spritzer

Why are people using CMF60 resistors for the bias ballast? Doesn't anybody read the bloody spec sheets?

Improved version naturally. Fits well with the Exstata V2... Onboard sinks too. Hey, I quite like those amps given how small they can be made. I'm building one now into a SRD-7 box for the smallest fully balanced amp I can make. That would be marzipan or rather persipan in most (not pure almonds but cut with apricot kernels). Lovely stuff we use to make cakes up here mixed with 50% sugar and a bit of eggwhites.

Happy birthday Fitzy!!!

Looks like fun!

Let's just put it this way, there is a reason for the pile of amps, dacs etc. in a spare room.

Yup, I get regular care packages from Kevin.

Things are indeed getting bad but we can only hope that there will still be some demand for high voltage BJT's. The IXYS part is available at Mouser, you just have to search for the TO220 version (P) and not the SMD (A). Naturally not available outside of the US...

Yeah, Kevin has been working on a KGSSHV setup sourced exclusively from Mouser and that uses fet's instead of the BJT's.

Very nice and now my Mouser is in Swedish. Seems appropriate since I just got off the phone to Sverige....

Not a bad price at given how much people are willing to pay for fubar sets. As if there was ever any doubt but the 007 Mk1 sounds great with the KGSSHV.

No veil in my rev.1 either or reverb or anything like that. This is mostly linked to amplification used as the "ortho amps" over on HF are almost all ehhh... lacking in true power delivery. I do think the LCD-2 is a very nice headphone but it's never great, similar in many ways to the HD600. Does most things well but they always fall a bit short in absolute terms.

Amazing similarities but let's see how Stax did it in 1982: and the 323A:

Even HE-5's? Those are truly awful...

Why are they painting old hookers? I think the fumes are getting to 'em....

Measuring anything while in circuit is always a crapshoot. Way too many variables to list. While we are on the subject, the HV sounds fucking amazing!! Who stuck a subwoofer to my 007 Mk1's?

The output on the stators is AC but the polarizing voltage is DC. The only thing the bias does is to set the potential of the diaphragm so it can be pushed and pulled by the AC voltage on the stators. The ballast resistor for the bias supply is used to set the diaphragm to constant charge for lowest distortion but in reality it acts much more as a safety feature. The diaphragm is an open circuit in essence so if something were to close that circuit the ballast resistor would drop most of the voltage. What you are doing is something rather different and those 10M resistors are used to balance out the output stage and to drain the output caps.

This should help... http://i.imgur.com/xgvci.jpg Not small... Edit: Yeah I went utter overkill on it. Some Loxeal too just for good measure. Yup, BHSE castoffs. Having the same knob as Steve is just the icing on the cake...

I wouldn't bother with those resistors and keep the 5M resistor as well. It costs nothing and if something goes horribly wrong it will kill most of the bias voltage. I would place output resistors (5K1) if you want extra protection but there is no need for the 10M units.

I don't think messing with the current on the onboard sets is a good idea since it is hot enough as it is. Now with huge offboard sinks then the sky is indeed the limit and I'm going to go damn close... Now if somebody can spot my way of dealing with the 10M90 sinks with only metric screws at hand...

Proof that a 2U is all you need... It's running in that pic, I just couldn't be bothered to hook up the indicator LED. This was a difficult birth though with an intermittent pot in one channel and the other was just fubar. I swapped pretty much everything and it still didn't work so I finally gave up and built a new channel. That one also needed some work to get right. Still, build enough amps and once in a while one is bound to be like this.

With that level of effort it would be better to just build a ESX mini with ECC81's and 6S4A's as output tubes. Sounds like a plan but I'm sure we'll draw up and test a fixed version just for kicks. As for the box, It really depends on the transformers used but I'll probably build the first one into a couple of die-cast aluminum boxes which need to the powder coated. I was thinking purple with glimmer or something crazy like that...

That was just NoNoNoNoNoNo trying to muddy the waters. Let's put it this way, the BHSE is a Blue Hawaii but not all Blue Hawaii's are BHSE's. Kerry's version is close to the BHSE and the original design run at full tilt is so as well in terms of spec. I don't think the OPA541 could ever be used in anything meaningful but then again the Darkhole does just what the Dorkstar was meant to do but properly. Production of boards as in I will design it for my use and if somebody wants one, they can have it at cost. I only sell high carb items for profit...

I like to build pretty much anything so why not this? I've built 3 Egmonts (and I'm working on a fourth) when I could just as well build a ESX. Why am I working on old Stax amps when I could just as well assemble a KGSSHV which I have all the parts for? Why am I building a WES when I know it is bad? I could go on... I for one don't give a fuck about Ray but people stating that the A-10 is good just because it costs 6500$ has to be responded to. Well that and I have to find some use for the my new stacked PSU....

Sorry for leaving you hanging like that but work called. Thanks Kevin for stepping in and stating rightly that it isn't wise to fuck with the Mafia. We've always known that the A-10 was bad but it is shocking just how bad is is. Ray states a voltage swing 600VP-P (roughly 210V RMS) which is just barely meets while generating way too much distortion so it is clearly clipping at that point. To put this into context the BHSE swings 1500VP-P (530VRMS) and it costs a lot less than the A-10. Hell,the SRM-252S swings 280VRMS and never comes close to clipping... hen we have the issue with no adjustments at all in the amp. Ray states on the top panel that you need matched ECC83's for the diff amp and 6SN7's for the preamp output but this will never work to balance out the amp properly. The diff amp has to be adjusted and ditto the phase splitter. There is also no offset adjustment so that 600VP-P voltage swing is purely theoretical. The amp will never reach that in practice... To make matters worse these are not enough amplification stages so the gain is driven to the max with bypass caps on the cathodes so this thing is noise central. Massive amount of gain with no voltage swing is never a good idea. Then we have the over all layout of the amp, it's just a mess with stuff run all over the place, it's like auto routing gone mad. As for the PSU, it is pure shit but Ray was clearly looking at Mikhail for inspiration there. Two bias lines run from the PSU to the headphones when a simple voltage divider in the amp chassis would have done a far better job. Mikhail did the same in the ES-1/2 wasting "precious" umbilical wires on nothing. Then we have the Cincon CMF40/60 switching PSU's used to run all the low voltage stuff from relays to the tube heaters. Grounding the heaters in the 5687 is a shockingly bad idea same as it was in the ES-1/2. Now the real question is, should I leave the circuit as it is or apply fixes so that it at least sort of works. Isolated heaters are a no brainer but I really want people to appreciate just how bad this amp is.

Who needs low distortion and high power? What about some high distortion, high noise and very limited power output. Apparently some people want that in an amp... This has been a long time coming but this one will bear a striking resemblance to certain production amps but combine dynamic and electrostatic output in one amp. More to come...