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stax srm-1 mk-2/lambda pro channel imbalance! - Page 2

post #16 of 56
Quote:
Originally Posted by d-cee View Post
yes I did

What options are left, is there anywhere to buy just the drivers? I imagine it'd be cheaper than buying a whole new phone

If I go down that path I'd also like to keep the black casing, looks better than the brown of the SR-404 of which I am strongly considering and putting money aside for
The drivers have most likely gone bad. You could sell them because there has to be somebody else that has the same problem and could fix them this way. You can get new drivers from Stax or from the distributor. There are two models to choose from, the 202 Basic driver and the 303/404 driver. You can keep most of the Pro's sound be keeping the fiberglass inside the cups if prefer it.
post #17 of 56
It might be worthwhile to buy some mylar and replace the diaphragms. It wouldn't be too difficult to make a stretching jig out of wood to tension the mylar. You'd also need to rub some graphite powder into the diaphragm and use some type of glue to reassemble the driver.
post #18 of 56
Quote:
Originally Posted by tyre View Post
It might be worthwhile to buy some mylar and replace the diaphragms. It wouldn't be too difficult to make a stretching jig out of wood to tension the mylar. You'd also need to rub some graphite powder into the diaphragm and use some type of glue to reassemble the driver.
Unfortunately the lambda diaphragms are epoxied shut, so you can really fix them the way you can SRX drivers.
post #19 of 56
Thread Starter 
Quote:
Originally Posted by spritzer View Post
The drivers have most likely gone bad. You could sell them because there has to be somebody else that has the same problem and could fix them this way. You can get new drivers from Stax or from the distributor. There are two models to choose from, the 202 Basic driver and the 303/404 driver. You can keep most of the Pro's sound be keeping the fiberglass inside the cups if prefer it.
hmm, i'll put up a WTB for some drivers, who knows who else it's happened to! I'll also email distributors local and abroad, somehow I think if i buy from the official australian distributor it would probably cost more for the part than completely phone from say audiocubes... just the way it is here for most stuff
Quote:
Originally Posted by tyre View Post
It might be worthwhile to buy some mylar and replace the diaphragms. It wouldn't be too difficult to make a stretching jig out of wood to tension the mylar. You'd also need to rub some graphite powder into the diaphragm and use some type of glue to reassemble the driver.
could you elaborate? are you suggesting that I can make my own driver?
post #20 of 56
Quote:
Originally Posted by d-cee View Post
could you elaborate? are you suggesting that I can make my own driver?
Electrostats are very easy to DIY.
post #21 of 56
Thread Starter 
Quote:
Originally Posted by Carl View Post
Unfortunately the lambda diaphragms are epoxied shut, so you can really fix them the way you can SRX drivers.
Quote:
Originally Posted by Carl View Post
Electrostats are very easy to DIY.
whoa what on earth! got links to articles explaining the process!?!?

I might do it just for the sake of trying...!?!?

incredible...

edit: so far found a great article by andrew radford
http://www.hifihacks.com/?page_id=17
http://www.headwize.com/projects/sho...dford1_prj.htm
post #22 of 56
Quote:
Originally Posted by Carl View Post
Electrostats are very easy to DIY.
Easy as it get sound from it but it's impossible to get the exact same sound as the stock drivers have. There are way too many variables to consider.

It's very hard to open the Lambda drivers because they are glue together and any way you use to tear them apart will most likely destroy the very important spacers. The you have to source the 2um Mylar-C and never use graphite as coting or you will blow up the amp. It's easy to get some 3.5um film and proper coating material. Try here and it is even in your neck of the woods.

All you need to stretch the film is a flat surface (mirror works great) and some tape that will stick to it. Anyplace you have the film or the drivers has to be spotless because a tiny spec of dirt will destroy them.
post #23 of 56
Thread Starter 
Quote:
Originally Posted by spritzer View Post
Easy as it get sound from it but it's impossible to get the exact same sound as the stock drivers have. There are way too many variables to consider.

It's very hard to open the Lambda drivers because they are glue together and any way you use to tear them apart will most likely destroy the very important spacers. The you have to source the 2um Mylar-C and never use graphite as coting or you will blow up the amp. It's easy to get some 3.5um film and proper coating material. Try here and it is even in your neck of the woods.

