el84 vs. ecl82

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el84 vs. ecl82

Postby howling_mad on Tue Jan 25, 2005 3:20 am

Okay, here's another question from a novice. I'm studying up in preparation for building my own amp. I played an amp not long ago that was running 4 el84s. The thing had some great tone, but too much gain for me. I read that that amp's preamp circuit was designed to be high gain, so I considered building my amp with 4 el84s, and just modifying the preamp, but then I read some things in one of the boards here about amps running ecl82s. They were all low wattage, but only ran 2 ECL82s. I figured that if I ran a quad, I could get close to 25 watts out of it. Also, I was first introduced to the ecl82 by an old Roberts reel to reel deck I have.

Does anyone have anymore details about the characteristics of this tube, especially compared to el84s. The sockets are the same, so I figure that if I tried the ecl82s, and didn't like them, I could do some (or a lot) of re-wiring, and then switch.

Thanks.
Andy
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Re: el84 vs. ecl82

Postby Green on Tue Jan 25, 2005 1:11 pm

Look at Duncan's amp pages for tube data. The ECL82 has a triode and a power pentode in it, the EL84 is a power pentode only.

I've heard that the ECL86 is a better swap for an EL84 application, although an ECL82 should work if set up correctly.

I don't know what you'd do with the triodes though. Normally for a push-pull amp you have 2 ECL86s and use the two triodes as a phase splitter but if you're using 4 of these valves you have two spare triodes...

Ed
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Re: el84 vs. ecl82

Postby howling_mad on Tue Jan 25, 2005 2:13 pm

Thanks Ed. I initially posted this wondering what the tonal differences were between these tubes, which I'm still curious about, but what you wrote in your response is more important for me in trying get a clearer picture of how all this works. I have read things that talked about triodes and pentodes, but for some reason, I didn't understand it until I read your response.
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Re: el84 vs. ecl82

Postby howling_mad on Tue Jan 25, 2005 2:14 pm

Oh yeah, and I'll definitely check out Duncan's Amp pages.
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Re: el84 vs. ecl82

Postby ozsubrosa on Wed Jan 26, 2005 10:43 pm

Getting late, so I haven't checked it out and done the links. Work for you guys... :)

I noticed fleeb.co.uk has two WEM Westminster MkIIs up. One of the auctions lists the toobs as all Mull and the power ones are ECL82s. That's news to me, as I have a Dominator Mk III with the expected EL84s (also Mulls and very yummy). The circuit differs between the two, but WEM searching may be a good start. Our own TimF runs a WEM site (along with Selmer, Bird and others) and Charlie Watkins still does his thing complete with URL.

Of course, Mull ECL82s are even cheaper than the relatively reasonably priced Mull EL84. Stockpile enough for the grandchildren, though. I don't think the usual new-makes will bother tooling up.

Oz
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