spritzer

Yup, too busy building amps to work on it though.

All of these BJT's have the same pinout. Yes on the new part but I'll never sell any of my 2SA1968's.

Yeah that and I have a huge pile of 2sa1968's and they are fully insulated which makes my life easier. One thing I missed, the zener string should be 230V as that is the max normal bias voltage. A KGSSHV plus a higher normal bias voltage is not a good mix. It's ARC time!!!

It would make sense to make sure this project doesn't go the way of the Dynahi and be killed by parts being discontinued. It should also be noted that this is the part intended to be used in the KGSSHV all along. The 4686A was just easier to source... No need for that. The audio slush fund covers this...

The current board just about fits a Modushop Pesante Dissipante chassis...

So a question for the group. As we all know high voltage BJT's that can take the full force of the KGSSHV are going away quite quickly. None are currently being made and I quite frankly don't see them making a comeback, certainly not as TO220 devices. There is a new mosfet on the horizon but it's a poor substitute for the real thing. With this in mind I used the mafia network to try and source some NOS and I've hit paydirt. Now 2SC4686A's are all but gone but I've been offered another part which was clearly meant to be used in the same role, all specs identical plus some (like the output capacitance) are even better and it's fully isolated package too. These are also guaranteed genuine and made in Japan. Now the catch is that I have to buy a lot of them, thousands, and the end price is unknown though I hope it comes between 2-3$ when they would reach my hands. The 4686A is currently at 4$ from Bdent and supply in Japan is all but run out. I would naturally sell off my stash as needed to anybody building an HV so this would be enough for a few hundred new amps. So does this make sense to anybody? I see no problem with that.

First off, never use a screwdriver to adjust the pots, that's what trimpot adjusters are for. Non conductive too... As for the pots: New version has the balance moved so the terminal block doesn't obstruct it.

The PSU isn't current limited so it will easily fry the amp given the chance.

Massive issues with anything like this. While it is certainly possible to use adaptive biasing (i.e. Krell with sustained plateau bias and the new iBias) simply cobbling together a switch with some wires and resistors would never work properly.

You can do a diode test but they seem to be damaged but still functional. Personally I'd just replace the entire output stage but then again I like scorched earth as a policy...

Yeah, major misunderstanding of what is going on here. Let's just make one thing clear, running the KGSSHV at the same current as the BHSE will not make them sound close, let alone identical to one another. Major difference in terms of circuit design which has a clear impact on the final output. Even if we did a Blue Hawaii with sand instead of tubes it still wouldn't sound the same. As for the question, yes the KGSSHV can run at 16mA but there are other things to consider. First of all, why on earth would you want to do that. There are certainly no benefits to speak of and those talking about "major improvements" must be smoking something. I'd certainly love to see some date to back up these claims but there are naturally none to be found. There is a subtle change when moving from 5.5mA to say 10mA but after that it is all diminishing returns. Now say you have taken leave of your senses and want to pursue the magical 16mA then there are three major issues you need to tackle, what is the maximum power rating of the output device, do you have sufficient cooling and can the PSU supply the extra current.

Don't care about the money so no. All it needs is materials and time...

That could be arranged later on...

We might have measured it at some time but this was 5 years ago.

The two on the left are one-off's so more won't be made. Simply not happy with the chassis... I will make a few of the smaller one when I have time. Parts have been ordered and boards assembled for some of them but it will take a while to source the parts. Nobody will ever make a T2 so that's out and the Megatron is way too complex.

Things might have changed but back in the day they were run to simply break even, no profit at all. Some rich benefactor who didn't care about making money on his investment. Those servicing prices are insane though. Who would spend 8 hours swapping out caps in a DAC? 1 hour max...

Yup, the small one is at 9mA and the smaller one on the left runs at 11mA. Well it will once I get more transformers...

Mouser has some nice filament transformers too. Dirt cheap...

...goes off to start on the third one...

Prototype nr. 2 of the tiny HV up and running. Different output devices, pcb's mounted closer to the sinks, different assembly technique, new chassis feet plus a lot of holes drilled into the bottom plate to see how much cooler inside is. It isn't SRM-T2 hot but then again the T2 didn't have electrolytic caps inside the amp section. I'll send the first prototype to the US next week to see how it plays in a warmer climate and for some measurements. These small amps seem to be multiplying like rabbits though... It is Easter after all. Speaking of Easter, it marks the anniversary of me giving up on making new offboard PCB's for the HV so to celebrate I've started work on them again. Glutton for punishment here...

You are right, it changes fuck all. I guess it does mean I have to start building more amps so that Justin and I will cover the entire market. It must me nice for them in the short bus...

Didn't know about that and as usual they are too cowardly to discuss anything with me. Doesn't surprise me the least though but can anybody explain to me how I can be an MOT when I don't make any money on what I sell? Sure seems profit should be a factor in this with me more adopting the Spectral Audio business model. Looks like I'll have to send the half-wits a PM today and demand an explanation. I don't mind the label though as it means I can now have posts by others about my stuff removed. I don't think they thought this one through... That's exactly my problem with him and his ilk. Clueless idiots that can't draw meaningful conclusions at any cost. They seek acceptance like an addict seeks his fix but they are never going to find it.

Many tubes have claimed to equal the XF2's over the years but it's never even close to being true. Large part of why the XF2's are so good is the build quality, very thick plates which are welded by hand. Nobody can match that...

Yup and add to that the amps simply don't sell on the used market. Last I heard the LL1 is closing in on 1k$...

The BHSE hits the last bastion of good audio press: There is a good article in there too about headband resonance in headphones.