JADIS ORCHESTRA

Thank you, Denis, you're too kind. I'll mention that at the time I had the bias procedure only half right. Credit my own stupidity, though I'll warn anyone who sees the documentation that the translation is extremely rough (having gotten to know them over the past year, they apologize incessantly about their poor English), so you might want to contact me if you ever are interested in doing it. I considered posting a youtube video, but out of safety concerns for the end customer, the company requested I do not. I do have to warn folks who are not comfortable with this stuff that the voltages inside the unit are pretty high, so it's better to be safe than sorry.

The bias procedure is not all that difficult, it's the reassembly of the amp that's the headache, as you need to remove both side panels and the bottom plate. Getting them back together right requires time and patience. I used to think that given all the holes on the bottom plate, it would be wise to tap a few more that line up with the bias resistors and potentiometers, which would make bias a quick operation. Instead on mine, I figured out a better way, where I installed the bottom plate on the outside of the side panels. The only issue with that is the bottom feet screwing in, but I installed threaded clips that solved that issue.

Aussiedrummer, you lucked out when it comes to the cap, thank heavens!

You will get more bass with the KT88, and a bit more loudness. I should install a quad in mine to gauge the differences again, as it's been a while. But, I will say that after hearing both tubes, to me, there is no comparison, the JJ E34L is the way to go. As Denis mentioned, with that tube the amp possesses a simply magical midrange, one difficult to find in any product, regardless of price. I also have JJ KT77 and will try them at some point, but I generally do tube comparisons in my DA30, as the cathode bias (Orchestra/JOR is fixed bias) circuit makes everything plug and play - VERY fast. The KT77 are pretty good, and make more low end, but in comparison, I really do miss that midrange. My good friend, Jeff Carder, who builds the incredible sounding CarderSound speakers goes crazy over my DA30 with the E34L, he claims it's the second best amplifier he's ever heard, behind a far more expensive Audio Note. I do agree with him in that there's simply a naturalness present that eludes just about every high-end audio product. Also, little known thus far, but JJ recently introduced a big bottle 6CA7, I'm curious enough to give them a try.

For 12AX7, the best kept secret in high-end audio today is the Shuguang triple mica 12AX7B. Just about a week ago, another gentleman in Oz tried them out in his JOR based on our correspondence, replacing his EH 12AX7, and could not believe the improvement. I found it impossible to accept at face value, but those Shuguangs really do beat out most of the vaunted old 12AX7 tubes.

Cap is now are fixed. Yay!Comments were that the cap is held by a rivet and the spacer was stopping the two tabs to reach down past the chassis and get soldered properly.All hand made he said,great point to point workmanship but thought that the finish was reflective of a Chinese made amp. He also said that the heaters of all the output valves were wired in series and he would advice that this could be done in a better manner. He lost me here when he mentioned cathods and so forth. Could someone explain in lay man terms what this all means? I was working and on the phone so did not have the time to ask for explainations.He said he is going to change that. He also said that we needed to measure current as well as adjust bias so he will drill the additional holes to do this. All in all the amp is running and is to be auditioned next to his solid state amps and ribbion speakers on Monday.

Trelja, thanks for all the advice you seem to be guru in regards to these amps. Thank you sir. I gather from your response that I can use KT88 tubes. Am I correct?

I shall try the JJE34L or the Shuguang 12AX7B.
All of you have been very helpful and I have learnt a lot about tubes and I only picked it up last night.I am sure I have lots more to learn and am sure I will be learning till I lay to rest.

Aussiedrummer, I'm not the guru, just a fan. Hopefully, you will become a fan as well.

According to Jadis, you can only use EL34 variants in your Orchestra. The Orchestra Reference, with its upgraded transformers, allows use of the larger tubes. I have my own opinion on the matter, but suggest you contact Jadis if you are that interested in using KT88.

