spritzer

First off the disclaimer. This is live AC voltage you are working with so do this at your own risk. If you do not know what you are doing have somebody that does take a look at it. While I've tested the 240v version and it works fine this is posted without any responsibility on my part for any damage due to Stax changing the design at some point. This works with my two C-series SRM-1 Mk2's and my B-series SRM-T1. This is only intended for those amps that didn't ship with a voltage selector plug. If it did come with one... then use that then! The picture above is how the rear of the socket should look like but Stax often changed them around to have the component only for one voltage. If it reads 100v (or 117v, 230v etc.) only on the back and there is no plug in the voltage selector socket odds are that the socket is wired differently. It needs to be changed to the above configuration or the amp can catch fire or worse. Since there are two white wires I marked them on the picture, AC power in and from transformer. The AC power comes from the power switch and is in the upper row. It is connected to 3 pins while the other white wire is in the bottom row and only connected to one pin. That one is connected to the primary of the transformer. The only other pin that has more then one connection is the gray one. You can connect to any of the joined pins as they are all the same. Here is the list. You need to put a jumper wire between different colors where the + sign is. There are always two different connection per voltage with either two or three different colors. 240v configuration Gray + Purple AC power in + Blue 220v configuration AC power in +Green Blue + Gray 117v configuration Blue + Purple + AC power in White + Green 100v configuration AC power in + brown Green + White

You could also lower the bias voltage with a resistor to ground. I don't know the exact values for dropping 80v but I'm sure Kevin does.

If you have less then 220v then it is a problem. The transformer will just half the voltage it gets so you could be running the amp at 10?v. I would talk to some local transformer manufacturer and have them make you a 5A (at least) transformer matched for your line voltage. It's a great investment and not that much more expensive then many stock units.

If you are using a 220v->110v transformer but feeding it 230v+ like we have here in Europe then the amp is getting half of that or 115-117v. The only effect the transformers has is current limiting so it has to be very over sized. I'd never use a 727 with anything less then a 3-500w transformer.

That would be a cool project. I'm probably going to mod another one of my Sigmas and mount the drivers next to the ears and see what effect the then ported enclosure has on the sound.

Ehhhh ok... ... good for you... The grill is painted so it should be a good conductor and they often oxidize with age so the conduct even less. I wouldn't worry too much but if you want to fix it I can help you.

It could be a system compatibility issue or that the phones are defective. The SR-007 will sound like a puddle of mud in the wrong system while other, lesser cans sound just fine.

It would be touching the stator then but it's very hard to fix and could damage the driver in doing so. If you don't get shocked then I wouldn't worry too much about it as the grill isn't connected to anything.

There is a possibility that the phones are defective (known issue) or that you simply like the K701 more. Nothing wrong with that as you wouldn't be the first not to like the SR-007 or stats in general.

I posted this over on HF but it should also be here. What I did for those not in the "mafia" is to rip apart a SR-Sigma and a SR-404, swap drivers and cable and then put them together again as a SR-Lambda and SR-Sigma 404. The Sigma line used Lambda drivers or rather the SR-Lambda used the SR-Sigma driver design so swapping them is relatively easy. Stax has been doing this to broken Sigmas for the last few years but why pay them to do something I can do in a few hours. Before anything like this could be done I put a lot of hours into ripping the SR-Sigma apart, cleaning it thoroughly and removing any glue residue that was left over. That is a nasty, time consuming job and leaves you with very sore fingers and no fingernails. I didn't do any mods to the original design so the drives are out of phase like they are supposed to be and I even replaced the glue that holds the damping material in place and provides a better seal. SR-Sigma and SR-404 drivers side by side. It's startling how much things have changed in 30 years... Here are most of the parts that make up the headphones. The damping material was still drying out after the cleaning treatment and the arc was still in pieces after a thorough cleaning. Also missing is all the glue needed to mount the drivers and the damping material. The cable has been fitted and glued in place, drivers mounted to the metal baffles and all the glue to hold the damping material is in place. Drivers soldered to the cable and damping material fitted. The only issue is that the soldering connections for the bias are now facing the baffle and thus useless so I had to be creative. It would be possible to solder the cable before the drivers are mounted to the baffle but it would be much tougher to work with. Here they are ready with the "left over" SR-Lambda. I used Sigma earpads but Yamasinc has used Lambda pads for some reason in the past. I know that the Stax factory uses Sigma pads for this job so I went with that. I haven't had much time to play with them but first impressions are positive and they outclass the SR-Sigma Pro, that's for sure.

