spritzer

I aim to please!! I think these are old though... but can't find anything on them.

Hehe, this unit was never set to 115V so unless it was natively 230V, I'd doubt it. There are a few of these floating around out there though, at least 4 have sold in recent months and this one was by far the cheapest.

The pics are too low res to make any values out but it looks like it is multiple opamp stages feeding into a low power push-pull stage. I wouldn't call that reference in anyway. The person doing this doesn't seem to understand RMS values and that bias supply is super sketchy... None of those resistors are rated for that voltage. Clearly voltage divider into RC filters but one 2010 resistor to ground and the ballast is a 1/4W unit? Yeah... no.

Well this one came from Europe but one never knows.

That's never going to happen and interesting to see the headband on what was probably a prototype.

Time for a necro bump but this arrived a couple of weeks ago: Naturally I bought them used as I always wanted to try these and well... they are some of the worst headphones ever made. Seriously... this is so fucking bad it isn't even funny. Now they barely fit my head so that might be a factor but they are somehow very peaky and dull sounding at the same time. Open baffle and all that but the sound is just all over the place. I'm sure these would benefit greatly from an adjustable arc setup and some earpads to close them up. Maybe something like the PMB units, an L-shaped pads at the back of the ears. At the same time I got these, I refurbished what might be the most disgusting SR-Sigma I've ever seen (though the drivers were fine), and they are much better in ever way. Super soundstage, nice extension at both ends of the spectrum and they just sound lovely off a SRM-313. Now I naturally had to rip the Transdyn box apart and well... It doesn't start well, this is the power switch. Yeah... one trace of something conductive and all hell would break loose. Bia Bias supply and why they have it half populated for 230V and then add more parts for 115V is beyond me. Just throw a transformer on it (also for safety). Speaking of which... Gotta love it seeing this trash in there. Rifa caps known for going bad and blowing up right on the mains. This set is fitted with a motorized RK27 but I didn't get a remote control with it. The sensor underneath the front panel. This is actual Transdyn module and I can't say it made much of a difference to me. Another angle. The actual power amp driving the transformer: Not sure what Icepower model that is, haven't looked into it yet. This is certainly a way of doing this... It's hard to tell but no insulation on the mains wiring here either. I don't know what to think about this setup but it does work but looks very silly indeed. I'm tempted to design something long the lines of a 4070 arc setup which would carry the weight and be adjustable as this is not comfy for me. The space between the arcs just isn't wide enough for me. This cable is super thin, roughly 5mm in diameter and to think of the voltage in there... I hope it is made out of something very insulated. Genuine Fischer plugs though these are not the special HV ones used on the HE90 Just normal pins and 12mm across so a S104 plug if I remember correctly.

Woo Audio and Lampazitor in the same system... damn this one is a glutton for punishment

I think they are HD650 pads but they were just some I found in my stash of earpads. I had to trim off the plastic ring at the bottom and attach them with double sided adhesive but it fits nicely on there.

Well he has lost his marbles... I must say though that I feel the same way for current day Stax, they just sound a bit soulless and appear to be lost. They came out with the L series... but why make those changes? What is the purpose of fucking with the imaging on those and the X9000? Take this SR-Alpha Pro (Japanese Gamma Pro btw.) I got this week, it was utterly disgusting when it arrived so earpads and headpad had to go and a lot of time spent cleaning them up. Drivers were perfect though and they did clean up nicely: They sound far from perfect but I'd much rather use these than the 007S. They sound more alive despite their limitations and the tiny driver.

I wasn't sure where to put this either but this should be rare enough, the Sony ECR-800 energizer or the ECA-80 to be precise. Now there is a bit of a backstory to this one, I've never found a ECR-800 but I found this one for a song in China so I had to snap it up. It was in a bad way when it arrived, damage all over and the back sockets all a bit crooked but the worst was inside. See, Sony in their infinite wisdom, used a mercury switch for the input switching and that had broken in shipping. There was mercury all over the inside so I had to clean everything and dispose of it properly. It's a shame as its a very early unit with the custom Sony sockets, they later moved onto using Stax 6 pin sockets with these. I let it sit for probably a year before I decided what to do with it as so a full rebuild was in order. These are 100V only so for my use I need a new transformer, I fitted an IEC on the back, new binding posts with the switch function bypassed and all caps replaced. I also fitted a 6 pin Stax socket to the front as I don't have an ECR-800 and if I ever find one, odds are it will have that plug. Plus this works nicely with Stax normal bias sets. For the circuitry as it is a bit odd for 1978 or so. Most of the what's there is a protection circuit and output relay but the gray brick on the bottom is the bias supply, a DC/DC converter. It has clearly seen some use as there should be paint on there but it seems to work fine and there is clearly a ballast resistor in there too. It's also odd that the transformers have two sets of wires so each socket is fed from its own set of wires. See the 4 purple bias wires too, they are all common on the bias supply.

