Apr 15, 2024 at 5:25 AM
early srm313 are identical schematic to srm212. no adjustment pots.

for transformer boxes, 5.1k resistors absolutely required. 1/4 watt. you want the resistors to blow first.
as far as zeners, anything that adds up to 600v in series and back to back. so a total of 32 x 150v zeners. or 24 x 200v zeners etc.

Apr 15, 2024 at 5:27 AM

Apr 15, 2024 at 5:38 AM
...5.1k resistors absolutely required. 1/4 watt. you want the resistors to blow first.
as far as zeners, anything that adds up to 600v in series and back to back. so a total of 32 x 150v zeners. or 24 x 200v zeners etc.
Can you share a circuit diagram or drawing? I guess this stuff is relevant for safety, and a mixup of the connections might turn out bad.

Also, 600 V limit would correspond to about 400 Vrms for a sine signal (again, depending on the Zener connections). 400 Vrms through 5.1 kOhm is about 80 mA, which works out to 400 V x 0.08 A = 32 W, which is wayyyy more than the 1/4 W spec. What's the catch?

Apr 15, 2024 at 5:42 AM
Can you share a circuit diagram or drawing? I guess this stuff is relevant for safety, and a mixup of the connections might turn out bad.

Also, 600 V limit would correspond to about 400 Vrms for a sine signal (again, depending on the Zener connections). 400 Vrms through 5.1 kOhm is about 80 mA, which works out to 400 V x 0.08 A = 32 W, which is wayyyy more than the 1/4 W spec. What's the catch?
...you want the resistors to blow first...
Safety Resistors meant to blow...

Apr 15, 2024 at 9:20 AM
...you want the resistors to blow first...
Safety Resistors meant to blow...
Sure. A 5.1 kOhm resistor dissipating 1/4 W will have a voltage drop of 36 V(rms) and and 7 mA(rms) current running through it. That's not much, and I'd guess it's not enough to run a headphone properly. The usual recommendation is to use a 2 W resistor. But, again, I (and others) may be misinterpreting the above post by @kevin gilmore . A drawing/diagram/schematic of the intended connection would be in order to make sure everyone understands how the connect the parts properly and safely.

Apr 15, 2024 at 11:30 AM
like this

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Apr 15, 2024 at 11:46 AM
What is the difference between the Blue Hawaii BJT and the Blue Hawaii SE?

Apr 15, 2024 at 2:55 PM
My SR-009 and SRM-007TA arrived and I am really enjoying them. However, to my surprise the 009 feels very big on me. This is unusual for me. I have them on the smallest setting, but I would like to tighten the headband further, and possibly add to the clamping force.
Is there anything that can be done?

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Apr 15, 2024 at 2:58 PM
Different input transistors for the BHSE and the BJT - the BJT uses bi polar instead of the (MOS?)FET

Apr 15, 2024 at 3:31 PM
Apr 15, 2024 at 4:34 PM
My SR-009 and SRM-007TA arrived and I am really enjoying them. However, to my surprise the 009 feels very big on me. This is unusual for me. I have them on the smallest setting, but I would like to tighten the headband further, and possibly add to the clamping force.
Is there anything that can be done?
With a lack of any other ideas I unscrewed the suspension strap, made a couple of new holes about 5mm up the strap from the original ones and put it back together using these new holes. Problem solved.

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Apr 17, 2024 at 5:50 AM
I'm thinking of selling my Mjolnir KGST amp. I'm in the UK but can probably ship within the EU. If interested pm me. Listed in Classifieds.

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Apr 17, 2024 at 5:33 PM
Just bought myself a Sansui Alpha 907MR for only \$1500 somehow. Basically the pinnacle of Japanese amplification from the 90's when money was flowing and tech designs had no budget. This thing is 33Kg and probably half of that is copper, it's insane. I could probably get my money back just from the scrap value. Copper and silk Silmic capacitors custom made just for this line of amps and some of the best transformers to ever exist. https://audio-database.com/SANSUI/amp/au-alpha907mr-e.html

Supposedly is voiced very close to their coveted AU-111 tube amp from the 60s.
I have a RAAL Immanis on order and wanted something special to drive that but I also can't wait to hook up my X9000/Nova to it and see if the Novem gets dethroned as my favorite.

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Apr 17, 2024 at 11:29 PM
Just bought myself a Sansui Alpha 907MR for only \$1500 somehow. Basically the pinnacle of Japanese amplification from the 90's when money was flowing and tech designs had no budget. This thing is 33Kg and probably half of that is copper, it's insane. I could probably get my money back just from the scrap value. Copper and silk Silmic capacitors custom made just for this line of amps and some of the best transformers to ever exist. https://audio-database.com/SANSUI/amp/au-alpha907mr-e.html

Supposedly is voiced very close to their coveted AU-111 tube amp from the 60s.
I have a RAAL Immanis on order and wanted something special to drive that but I also can't wait to hook up my X9000/Nova to it and see if the Novem gets dethroned as my favorite.
Thing of beauty! Congratulations! Jealous that you have Immanis incoming!

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Apr 18, 2024 at 8:34 AM
Thing of beauty! Congratulations! Jealous that you have Immanis incoming!
Yeah, built like a tank. I just couldn't get it out of my head after seeing @aokman's videos on it and had to get one. He uses it with his Lundahl transformers (that I also use) and seems to love it. https://www.youtube.com/watch?v=M25GISNbfhE and at 200Wpc it's powerful enough to work double duty running my Magnepan speakers as well.

Probably two months still until I get my RAAL order, I actually ordered both Immanis and Magna and will be keeping whichever I prefer.
Will be doing lots of X9000 comparisons here since that's the only headphone I have that I suspect will put up a fight.