Congested ! 6CA7 Candidate ??

[alanfc]

thats the only way I can describe it :(

Now that I have better ears this is what I'm hearing.
Rivera R55 into 2x12 (v30-G12h30) partial open back
Power EL34 Winged C's.
Strat with JB Jr. bridge (ceramic mag), pickup height 1/8" off strings.

at full band volume, 'hard rock' slightly 80's/sorta EVH tones.

one minute I'm turning down the mids because it sounds boxy and congested, then I turn the mids back up because I'm getting no bark. But then its harsh and congested.
I had an EQ pedal in the loop but the poles aren't affecting what I want....

Am I a candidate for : 6CA7's ?!?!? ? ?

is it the partial open back cab? Should I seal it?
The ceramic magnet pickup.? (I loved my Alnico 2 Custom Custom in another guitar)

OR, am I wanting a 6L6 powered amp. I hope not !

thanks for your diagnosis
:)

[aleclee]

IME, 6CA7s have a much flatter response than EL34s. You can get a duet of EH 6CA7s for about 25-30 bucks. I think the EH version retains more EL34 character than the much more expensive GT version. Worst case is you have an inexpensive set of backup tubes.

Though the open-backed cab might be contributing to the boxiness, putting it all the way up against the wall might give you an idea of the effect of the open back.

[Old Tele man]

...the 6CA7 is the US-version of european EL34...and they're both power pentodes, not power BEAM tetrodes!

[alanfc]

OK thanks guys

Old Tele man, is this some sort of amp tech inside joke? !
:D
I'll look up this tetrode pentode business.
I know on paper the US-Euros are similar but I 've always read they're difference to the ear..

[UfoPilot]

Originally posted by Old Tele man
...the 6CA7 is the US-version of european EL34...and they're both power pentodes, not power BEAM tetrodes!
Acording to EH it is a tetrode. Here is a quote from thier web site.
Designed to the exacting specifications of the Phillips 6CA7. This classic tetrode returns to life in a big bottle design. The 6CA7EH is built to withstand today's high-gain amps while still retaining the detailed tone and component integrity of the original. A direct replacement, with military reliability, for any EL34.

[alanfc]

OK thanks:)
Would I have to take the amp in for a re-bias if I went from the EL34 to 6ca7?
thanks

[aleclee]

Originally posted by alanfc
Would I have to take the amp in for a re-bias if I went from the EL34 to 6ca7?Yup. It's just like any other tube replacement. Scott P and I have both run 6CA7s in our Riveras and have had great results biasing them relatively cold (32-35 mA). YMMV but there's some very good tone to be had without cooking the tubes.

[alanfc]

Originally posted by aleclee
Yup. It's just like any other tube replacement. Scott P and I have both run 6CA7s in our Riveras and have had great results biasing them relatively cold (32-35 mA). YMMV but there's some very good tone to be had without cooking the tubes.

OK thanks,
at my last checkup my bias on the EL34's was approx 34-35 I remember,
Do I still need to take it in for re-bias?
My tech is great but in very high demand:(
Thanks

[aleclee]

Originally posted by alanfc
at my last checkup my bias on the EL34's was approx 34-35 I remember,
Do I still need to take it in for re-bias?It should be re-biased. It's probably okay but...

Frankly, I'd suggest buying a bias meter (e.g., Weber Bias-Rite) and DIY. It's not hard if you don't mind pulling the chassis and allows for immediate gratification in terms of tube swaps and tube replacement. Between the time and $$$ saved, it's money well spent, IMO.

[alanfc]

Originally posted by aleclee
It needs to be re-biased. It's probably okay but...

Frankly, I'd suggest buying a bias meter (e.g., Weber Bias-Rite) and DIY. It's not hard if you don't mind pulling the chassis and allows for immediate gratification in terms of tube swaps and tube replacement. Between the time and $$$ saved, it's money well spent, IMO.

thanks,
I'm always thinking about doing this but never do it:rolleyes:
I think I have some motivation now.

[UfoPilot]

I agree. Get a bias meter and do it yourself. It's easy and you can tweak the bias for the best sound.

[Erik]

Originally posted by UfoPilot
I agree. Get a bias meter and do it yourself. It's easy and you can tweak the bias for the best sound.

I'll third what UfoPilot and Alec have said.