I like that riser for the power switch and the tubes visible through the front.

That looks rather old and not fun at all to work on. When was this made, the 90's?

No idea as I've never had a broken set here to experiment on. Based on this set the coating is definitely helping and I'm about 85% balanced now. The plan is to rewire them and see how much that changes. I'm not a fan headphones being out of phase in general, I always reverse it on HE60's when I work on them as they are also wired out of phase from the factory.

You can't plug normal bias headphones into a Pro bias output, that will just blow them up even on trash like the D10. If it is just the plug you want to modify, no you'd need to connect the left side bias somewhere in the cable as it is only connected to the center pin.

In an effort to try and finish up some of the gigantic pile of projects, here is a fully DC/DC powered KGSSHV. The unit is close to 10 years old but not really used at all as it ended up at Kevin's with some transformer trouble. A couple of years ago I made an effort to bring all those amps home so I stripped it down for transport and the transformer went in the trash to save on weight. Then I found those lovely 400V DC/DC bricks, added one for 600V bias (with a bit of a trim and filtering) and one for +/-15V, all driven off a 90W 24VDC Meanwell brick. I had to lower the output stage current a bit from stock and there is a tiny bit of coil whine coming from those HV supplies but it works well. The B+ supply is the hottest part in there at 60°C.

Kevin warned me about that stuff as it is toxic if I remember correctly. I have a rule of thumb, if Kevin says something is nasty stuff then I keep well clear.

Probably, never tried it and it always a question how long the coating would last but well worth a try.

We aren't in the EU and that muddles everything. I'll try that plus I should have some airbrush equipment somewhere. I just made some new stators for my Senn HD6x0 design that I want to try out.

Licron is not available here and shipping anything under pressure is a no-go. The Comfort was available at my local store so I'll give it a go. Nice consistency too and dirt cheap.

Interesting, I'll see if I can find that locally. Do you apply it with an airbrush or a sponge?

It was antistatex spray, it was what I had at hand and could use in a small dosage. I went away today and when I arrived home again the imbalance was back. Might not be as bad but yeah, not a good fix.

Yeah, pretty much. I was clearing up and found the broken X1's so time to do some tinkering. Sure enough, one driver started failing after an hour or so it's trash at this point... time for something drastic. I opened them up and nothing looks wrong so I just added some coating to the diaphragm, just a tiny bit. It's been an hour now and they sound pretty much balanced so this might have worked but it adds another issue, are Stax having coating issues 65 years in? Another thing about the X1, the drivers are wired out of phase as in the + signal goes to the back stator. Might be worth adding a cheater plug to these to reverse the phase to try out and the earpads on the X1 are clearly made by the same company as the 007S pads.

The original is on the right... the left one is clearly a fake

This is the 12th eruption and we have reached the point where people are protesting unfair police closures. It's well away from anything and already fizzling out so nobody is worried.

I see we have a member of the audio religion in our midst, how fun to see the scientologist poke their head out of their echo chamber. Arguing whether Class A is better than Class B is fucking retarded so let's not but the question of measurements is a fun one. Are you measuring something that actually matters or is it voltage swing in an electrostatic amp, meaningless stat that is measured in the one spot that makes it even more meaningless? If you go from 0.01 THD to 000.1 THD... how does that change the sound? Do we have hearing good enough to spot that or are we picking up something different? If something measures badly but sounds good, which is correct? If you claim something terrible sounds good... do you have enough experience to know it sounds bad? Just because you have ears, doesn't mean you know how to use them. Same goes with a scope or a test suite, just because you have it, doesn't mean you know what to look for. If you take a cult leader, hand him a device he doesn't understand because he's as thick as brick, he measures it incorrectly and claims "I don't understand why anybody think this is good"... was the device at fault or was the cult leader being retarded? If you smother everything in feedback, can you hear that? What if you remove all the feedback and make an unstable circuit, can you hear that? There are so many good questions out there...