spritzer

It does say OTL in the text but they could be using a push-pull choke to act as a primary on an output transformer similar to what Jones did in his 845 DD ESL amp. I quite like the output transformer box you can use with the amp...

Nothing really. Bog standard kettle cable.

It's for its own good.

The old mini-disc players were much better then the Apple junk and some even very good. Mini-disc was so very cool in 1995... 100gb disc and Rockbox. I might go to town on the output and fit a high pass filter off the dac or dsp chips bypassing all the active crap.

Ghetto and dangerous... I like it!! Molex pins (PSU connectors in computers) work great as ghetto Stax pins and sockets so they can be used with plenty of electrical tape.

It's good to hear that it's working. We did know that the current requirements would kill anything but the BH but it does work. So does anybody at Canjam have a 4 pin XLR socket, a Stax male plug and some 1000v teflon wire?

Thanks for that. There appear to have been 3 different drivers, color coded. My ECR-400 had red drivers but what's in the ECR-500?

So there is foam damping in your set? The ECR400 I had (in parts now due to channel imbalance) had mineral wool as damping though it wasn't as thick as the stuff Stax used. The SR-5 pads are nearly identical but I suppose SR-007 pads would fit as well... You polygamist you... The amount of damping has a huge impact on the SPL level as you are wasting away energy to tame tame the drivers. I'm getting a modified Toshiba Gigabeat soon that shouldn't have any problem driving the phones That's what I did. Call up the US distributor and ask about a replacement 202 cable. You can also buy a whole lot of Koss extension cables but they are a bitch to work with. Woodies would be nice as the drivers are quite good. If I find a better headphone then the UR18 I might just mod that as well for kicks. I can always buy more drivers...

I have a ECR-400 and the drivers are true works of art. An SR-X type of chassis might prove to be very good indeed.

Great little drivers but this particular version will never be used with an ipod. I just borrowed my brothers 80gig unit and it hasn't got the power to push them to anything more then background listening. I have to admit that I'm nowhere as crazy as you though with your quadro setup

I figured this topic deserved a new thread and I'll kick it off with impressions of my new Koss UR18 foster phone. Those that have been following the ortho thread on HF know about the SFI drivers that cost next to nothing yet deliver in spades. I found a Koss UR18 cheap brand new today and it had all the right characteristics of a good foster phone, pleather pads, dual entry (I just like it like that) and thin earpads and a small enclosure. By sheer luck they had drivers which were exactly the same diameter as the SFI units so conversion was easy. Remove the old drivers and insert the new ones. Here you can see one earpiece and how I damped the housing. I didn't use the loo paper in the end and used some fiber paper instead. As you can see I left a few of the ports on the back open but heavily damped. The old drivers are there for comparison. The drivers have been glued in place with some old epoxy I had and more damping added to the baffle. I didn't really experiment with this but now that I have them playing the chassis could do with some more damping as it resonates quite a bit. They are now ready for assembly. I used 3 sheets of fiber paper over next to the driver, then came the stock foam damping and last came one sheet of fiber paper next to the earcup to damp the ports. Two really similar headphones so now we know where Stax stole the design. Also note the different size of the earpads. I just stuffed some rubber tubing I use to make cables under the pads and twisted them so the middle part is double the thickness of the ends. The Lambda pads were a great idea so why not borrow it... It really helps the imaging by controlling the angle of the drivers. As to the sound then they have no right to sound this good since the stock headphones are horrible. The bass is tight and controlled, plenty of treble though never bright and the midrange has great presence. The soundstage is what you would expect from a supra aural though slightly diffused. They haven't even been trough a 700 hour burn in yet they sound great. There are some nasty resonances due to the chassis and therefore low level detail isn't up to ESP level but who cares as these cost less then 50$ new. They are also foldable and come with a 3.5mm jack so portable orthos!!!

Way ahead of you... I'm now moving upscale with some Tork's fiber paper to see if I can get some more bass. I've also angled the earpads to good effect as the POS Koss frame if too weak for a firm seal. The epoxy is still not ready so they just sit here playing in the mean time. It's a nightmare all right. I spent one evening trying to beat 3 SRM-T1's into submission... ohh the horror!!! That can certainly be an issue and will make it much harder to bias properly.

Congrats!! There is no need for a matched quad of tubes but matched pairs will make your life much easier as biasing Stax amps is a bitch!!! I need to get me a Trends UD-10 for the computer one of these days... Btw. I just finished converting a Koss UR18 by swapping the driver for the SFI ones. It's a great foster phone since it's cheap, the drivers are the exact same diameter as the SFI units and it's foldable. It needs more damping but the sound isn't half bad...

