Power tube pulling in old Dual and Triple Rectos

[r_cod_81]

Hi everyone,

I gather that in the old (two-channel) rectifiers you can pull power (and rectifier) tubes to reduce output. The manual specifically mentions pulling the outer two power tubes and one rectifier tube on the Dual for 50W o/p, I was just wondering if, on the triple, one could pull the oputer set for 100W and the two outer sets for 50W, bearing in mind that the older rectos don't have the switchable multi-watt option.

Ta muchly,
Richard

 

[domct203]

When I owned a Triple Recto I called Mesa about this and was told it was OK to pull 2 powertubes, but not 4. Pulling 2/3 of your powertubes really throws off the impedence matching through the Output Transformer.

Some guys here have done this, but I wouldn't if you regularly play at stage volumes.

This has been discussed many, many times here........
http://forum.grailtone.com/search.p...t&sd=d&sr=posts&st=0&ch=300&t=0&submit=Search

You are not trying to use a 150W amp at bedroom levels are you?

BTW- when I did remove two tubes from my Triple Recto it really neutered the bottom end response and made it looser. I went back to all 6 tubes in short order, YMMV.

Dom

 

[MrMarkIII]

FWIW, the difference between 100 and 50 watts is only going to matter at some kind of stage volume.
If 100 watts is much too loud for bedroom practicing, you are not going to be able to crank the master at 50 watts.
50 watts is NOT half as loud as 100 watts.
10 watts is half as loud as 100 watts.

 

[piggyboy]

The manual specifically mentions pulling the outer two power tubes and one rectifier tube on the Dual

it actually says pull the 2 inner and leave the outermost ones

got this from the manual:

On the DUAL Solo Head it is possible to run two 6L6 or EL34 tubes by pulling the two center tubes leaving the far left and
far right tubes intact. This procedure reduces the power by approximately 50%. Remove one of the Rectifier tubes if you are using
the Tube Rectifier setting to assure a correct match.

Dont know what'll happen if you pull the outer ones.

 

[ironjose]

FWIW, the difference between 100 and 50 watts is only going to matter at some kind of stage volume.
If 100 watts is much too loud for bedroom practicing, you are not going to be able to crank the master at 50 watts.
50 watts is NOT half as loud as 100 watts.
10 watts is half as loud as 100 watts.

for sure... is not going to change the output but it sure does change the feel of the amp... as Dom said... the lack of bottom end or head room...

 

[r_cod_81]

Thanks for the responses guys. I'm not doing anything daft like trying to play one of these at bedroom levels - I have a 5W class A jobby that I use for that, fed by my Mesa preamp. Even a mini-rec's way too loud for playing in the house!

I know about the non-linear power O/P volume thing, and yes I did misquote the dual rec. manual, thanks for pointing that out.

Thanks for the link to the other thread, I guessed this must have been discussed before.