spritzer

Much better! I can understand that they are a bit sensitive about that as something original that is made in China is quite rare indeed. Rip apart and modify... Depending on how the new ones will turn out I think there is some ground for improvement... maybe quite a bit even. On a side note if there is some thing not clear about the ES principle, ask away.

It's very hard to beat the direct connection to the drive especially if crap like Toslink is used. The upcoming APL DAC will have some propitiatory link to a from a modded transport so if they can do that in some PCI card then it would be awesome. The horrible environment of the PC is still to be dealt with but an external PSU for the PCI card could be an option...

ETF is one of the few audio shows I'd like to attend. Lats year some engineers at Philips recreated the original triode to celebrate its 100. anniversary and they even built an amp around it. Way too cool!

A lower resistor would possibly lead to arcing and if something does go wrong it is there to protect you as it burns up with very little current going through it. The HEV amps are not matched to the HE phones in any way. The only way an amp can hurt ES phones (ESP's?) is by arcing them with too much output voltage. That simply isn't going to happen with any of the amps currently avaialble. The HEAudio 1.3 is in no way, shape or form a HE90 clone so they shouldn't be compared like that. The construction is very different and it is hard to speculate about them unless I have spent sometime with them here and disassembled them.

Some are more complicated then others. The whole fault with Sony units was a horrible output stage and some questionable things on the dac boards. A normal eXemplar or Modwright mod is a new clock and outputstage with a replacement of a number of components but it's pretty far from a complete redesign. They still do solid work at a lower price and that is to be commended. Some of the other modders... are more questionable. I can't wait to get mine... This is certainly true as most modders are spread very thin with a lot of different manufacturers and not very many units of any one kind but APL stopped doing that a long time ago. If my Denon will need to be repaired it will go back to APL. I know they have been replacing drives and all the usual stuff that fails and they will continue to support it. Some of the modders aren't as helpful to say the least...

Going with those comparisons I've read they don't stand a chance. They are after all simple mods while the APL is a complete rebuild. Why on earth not? You get much better service and better bang for your buck. The product is never outdated as if there is a new version you just send yours in to be updated. The APL gear isn't really a modification as they are working with Esoteric so i would much rather call it a rebuild, doing things Esoteric could never do and stay profitable.

You don't need any transformers to generate the bias. It's almost always generated by a voltage multiplier which is just what the name suggest i.e. it takes any input voltage and outputs a multiple of said input voltage. The level of multiplication depends on how many stages there are. You can also just borrow the bias from the HV or B+ line as it's current is so small. I'm certain your amp has a 560-580v bias. The bias voltage is the potential of the driver and it's voltage depends on the airgap between a stator and diaphragm. Stax used 200-230v for it Normal system and that has a distance of 0.3mm from stator to diaphragm. The Pro bias has a bias of 580v and a distance of 0.5. A keen observer sees that this isn't linear in the common sense and the reason for that is that the strength of an electrostatic field falls by the square of the distance. A closer space gives you more output at a lower voltage level but you get more excursion as the space gets bigger. Like everything in life this is a compromise and by studying ESL design you can know a lot about the design by simply listening to it. When you go to a lower bias voltage you loose more potential of the driver so it's harder for the drive voltage to make the diaphragm move. Stax says that the sound will be softer and that's exactly true as the drive voltage can't control the driver as well. The HEV70 has a 540v bias but there are other factors here such as the bleeder resistor. This resistor controls the amount of charge there is on the diaphragm at any given time and it has to be at the right size for any given design as the coating material for the diaphragm will vary greatly. If HEAudio used graphite to coat the diaphragm then it will loose it's charge rapidly (relatively) when compared to the Sennheiser coating. That could cause stability issues but shouldn't really be a problem in the real world. The effect of a lower bias will depend on the D/S spacing like I said before but the sound should loose definition and some focus.

