Just installed EL34s in Herbie/tone lacking initial warmth

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mad-axeman

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Guys, Peter,

I just installed SED EL34 winged Cs into Herbie. The clean is awesome but Channels 1 and 2 are lacking to my ears; I loved the way these channels sounded with the original tubes, and am missing those tones. Does anyone know which tubes this amp shipped with originally? I threw the old ones out and didn't pay attention. This Herbert was purchased in 2006, and is pre-external bias points, if that info would help.

Could this simply be an issue of replacing some pre-amp tubes? Might I be happier with some mixed power tubes? If yes to either question, I'd love some suggestions.

I guess the way I'd describe it is a general lack of warmth over the originals. Mind you, it's not terrible by any stretch, but I really loved the original sound I had when I purchased it. I apologize if this has been covered, but my searches didn't really yield any info.

Thanks in advance for any responses,

Stu
 
I think the Herbert shipped originally with Ruby EL34's.
 
What's the bias set to? Raising it would make it sound warmer.

If that doesn't work I'd keep 4 of the SED EL34s in there and then use 2 TAD 6L6GCSTRs for the other 2 tubes. I haven't tried it (I have a VH4 and can't mix tubes) but from all the tubes I've tried this combination seems like it would be phenomenal.
 
i just revalved my herbie again, about 4 months ago i put TAD preamp valves in and replaced the stock ruby EL34's with the same again. It seemed to be slightly muddy though and not bright enough. This time under advice from watford valves i put Svetlana winged C EL34's and Harma ECC83/7025 Cryos in and i have to say what a difference. Specially at gig volume, the amp is so crisp and clear and no longer muddy like it seemed to be before.
anyone else tried these valves?
 
duesentrieb":x3dpwkgt said:
Bias values?
Click to expand...

Thanks everyone for your quick responses!

I went middle of the road here, as you can see

A = 65.5
B = 65.2
C = 66.1

What do you think? I am more interested in tone than longevity, so if upping the bias would potentially add to the warmth factor, I have absolutely no objections? Dusey, do you think the bias is the issue then? No need to fool around with preamp tubes in your estimation?

Stu
 
To get more warmth set it up to 70mA per pair - and hear if you prefer that.
It does make a difference soundwise.

I wouldn't go higher than that. If you're still unsatisfied, go back to STREL34s
 
duesentrieb":1usevoct said:
To get more warmth set it up to 70mA per pair - and hear if you prefer that.
It does make a difference soundwise.

I wouldn't go higher than that. If you're still unsatisfied, go back to STREL34s
Click to expand...


Thanks much for your quick response. I've got them all set to ~69.5. I've got band practice tonight so that'll be a good test.

Incidentally, is it normal for the rating to drop 2 or 3 mA on new tubes? I ask because a check of the current before any changes were made yielded values less than I initially set them. If this is to be expected, how long before they hold steady? That I'm sure was part of the problem. They were reading about 63 mA before I upped them.

Stu
 
Well that depends - 60 something isn't hot - and the hotter, the faster, you know.

The tubes in my Herbert are 3 years old, still running good at 60mA/pair.
 
hey ,
regarding the newly set bias "moving" , my einstein did this also .
i just installed a set of winged C svetlana EL34's , set the bias to 70 .
when i checked it the next day the bias had dropped to 66 :confused:

so i reset it to 70 and left the amp on for a few hours , then checked it again .
what i noticed then is that the bias reading continually fluctuates between 68 -71 .
it wont actually settle on a reading .
why is this , and is this normal ?
 
You have a different main voltage. It will be
switched by the voltage supplier all day long.
That´s usual.
 
cool - they sound awesome , btw :)
makes channel 2 MUCH nicer .
good choice peter !
 
slate":39n5moyf said:
hey ,
regarding the newly set bias "moving" , my einstein did this also .
i just installed a set of winged C svetlana EL34's , set the bias to 70 .
when i checked it the next day the bias had dropped to 66 :confused:

so i reset it to 70 and left the amp on for a few hours , then checked it again .
what i noticed then is that the bias reading continually fluctuates between 68 -71 .
it wont actually settle on a reading .
why is this , and is this normal ?
Click to expand...
Normal. Tubes need some time to burn in. Just set it, play some hours, reset - done. Don't make yourself crazy by checking it twice a day, you know :D

Once you've cranked the shit ouut of them they are burnt in and at 65mA or so (try 60, 65 and 70) they stay like this.
 
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