spritzer

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.

Yup, they will fit. I use the Hirschmann clip on probes and they are excellent. They don't like 5A passing through them in an instant but that is to be expected...

Since you are dealing with 600V only mm from the ground plane it would be a good idea to make a small loop on the PSU side of the 5M resistor to make measuring easier. The PSU is regulated at +580V so it should just work.

I do have a new transformer box that needs to be tested so I'll probably report back soon. Now where did I put that T-amp... Let's just put it this way, I know the 009's traits well enough now to know what works for them and what doesn't. Super transparent amps are not an ideal match in my book. For your requirements I'd get a mint 007Mk1 and never look back. Perfect amount of top end and the reward every upgrade to the signal chain.

Yup, that would do it. We really should add a bias test point on one of these PSU's...

Well they are sitting next to the amp but I'm sure it will not be a match I'll like. They will be waiting for my SRA-10S mods (all new active parts).

...and reversed caps and some solder blobs.

Haven't touched the 009's yet.

From those specs the OTL version of the Electra is far better than the WES so I hope we'll see something crazy.

I figured it was time to say a few words about the KGSSHV since I've finally been able to live with a "fully built" unit for a while now. It's always hard to comment on that pile of parts over there... Now I'm a bit biased when it comes to the HV given my involvement in the project but I'm also very hard to please so it should balance out. I also constructed the HV to be as close to my KGSS as is possible and vital parts such as the volume control are the same. The goal with the HV design was to eliminate the slight bloom and the ever so slightly warm nature of the KGSS and I must say this was accomplished without going too far away from what made the KGSS great. The KGSS was always very revealing while being forgiving of less than stellar material and the HV is still like that but now even cleaner sounding when the going gets tough. Even with the 007Mk1 at silly levels it never runs out of steam. This was a particular concern of mine since the onboard heatsinks limit the standing current of the output stage but I'm glad it wasn't a problem. Anybody who thinks the LCD-2's are the bass kings really needs to hear the HV/007 setup. Even in sheer output the Stax wins... What has really stood out for me is the layering and detail retrieval of the HV. Feed it something good and it can dig out miniscule details and revealing slight mic differences. Not sure why this is the case compared to my old KGSS but this is BHSE territory. The extra power and extended frequency response seem to be doing wonders to open up the top end of the 007mk1. Color me very impressed. even if this can be a bit scary at times.

The KT120 is a promising tube and I'm glad Craig dropped the 300B. I'm building a SE amp with 300B's (or rather I have all the parts but no time) but to me it's just a curiosity. I know it will never work as well as a full push-pull circuit but at least it will never be as bad as the A-10... I don't think anybody who's seen inside the EC amps will ever contest the use of less than optimal parts. I'm all for cheap parts that perform well (as in not spending a fortune on Mundorf caps which are just rebadged F&T units for instance) but some of the parts are too cheap and do not hold up with use. Take the Lorlin/Alpha/"who else makes them this week" switches he uses and all the issues they have caused. There will be a full circuit analysis of the LL shortly after the first units ship but seeing how hard some people are pushing IXYS parts as some superior beings (which they aren't) I'm guessing mosfets for the output devices. A truly bad idea compared to excellent BJT's such as the 4686/4686A.

Ahh 6L6 makes a lot more sense. Don't know why he didn't just go with EL34's but then again Craig likes to be a bit different. I do have high hopes for the Electra since the WES is a dud and so is the LL (unless you happen to like a SRM-323 with mosfet output). I just hope Craig has given the assembly monkeys a good thrashing and spent a bit more money for more reliable parts. As for the SE electrostatic amps, you basically have all the issues of a SE amp plus have to deal with a transformer doing the phase splitting and probably some gain. As such it will never be a contender for a TOTL solution but should be fun none the less.

Single ended fed through a transformer is a novelty act, no more than that. Also, is he using 6SL7's as output tubes in the OTL version?

I'm looking at the schematic for the digital inputs but I don't think I understand half of it. Edit. I see Kevin got the service manual.

Long live simple fixes. If anybody wants the full service manual, drop me a line since I do have it.

So if you tap the board and it gets better? If so then the relays probably are acting up and I'd start by replacing them. Those Omron's look to be no longer made but I'm sure they have a pin compatible replacement.