spritzer

It's certainly a grounding issue or something is radiating an awful amount so the headphones are picking it up. If you have something earthed then run wires to that and see if it fixes the issue.

Well somebody has to keep some in stock for the apocalypse. I also have some BH's to build...

The connector is a multipin job but they just use 5 of them. Not compatible with Stax in any way, 1500V bias and four times the voltage swing... Horrendously expensive too.

Most of the sand for the original BH is either all gone or almost gone.

Happy Birthday Al!!

It's most likely the servo for the output stage was off. Basically the "batteries" need to be adjusted to 740V and then the servo can kick in and null the output. If it isn't at 740V then you can hear noises like that.

Tube input makes no sense as it gives us no benefits. That's the whole issue with most hybrid amps, most of them were designed with a SS front end but then tubes were added after the fact by somebody else.

Graphene is strong but size would be an issue for a large (50mm or larger) driver.

Nice twist on the plasma concept but as with so many of these things, it has limitations. I for one remain skeptical that thinner diaphragms are necessarily better for electrostatics. The weight of the air the diaphragm is asked to excite is an issue as is the stability of the material and its damping properties. Now if we could get a material that is stronger than mylar at any given thickness and provides better damping then we'd have something great.

Yup, I used them on most of my amps. Tracked down the data sheet at some point and they are rated at 500V.

More the unreg voltages but mine have been faultless as well.

Something like this? I use these and they are ok in terms of build quality.

Not on a constant charge basis.

Going by the document they didn't measure distortion at all. That's where constant current ESL's come into their own, something you can't really do with a highly conductive diaphragm. Now if they took the Final Audio root and biased the stators and put the signal on the diaphragm...

Funny thing about the Asian forums, the people selling the Rudistor stuff have a huge presence there. When the SR-009 first came out a guy was claiming the Cirolian was an excellent match... that he just happened to sell said amp was naturally not a factor.

The gain of the HV is a bit on the high side but it can be lowered. Ahh Rudi, as braindead as they come. Remember the "independently tested" specs he posted? Turns out he was in good company with Cavalli on that one...

The servo is limited in its range so if the trimpots can't even get close to 0V then then servo will be useless. Matching is important but I did build a Dynalo with no matching at all (except for grade) as a test and I had no problem getting it down to 0V. I didn't even install the trimpots, just used drop in resistors like I did on my last build.

I'd just call them a good counter to the brighter transducers of this world. I always used the HD600's back in the day with some very powerful amps and I had no complaints. Never did care for the HD650 though... One odd thing though, this hybrid I have now sounds much more like the HD600 than the 650 despite having brand spakin' new 650 drivers. The baffle is an old 580 unit so that could account for the change in tone.

Fakes would explain it. At this point I just strip all the active bits and start anew....

A marginal part would also account for this as the amp jumps from normal to fubar. Not probable if both channels act this way though.

A thin sheet of graphene is highly conductive so it wouldn't work as an electrostatic. Plenty of other ways to do it though.

It uses the same circuit as any of the Dynalo amps so yeah. It's more like the GS-1 and older amp Justin made (V2 etc.) though.

Dynalo would be perfect and if you can't find one of Justin's amps then there is always the Sheer Audio version. Kevin had one of those and he approved...

That is true.

They are twice as good...