All you need to stretch the film is a flat surface (mirror works great) and some tape that will stick to it. Anyplace you have the film or the drivers has to be spotless because a tiny spec of dirt will destroy them.
thanks for the lead!

quick Q: is it definite that it's the mylar that is damaged? Absolutely anything else that it could be that is causing problems before I even think about this kind of project!?

thanks again so much for your help, always learning something from head-fi

you guys are the breast.
post #24 of 56
Quote:
Originally Posted by d-cee View Post
thanks for the lead!

quick Q: is it definite that it's the mylar that is damaged? Absolutely anything else that it could be that is causing problems before I even think about this kind of project!?

thanks again so much for your help, always learning something from head-fi

you guys are the breast.
I very much doubt that it's the mylar that is causing this. It could be that the coating has deteriorated over the years or the metal contact with the mylar inside the driver has oxidized. The film will still sound great with a number of large holes in it. It even makes sound in tiny, broken pieces but very low in volume.

One side note. The new drivers aren't the same as the 1982 versions you have in your phones now. They are a much improved version even though the phones superstructure hasn't changed all that much over the years.

It's good to know that we are the breast...
post #25 of 56
Quote:
Originally Posted by d-cee View Post
whoa what on earth! got links to articles explaining the process!?!?

I might do it just for the sake of trying...!?!?

incredible...
You'll need:

2x sheets of electrically conductive metal mesh/ puntured metal plate
3x sheets of thin, flexible, light plastic film such as boPET/Mylar
4x rigid, non-conductive rings in whatever size and shape you want the finished product to be
Some very strong glue or epoxy
A small strip of very flat rigid metal.
A pencil or some other source of graphite
2x three core or ribbon cables of acceptable audio pedigree
A soldering iron and solid soldering skills
A plastic film stretching rig of some kind

Step one, stretch a section of plastic film until it's very tight but still able to move. It'll make a drumlike sound if you tap it gently. Carefully cover a section of it that's larger than your spacer rings on both sides with the graphite. Make the coating even and thick enough to properly cover the film without drowning it in the stuff. If you damage the film in the process, get another section of film and start again.

Step two, first, epoxy/glue the metal strip onto the diaphragm such that there is an electrical connection between them. Put some graphite on the strip if you feel you need to. Next epoxy/glue the spacer ring (place it so the tip of the metal strip is just poking out from the spacer) onto the covered section of stretched film making sure a strong contact is made and wait until the bond is fully set. Cut around the film (eg, with a box cutter, but be careful) leaving some leyway around the outside, and not damaing the protruding metal stub, for the time being

Step three, onto the spacer epoxy/glue the conductive mesh. Wait until it sets fully. Epoxy/glue another spacer onto that, set fully. Like with the diaphragm, cut around it leaving some leyway. Use tin snips if need be. Again, gently. If you cause the epoxy/glue to unbond doing this then you'll have to start over.

Step four. Stretch another section of film to roughly the same tension as the diapragm. No graphite on this one, it's just a dust cover. Epoxy/glue onto the outer spacer. Set. Cut out film (you can go right up to the edge of the spacer with this one, as there is not going to be any electrical connections to this sheet of film.

Step five. You're half done. Now flip the thing over and repeat the steps so you have diaphragm-spacer-stator-spacer-dust cover on the other side, making sure you set the epoxy/glue between each stage. You may wish to add an extra ring outside the dustcover to prevent it being punctured before you do so.

Step six, trim the stator sheets so that it all lies flush with the outer edge of the spacer except a tiny little bit that you will solder the cable on to, which I recommend you leave on the same side of the driver as the metal strip from before. The smaller it is the better, but use your own soldering skills as the judge of how big you wish to make it. You don't want to have the cable ripped off.

Step seven, trim the diaphragm so it's flush with the spacer, leaving just the metal strip from earler. If the metal strip is too big, carefully trim it to a manageable size. Cover the whole edge except for the three metal contacts with some non-conductive substance like epoxy so that the diaphragm and stators don't arc together.

Step eight, now you should have something that looks like an actual electrostatic driver (hopefully!). Unfortunately, now you're going to have to build another one exactly the same. Remember that all film tension levels, thicknesses of parts, and the way it's built must be identical between both drivers (you don't want to build in a channel imbalance for the start, right?). Take it slow and get it right.

Step nine, now you have a pair of drivers. You'll need a housing that'll fit them. If you lack a spare headphone you don't mind trashing, you can make a housing out of wood. Epoxy/glue the driver to the baffle of the headphone housing and set.

