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Starsailor 2nd December 2006 02:08 AM

Lectron JH50 Tube Bias
Hi, gang. This is my first visit to this site, so please be gentle. I have long had a Lectron JH50 tube amp, but when I moved recently I lost the diagram and instructions on how to set the tube bias. Does anyone have a copy of the tube bias instructions (hopefully in English!) that they can forward to me so I can set the bias without having to take the thing to a repair shop? Thanks so much!----Starsailor

(PS----When it's right, it sounds just HEAVENLY with my Magnepan speakers!)

Nilau 20th January 2007 05:08 PM

Hi "starsailor"...

Did you ever receive the schematic regarding the bias adjustment?

I also need this information! ;-)


Starsailor 25th July 2007 12:41 AM

No, I haven't had any reply but yours. A bit disappointing, even though I know this amp has not been very widely distributed in my country (the US.) I have had to guess at the the tube bias, but it STILL sounds wonderful....and that's the real goal, isn't it......? -----Starsailor

Pano 15th August 2007 10:29 AM

Re: Lectron JH50 Tube Bias

Originally posted by Starsailor
Does anyone have a copy of the tube bias instructions (hopefully in English!)
I sure wish that I did. You see, I wrote the English manual for the JH-50. :)
But my copy has long since vanished.

I was hoping to find a schematic of the JH-50 somewhere when I stumbled across this thread. Anyone seen a copy? Would it be in the Revue de l'Audiophile? Maybe #41?

jacco vermeulen 15th August 2007 12:31 PM

The Lectron JH-50 is covered in #40 and #41.
Sounds great on ESL63s too, as does the Jean Hiraga 60.

Pano 16th August 2007 08:12 AM

Thanks Jacco! I'll have to get the Revue in CD.

The JH50 was amazing at its debut on the big 4-way horn system. Probably more the speakers than the amp. =)

jacco vermeulen 16th August 2007 11:53 AM

The $65 for the Davidenko CDs are worth it, considering the many Francs transferred to France for the paper versions. I found the foreign annual subscriptions pretty expensive.

The EL34s in the JH-50 are biased at 25mA.
Either just with a DMM or sweeped with a tone generator and a scope, as preferred by the French-Japanese gent.

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