A Visit to Jadis

mep

Member Sponsor & WBF Founding Member
Apr 21, 2010
9,483
0
0
#42
Maybe it's just me, but those speakers remind me of Yosemite Sam. As Sam would say "All right now ya wise guy … Dance!”
 

garylkoh

WBF Technical Expert (Speakers & Audio Equipment)
Sep 6, 2010
5,416
1
36
Seattle, WA
www.genesisloudspeakers.com
#43
That's exactly right, Gary. And thanks for posting. That's a Jadis lover's dream go to place. I had a JA200 and JPL combo before and it's not more colored. In fact, I found a CJ MV 125 to my my JPL more colored. :) My sister lives near Pau, which is very near the Spanish border. I will ask her how near she is to the Jadis factory. Maybe it will push me to visit her finally.
Pau is just a couple of hours away from Jadis. We have a mutual customer Jadis/Genesis there, but didn't have time to visit this trip.
 

garylkoh

WBF Technical Expert (Speakers & Audio Equipment)
Sep 6, 2010
5,416
1
36
Seattle, WA
www.genesisloudspeakers.com
#45
The week after the trip to the Jadis factory, we visited an audiophile in the Parisian suburb of Vaucresson. It was a thoroughly musical system - Genesis 2.2 Junior loudspeakers, the new Jadis JA120 monoblock power amplifiers, JP-80 preamplifier with external power supply, JS-1 DAC with external power supply, and JD-1 CD Drive with external power supply.

We spent all the time listening to music and clear forgot to take pictures!!
 
#50
I've repaired Jadis amplifiers in my shop (south western tip of CT has obscenely rich people) and they have quite nice build quality, but the circuit topology is very ordinary and nothing unique or original. Amplifier performance is decent, but not the best I've measured in a tube amp. Probably the best tube amp I can remember measuring is the McIntosh MC30.

One annoying design in the Jadis Orchestra Reference, for example, is the fact that all the output tube filaments are in series. In one unit I tested, the filament voltages across individual tubes varied by more than 20%, and some tubes ran cooler than others and filaments were even visibly more orange or more yellow, depending on the resistance of the heaters. Series heaters are for tube types that are designed with heaters that have exacting specs for heater resistance and can provide consistent voltage division across multiple tubes. EL34s are not designed with that in mind, so filaments have varied resistance and in a series string, that results in drastic differences in thermionic emission and tube life. For a push pull amplifier, this is a bad idea.

The worst tube amp I've measured to date was the Carver VTA20S "Black Magic", which couldn't pass 20Hz despite the manufacturer spec stating 8-43,000Hz. The transformers only weighed a pound, which explained a lot right there. A lot of hype and exaggerated specs on vacuum tube amplifiers out there. One has to be careful when shopping.

BTW, I didn't see any acoustic treatment for room reflections in that 'test room' photo above. A series case of "Michael Fremer" in there.. hard plaster walls=bad audio evaluation room.
 

MylesBAstor

Member Sponsor & WBF Founding Member
Apr 20, 2010
11,221
0
0
#51
I've repaired Jadis amplifiers in my shop (south western tip of CT has obscenely rich people) and they have quite nice build quality, but the circuit topology is very ordinary and nothing unique or original. Amplifier performance is decent, but not the best I've measured in a tube amp. Probably the best tube amp I can remember measuring is the McIntosh MC30.

One annoying design in the Jadis Orchestra Reference, for example, is the fact that all the output tube filaments are in series. In one unit I tested, the filament voltages across individual tubes varied by more than 20%, and some tubes ran cooler than others and filaments were even visibly more orange or more yellow, depending on the resistance of the heaters. Series heaters are for tube types that are designed with heaters that have exacting specs for heater resistance and can provide consistent voltage division across multiple tubes. EL34s are not designed with that in mind, so filaments have varied resistance and in a series string, that results in drastic differences in thermionic emission and tube life. For a push pull amplifier, this is a bad idea.

The worst tube amp I've measured to date was the Carver VTA20S "Black Magic", which couldn't pass 20Hz despite the manufacturer spec stating 8-43,000Hz. The transformers only weighed a pound, which explained a lot right there. A lot of hype and exaggerated specs on vacuum tube amplifiers out there. One has to be careful when shopping.

