+++ Dual Rect Tubes +++ Would this work ???

[STUART]

Got here an early 2 channel Dual Rectifier.
Can i go ahead and replace the stock Mesa tubes (el34)with Sylvania 6CA7'S and the two rectifier (5u4g) with a pair Mullard GZ 34 or is this just not on
Thanks in advance !!

Stu

 

[Elpelotero]

as long as they fall within the acceptable range for Mesa's bias, it should work fine. I think the Groove Tubes scale between 4-7 is Mesa's range, but don't quote me.

 

[NoGlassNoClass]

The GZ34/5AR4 type rectifiers will work fine, however they will change the amp's response...less sag, tighter, louder, fuller bass response (closer to the silicon diode rectifiers). If that's what you're after, it's all good.

While the 6CA7 is interchangeable with the EL34, you will have to check to make sure the particular tubes you have will bias up properly with Mesa's fixed bias setting (or have the amp modified for adjustable bias)

 

[STUART]

Do the pair of rectifier tubes work together all the time with either channels 1 or 2 ?? or one rect tube for channel 1 and the other for channel 2 ??
So best maybe to use a matched pair same brand etc for optimum performances if they work together always

Also anyone know too maybe Mesa's EL34 fixed bias setting tolerance range info for a Dual Rect,
I think my 6CA7'S will be well out here but the adjustable bias is certainly a good option thanks :wink:

Thanks for your time !!

 

[Boogiebabies]

For the money you spent on amps and tubes, it may be a good investment to buy a bias meter.
This way you will know if the 6CA7's would work and you don't have to second guess yourself when $ 300.00 worth of tubes blow up.

 

[STUART]

Absolutely Ed,
I do have a Fluke multimeter and a pair of probes which measure the tube cathode current as DC voltage

What would be the specs Mesa EL34 bias range min /max (mA) for an early DR, therfore keeping the 6ca7's within limits

 

[LynchLicks]

as long as they fall within the acceptable range for Mesa's bias, it should work fine. I think the Groove Tubes scale between 4-7 is Mesa's range, but don't quote me.

The GT rating range is 4,5 or 6
You can ask for tubes other than GT's with these ratings from most of the on line tube stores, like Dougs tubes.com, the tube store.com, etc.

 

[TP Parter]

My Tremoverb sounds outstanding with GZ34/5AR4 and Svetlana EL34. If you have a tech bias them up the 6CA7 out to be fine in the amp. I bet it'll sound kick ***.

 

[STUART]

Thanks for the info guys !! ...very muchos appreciated here ... GZ34'S now on the way

Anyone done or any picts of the bias pot modification with the D/Rect ,definitely want to get these 6CA7 Sylvania's glowing

Stu

 

[Elpelotero]

some people have done it, but don't remember who. Try doing a Search at the top of the page and see if you have any luck