spritzer

I would never buy a stock Quad as the build quality has only deteriorated over the years and especially with the new Chinese plant. Get the refurbished and rebuilt by somebody who knows what they are doing so that they will sound like they should have in the first place. There are always risks when buying used headphones but if you stay off ebay it's mostly all good. That being said electrostatics are often easy to fix if you know what you are doing and have steady hands... The SR-007 A/mk2 is good step down from the old model. Just get a rebuilt one from the likes of Electrostatic solutions or Quads Unlimited, that's what I'm going to do. Quad's were always badly built and the only testing they did was to line up two speakers at a fixed position, play a squarewave through them and if they canceled each other out then it was a matched pair. They might even still do this today...

Somewhat?? I do like his DAC though so call me fan as well.

To match the SR-007 on a BH you need some serious kit but a basic Quad can do amazing things. I've heard the new model briefly and it sounded pretty much the same as I remembered the 989 sounding. It's the same speaker and the brace doesn't really work as the elements are "floating" inside the speaker so just buy a 989. I've been under a gag order for quite some time now so it's good to be able to talk about the Koss...

The M-L's are all meh at best but the CLS did show some signs of greatness and at 2k$ or less used they are a good buy but the Quads are better. The CLX is way too expensive and the Apogees should be very good but small scale of manufacturing really bumps up the price along with the magnets.

Sure thing. I have at least 5 or 6 quads of UK milspec tubes here though I've never used them. They, amongst others, are for the BH I'm building.

I can supply the tubes as I went a little crazy when buying 3D21A's...

It's really not that bad or rather it shouldn't be. I'll see if I can find some cheap headphones to mod if you'd like to try it out.

True... I'll break out the tools and start work on it.

It's all built into a small PCB which as all the connectors as well so there is nothing protruding above the drivers.

The Quads do have plenty of bass and the newer, taller speakers will overpower most rooms but you need a Sound Lab or a triple stacked ESL to get something close to what the SR-007 drivers achieve in a small space. I would go out and listen to a set of Quads if you can and even M-L's.

The bias supply is easy to deal with as the Stax SRD-7 Mk2 works perfectly well and is cheap to build. It's also runs directly of the wall voltage so no issues there. The transformers are a problem though as the old Stax units aren't good enough but I have a few cheap-ish alternatives lined up that might work well and even drive the SR-007. I'm sorry... Where do I send the royalty checks?

I don't own the SR-SC1's any more... My collection is in a sorry state so much so that infrequent visitors are shocked at all the empty headphone stands. The drivers are flat and so is the wiring for the new drivers. It's much harder to squeeze a SR-404 driver into a Sigma then fit one in a flat wooden housing.

Add Stax transformers, a three way switch (headphones, speakers and Stax) plus some other minor stuff. Nothing major but since I will be short an amp soon it will come in handy.

I would keep the drivers where they are as that glorified voltage multiplier Koss calls an amp is destroying the soundstage. They aren't Sigmas by any means but can throw some. The SR-007 Mk1 will be the king for quite a while is Stax doesn't fix the Mk2... Quad ELS57 or 63 would be my first choice. You can find them cheap but a properly restored pair is the way to go. They work well in any room (designed for the small UK living rooms) and when fed well really shine. There is the same crap out there about the Quads as is said about ESP's so go listen to the new models and decide for yourself. Get the Mk1 as it is better to my ears. The Mk2 is impressive sounding but more forward and has a bass hump which drove me mad. Even modified they aren't as good as my Mk1. I use my B22 to drive ortho and iso dynamics but after a few mods it will drive Stax as well. It was built by n_maher

I really need to go headphone shopping to find some fosterphones and cheap headphone cables. The 120ohm drivers are perfect to cram into a Lambda housing but those things just don't want to die!!! I've managed to fix everything thrown at me...

You are not the only one putting down a deposit for a RK50 model no less... I'm also building my own souped up BH so I think that makes me extra crazy. The 3D21A's should work in the BH no problem and I offered to send him a quad. Anything is better then paying for the NOS EL34's...

Nope... Btw. The picture above shows how easy it is to rewire the ESP950.

I'm with Marc that they are basically a better version of the HE60. I do like the Senn but there is something not quite right with it's tonal balance and the ESP950 is a much more balanced unit. I would like to build a woodie ESP950 some day and fit it with HE90 earpads for some sort of an Orpheus clone. Add a SR-007 headband with specially made forks and we're in business.

Why not?

There is a black frame around the 120ohm drivers, much like a speaker mounting with 4 holes in the corners. The drivers are either pressure fitted into it or glued in place. They were obviously intended to be uses as tweeters How can you break off the tabs? I've been messing with them quite a bit but all the drivers are intact though I always bend the tabs so that they face backwards on the drivers.

You can also tell them to get off their ass and build us a new Sigma with SR-404 drivers.

Lundahl

ditto.

The do open up at around 620v but I found them a bit strident and edgy for the short while I tested them with my variable bias supply. I really should experiment some more now that I have a DC meter that can go above 1000v but I doubt that they would like some 800v of bias... What about just fitting a new Stax cable to them? Shouldn't be that much more expensive...