spritzer

That's them running off 580v bias. The GES clearly has the stock tubes as the yellow lettering on the EH ECC83 tubes is hard to miss.

No, only the SRD-7SB Mk2 can be used with pro earspeakers. You could also convert your SRD-7 by building the Mk2 bias supply. No problem. I think I have this need to spew electrostatic facts around as I'm suffering withdrawals from the usual flood of HF PM's. \

Amen to that brother!

The SB's are more expensive then the AC unit's. A transformer is always more expensive then a AC cord and that is the only difference in the Mk2's. The old SRD-6's used a multiplier without a transformer so you are very dependent on the speaker input level to maintain the bias. I've never had any issues with the SB's but then again I don't listen to a lot of music with quiet passages.

That must mean they have recovered the Predator preorder thread so the site is mostly ready...

I stand corrected. He would have made it huge with some horribly ugly golden bits screwed onto the chassis. It still has the same reliability as a RSA product...

No wonder you preferred the GES as HEV70 is so bad Ray could have made it. Any Stax amp ever made (except maybe the SRM-001) is better then that steaming pile of crap. Do you have any pictures of the Chinese stats?

I'm simply waiting for the right set of Gamma Pro's as I'm a bit particular about the condition so I would be prepared to well over 400$ but not for the set on ebay. One problem with the Gammas is that there are no pads to be had from Stax which really blows and the headpad is the biggest piece of crap ever. It turns into this black powder and since it was meant to be cheaper they are a bitch to remove and clean properly. I sure hope that the Stax hype is over or may God help those poor souls that stand between me and the few phones I'm missing...

There was clearly something wrong with the unit or is was a very early SB as there is enough energy stored in the bias supply to keep the headphones going for at least an hour without any power coming in. The Mk2's used a pretty high ratio transformer coupled with a double zener input so the bias supply would always be fed even if the input voltage was pretty low.

The website is very outdated so I'm sure they are using the better ECC99 tube, though I'm not quite sure

They aren't worth that much but the Stax hype knows no bounds. It was also in terrible condition. An Alpha Excellent would be worth that much but only to us crazy collectors.

First off, the SRD-7 isn't a Mk2, just a normal 70's type SRD-7. SB is in no way inferior to the AC biased designs and they could even sound better with no crappy AC inside the unit. They are the same more or less except there is a small transformer that borrows a bit of AC of the Right+ line. The Mk2's are highly sought after and can go for way more then 200$. That's certainly what I just sold one of mine for but it is NOS.

The APL sure looks nice For those that don't know, everything after comes off the drive is upsampled to 211kHz/32bit and fed to the stacked dacs. The output stage is transformer coupled so the signal only sees a single transformer and the ECC99 tube. There is no muting circuit or anything else to damage the sound quality. Nice to know I'm not alone here...

I'm not crazy, I'm just special! The adapters normally present a fairly benign 8ohm load and while they do require a bit of current it's voltage they need and they get that from the first watt or two. You can continue to push them but I've seen way too many burned up diaphragms in my time to ever do it myself. I fully agree about the passives and while a top level system should be active there are simply too many compromises at lower price levels to consider going active unless you are dealing with impedance issues or long cable runs. TVC's are a clever way of controlling the volume as you gain some current as you lower the voltage but there is a whole lot of wire in the signal path.

There are indeed multiple gain stages but the gain in a preamp is pretty low but even some CDP's aren't operating at 2v and many output 6v differential.

That is my understanding though I have never owned a Gamma Pro... I've also made my own pro driver by converting a normal Mk3 driver with some 0.3mm copper. Worked like a charm but was way too much work and the Pro drivers used 1.5um diaphragms compared to the Mk3's 2um.

Carl had another set but I wasn't prepared to pay his kings ransom for them... One will show up and it will be mine. >

Ok, I'd buy four just so Larry couldn't get his hands on them. I did the world a favor when I rescued the second to last remaining set of NOS SR-Omega earpads from his butcher hands...

I'd buy one.

Almost any amp can give the voltage necessary but dynamic drivers need plenty of current for all those nasty curves on the impedance graph. The voltage is about 30v or less so that times 25 (1:25) is the voltage swing on the stators. The adapters are fitted with resistors to dissipate all extra current as heat should the volume level be too extreme. A 350w amp will eventually melt the K1000 but not at low volume level. The amp might only be delivering about 1w at said volume level so it won't hurt the phones. As you know a basic volume control is a variable resistor that drops the voltage of the input signal from the standard 2v. The amp has a gain level that is the multiplier of the input voltage. The current draw depends mostly on impedance and where speakers are said to have a nominal impedance of 8ohm they vary quite a bit and can be quite a bit higher and lower. Electrostatics are terribly bad at this, requiring large amounts of current in the bass and treble.

The cost of a 845 based amp would be horrific and it would dwarf any headphone amp ever made. The amp it self is relatively easy to design and build but the power supply is a huge headache. A simpler amp could be built but I just don't get the point of a compromised design around a world class tube. A 572-10 might be a better tube choice but they aren't produced any more.

Mine are so far from stock as I used them to test different diaphragms but they do sound ok for what they are but I would never pay more then what a SR-5 is going for these days.

Do I have to come over to your houses and beat you over the head??? .... A 350w amp only gives out that much into 8ohm at full output. It gives out much less with a lower input level i.e. at a lower volume. Most amps are running at about 1-10w most of the time. The extra power is more in the form of extra current with the voltage being so low and the SRD-7 needs voltage and a bit of current.

The 6s4 is a good choice especially since I have a nice stash of them. That is one toasty amp. I was considering a 845 driving a 845 in a Stax amp so that would be 8*35w just for the heaters... There is a design already out there in the second edition of Morgan Jones's book. It was conceived for loudspeakers but will push the SR-007 really nicely but he says in the book that it is the scariest amp he's ever built and none of his measuring equipment worked with it. 1200v can do that. I'd like something simpler like a push-pull SET and use a push-pull choke instead on the output transformer like Jones did. An amp like this should also work just fine on the Quad ESL.

It can only take about 10w before the internal resistors self destruct. The older phones with unprotected stators and maximum voltage of 400v will be goners but the new ones should be able to handle it. The Senns would have gone up in smoke a while back.