spritzer

Sure does...

The issue of the amp being sensitive to the impedance of the transducers is a huge one IMO. HFN reviewed the ML Spire in the April 2009 issue and they found the speaker to reach 0.4ohm impedance at 20kHz and it would go even lower into ultrasonic frequencies. This is of course a byproduct of the transformers used in the speakers but shows just how much the impedance changes with frequency. The Quad ESL reached down to 1ohm and up to 30ohm so if we give them a modest 1:150-1:200 turns ratio it is a frightening impedances range (multiply the square of the ratio*the impedance to find the speaker impedance). While ESP's have smaller drivers they are by no means a much easier load. The heavily airdamped stators of the SR-007 and SR-001/003 make things even worse by trapping air next to the diaphragm and thus increasing the impedance of the air. I view the role of high-end to be a straight wire with gain and taking the amp (or any other component) as much out of the equation as is possible. Making sure that the amp can deliver it's full output voltage into any impedance load is a fundamental necessity for electrostatics or the amp will be a limiting factor and alter the sound output. Just listen to a SR-007 or SR-Sigma driven by anything but a Blue Hawaii and you hear how much of a difference maintaining a stable output voltage really makes. All this power isn't cheap so it's no wonder that Stax (with the exception of the T2), Koss or Sennheiser have never come up with an amp that isn't a compromise. Those that are involved in manufacturing know just how cheap those Stax amps are to make given the retail price. Now with something like the BHSE and A-10 there is no retail network to a take a large slice of the price but also no economy of scale. It is far cheaper to make 2000 amps then 20. The A-10 is a very expensive amp though so we should at least expect performance to far out pace something like the 6S4A based Woo GES let alone the PoorMan which will be less then 500$ built and in what looks like two versions (hybrid and SS). Given the data at hand that is far from certain. I've thought about that as well but you would need multiple taps on the secondary to cope with all the different headphone impedances. I sent Justin some of my spare transformers to test the amps with but I don't know if he had any success with that approach.

There is very little Stax related that we don't know of... I do wonder though that the extra angle isn't doing more harm then good and the true magic if due to the very stiff chassis.

Couldn't have said it better myself.

This is what happens when you try to apply logic to the RSA crap. Here we were thinking that Ray might have just a hint of sense and used the high voltage version of the 6SN7 but he used a 300v max tube instead. We bitch about the 6CG7/6FQ7's in the Stax amps but at least they can handle 330v.

That new C-J budget preamp has gotten nothing but glowing reviews, even from HFN which are notoriously picky. I've heard the Pass X2.5 and it was excellent the same as the old Krell units. I even put in a bid this week on an old Stax preamp but thankfully lost. Still I have to buy a SRA-14S one of these days...

More power basically, both voltage and current. It's far from a perfect amp but very hard to beat at that price point.

You can also just use good old fashioned heat sink compound if the transistors have a plastic back. Just remember, less is more with that stuff.

Lets just look past how cheap and nasty the preamp section is in the B52 and there is a whole world of choice at this price point, either SS or tube. Many will easily drive headphones from the pre-outs as well. If you want some brands then BAT like Nate suggested plus vintage Krell, ML, Spectral, Pass, ARC, C-J etc. If you start with any burn-in crap then the ridicule will come. If you like the A-10 then that's fine but you should try and find a SRM-717 to use as a comparison since it manages to do an ok job with the Omegas at less then 1k$ used.

Yes. Most people don't realize that capacitors hold charge for a long time so once the equipment is off they believe it to be safe. Touching the exposed pins is just as bad as touching the terminals on the capacitors them selfs.

Being a nation of drunkards the weekend starts on Thursday and ends on Saturday night which makes Monday night the middle of the week.

Could be the beer or that fact that you are drinking on a Monday. Strange things usually occurred when I drank in the middle of the week...

Santa Claus??

The tubes is the Stax amps last a long time and they sound ok at low volume levels and into an easy load like the HE90 or a Lambda. It's when you want to use headphones that are hard to drive or need more volume is when things go down hill, fast. If this is the topology then the GES should have it beat (let alone the new version) and Ray is going to have a hard time explaining why the 300$ PoorMan amp can rival his expensive monstrosity. We may be thinking of two different amps but the only one I've seen with a "Koss" socket didn't use the normal Koss connector. It was more similar to the Stax typer of plug, circular but the pins arranged differently.

Happy barfday...

The only source I can think of is the Koss extension cable but they have to be modified. Cheap as chips though...

The 6SN7 is a bad choice in the Egmont (the reason I'm using 6S4A's) just as the 6CG7 is a bad choice in the Stax amps. I think the only voicing Ray did was not understanding what a CCS is and thus made an amp that Stax could have sold in the late 60's. By pure chance that works brilliantly for the HE90 and Jade and they really don't need a ruthlessly reveling and powerful amp behind them. Well you are just about the only one with a Stax cable on your set...

That thing has to be one of the ugliest amps ever made. Does Ray even know what subtle means? There are quite a few that have also done this besides Chord. The tube names are silk screened on the chassis but I can only make out the 12AX7 for that center tube. It's hard to tell but the output tubes could even be 6SN7's and then Ray (who is probably running the whole thing off one filament supply) is going to enter a world of pain. The SR-007 not only needs a lot of voltage swing but more importantly current. For that you need a massive CCS on the output tubes with the necessary heatsinks and that's far, far beyond Ray's capabilities as an "engineer".

The squeal can be any number of things but some debris stuck inside the driver could be the reason. The dustcover on the front of the driver looks like an afterthought and the back dust cover is of the same caliber as the Jade.

The "problem" with the brown models is that they aren't very photogenic. They look much better in person.

Now if they had only stuck with the dark brown cable used on the SR-Omega they would have looked even better. \ Btw. Nice avatar pic...

A simple question, is there a charge up issue when using the E/90? All these headphones are just a blur to me but I think I bought them about a year ago from Mapstec who had the recable work done.

Very Dartzeel of you...

That should be enough to get the SR-007 going. For those that don't know, the Dayton-Wright speakers were driven in a sealed pocket of gas so that they could be driven at higher voltages then what normal air allows. That accounts for the truly terrifying voltages.