CJ MV55 triode mode

net-david · 28th November 2004, 07:48 PM

I just purchased a used Conrad Johnson MV55 amp. I have read a lot about the tride mode mod CJ can perform. Since I ALWAYS have to open up everything, I had a look inside and found what I think are simple jumpers to switch the mode from ultralinear to triode! Can anyone confirm this? Here is a pic:

Here is a hi-res pic if you need it:
BIG jumper pic

There is another pair of jumpers for the other channel. The dealer I bought the amp from was willing to do the mod for a charge, but I would rather be able to experiment. Somewhere I have some info for doing this to the old EICO amp I used to have.

Thanks,
David

SHiFTY · 29th November 2004, 07:44 AM

Get yourself a basing diagram for an EL34 (remember it is viewed from underneath.)

You will find in ultralinear mode, G2 is connected to a winding on the output transformer. In triode mode, it is connected to the anode via a low value resistor (100 ohm or so).

Check that this is the case and then break out your soldering iron. Should take you 15 minutes at the outside...

28th November 2004, 07:48 PM	#1
net-david diyAudio Member Join Date: May 2003 Location: Duluth, Georgia	CJ MV55 triode mode I just purchased a used Conrad Johnson MV55 amp. I have read a lot about the tride mode mod CJ can perform. Since I ALWAYS have to open up everything, I had a look inside and found what I think are simple jumpers to switch the mode from ultralinear to triode! Can anyone confirm this? Here is a pic: Here is a hi-res pic if you need it: BIG jumper pic There is another pair of jumpers for the other channel. The dealer I bought the amp from was willing to do the mod for a charge, but I would rather be able to experiment. Somewhere I have some info for doing this to the old EICO amp I used to have. Thanks, David

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29th November 2004, 07:44 AM	#2
SHiFTY diyAudio Member Join Date: Jul 2002 Location: New Zealand	Get yourself a basing diagram for an EL34 (remember it is viewed from underneath.) You will find in ultralinear mode, G2 is connected to a winding on the output transformer. In triode mode, it is connected to the anode via a low value resistor (100 ohm or so). Check that this is the case and then break out your soldering iron. Should take you 15 minutes at the outside...