[kyrill]

hi

I could not let it go, a pristine maintained Jadis Orchestra out of 2004


it is an EL 34 pentode 2x40 watts integrated amp with 2x 12ax7

the one i fell for is modded into triode mode ( 2x20 watts) bypassing mute and balance control and with upgraded coupling caps and some power caps

I had to sell my RW 30.2 amp to pay for taxes and within 2 weeks i got a correction and got even more back from the tax man

Divine intervention wanted me obviously to have this beautiful amp.
I lost some naturallness that went with the 30.2 and got spooky transparency back.

My big surprise is, is the SB3 modded by Wayne (digital mod, 3.3V and 5V out. Hynes pws, Pats's S/pdif mod) that it can sound so transparent, analogue like. Sometimes too transparent, is that possible?

Now i would like to share information with other Jadis ( orchestra) listeners. I want to tube roll or even tweak it further to bring it closer to Vinnies naturallness.

But any info from whatever angle is welcome : )

ah pff, this is posted in the wrong forum  dear Josh?

[JoshK]

Well if you are looking to understand the operation and design of the Jadis, then this forum is appropriate.  If you want me to put it somewhere else, just let me know.

Do you have a schematic?  I am assuming you are most interested in tube rolling then modding, right?  I don't blame you, just asking.

I'll take a wild guess and say that given the output is PP and there is one dual triode input per channel, they are either doing a long tail pail or a split load phase splitter.   That is pretty much all you can do with one dual for PP outputs.

[kyrill]

hi Josh 

even when i would have the schematic I would not post it

It is still a "modern ämp in sale by the manufacturer.

I think it should be better in the"normal"audio forum
Can you transfer it there,Josh?

[JoshK]

hi Josh 

even when i would have the schematic I would not post it

It is still a "modern ämp in sale by the manufacturer.

I think it should be better in the"normal"audio forum
Can you transfer it there,Josh?

Yeah, if its non public it should stay that way.  I'll move this thread. 

[poseidonsvoice]

Hi,

Saw this post in the morning in the Lab, but I guess it got moved. Anyway, nice amplifier, beautiful chassis! I was going to ask for a schematic as well, but I understand given that it is a modern amplifier, and copywright laws. I agree with Josh, this is a 2 stage push pull integrated amplifier, with a high gain input tube, 12AX7's wired as long tail phase splitters that are cap coupled to the EL34's in the output stage. Its an okay, very conservative design. There are better designs from a sonic standpoint in my honest opinion. I would ask Kevin Carter on his K&K forum, as he has just come out with a very nice board that replaces an entire Dynaco ST70. It is a full blown differential design. It is also a cap coupled design but definitely in the extreme. Uses 6N23P's in the input stage with current sources for both this tube and the EL34's. Kevin may share the schematic with you. Here is the link to the discussion on his forum (if this is illegal moderators, please delete this post): http://www.audioasylum.com/forums/KandK/messages/7012.html

Hope this helps,

Anand.

[kyrill]

thx anand
i can show a photo of the innards of the lovely lady, would that help
however Kevin's kit is designed to work with the original ST-70 power transformer and uses all of the secondaries that it provides. Filaments are all AC. You will need something like 375-0-375 VAC at 400mA, 2 x 6.3vAC at 3.5A (center tap a convenience, but not necessary), and 25-50VAC at 50mA for the front end negative supply. I wonder if the Jadis would have those exact voltages?


Jadis is known generally not to follow conservative designs


kyrill

[poseidonsvoice]

Personally, I would pop the thing open, and start making measurements from the power transformer on out. That's the only way you are going to know what you are dealing with. I realize Kevin's board is designed to work with the original ST70 power transformer, but you can always 'adapt.' Without measurements though, you are nowhere. You are then walking the fine line of violating copywright infringments and getting help here on the forum, if you start posting any info regarding the original Jadis design! If it were my amp, I would pull out all the innards, except for the transformers, make measurements of the off load voltages on the trannies and start from scratch. You may be able to design in something very similar to Kevin Carter's ST70 mod, point to point wired. Otherwise, its just replacing a resistor here with a Riken or replacing a capacitor there with a Hovland, etc...simple tweaking.

Best,
Anand.

[kyrill]

Hi Anand
Iam not so experienced as you at all

And then Jadis is not an average tube manufacturer

Iam more interested in tweaking

[KeithR]

i'm not sure why you would even think of modifying a Jadis.

just my opinion.

[kyrill]

i understand you Keith 

It is already  wonderfully mod into triode, bypassing mute and changed  couplin caps It sounds more open much more transparent than the original Orchestra,according to the1st owner.

I was more interested in the last tweek and tube rolling

[poseidonsvoice]

Okay so if you are into tweaking, i.e. replacing part for part but different manufacturer, you can flip the thing over and take a picture. As far as tweaking, make sure its reversible just in case. But then again, if another fella already modified the thing, it might be fully 'tweaked,' and you should leave well enough alone!

Best,
Anand.

[kyrill]

Anand you are right

tube rolling then

The sound is already spooky transparent and musical, but somehow not so "human like" as
Vinnie's 30.2 amp It is when you dont have it, you start to notice what you miss.