spritzer

The HE60's are also better... More neutral and with a more honest soundstage. They just love powerful amps and work perfectly on Stax Pro bias outputs (with an extra ballast resistor inside the plug). They also weigh nothing so very, very comfy.

That's what I was afraid of so I'll see what I can cook up. The sole reason for buying these was my utter lack of "normal" dynamic headphones as I need something for the ipad... Just reterminated the HE60 I got on Friday and yeah, the HD800 has its moments but the 60's are clearly the best headphone Sennheiser ever made.

I'll try out that mod once I can get some supplies but the Luxman could be harder to source. I have it running off a Dynalo built in the usual mafia style but the Luxman is a rather different amp.

I've been the proud owner of a HD800 since Friday and while I've listened to the HD800 a few dozen times it's my first opportunity to spend some quality time with them at home. This one isn't brand new (S/N: 8329) but in perfect condition. They are clearly the best dynamic Sennheiser have ever made, imaging is almost as good as the Stax Omega's (though it lacks the layering of the 007) and the detail retrieval is quite good but the midrange is distant, the bass a bit lacking at times and they can be a too bright. Mods are clearly in order but I wonder just how far people have pushed this and I don't really feel like reading the huge threads on HF. Damping the back of the drivers a bit could yield good results and it might also be good to mess with the impedance a bit. Once we rip apart the new Senn amp then we'll know what impedance they design their headphones for but it should be worth the time to experiment on.

Is it suicidal? The rabbit I had as a kid really liked to chew the various AC cables around the house but suddenly stopped. I'm guessing it managed to bridge live and neutral and came to the conclusion this wasn't the smartest thing to do...

That is a good plan. I would suggest the Soundlab 945's though as they are up to 9' tall.

I'd be worried about the cat judging by the way it's looking at the speakers...

Happy Birthday my friend!!!

Is Johan in Sweden out of 389's by now? I made a large dent in his stock earlier this year...

As the semi proud owner of an identical car with the same wheels then it could be possible to loosen the bolts with the supplied wrench. The bolts are recessed a bit into the wheel and the wrench is pretty small....

Bloody modern electronics with no real high voltage capabilities... It would be interesting to nail down the resonance frequency of these drivers if only to see how it interacts with the sound. Stax clearly makes small alterations to the diaphragm tension between models to get the performance they want. As the engineers get older they seem to be leaning towards a brighter sound though....

Could be but in my experience it is the need to keep things simple that is the ultimate deciding factor.

Fake it 'till you make it works for me... Some proper simulations would be cool and it might be a good idea to contact DuPont and see if they have any data on how mylar behaves while under such tension and heat annealed. The newest sets use some other polymer but mylar would be a good start. A proper simulation could also dispel the age old myths that electrostatics are just capacitors that require virtually no power and are just voltage creatures.

I'm sure Quad would have tried to build something like that but they also never bothered to hire production engineers or look at how much some of this actually cost. The diagram tension is essentially fixed (though there is some variation) and it is then put in an oven to rearrange the polymer and lock that tension in place. The tension is very high though and there is next to no excursion even at silly levels. The diaphragm certainly can never hit the stators as you can't push it that far with a finger, let alone using the very weak electrostatic force. What the diaphragm can do is vibrate while being locked in place thus creating the very low distortion output. The bias voltage sets the film to stator distance or rather it's the other way around. If you use a voltage that is too high then the driver will arc and burn up the film. Low voltage will lessen the grip the stators have over the diaphragm and lower the sensitivity of the system. In the middle is the sweet spot which will allow enough control while allowing plenty of voltage on the stators. Now lets discuss that a bit. The electrostatic force is by definition very, very weak and it's strength diminishes by distance squared. That's why the normal bias Stax have a 230V bias voltage of a 0.3mm D/S gap but the Pro bias is 580V for 0.5mm. The gap is up by 60% but the bias is up by a factor of 2.5. Stax could have pushed it further but they clearly wanted the same sensitivity for both standards so they could be used together on the same amps. While the SR-Omega was being designed they tried going even further (1100V or 0.6-0.7mm) but decided against it for some reason. Now the extra distance could give more excursion but in reality is just gives the ability to put more voltage on the stators without damaging the diaphragm. The max voltage any electrostatic driver can see is bias*2 which is why the SRD-7Mk2 boxes have 450V zener diodes forming a clamping circuit for the normal bias output. The transformers are capable of crazy voltage swings so Stax tried to limit it somehow but they would never reach the 1200V needed to damage the Pro bias drivers. More voltage means more control and that the drivers can go louder without damage. Anyway, enough from this lowly baker in Iceland as Sachi put it...

Yeah, ineffective dustcovers and the cable entry is too cramped leading to arcing issues. Still I want to buy one and tinker with the amp a bit...

Given the distances involved it would be very hard to use only two stators. Stax pro bias diaphragm to stator gap is 0.5mm so if you want to use two diaphragms then the bias has to go down quite a bit and with it, sensitivity and the "grip" the stators have of the diaphragms. The breakdown voltage of air is around 100V/mill (not mm mind you and can be much higher depending on external factors) so there isn't a lot of room for error here. Now if we were to just layer one diaphragm on top of the other with just the thickness of the glue separating them then that will make the driver less linear (the diaphragm is never exactly in the center) and just add distortion. I also wonder how much an effect the vibration of one diaphragm will have on the other.

The isobarik was designed to compensate for the inherent non linear nature of piston drivers but will naturally bring it's own issues. No use for this with electrostatics as the issues with dipoles are more to do with baffle size and the bleed between the sides. The idea of using essentially a tweeter and woofer is intriguing but I'm worried about the backwave of the smaller driver collapsing with the back driver and cancelling out part of the range. Only real way to deal with that is a small time delay but even that isn't a perfect solution. Quad's PJW's Egg speaker springs to mind as a neat way of stacking diaphragms but we would need a time delay there as well.

Plenty of preamps use the ECC83 but many designers think that with our low gain preamps and high output sources a tube with a mu this high can only lead to issues.

Pretty much anything is possible but the normal electrostatic wiring setup limits all of this somewhat. I'm not sure many would like a 10 conductor headphone cable needed to feed different bias voltages and time delayed signals to the drivers. I do think that operating two full range drivers sort of misses the point though so one should be designed for higher frequencies while the other for lower. A simple way to do this would be via diaphragm thickness and bias setup.

Lovely tube but an odd choice for a linestage.

Stacking diaphragms is certainly possible and both Sony and Koss have done that in commercial products. It does bring up the idea of how do you drive them, three stators and two diaphragms with them working in tandem though a time delay or run the out one out of absolute phase. It would also be possible to simply ground the outer most stator (so it wouldn't be running at full power) for a semi passive radiator. The other approach would be to stack two different drivers but then you have interference issues plus how to handle the backwave off the front driver which will bounce off the second driver. One could use ports and a bass reflex design (like the 4070) but then it becomes very complex. Let's just say I've been thinking about this stuff for some time now... Wasn't it Linn who make the IsoBarik speakers?

The Stax amps use just a standard relay but the AC voltages are far lower. I'll check out the part number when I do final checks on this SRM-007tII I have here.

I'm trying to get some trade info on this line as I'm curious as well. Something like the 6922 alternatives spring to mind as the tube of choice. It's clearly a dual triode and normal noval size. I'd sure like to see the circuit as Samsung has an army of engineers so they could come up with something cool.

Stax switch the secondaries. Simple DPDT relay each half switching one wire.

All my HV transformers are 100mA+ and no problems at all aside from some buzzing. I'd be all for some R-cores but we'd probably have to go to Japan for them. The Chinese ones are rather poor...