JoaMat

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It’s a small rip, a couple of millimeters. I guess a return for repair is the only option. But the headphone is not completely useless. I use Roon and its signal processor, -12dB on good side and +6 dB on bad (damaged) side. Playing at low to normal level the headphone sounds really nice. I imagine the small wound will grow larger by time. Changing the cable on 007 shouldn’t be a problem (knock on wood).

Well… I’ve finished the work with the new headphone and it ended in a disaster. I decided to resolder all solder points, so I took the driver package a part. Even removed the small cable connector. After cleaning all solder points, I connect outer stator and put into its position. It was a bit tricky to arrange the short wire in the connector house. Next was the diaphragm and here I made the disastrous mistake and got a scratch on the membrane when I should solder its wire. I guess I’m getting to old and clumsy for this kind of delicate work. Nowadays I have to wear headband magnifier which also makes it more difficult. Anyhow, I finished the assembly and have one good side and one bad with a small defect on membrane. After visual inspection with good light and magifier I don’t think the lower loudness had anything with dust or any foreign particles to do nor bad connections. So, I really should had waited for this… Thanks a lot, Wachara and Birgir!

It seems I’m running out of luck. SR-X9000 was the best headphone I’ve listened to only for a couple of days. You better keep your Omega, Andy. Today the Stax have a terrible unbalance. Left side is more than 12dB lower then right side. It was left side I opened, lifted inner stator and flipped as you see on picture a few posts above, removed plastic ring and easily lifted the diaphragm and gently held (didn't touched the membran) it in hand for a short while before I put it back. Could that be the reason or is just an unfortunate coincidence? No worry though. It’s a calculated risk and mostly nothing bad happens. If just had been something cheaper. 😭

Sorry Andy, no review or opinion from me. We have to wait for the trusted - Birgir. I just tear things down, a bad habit. P.S. I think SR-X9000 is the best headphone I’ve listened to. I haven’t listened to original Omega or HE90.

"Diaphragm" side of stator. Zoom in and you can see the structure of net (copper??). Stator with plastic ring. Outer diameter 94mm and inner 84mm. Thickness of diaphragm ring is 0,95mm on my digital caliper, so I would say spacer thickness 0,5mm. To me spacer material looks like aluminium.

This broke after a couple of years. But a piece of aluminum and 2 component epoxy fixed it and a cnc milled small PCB replaced another broken original part.

Until trusted person gives a reliable review here, you might study the interior of the new Stax SR-X9000. I let the pictures speak for themselves.

The new Stax just arrived. Sorry for posting in CRNB thread.

Tomorrow before 6pm Swedish local time, according TNT.

Years ago I had problem with high temperature when stacking two transformer. It was so high so upper transformer started to “boil”. I bought some BERGQUIST GAP PAD VO Soft, 3mm thick, from Mouser. One piece between lower trafo and 3 mm aluminum bottom plate, one between trafos and finally one between top trafo and top aluminum plate bent and bolted to heat sink. This way the temperature was reduced considerable. Determine inner temperature of a transformer is not easily done. One way is the measure resistance of primary winding when cold and when hot. Put those figures in this formula, T(hot) - T(cold) = [[R(hot)/R(cold)]-1] x 235 and voila.. you have calculated the temperature raise of the transformer.

Early draft of a modified Megatron. Top EL34 is replaced by 3x2SC4686 and a 10N100D. Less transformers – reduced risk.

I'm sorry for your trouble. Transformers are not always nice things. When temperature rises - copper resistance goes up – power increase – transformer temperature goes up - copper resistance goes up more, as temp … und so weiter …

Nice progress Kevin. Did this test board today. I’ve an idea (have to many ideas) to replace top el34 with CCS. Save you lots of wires. Here a CCS of 10M90S/DN2540 and +/-400V applied. Current set to 22 mA gave 400V cross tube and cathode resistor.

So, another quarter has elapsed. Raised the current through output stage from 11 mA to 17 mA ...and, it all sounded shitty bitty. Fired up the desoldering gun. Removed FJPF2145 and replaced them with 2SC4686. Wow, what an upgrade and I’m happy again.

It’s a troublesome, difficult time – all shortages of components. KSC5026 might be replaced by STN0214 in a KGSSHV style PSU. Solder it in standing, bend outer “pins” slightly outwards if necessary.

Have you seen this, BCV61? To be used as current mirror. You get a hundred pieces for 22 USD, less than one 2SC3381.

Which ones do you have in mind?

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From above picture it looks like there are 12ax7 anode current sources and 330K anode resistors. You shouldn’t have both, should you?

I use/have used those CCS. Good for +/-500V. I’ve replaced 2SA79/2SK216 with KSA1220/KSC2690. Looks like KSA1220 is ended, but TTA004/TTC004 should be fine.

Bohuslan Big Band plays Blue Note Available from Swedish public service company SVT, worldwide until 15. Dec. 2021. https://www.svtplay.se/video/31377250/jazzsommar-bohuslan-big-band-spelar-blue-note

Send me gerbers and I’ll take a look into it.

Happy Birthday!