6G15's and have a 6G16 started on the bench!).
Your project idea would be a very unique amp. It wasn't that long ago that I heard about this EL84 Fender amp. I think I would like the EL84's over the 6V6 tubes myself.
Mark
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Mark and Cliff, since you guys are delving into these brown-era amps, here's an alternative to the tapped treble pot used in the tonestack. This idea popped into my head over the holidays, and a sim shows it to be very close to the original in frequency response. There is just a bit of additional mid scoop, and it doesn't kill the high-end quite as much, but it is very close.
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M Fowler wrote:Martin thanks for the information very appreciated.
I do have the tapped pot so will proceed that way but nice to know one can work around that.
Mark
I don't have a pot and I don't want to buy one. I'll give Martin's circuit a shot for sure. Martin do you mind my asking how you came up with the idea? I guess I can see what you are doing but tapped pots always give me a headache when it comes time to actually design them into a circuit (too many degrees of freedom). Sorta like how those crazy Switchcraft switching style jacks can profoundly confuse with how many solder lugs there are (see below). I did find a 250k pot with a 50k tap (same ratio as 350k/70k) but I don't like changing the tonestack loading unless I adjust all of the R's and C's accordingly.
Cliff, it was like this: Hmmm... need a 350k pot. OK, put a shunt across a 500k pot. Need a 350k tapped pot... OK, put the tap on the shunt! The real test would be to A-B it with a tapped pot, but I'm betting it will get the job done in good style. A 1M is close enough if you lack a 1.1, the response changes very little. Turned out to be very simple to implement, too.
Last edited by martin manning on Sun Jan 15, 2012 6:48 pm, edited 1 time in total.