BTW, I didn't see any acoustic treatment for room reflections in that 'test room' photo above. A series case of "Michael Fremer" in there.. hard plaster walls=bad audio evaluation room.
The best analysis I've heard of Jadis amplifiers are that they're basically a Hegeman circuit with the best damn built and measuring output transformers my friend ever saw. It too Da-Hong Seetoo however to get them to work properly. (BTW, some may remember the name Seetoo because he's gone on from his audio days to become a Grammy award winning producer and engineer. Wilcox everybody knows!)

http://en.wikipedia.org/wiki/Da-Hong_Seetoo


 
May 30, 2010
14,115
78
48
Portugal
#52
I've repaired Jadis amplifiers in my shop (south western tip of CT has obscenely rich people) and they have quite nice build quality, but the circuit topology is very ordinary and nothing unique or original. Amplifier performance is decent, but not the best I've measured in a tube amp. Probably the best tube amp I can remember measuring is the McIntosh MC30. (...)
Mark,

As far as I know many Jadis power amplifiers are based on the old Pierre Loyez design - an interesting design using some local crossed feedback through 10 Mohm resistors that you can see at http://www.bonavolta.ch/hobby/fr/audio/el34_2.htm. Your are right that they measure poorly on classical parameters, but can sound excellent when coupled to their matching preamplfiers. Also IMHO , the Jadis Orchestra, their entry line integrated, is not representative of the quality of their better products, that as Myles says used excellent and expensive output transformers.
 
Oct 6, 2010
66
0
6
wash dc
#53
Gary:

This was a great thread. I was owner of the JS1 and JD1 for about 12 years. That combination was very seductive. My friend at Music Technology reworked the power supply and analog board with better components. I had to unload them due to there age.

I am hoping that Jadis will update the JS1 with today's current 24/192 DSD capabilities and then paired with the Calliope; they hopefully will challenge the MSB/DCS throne.
 
May 30, 2010
14,115
78
48
Portugal
#54
It was - I discovered Maria Joao Pires!!
Revisiting this thread made me find this post that I had missed in due time - I am very happy Gary refers to Maria Joao Pires, a great portuguese pianist. Happily I had to opportunity to listen to her wonderful playing Beethoven and Mozart sonata's when she was living in Portugal. She was on the newspapers recently due to an uncommon mistake - she was ready to play in a lunchconcert of a Mozart piano concerto with the Amsterdam Concertgebouw conducted by Riccardo Chailly, only to hear the orchestra begin playing another Mozart concerto – no 20 in D minor, K466, not what she was expecting or had prepared for. See it at:

http://blogs.telegraph.co.uk/culture/stephenhough/100071203/maria-joao-pires-the-panic-the-miracle/
 
#55
Mark,

As far as I know many Jadis power amplifiers are based on the old Pierre Loyez design - an interesting design using some local crossed feedback through 10 Mohm resistors that you can see at http://www.bonavolta.ch/hobby/fr/audio/el34_2.htm. Your are right that they measure poorly on classical parameters, but can sound excellent when coupled to their matching preamplfiers. Also IMHO , the Jadis Orchestra, their entry line integrated, is not representative of the quality of their better products, that as Myles says used excellent and expensive output transformers.

All fancy BS, aside, that circuit uses a Cathodyne Inverter, a very old topology dating back to the 1940s. The output circuitry is plain vanilla as it gets, with the only "unique" feature being a totally useless fuse in the suppressor grid circuit, which, if open, leaves the suppressor grid to float at positive potentials and cause mayhem. And the implementation of Cathodyne is flawed: he puts a cathode bias resistor in series with the 100K cathodyne resistor, and doesn't bypass the audio signal with a cap, leaving the cathode (non inverting) side of the driver slightly lower in output than the plate side, producing unbalanced drive and higher distortion than would otherwise result in a properly implemented Cathodyne inverter. Again, there is nothing about this circuit that one can rightly put their name on and call "special". It's marketing hype for people who are ignorant of basic amplifier circuit design.

And the Loyez' "design" was not invented by him. Local feedback goes back to the 1930s. I have text books from that era with circuit diagram examples. I actually used some of that stuff in my designs in the 1960s. Even Alan Kimmel uses it in his OTL designs. The output design is Ultralinear tapped output primary, originally developed by Williamson of England in the mid 1940s. Nothing original here.

To a certain extent, two out of phase non-linear stages can tend to cancel harmonic distortion to a point, but not completely. However, vacuum tube amps which approach 1% THD well below full output do not fit my definition of high fidelity. High fidelity does not mean 'it sounds good to my ears'. It is an objective measurement of how well a component, or chain of components amplifies a program source, without adding or taking away anything else but amplitude. The subjective definition of high fidelity is that the playback sounds indistinguishable from the source. Anything that adds distortion has already failed at that mission.
 
Aug 26, 2012
1,379
2
38
#56
That's a great write up Gary. I owned a JA-500 for years and just parted ways with it in 2012. I had a hard time moving the four chassis around and found that it was impracticable as a reviewing tool for base line testing. Also, I found a modern amplifier that surpassed it sonically (but not visually).
Peter, mind telling us which amp that might be ....
 

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