Can I pull two power tubes from Tremoverb?

[57Strat777]

I have a 1994 Tremoverb and want to try some EL34 tubes in it, but I only have two EL34 tubes. Can I run this amp with only two power tubes? If so, does running with two power tubes affect speaker OHMs?

 

[RPercival]

You'll get mixed answers on this and both sides will swear that they're right. I can't say 100% that it's safe to do so, BUT! if you do run only two, use the two in the middle and pull the furthest rectifier tube also.

 

[RR]

I'm going to put a disclaimer 'cause what I say and you attempt this, its your own doing :

I read somewhere you could pull two of the power stage tubes and they have to be either the inner two or the outer two if I'm not mistaken. You do not stagger them.

But its best that you pull both 5U4 rectifier tubes and replace it with an 5AR4 in either socket.

The output jack what was for 8 ohms load is now 16 ohms if I'm not mistaken. Same for the 4 ohm jack is now 8 ohm tap.

Now I don't know if you could do this with "silicon diode" rectifier.

Now that you are using only two power stage tube you could crank up the amp because its 50 watt and push the power stage tubes. Uh, it doesn't necessarily sound like a 50 watt amp because the output transformer is a 100 watt OT not a 50 watt OT. There's some "mojo" in the OT to sound like a lower power amp.

Yes, I've done the above. Taste may vary.

 

[piggyboy]

if you check out the manuals on the mesa site for the 2 channel dual rectifier it has in there about pulling 2 power tubes.
up to you if you do it on your tremoverb. FWIW I use 2 tubes on my tremoverb.

from top of page 9 in the dual recto solo head manual (I know its not the tremoverb manual) 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

I thought there was something about which output to connect speakers to when using 2 tubes but I couldn't see it when I had a look just now.

 

[afu]

Pulling two tubes doubles the output impedance of the speaker outs. A 16 Ohm cab would need to be used with the 8 Ohm out jack.

http://www.premierguitar.com/articles/20713-ask-amp-man-removing-output-tubes-to-reduce-power

 

[RPercival]

Pulling two tubes doubles the output impedance of the speaker outs. A 16 Ohm cab would need to be used with the 8 Ohm out jack.

http://www.premierguitar.com/articles/20713-ask-amp-man-removing-output-tubes-to-reduce-power

Which is why you need to remove one of the rec tubes. Outputs work the same.

 

[domct203]

Pulling two tubes doubles the output impedance of the speaker outs. A 16 Ohm cab would need to be used with the 8 Ohm out jack.

http://www.premierguitar.com/articles/20713-ask-amp-man-removing-output-tubes-to-reduce-power

Which is why you need to remove one of the rec tubes. Outputs work the same.

The rectifier tubes have absolutely nothing to do with the output impedance.

The rectifier tube's sole purpose is to convert AC voltage to DC voltage. They are part of the power supply circuit, and have nothing to do with the audio signal.

If the amp is set to silicon diode, and you remove all the rectifier tubes, the amp will operate normally and safely.

The reason it is recommended to pull one of the rectifier tubes is to retain that rectifier tube sag & bounce (when using the rectifier tubes) with the reduced demand for current. Two rectifier tubes with only two 6L6's would have no trouble keeping up current flow, and have the equivalent feel as SS diodes.

Dom