One thing about the JOR is that it buys you the better cosmetics, as you mentioned the Orchestra's finish is reflective of a Chinese amp. I'll say that these days, the Chinese put a lot of resources into the casework, using a lot of metal and CNC milling equipment. But, in the effort to come across as distinct, classy, or even edgy, the cosmetics have a short shelf life, and come across as tacky within a few years. In my opinion, many of the Chinese marques would be better served by investing the time in bringing the design and implementation of a circuit to a higher level.

In the simplest terms, think of a tube as a conduit for the travel of electrons. They go from one place (cathode) to the other (anode, also called the plate). That's basically it.

Of course, amplification is a product of going from that one place to the other, which is why tubes are used in amplifiers.

Still keeping things simple and easy, because a tube works so well at the aforementioned task of having electrons go from the cathode to the anode, the tube can burn up quickly. Then, we'd need a new tube well before its time. So, we want to moderate/modulate that process and slow things down to a manageable level. That obviously requires something else to be added into the equation. The third element is called the control grid. Three elements in the tube means we have what's called a triode. Prior that, we had just two elements (cathode and anode/plate), a diode.

As we all know, opposite charges attract each other, which is why the electrons fly toward the plate in the first place. Conversely, like charges repel each other, so two electrons will try to stay away from each other.

The control grid sits between the cathode and the plate, and, again its job is to modulate the electron flow from the cathode to the plate (anode). It does this by having a negative charge, and as we said, like charges repel each other. The electrons now see a negative charge in front of them, and their impetus for the travel from the cathode to the plate has been reduced. That negative charge, which we'll measure in voltage and call bias (yes, that's what we mean when we say bias), can be nothing (ZERO) which would be as if the control grid wasn't even there, or high enough so that no electrons make the jump at all (tube is essentially "off"). Ideally, we'll look for some value that's high enough to allow the electrons flow and make music, and low enough so we're not replacing our tubes more frequently than our socks.

Note, as we said, the bias voltage is negative, which confuses most everyone so we'll take a second pass at it. A MORE negative (-70V is more negative than -40V, as -70V is further from 0 than -40V is) voltage will allow LESS electrons to flow. A LESS negative (closer to 0) voltage will allow MORE electrons to flow. Once we understand things that way, it all actually begins to make sense. Colloquially, people will use the terms "hotter"/"warmer" and "colder" to describe all of this.

Quickly, and keeping things simple there can one or two additional elements in the tube that will make the tube work better (whether or not that is true when it comes to high-end audio will bring us into a lot of, um, "discussion" shall we say). Adding one additional (fourth) element the screen grid, make it a tetrode. Adding another (fifth) on top of that, the suppressor grid, makes it a pentode like the EL34 and KT88 we've been talking about.

Along with going deeper into what the screen and suppressor grids do, there are other more esoteric things to talk about one day like cathode bias and fixed bias, and even making the control grid positive (yes, positive). But for now, just try to first understand how the cathode, control grid, and anode/plate work, and get comfortable with that.

I use KT 90's because they came with my unit, along with a spare new set of them. They sound deep in the bass end, and I like the midrange too, although I have not tried any others. Apparantly the Ei factory which made them had a fire and no longer produce them, and I am told the EH 90's are not the same in sound quality. The above has been most informative. Thanks, and enjoy your amp.

wow! I heard them with ribbon speakers and an active cross over while the bass being driven by another amp. Sounded really easy a little bright and slow to what I am used to. Great imaging and no fatigue after two hours of listening and chatting. Keith Garret and Jack Dejohnette and Sonor Lights in scandi birch finish, what a dvd. Wow!Keith and his theatrics can be a little too much to watch.
Hooked the amp to my proac supper towers and the highs and mids were like never before. The detail was amazing but the bass was really mellow and faint. I heard Jaco Pastorios and heard things I have not heard before. Melody Gardot sounded sublime, yet Katie sometimes fell short and I have always loved Melua.
Learnt how to adjust the bias. Thank you Trelja for lesson 1.
nearly out of batt so will continue later as charger is at work.
All in all great day!!!