spritzer

One funny here, I've been working on a Stax SRM-007tA today and it is one of those long rumored units that use GE 8CG7 tubes and not the EH 6CG7's. It must have have been a fuck-it-Friday though at Stax as did they use a different heater supply for the 8.4V tubes? Nope... they jumpered the 1ohm resistors in the heater supply but it is still run off the same 12.6VCT winding, fed through a bridge and some caps. End result was a blown heater in one of the tubes as it was being run at 6V... 😂

The tuning is in the diaphragms so yeah, that wouldn't work

It's been close to a decade so I just don't remember but well over 1k$. Everything under Edifer is getting worse, they should have the resources to do something good but no, performance across the board is just worse and everything is much more expensive.

Indeed, the bias has to be + polarity for that reason.

I just used up my last pair of spare drivers for repair and I'm not sure where it is possible to get any more. Sourcing anything from Stax now appears to be a massive pain as the parts I've been ordering through various distributors, just aren't showing up.

Yeah, there are no shortcuts here. You could run a simple Class A amp off +/-24V rails but I'd stay away from the old Hood design. It has an output capacitor (as it is a single rail design) and that is just asking for trouble with this kind of load plus limited voltage swing.

Fuck this is dire, sure they were just on the cusp of making the best electrostatic amp there ever has been. That is a lot of transistors, any joy with piecing it all together?

I seriously doubt that but then again, people paid good money for the Single Power, Woo Audio, Cavalli, LTA, Ray Samuels amps (and the list goes on and on) thinking they sounded good...

Anybody who measures for lowest distortion and thinks that is some sort of a golden benchmark, knows absolutely fuck all about amplifier design let alone the history of hi-fi. I have nothing against meaningful measurements but when something sounds like crap and measures ok... you are doing something wrong. Same goes for awful measurements, if you sit down and it sounds good then something is wrong. Like when Amir showed the world he's fucking retarded by not understanding how electrostatic amps work. A real Schrödinger's cat quantum phenomenon, the device sitting in two states at the same time. The issue for me here is twofold, it's a low power amp which is asked to do far more than it can deliver and then we have the whole can of worms of using transformers to step up the signal with all of their limitations. Anybody who's taken a SRD-7 and some cheap chip amp off ebay knows if can swing a lot of voltage (hence why Stax put a clamping circuit into the later ones) but it doesn't sound all that great.

8mm should fit in there just fine

Because idiots think this sounds good? What gets me are the cheap parts and just pure stupidity of using power supply caps which are known to fail as a dead short for audio coupling.

It should be ok. The volume control could be an issue but power stuff like the transformer is packed with resin so nothing should get in there.

There should be an export site, that's what I've used in the past.

That's impressive... shame they sound like shit. Something new for me, I came across my first ever arc'ed over SR-007 driver yesterday. Utter carnage in there, a hole in the diaphragm roughly 30mm across and burn marks on both stators. Other driver was just fine but yeah, there is a reason we fit protection circuits.

Nope, it has never been released but I've heard hints that it's just a version of the HEV70 circuit with a very bad tube front end.

That's really all the procedure for this. I never tried it on the L300 LE's but the labels on the earcups might be an issue. I just never use mine but I might test it out.

It's a bit close to where my storage lockup is...

You have to add some hot glue as well. It is a necessity... Come to think of it, I've never even owned a hot glue gun... 😂

They are still going and I really want one of these amps for my wall of shame.

Might be to get more volume out of the amp as for a lot of people... moar loud... moar powah!!!

Preamps driving Stax amps is very much becoming a thing and I don't understand it.

Thanks everybody. I almost got a volcano as a present but nope... not yet. As I wrote this an earthquake shook us...

Nope, that's the production stuff.

In reality the bias harvest a negligible amount of energy from the audio signal so the effect is pretty small. My main issue is with the cross talk it will generate as Stax always placed the bias supply (or the transformer on the later versions) between the channels to maximize the potential available. Well that plus the extra inductance of the second transformer is bound to have some effect. That all being said, I'd really pick this over having the mains effective rigged directly to my head which is the case for all of the mains units. Couple that to 40-50 year old diodes, caps and carbon resistors and it is a scary thing. As for the Topping, I've been thinking about what to do with it. It's main issue is the crap amp and bias supply so that could be fixed. Retrofit the small bias supply Kerry designed for the portable amp project (200V boost battery charge chip fed into a voltage tripler) and change the amp boards for some Class D design. I've been using Icepower for over a decade to run my transformer boxes so something like that.

Completely different package so you need to match the pinout but that should be it. Could be some freak oscillation though to look out for. Still this wouldn't be worth it as real 2SA1968's are probably 50$ each now for low quantities and most for sale are fakes. I can't remember the rail voltages on those amps but if it is +/-300V, then a 700Vpnp would work. There are none in current production but they can be found.