EL34's in a Bluesbreaker RI

lpnv59 · Oct 8, 2001

Is this not a good thing in a BB reissue, because I haven't read about anyone here doing this. The stock 5881's are generally disliked from what I've read here, would the EL34's be a cool thing to install. If anyone has done this what are the results.

RICH · Oct 8, 2001

You could try putting KT66s in it, that seems to be the choice of bluesbreaker owners. From what I understand you'll have to squeeeeze them in because of room constraints. A rebias would most likely be needed, but thats no big deal.

Michael Papenburg · Oct 8, 2001

Actually, I did install EL34s in my re-issue bluesbreaker (with proper mods & re-biasing). It sounds great, but I would still like to experiment with different speakers because the greenbacks are still mushy in the open backed cabinet. It is definitely not as loud as when I had the 5881s in it but that is a good thing as I can get away with cranking it a little easier. It also has a lot less headroom (also OK). I use an S.I.B. Varidrive in front of it with my Les Paul & my Tele & find that this combination sounds incredible. I would love to say that plugging straight in sounds as good but it doesn't. Hope this is helpful.

Joel DC · Oct 9, 2001

I had a Bluesbreaker cabinet, built by Bennetts Music Labs, so I could put my Plexi 1987 RI or '77 JMP 1987 chassis. The RI has EL34's and the JMP has 6550's. After A/B'ing them, I found that I like the JMP better. I don't know if it is due to the tubes or just the difference in the amps. (I like the brightness of the JMP.)
I'm also trying to figure out which speakers I want in my Bluesbreaker. I have tried a pair of Jensen RI C12N's and a combination of a C12N and a P12N, it sounded good both ways. Now I'm using a set of Celestion G12L's w/Hot Plate that I like also. They sound more "British". Now I'm waiting for a set of Vintage 30's that I just bought on ebay. I would like to hear your experience/ideas for some speakers. I been thinking about the Celestion Blues as Music123 has them for $189.

lpnv59 · Oct 9, 2001

I haven't got the amp yet, probably next week, so I don't know whats needed. A pair of G12H 30 worked alot better than 25w greenbacks. I have an older one being reconed. I also have a pair of 20w greenbacks that I don't think will work but I will try anyway. I also have a set of Blue Alnico in my AC30 and I'll try those out as well. I'm sure it will need some help, but I got a good deal on it so........

Siegler · Oct 9, 2001

Bias adjustable in JTM-45 (orginal or reissue)?

RICH:

It'd be great if you or someone else could confirm that the bias is adjustable in both the JTM-45 and Bluesbreaker combo, original as well as reissue. Where, by the way is the knob?

You will be amazed to hear this, I suspect, but a very well-known "amp guru" told me over the phone that there is no bias adjustment on these amps, though he was specifically referring to a '66 JTM-45. I don't like withholding information, but I also don't like slamming people in public as long as they have not specifically declared war on me.

Thanks

Joel DC · Oct 9, 2001

lpnv59, I'd really like to hear your opinion on those Blues when you get the amp. I'll be looking for your "reveiw".

lpnv59 · Oct 9, 2001

It is 2nd on my list of things to do when its delivered, number one being to play it as is. Doing that is kinda like shaking salt on a plate of food before tasting it. But them Bluedogs are a great sounding speaker. I predict a great improvement, as long as the amp works when I get it.

Ya never know with an Ebay deal! Rrrrrrrrrrrrrrrrright!!!!

TedB · Oct 9, 2001

My RI BB combo has all the 'authenticating' mods, including a pair of original ancient Celestion alnico G12s (the original speakers for these amps). The alnico G12 (e.g. alnico blues) sound fab in this application. Coupled with KT66s, MM repro OT and circuit tweaks, the amp has a lot of character.

As far as bias adjustment, the original JTM45/BB amps did not have an adjustable bias. You have to change a resistor to adjust the bias setting.

The RI amps have a bias adjustment pot. The RI BB has two pots. One adjusts the tremolo JFET, so don't turn that one, or your tremolo won't work. The one you want to turn (if my memory serves correct) is the inside pot (i.e. not the one closest to the end of the PCB).

BIG Dave · Oct 10, 2001

Don't forget to replace the filter caps with original values! You'll need a 16uF x 16uF on the preamp side and a 32uF x 32uF on the power amp side. (Credit goes to Ted B...)

EL34's in a Bluesbreaker RI

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