I know about that amp but I've never heard it. It should be pretty good with those tubes and all that Tango iron... The design was posted in some Japanese hi-fi magazine and it is rather popular over there. The schematic is also at the site where there are simulation tests of many Stax amps. Gotta go finish this SR-Sigma 404... ... the Lambda portion of the project is up and running...

It can be a combination of charging and amp warmup. My Blue Hawaii is quite a bit better after its been on for about 2-3 hours and the same goes for every one of my amps. My SRM-212 is on 24/7 and the same goes for the T1 and all source components. Charging is more of an issue if the phones haven't been used for a long time. It took my SR-007 once 6 hours to reach its normal sound after I hadn't touched them for some months. The bass was bloated and hollow and there was not much treble at all.

The peeling sound is normal so don't worry about it. The stators are insulated so the diaphragm won't get damaged. If you want to add the resistor I would do it on the amp as it is much easier. Open up the top and the bias supply is next to the transformer. Just retrace the wire from the Pro sockets and cut it somewhere and add a 5M resistor.

I've compared new and well used electrostatic diaphragms under a microscope (from the same batch) and the tiny wrinkles get mostly ironed out with use so the sound should change over time but it's nothing colossal after the first hour or so. The drivers are always tested after assembly so we never get to hear a truly fresh set unless you DIY them. If there is some change after 50 hours I would say that the amp is still running in not the phones.

Happy birthday!

He might also just be getting used to the sound of the SR-007. They fall into the same category as Quad ESL since neither of them is trying to impress so first impressions are often only lukewarm but they grow on you really quickly. A stock KGSS won't cut it either. A better PSU is a good idea and a much bugger +/-15v supply is a necessity plus it's also a good idea to bias the output stage even higher.

If the sound becomes muddy it is the amp running out of steam. The larger the excursion of the diaphragm the more power the amp needs to feed the stators to control the movement. The bass and treble are harder to drive then the midrange so thats where the sound suffers the most. Not even the Blue Hawaii in stock form can fully control the diaphragm when the going gets tough so the 727 has no chance in hell of pulling it off. A treble spike is not something I'd ever accuse the SR-007 of. They are so damn smooth that the HE90 is harsh by comparison. I would look elsewhere for that part, the source perhaps? The soundstage is supposed to be small by design or rather is it supposed to be just right and reflect what is on the recording. The other great ESP's like the HE90 and SR-? both have a larger soundstage but can't match the precision of the SR-007 neither can they do soundstage layering.

I bought a bunch of the original Musical Fidelity units dirt cheap and the short answer is that they do a lot more harm then good or rather they only harm the signal. The build quality is the classic MF, cheap and nasty, so there is no way it can improve the quality of the signal. It's been many years since i got rid of the last one but I do remember is dulled the system down and made the midrange more prominent while rounding off the rest. Bass was boomy and I lost a lot of treble. I rank it with crap like Virtual Dynamics cables and other such tone controls for deaf people who should just have bought B&O in the first place. DC is right that is can provide impedance matching but that's really why you have a preamp...

Congrats!! It's tough to do better at that price.

If the set is in great condition then that is a very fair price.

Well you would need some pleather for the earpads but I get your point...

I waited 4 years for mine so I fully understand where you come from. The fact that I got mine at a really good price only made the waiting all that better...

800-1000$ is the norm but you can find higher and lower as usual.

Looks like 1/3 of my collection but truth be told I'm glad to be selling off parts of it. All you need is the Sr-Omega and SR-007 and the rest is just for show... I really should make some SR-X Pro for him.

The stand is finally here and it looks great. Thanks Michael!