Cool, please keep us informed how it works out for you.

Koss UR18,time for some high end headphone listening! ...or using them as a foster phone for some SFI drivers.

By making the arc taller it should decrease the weight carried by the headband and transfer it to the earpads instead.

Happy Birthday!

True. The bottom line is that the damn strain relief isn't flexible enough.

I had a rabbit once and while they think wires are made for chewing and are a bit paranoid they are fun to have around an not much trouble.

The Stax fart is high on the list though it doesn't bother me much. It's basically a squealing sound made when air tries to escape or enter the air cavity next to the ear when the pressure made by the pads changes i.e. they are pushed or pulled changing the size of the air pocket. All electrostatics produce noise like that but the SR-007 is completely airtight so it's worse on them. The earpads are also an issue for some as they are snug fitting and not very deep so some ears are crammed up against the protection plate covering the drivers. The Mk2/A fixes both of these issues as the earpads are taller and have more room inside. The cable has been known to be a problem as the strain relief doesn't really function properly so with abuse the cable can be broken. Again this was changed on the Mk2/A over to a system similar to the SR-? cable entry though not removable. As our baby Elephant has pointed out the earpieces on the Mk1 can rotate much too easily so the optimal position can be lost. This isn't much of a problem if you store them on a Stax stand with the earpads clamped in place but this was mostly fixed on the Mk2/A. The earpads can be fixed in place but jamming something between the pieces or taking a bit of tape and stopping the movement like that. Not pretty but functional. Other then the basics of being a bitch to drive properly and position sensitive I think that's it.

I bought mine used from one of our members but I have no idea how many hours he put on them. There is no charge up time to speak off and the only time that happens is due to the electret effect i.e a charge present on the diaphragm of opposite polarity hindering it's movements. It's a myth that the phones need to charge up but the amps have to. Most of the Stax amps are only good after about 24 hours and the BH is utterly awful until after 2-3 hours and it gets better after that. The treble is indeed a bit more open which is a welcome change as the phones work better with less powerful amps. I'm using the SRM-1 PP while typing this and it lack the control and poise of the BH, the detail and air but it's definitely not as bad as with the Mk1. There is a slight midrange coloration which presents as a slight resonance on the diaphragm under some conditions like massed male vocals. I just noticed it on Steely Dan's - FM but it could be something that gets ironed out with more run time since the diaphragm gets better with music playing as all the tiny wrinkles are ironed out. The headstage might be a little bit more diffused and therefore larger then the Mk1 but it's is still highly focussed and true to the source. The pads are looser as the flap used so secure them to the chassis is much looser then on the Mk1 so you can push them around while fixed in place. This is a design choice as it allows the pads to stand taller and thus gives people with abnormal ears more room. I've been bending the arc's for a tighter fit with good results but there is always some "thump" sound which gives the illusion of deeper bass but the MK1 goes much deeper. The pads can be swapped and that should reign in the bass due to the different internal volume. Now if Stax did indeed install a port somewhere to combat the "fart" there is nothing that can be done short of disabling it if that is even possible. There is definitely some air escaping out of the ear cavity as I just pressed the phones hard against the head (there was still some bass bloat with the metal grill resting against the tip of the ear) and there was only a mild sound emitting from the diaphragm. Do this on the Mk1 and all hell breaks loose... \ As it stands now the Mk1 is the no compromise design with issues but the best sound of any headphone IMHO and the Mk2/A is a slightly compromised version which is good enough for most and has no issues. I'm sure many will love the bass boost and it is impressive while playing Megadeth on full blast yesterday but it's too "dynamic" for my tastes. It's one of the two professional versions of the SRM-1 Mk2, the other being the ATR. They had two Pro outputs, were always black in color and have upgraded wiring and connectors over the standard model. I'm not sure is the circuit was upgraded or not but could very well have been. I'll take some pictures of it when I rearrange the computer rig. Congrats to both of you. I'll let you know, Deepak, if I see a Mk2 or a Pro SRD-7 floating around.

I have plenty of random tubes resistors and caps so I can just make my own version. I'll just claim it's patent pending like Mikhail if anybody starts asking questions...

This is what's been missing from my system all these years!!! I want one... no I need one.

It's not bad really. Cracking little amp and I'm glad that I kept it...

You... you... amp killer!!!! :'( Common ground and switching amps doesn't mix but it doesn't really hurt to try...