i'm on a roll... the kgsshv

[morphsci]

"Her name was Magil and she called herself Lil, but everyone knew her as Nancy."

[HeadphoneAddict]

"Her name was Magil and she called herself Lil, but everyone knew her as Nancy."

Or, she is the Walrus.

[wink]

Rocky Racoon has a KGSSHV?

That's worse than Bob Dylan singing opera.

[cutestory]

Amy's her dominant personality's name, Evelyn's one of her secondary personality's names, silly. Amy doesn't know Evelyn's passwords, even, so of course wouldn't realized she called you before. It's like Jekyll and Hyde and shit, except it's Amy/Evelyn/Whateverthefuck.

Occam's razor, right?

[headinclouds]

Hello Guys, I’m a new member. I’ve been lurking for weeks. I was thinking of building a KGSS starting with the original article on Headwize. I read all the posts on the KGSS and the KGSSHV. I've found this thread particularly interesting, thanks to KG for his designs and all the contributors who've shared such useful info

Well it seems that I should use the circuit of the KGSSHV and by the time you’ve built it at a slightly lower voltage (say 350-400 rails) you have spent nearly the same amount of time, effort and money and it is still the same size so I figured I’d just make a KGSSHV anyway.

Any one second that?

But the main reason I am posting here is that I have been getting a few quotes for the mains transformer. An experienced maker of toroidals states;

“Due to the absence of an air-gap toroidal transformers are not suitable for circuits that introduce a DC current into any of the windings (e.g. half-wave rectifiers, voltage doubling circuits etc”)

I can see that builders have had success with generously rated toroids but does anyone know whether the voltage doubler circuit that produces the bias voltage at a very small current has any detrimental effect on a toroidal transformer?

[jwzhan]

Well it seems that I should use the circuit of the KGSSHV and by the time you’ve built it at a slightly lower voltage (say 350-400 rails) you have spent nearly the same amount of time, effort and money and it is still the same size so I figured I’d just make a KGSSHV anyway.

Any one second that?

I'm inclined to say not really. If you look at Justin's KGSS builds, you will see that the amp fits in a case slightly smaller than a 2U400 with plenty of room. For KGSSHV, the on-board heatsink version will barely fit in a 2U400 case, (Spritzer did it,) but things are way to close for my liking and I'd prefer it to be in a two case design. As for the off-board heatsink, you will need at least a 3U400 case. The cost of case+case work for both will be significantly higher than that of the the KGSS. Same goes for the effort and time. As for the building part, KGSSHV is a little bit more dangerous than KGSS, because some parts of the PSU run as high as 700VDC, but it shouldn't be more lethal than 400VDC... Overall, I'd say KGSS should be a easier and cheaper build. Why do you want to build KGSSHV instead of KGSS anyway? With lower voltage swing, KGSS has much more output current. According to Kevin, KGSS output current is 8.3mA while KGSSHV is 5.5mA. I'd be happy with either (but team over-kill won't be.)

I can see that builders have had success with generously rated toroids but does anyone know whether the voltage doubler circuit that produces the bias voltage at a very small current has any detrimental effect on a toroidal transformer?

I don't see how it can, since it's only tapping off the positive rail for a very minute amoung of current, but I can be wrong.

[spritzer]

The voltage doubler uses next to no current so it's a non-issue. If it did use any current then we'd quickly have to find new drivers for our phones. There is a reason why Stax uses 10nf caps in their multipliers which means they can't withstand any load.

As for the boxes, I like the challenge of building amps into boxes that are generally a size too small. Proper grounding and just wiring in general becomes very important but this stuff keeps me interested. You should see the new "super-symmetry state of the art amp" (Kevin's joke... ) I'm working on. Just about as small as I can build something fully balanced with a regulated PSU without building it in layers in a custom box.

[eggil]

I'm inclined to say not really. If you look at Justin's KGSS builds, you will see that the amp fits in a case slightly smaller than a 2U400 with plenty of room. For KGSSHV, the on-board heatsink version will barely fit in a 2U400 case, (Spritzer did it,) but things are way to close for my liking and I'd prefer it to be in a two case design. As for the off-board heatsink, you will need at least a 3U400 case. The cost of case+case work for both will be significantly higher than that of the the KGSS. Same goes for the effort and time. As for the building part, KGSSHV is a little bit more dangerous than KGSS, because some parts of the PSU run as high as 700VDC, but it shouldn't be more lethal than 400VDC... Overall, I'd say KGSS should be a easier and cheaper build. Why do you want to build KGSSHV instead of KGSS anyway? With lower voltage swing, KGSS has much more output current. According to Kevin, KGSS output current is 8.3mA while KGSSHV is 5.5mA. I'd be happy with either (but team over-kill won't be.)

I was surprised to see the output current numbers mentioned by Kevin at head-fi.

Besides being more fun to build , what advantage sound wise does the KGSSHV have over the KGSS?

(Johnwmcclean mentioned his amp sounded better when he increased the output)

[spritzer]

With the HV there was no other alternative but to decrease the current with the onboard sinks. The extra headroom, CCS, better devices and better PSU makes up for that. Now place the amp on some good sinks and yeah, it gets much better.

[headinclouds]

Thank you all for the preceeding comments - they are a great help. I will have to ponder as to which way I go forward. I have built some class A SS amps (only little 20W monoblocks and various headphone amps) and I agree the heatsinking is crucial. I am tempted by the off-board heatsink for that reason.