Step ten, solder the cables on. You'll need a cable with a Stax connector (or whatever you want to use). Make sure, with a multimeter, that you have the right cable soldered to the right terminal. If you solder you bias supply onto the right + stator it isn't going to work. Close the housing up, you're done.

Plug it in and play some music. It'll take a bit for the dielectric to charge, so don't crank it immediately even if it sounds a bit quiet and crappy. Enjoy your new headphone.


It's highly unlikely your first one will be putting the Orpheus and Omegas to shame, but if you play around with different tention levels, diaphrahm size and shapes, stator thickness, materials, and housings you can tweak the sound considerably.
post #26 of 56
Thread Starter 
Quote:
Originally Posted by spritzer View Post
One side note. The new drivers aren't the same as the 1982 versions you have in your phones now. They are a much improved version even though the phones superstructure hasn't changed all that much over the years.
improved as in clearly technically better eg. more detailed and better build or just different sound?

does the fibre glass padding inside give it its sound? cos i really love(d) the sound of these babies... if I could get a similar sound sig but improved then I will get some SR-303/404 drivers without hesitation or buy a whole new phone and put in the fibre glass mesh

and Carl: wow, just wow. That's an incredible guide!!! I must visit NZ one of these days and buy you a drink
post #27 of 56
Quote:
Originally Posted by d-cee View Post
improved as in clearly technically better eg. more detailed and better build or just different sound?
Different sound.
post #28 of 56
Quote:
Originally Posted by Carl View Post
You'll need:

2x sheets of electrically conductive metal mesh/ puntured metal plate
3x sheets of thin, flexible, light plastic film such as boPET/Mylar
4x rigid, non-conductive rings in whatever size and shape you want the finished product to be
Some very strong glue or epoxy
A small strip of very flat rigid metal.
A pencil or some other source of graphite
2x three core or ribbon cables of acceptable audio pedigree
A soldering iron and solid soldering skills
A plastic film stretching rig of some kind
...
Great writeup for future reference.

Some issues though. Don't ever use epoxy as a glue, polyurethane is much better to work with and it is slow curing so you can manage the thickness of the glue layer. I learned this the hard way as I was unable to get consistent results even if the drivers were made side by side from the same sheet of mylar.

While many manufacturers use graphite as a coating material don't use it on Stax phones. The resistivity is so low that is can fry the bias supply's and cause other nasty things. Add to that it's instability in humid conditions and that is is almost impossible to get a good coat with it.

Do not stretch the film so that it will be like a drum. If you want the Sennheiser signature sound it's ok but it much too tight compared to stock Stax drivers. Tension it just so that most of the wrinkles are gone and when it has bonded to the spacer heat the film with a heat gun for a second or two and it will shrink to the correct tension. This will impact the sound a great deal so experimentation is needed here.

The dustcover should only be on the + side of the driver and it shouldn't be very tensioned. Some sound permeable material should be on the - side so there aren't any reflections inside the drive unit.

Quote:
Originally Posted by d-cee View Post
improved as in clearly technically better eg. more detailed and better build or just different sound?

does the fibre glass padding inside give it its sound? cos i really love(d) the sound of these babies... if I could get a similar sound sig but improved then I will get some SR-303/404 drivers without hesitation or buy a whole new phone and put in the fibre glass mesh

and Carl: wow, just wow. That's an incredible guide!!! I must visit NZ one of these days and buy you a drink
The newer drivers are better because Stax has finally nailed down the correct balance between diaphragm thickness, tension, stator material and coating substance. The Pro's are my least favorite Lambdas because of the horrible midrange, peaky signature and plainly odd bass. It's down to taste whether you like them with or without the fiberglass but it has a pretty large impact on the sound.
post #29 of 56
Thread Starter 
Quote:
Originally Posted by Carl View Post
Different sound.
thanks for that
Quote:
Originally Posted by d-cee View Post
I must visit NZ one of these days and buy you a drink
until i decide to visit our neighbours and in light of recent head-fi trends... this one's for you Carl!



Spritzer I haven't forgot you ! We have a brand of fruit flavoured mineral water here called Spritz! I may have to get hold of some...
post #30 of 56
Quote:
Originally Posted by d-cee View Post
thanks for that

until i decide to visit our neighbours and in light of recent head-fi trends... this one's for you Carl!



Spritzer I haven't forgot you ! We have a brand of fruit flavoured mineral water here called Spritz! I may have to get hold of some...
I would like one Carlsberg now or a Spritz. There are elections here tomorrow I'll have a beer or 20 then...
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