spritzer

To bad they can't spell the names correctly. I wonder how many realize the name is bif-röst and not bi-frost....

Would anybody with a Woo WEE mind opening it up and posting pics? I'm troubleshooting one unit and I have some major concerns about the design which I need to verify.

I don't even want to think about all the pending projects and the cost of building them...

The HD600 leaving us is sad news indeed. I think I need to borrow a set and spin some Dire Straits...

Yup, it's just a very busy time of year for me so it will have to wait. I still haven't tested any of the last prototype boards I ordered... I do have a bunch of 6BL7's sitting here so I'm ready when the time comes.

There were some other circlotrons but every one was a bit different. It's been a while since I read up one this but a lot has to do with the way feedback was handled. Some of the older amps would oscillate like mad...

Reducing transparency to make them work is only part of the equation. If I wanted to do so then I'd just construct some heavily AC coupled amp and use the cheapest capacitors I could find. Hell, let's not stop there and mess with the operating points so the tubes are as non-linear as I can make them. In essence this is what Sennheiser did with the earliest Orpheus amps but they were after a certain "sound" and those transducers need a sympathetic match to reach their full potential. Put them on a wire-with-gain amp and the results are underwhelming. With the 009 you have a similar situation except they are a Stax Omega so transparency and neutrality are the name of the game. I just think they took the transparency too far, as in it pushes detail into your face instead of just putting it out there. Tame this a bit and you end up with a much more pleasant listening experience. I've said so before but I do think that the Stax voicing for their cans has been a bit "off" as of late. When making the diaphragms there are certain compromises that have to be made and I think Stax just ventured into the wrong direction. This might be done intentionally to make the cans fit the amps better or is could be something as simple as the new diaphragm material acting up. Let's not forget that Stax went to 1um in 1987 but back up to 1.5um after the extensive research done for the SR-Omega design in 1993.

They are basically circlotrons so the high impedance issue of tubes is tackled with multiple triodes in parallel so no output transformers or huge output caps..

I'm using the isolated USB connection most of the time. It's better than any transport I've tried recently but something like the ML31.5 might beat it.

My main source is a MSB DACIII Platinum with the standard modules but I have the same results even with the very warm AudioZone DAC-1.

Looks like a great time but you guys need some more gear...

There are no etch issues with the 009 but it shares many of the Lambda traits. Another candidate would be the SR-X Mk3 Pro which is pretty much a properly done Grado so a bit bright and upfront. I will never buy another cable so that's a no go and the only exception would be some Kimber Select stuff since it holds its value. The TCSS is too stiff for headphone cables though but I have a generous amount of mil-spec (made in 1957) silver wire courtesy of Kevin.

So it's basically what NXT were doing 10-15 years ago? Way to go ML for inventing something... Reminds me of their great advances such as Clearspar™ technology which are just transparent spacers inside the electrostatic element. Yay for transparent plastic...

Stax have never aimed for the euphonic mess which is the Orpheus setup but the 717 and 727 both employ circuit topologies aimed to make them sound a bit thicker while sacrificing as little resolution as is possible. With the 727 this is partially linked to higher distortion but some of it is just down to how the circuit is voiced. I'm not a fan of this any more than I'd cram an amp full of cheap polyester caps just to dull the sound. My way of thinking was sparked by the whole misplaced SS vs. tube debates out there and people not fully understanding any of it. Back in the day Stax were designing state of the art amps with the technology available at the time and that meant very low distortion amps but fitted with fully singled ended output stages AC coupled to the output. The rest of it is all DC coupled with current sources and a rather nice PSU so perhaps this would mean just the right amount of tradeoff... It certainly works for me but I have to find time to finish and test my version of this will all modern parts and report back. As a darker BHSE, I think part of the issue is adding some color to the amp, not having an "endless" current reserve available at a moments notice.

With Easter looming I seem to be making an endless stream of cakes. Here's one to make you all a bit hungrier... That's a chocolate and almond base with a chocolate, raspberry and cream mouse topped off with some 66% chocolate ganasch.

You need a CNC machine Victor...

Happy Birthday Doug.

The BHSE is pretty much neutral but the tubes will always have a bit of flavor to them. This is unavoidable as while they all adhere to the same general spec they are also all rather different. Think of it as a high voltage BJT, many of them fit the same points in some made up spec sheet but that doesn't make them all identical. The KGSSHV is also very neutral but the versions people see on the PCB's are a bit of a compromise to make the amps more user friendly (lower bias). That brings me to the general issue of neutrality in amps and that there is more than meets the eye. Now the normal classification would be an amp that has no character of its own and passes everything unhindered through it. I think this is unrealistic since all amps shape the sound in some way so a more realistic approach would be an amp that has some character but also has enough power to never restrict the transducer. Take the SPL amps for instance, pretty much neutral with a HD800 but try them with the LCD-2 and they don't sound too hot. Nothing wrong with the LCD-2 except it simply presents a load the amp doesn't like. I don't know if this makes any sense it's been a long day and the weekend will be worse...

With a DACT then that would be my first board of call for a fault. If that's not the case then just wire all the grounds to one point in the amp (I used one amp board ground connector for everything) and then it should work flawlessly. They are pretty tough so do a diode test and if they pass, try to power it on.

The KGSS is a lovely amp but 100% neutral it is not and neither is it the last word in driving the O2's. There is also the big issue of getting the correct fit for the 007 which takes some experimenting. It's a bit like HC, one simply does not pick up a SR-007 and starts to hear its full potential... A used LCD-2 is a very good deal and sounds just lovely. A bit larger than life at times and the top end is lacking quite a bit but I could live with them. What do I know though as I'm still using the stock Mogami cable...

Happy Birthday Buddy!! Tonight it's a toast and some Tubular Bells in your honor... Maybe some cake too...

Indeed, the difference is subtle and the HV clearly delivers on it's design goal, make an amp that can keep up with anything out there and yet only costs a fraction to build.

The large film caps and PSU caps certainly look identical but the smaller silver/gold etc. stuff is probably made for them by F&T. If you are going to use an OEM manufacturer then there are far worse choices than F&T though...

Yup. One could push the bias on the KGSSHV to ultra high levels and then they could be closer but the BHSE is a tough one to beat. It may not be cheap but given the build quality it is a bargain. One of the reasons why I keep mine is to have a benchmark which to aspire to when building my own amps...

The ones I use are rated at 60V but I think it's conservative to say the least.