Are the KGSSHV gerbers for this version without errors - as I saw some mention of a little bug?

[spritzer]

Flipped feedback loop but it has been fixed now.

[headinclouds]

Excellent -thanks for that. So I have the choice of either configuration. Decisions, decisions.

[justin]

Mr. Supplier in Florida went from offering me 2SA1968 @ $10 each to offering me 5000pcs @ $0.90 each

so i requested a photo...and i actually got one!

yes please, sign me up! lol

[kevin gilmore]

yep, those are the identical date code (0e4) that were the

fakes that birgir and I shoved up dalbani's ass.

Darlington, and good for no more than 30 volts.

[justin]

funny because i'm told this stock is from the UK

[wink]

Probably doing the rounds until they all become fried silicon.

[kevin gilmore]

8g3 also fake date code.

There is one other fake date code that will take me a bit to find.

[jwzhan]

basically done... it makes sound... ESP950 has some serious channel imbalance issue (which I know but didn't bother to do anything about it because energizer has separate volume control for each channel.) The left driver is also making some background noise, but I can't really tell if it's from the amp or the driver... Also... both drivers are occasionally squealing. Grounding still needs to be done properly.

I'm going to get the ESP950 replaced and then worry about the rest...

Also, for some reason the amp is blowing through 2A fuses like they aren't there, even with a thermistor. The 2A fuse can only somewhat survive with two thermistors wired in series... Now, I'm using a 3.15A fuse with 2 thermistors.

Not such a sweet moment as I had hoped

[eggil]

How did you ground your xlr connectors? Hard to tell in the picture but the wires don't look right.

Welcome to the club! It took me some time to get it right too but now my KGSSHV gets nightly use.

The 2 amp fuse has blown a couple of times in my amp too. I now have a dedicated voltage regulator and that seems to help.

I never bothered using the thermistor.

[jwzhan]

How did you ground your xlr connectors? Hard to tell in the picture but the wires don't look right.

Welcome to the club! It took me some time to get it right too but now my KGSSHV gets nightly use.

The 2 amp fuse has blown a couple of times in my amp too. I now have a dedicated voltage regulator and that seems to help.

I never bothered using the thermistor.

Thank you.

Sorry about the sucky photo. I had to turn of the light to see the LEDs... then the shutter speed slows down and my hand shakes..

I'm not quite sure about how to ground the XLRs, so I wasn't planning to ground them at all today.

But the noise in the left channel made me suspect it was caused by no groudning, so I just chucked the white wire in the left XLR and ran it to the amp board's ground. It didn't resolve the issue though... The noise is there even without any input, so I flipped the left and right channel at the output. The noise stayed in the left driver, so it is most likely caused by the driver...

Also, there is some noise coming from the IEC module... it sounds like AC line noise... I'm not quite sure what's causing it; I didn't even know that IEC is capable of producing audible noise...

[Victor Chew]

Nice work.

Wiring has been discussed over hear quite a few times.

1. In anycase, ground the XLR to chasis. They should not be grounded together with the boards which should have a different ground point. I used different grounding points for left and right channel.

2. If I remember correctly, the boards can share a common ground as the iec. ie. Star ground

3. The volume point also ground to chasis. I also had different ground points for both the channels.

4. Twist the wire together to reduce radio frequency interferences.

I believe there is no absolute correct grounding. The above is what I used and the amp is dead silent.

The fact that it is blowing higher rated fuses means it is pulling more current. Are you using slow blow? I had the same problem as you and the slow blow solved the problem. However, I am not using slow blow as I found the normal 3A sound "better" to my ears.

As for the buzzing of your iec, check that its not coming from the sumR?

Edited November 16, 2012 by Victor Chew

[spritzer]

It is a filtered IEC so it can buzz but the transformer is a more likely cause.

Mine has been running on a 2AT fuse for close to a year now with zero issues. Nothing wrong with using the amp on a 3.15AT on 117VAC then.

[jwzhan]

It not really buzzing. It not continuous nor consistent at all. It sounds exactly like AC line noise (random crackling-like clicking noise) that usually can be heard with headphone system plugged into a noisy AC line, except it's IEC that's physically making the noise. I can't actually tell if it's from the IEC or the transformer because they are right on top of each other...

The reason I don't know how to ground them is that there are too many options! Yesterday was just a functionality test, so I didn't bother with it. I will try different methods. For now, I have the ground wired like this...

Amp→PSU→Star Ground (safety ground)..

Transformer shielding is also wired to Star Ground...

XLR ground will be wired directly onto one of the screws holding the jack in place..

Pot ground will be wired to one of the screws holding down the PSU board.

DC offset drifts quite a lot, from -40V at the very beginning to 0V at around 1 hour mark, shouldn't be a problem right?

[spritzer]

The large heatsinks are causing the amp to drift so much. If it drifts once it's up to temp then you have a problem.

I would not recommend trying to use the chassis for grounding or rather as a conductor. Much better to just star ground everything in the PSU with wires.

[johnwmclean]

jwzhan, congrats on getting your amp up and running.

I followed Birgirs advice for grounding and it works flawlessly.

If your using AMB’s E24’s it must be grounded, right next to the transformer and IEC it will pick up AC hum and noise.