20W 2 x EL34

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Littlewyan
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20W 2 x EL34

Post by Littlewyan »

How are Marshall only getting 20W out of 2 x EL34s? This is obviously a recent thing as Trainwreck have done the same thing (actually 25W I think). You can only lower the HT Voltage so much?!
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martin manning
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Re: 20W 2 x EL34

Post by martin manning »

What amp?
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Littlewyan
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Re: 20W 2 x EL34

Post by Littlewyan »

The new https://marshall.com/marshall-amps/prod ... dsl/dsl20h

They do the same with the Mini Jubilee https://marshall.com/marshall-amps/prod ... ilee/2525h

Trainwreck have been doing low powered Express Amps which I THINK are 25W using 2 x EL34.
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Littlewyan
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Re: 20W 2 x EL34

Post by Littlewyan »

Just answered my own question. Someone on another forum contacted Marshall and found out that the 2525 is Cathode Biased. So with a low enough voltage and high enough impedance you could easily get 20W. Trainwreck are probably doing the same with the low powered Express amps.
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statorvane
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Re: 20W 2 x EL34

Post by statorvane »

Maybe it's a paralleled single ended design. I tried that last year with 2 x 6CA7s. Killer amp. I get around 20-25 watts. Cool thing, being cathode biased, I can swap in big octals at will. I have an impedance switch on the back to allow for 6550s as well. Preamp is from a Hiwatt DR103.
photos here (if you can stand the wait): http://s165.photobucket.com/user/JKCavi ... t=2&page=1
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Littlewyan
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Re: 20W 2 x EL34

Post by Littlewyan »

I thought that too but they specifically say that they use a Phase Inverter.

Awesome looking amp!
Stevem
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Re: 20W 2 x EL34

Post by Stevem »

Amps with that little wattage out of tubes that can pump 60 watts RMS out with 520 volts on then don't get much of the tubes true tonal nature out of them, however they should last a good long time!
For me I would preference a quad of EL84s or two 6V6s, or for a bit of a different dance 5791 tubes!
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TUBEDUDE
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Re: 20W 2 x EL34

Post by TUBEDUDE »

statorvane wrote: Tue Jan 30, 2018 11:56 pm Maybe it's a paralleled single ended design. I tried that last year with 2 x 6CA7s. Killer amp. I get around 20-25 watts. Cool thing, being cathode biased, I can swap in big octals at will. I have an impedance switch on the back to allow for 6550s as well. Preamp is from a Hiwatt DR103.
photos here (if you can stand the wait): http://s165.photobucket.com/user/JKCavi ... t=2&page=1
Wow, Nice amp! Very clean execution. I like the combined output transformers. I had to do a similar thing with a 6DQ5 SE amp with 2 hammond 125E xfmrs until the One Electron xfmr arrived.
How did you get the shading on your front n rear panels? Airbrush?
The red 6V6 Plexi is awesome also, thanx for sharing.
Tube junkie that aspires to become a tri-state bidirectional buss driver.
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TUBEDUDE
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Re: 20W 2 x EL34

Post by TUBEDUDE »

Stevem wrote: Wed Jan 31, 2018 12:56 pm Amps with that little wattage out of tubes that can pump 60 watts RMS out with 520 volts on then don't get much of the tubes true tonal nature out of them, however they should last a good long time!
For me I would preference a quad of EL84s or two 6V6s, or for a bit of a different dance 5791 tubes!
Ive heard EL 34 amps at high and low Vp and they all sounded great. Maybe that had more to do with the design than the plate voltage though.
And it's tough in PSE to use a Vp of 520V.
I hear ya on the plate voltage / tonality though.
In 6L6 amps of the PP variety, i prefer a 330ish Vp to the more common 450V. Less power, but sweeter tone.
Tube junkie that aspires to become a tri-state bidirectional buss driver.
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statorvane
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Re: 20W 2 x EL34

Post by statorvane »

How did you get the shading on your front n rear panels? Airbrush?
The red 6V6 Plexi is awesome also, thanx for sharing.
I used a powerpoint-like application Libre Office (used to be called Star Office). I converted to PDF and had them printed out at Staples on outdoor banner paper.

The 6V6 amp was built w/big iron. I later rebiased for EL-34s (pretty much a straight drop-in). What a beast! Thanks for the compliment.
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culturejam
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Re: 20W 2 x EL34

Post by culturejam »

I just got a DSL20HR and wondered the same thing. My first thought was single-ended parallel, but the cathode-biased + lower watts probably makes more sense.
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roberto
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Re: 20W 2 x EL34

Post by roberto »

TUBEDUDE wrote: Wed Jan 31, 2018 1:42 pmIn 6L6 amps of the PP variety, i prefer a 330ish Vp to the more common 450V. Less power, but sweeter tone.
Thanks, whith what impedance you use that voltage on 6L6GCs?
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TUBEDUDE
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Re: 20W 2 x EL34

Post by TUBEDUDE »

I've tried several from 4k to 7k, but preferred the 5.2K slightly over the rest.
(Sorry to respond late. I haven't been keeping up with notifications)
Tube junkie that aspires to become a tri-state bidirectional buss driver.
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roberto
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Re: 20W 2 x EL34

Post by roberto »

Thank you very much tubedude!
5.2k each pair of 6L6GC and 330V for B+.
I put it in the list of things to try!
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