Jadis Monoblock Amplifiers

[thedudeabides]

When did you initially notice the noise issue? Recently? Still under warranty? Sorry about the problem. It really sucks to be caught in this situation.

Ron, you really should not make excuses for the manufacturer for this failure. Not very professional or sensitive in my view. Are you a Jadis dealer?

 

[Argonaut]

When ordering the JPS2S preamplifier and the JA 80MKII amplifier, I also ordered a set of all spare lamps. Yes, I tried replacing the lamps in the power supply. The problem remained. I have one observation. When the equipment is not used for a while, the noise is noticeably lower, but it still bothers you during music playback. When I use the preamp for a few days the noise gets louder and louder.

I was unable to find a circuit diagram online which would be useful , however your observations and the commonality between channels would lead one to consider the possibility of a heat related fault condition within the power supply that is exasperated with extended use … which could be anything from a cold solder joint on the tube socket of the power regulators EF86 / EL84 , a B+ resister associated with either tube drifting further out of spec due to thermal increments to a rogue winding within the PSU transformer itself, similarly exasperated by thermal build up.

It would be worth acquiring another quality vintage EF86 and EL84 ( Mullard , Telefunken, Valvo ) , from a reputable source just to double eliminate the possibility of a faulty valve .

I would usually recommend with a universal hum condition that one should check ones mains for over voltage , however I note that the JPS2S circuit has the following modification within the PSU itself … Its specific power supply recreates a voltage for the module with a 80 Hz frequency in order to avoid problems that can occur due to the 50 or 60 Hz frequency from the mains supply .
There might be a fault condition within this particular module .

That said I would recommend measuring your mains voltage as overvoltage might still be a cause of thermal overload resulting in hum , in spite of the Jadis PSU module.

Just a few thoughts off the top of my head.

Ultimately I can see no practical solution to your situation other to ship your unit back to Jadis , either via and at cost of your dealer , if still under warranty ? , Or at your own expense .

 

[Atmasphere]

June 24, 2023. I know it's been a long time. In the meantime, I checked everything that could have affected the noise. The JPS2S is extremely sensitive to the proximity of its power supply. When they are close to each other, a very loud hum is heard, as if something is broken. The hum disappeared when I removed the power supply from the preamp. The noise still remains...

If the warranty is still in force it should be returned. If you bought it at a dealer take it to them. If you bought it directly then ship it back to Jadis.

It would be worth acquiring another quality vintage EF86 and EL84 ( Mullard , Telefunken, Valvo ) , from a reputable source just to double eliminate the possibility of a faulty valve .

He has already replaced the regulator tubes with no change. It simply needs to be repaired.

 

[Argonaut]

He has already replaced the regulator tubes with no change. It simply needs to be repaired.

And you have never experienced more than one Russian or Chinese EF86 or EL84 to be faulty ? Hence my double elimination comment No !

 

[Atmasphere]

And you have never experienced more than one Russian or Chinese EF86 or EL84 to be faulty ? Hence my double elimination comment No !

I've experience that and paid big dollars for an EF86 for one of my Neumanns U67s only to find it was horribly microphonic. But if all the tubes were changed and there was no change whatsoever, that really points to something else being the problem. At any rate, having done everything in good faith, this unit really needs to go back to the dealer or manufacturer.

 

[Argonaut]

I've experience that and paid big dollars for an EF86 for one of my Neumanns U67s only to find it was horribly microphonic. But if all the tubes were changed and there was no change whatsoever, that really points to something else being the problem. At any rate, having done everything in good faith, this unit really needs to go back to the dealer or manufacturer.

As per my last paragraph post 62 … however being in the position to inform his dealer,
With whom he appears to be having a little difficulty , and eventually Jadis France , that he has double checked the regulation tubes with two disparate sets is no bad position to be in … further more when all is checked , repaired and the unit running to spec then he may well find that good quality vintage tubes in those sockets brings further fidelity to the unit above the stock tubes as supplied by Jadis … we are not talking about the sale of a kidney here are we !