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marco3253

DT25 - JJ EL844 owners - sharing infos

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Hi guys,

I bought this amp with el844 tubes, and yesterday for the first time i retubed the amp with two matched el844 again. This because they seems to reach the breakpoints earlier and with lower volume compared to EL84 from electro harmonix.

Anyway, i did not check the bias with the old tubes that i changed, i checked the bias after i mounted the new ones, and i get -12.7 and -13 (i guess we can consider this matched).
I did not adjust the bias because i guess it is fully counterwise, so this is the max i can reach...
The tubes are lighted as always and the sound (in my house so i cannot reach the break point) sounds great.

What kind of values are you having you guys using JJ EL844 ?


Thank you.

post-842657-0-02013200-1489748240_thumb.jpg

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Don't do that. Go back to the original specified tubes. These are not all analog tube amps where you can

get away with doing things like this. These amps are not forgiving of modifications.These are optimized for

the specified tubes.

 

"... seems to reach the breakpoints earlier and with lower volume compared to EL84 from electro harmonix"---

Shortens the life of the tubes in these circuits, stresses the amp circuits and the digital board.

 

And you run the risk of voiding the warranty.

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mmmmm i thought that were a lot of people doing this, am i wrong?

in that case i can buy a set of two EL84, but now i'm used to this kind of sound, will i get a different sound later?

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I've had too many of our valve amps (Spider Valve, Alchemist, DT series) come across my

bench here at Line 6 HQ with other than specified tubes (JJ, Mesa, Groove Tube and others).

And the reason they failed was that they had the wrong version tube in them.

 

These are not all analog amps. The digital and analog section need to talk to work with each

other. Hot rodding an already Bogner designed hot rod amp messes with the digital program,

which gives the analog section incorrect functionality. And then things go wrong from there.

 

Stick to the specs, the amp will last longer.

 

Every year at the trade show here, I chat with the tube people, and am friends with a couple of

them. And there products are good and I like them, but not in these amps. Stick with the EH EL84,

and they have to be matched pairs.

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I am a tube rolling experimenting power tube kind of guy for 30 plus years. Its fun with forgiving circuits- Fender - Marshall- Laney etc...

However I would absolutely never put anything in a Line 6 amp but what it is specified pre and power.Especially the PI tube next to the output tubes. The way these amps are designed their is nothing to be gained by experimenting with tubes/ bias etc...

 

Get an old beat to death Bassman or some Peavey or something for that.

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It's interesting as I have been informed differently on the SVs, DT50 and DT25...I have been running Mesa tubes in both SVs, DT50 and DT25 ever since Line 6 sent them to me. I have been running slightly mismatched loads also. This was with very specific technical consultation...EL844 runs at about half the dissipation (~6 watts) and do not run nearly as hot as real EL84...They are an interesting choice, but I am not sure the bias pot has the range to do it properly or not...never measured it...

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Don't know who informed you differently.

 

All of the ones I got back with other than spec tubes, failed because they had

something other than spec tubes in them. And being biased incorrectly didn't help

matters any.

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the EL844 bias around 14 at the max value, anyway i will revert to the 84's asap.

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It was just a couple of guys I was talking to before these amps were released...doesn't matter...

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Ah,... okay.

I've come across a number of things since then.

No worries, I'm here to help.

Very good, carry on.

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ok guys, as you suggested, i replaced the EL844 with the EH EL84, as advised by line6 also.
Now i'm biasing, i get 27 on the V3 and 24 on the V2, is that acceptable? or one tube is defective?

 

i bought 4 matched tubes.

 

Thank you.

 

Marco

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