Just buy an APL player and be done with it. You can have a digital input, volume control and a universal player that plays any of the old formats. I don't quite know what the price and features of the newest players but you should drop Alex a line. The guy who sold me my APL 3910 compared it to a dCS P8i and ARC Ref3 line stage (the APL has a built in volume control) the last day before he shipped it out and the other gear was blown away in every aspect. That's 25k$ against a 4k$ player and it's not even the newest version. This was in an email sent to Alex and not me where the seller said he was nuts for selling me the player and he wanted a NWO soon. Now mine is even better with the new AKM 32bit.

That will only happen if they are left to fully loose all charge over some weeks. Then they will require time to spring back to life. The 500v he is referring to is driving voltage and not bias voltage.

You only need about 100-250v to get the phones to a normal listening level so 500v has plenty of headroom. These are all RMS numbers so peek-peek values would be higher. The bias voltage has nothing to do with the drive voltages other then that they have to be with in a certain ratio to function correctly.

Ahhh no,no we are talking about two totally different things. I thought you wanted to connect a Stax trafo to the tubes but I now see it was a result of me being barely awake. All the amps see with a Stax trafo is a benign 8ohm load but the transformer turns that into the 5kohm that electrostatics like (transformer ratio 2*input impedance) as well as stepping up the voltage and reducing the current.

I wouldn't connect them to a Stax transformers except maybe the other way around for a cheap/small/crappy output transformer for a push-pull amp. If you were to connect it before the output transformer of a SET amp you'll end up with a 1:25 step up of the output voltage of the tube. The output transformer steps down the voltage, impedance and steps up the current for dynamic speaker use. You can connect Stax phones directly to the tubes through a capacitor, no transformer needed. You will need some load on the tubes to make the amp more stable but thats given.

Not with all channels driven at once, apparently.

One problem with these drivers is the single point bias system so if there is any corrosion you'll get a very reduced output. Still I hate working with these drivers as they are very fragile... That would be cool. just make sure that the builder seals up the baffle airtight.

I've never had this happen to me and there is no theoretical reason for this...it could be a bad connection but the old SR-X driver are very temperamental beasts... \ I think it would be worth a shot to talk to the local distributor, Senn USA or some of the big ones. I'm sure they still have the parts as they cost next to nothing to make and Sennheiser has a bit of an obsession with spare parts. The Sennheiser cable is pure crap so you are much better off with a Stax extension.

Did anybody notice the power consumption on the right...13A

That's a whopping 3.33% difference so no. Such a small difference will not be noticeable. I'm much more interested in the recommended bleeder resistor as that might cause some compatibility issues.

We are getting screwed constantly. One nice thing this evening was that the post came with a package and I didn't have to pay anything... I'm really digging my Stax Gamma Pro's The RK40 is a very nice pot and I have a small stash here with me. It's a bit sad that my new source makes all volume controls redundant...

Ok cool. It's still odd that something is cheaper over here with our fun VAT and other small expenses the state burdens us with.

They are 50$ here in Europe... on ebay.... You can find them even cheaper in Japan if you know where to look. I know full well about the recent price influx... it's making my collection so much harder to put together.

Less vibrations is always better. Have you ever watched a cd spin as it is quite a workload for the error correction.

You can get an RK40 for about 50$(edit:typo) and it was even cheaper when this amp was made. I wonder what those caps are?

I feel the same way. I'm not going to use some crappy 2k$ player and invest a lot in tweaks to fix something that is a fringe tweak. Some disks are way off balance and they will benefit from this with the reduced vibration and wobble. I will also try an APL tweak to resample some of my disks to 88.2/24 and burn them as DVD-A's. It is supposed to be a good step forward.

The lathe is to make the CD perfectly round. That makes perfect sense given how they are produced since the center hole is rarely completely in the right place. That beveled edge might work but I file it under green markers and other fringe tweaks.

Poked a hole in the diaphragm!!!!!! I think going to lay down a cry for a bit... The driver should work just fine with a small hole. One of my Micro Seiki's produced sound with the film in small flakes... Are you sure you can't order the two pieces from Sennheiser? I'm pretty sure they get exchanged a lot during repairs because of the stupid screws they used. You need the front and back parts of the housing, the rubber o-ring that seals the baffle and a headband... and a cable... can't be that hard to get.