i'm on a roll... the kgsshv

[demented badger]

I hooked my completed kgsshv onboard final version power supply to its SumR transformer this evening and fired it up one circuit at a time. Everything looks good. + / - 453 VDC on the high voltage outputs and + / - 15.0 VDC on the low voltage. I could not measure the bias as my meter only goes to 500VDC. No sparks or smoke though.

[kh90123]

Instead of using 2A fuse, can I use a circuit breaker that can also function as a switch, like this:

http://www.mouser.com/ProductDetail/Schurter/CFTWF030C0/?qs=sGAEpiMZZMvNllHT6Fj2fpKRYrYTMEunwydsqwE%2fDFo%3d

 

Is 3A good? Or should I use 3.5A or 4A for 240V?

[astrostar59]

I hooked my completed kgsshv onboard final version power supply to its SumR transformer this evening and fired it up one circuit at a time. Everything looks good. + / - 453 VDC on the high voltage outputs and + / - 15.0 VDC on the low voltage. I could not measure the bias as my meter only goes to 500VDC. No sparks or smoke though.

Are SumR ok transformers. I read some posts with failures? I am not speaking from my own experience, only posts I have read from other KGSShv users.

[johnwmclean]

Wimpy 100mA HV windings on the earlier models?

[demented badger]

My SumR transformer seems OK. I have not run it under load yet. They seem well built and delivery was under 2 weeks at least to the US.

[luvdunhill]

So it seems okay, as long as you don't draw current from it?

[astrostar59]

Anyone tried these:

http://www.acoustic-dimension.com/attenuators/attenuators-main.htm

[kevin gilmore]

final production stax male jacks

http://gilmore.chem.northwestern.edu/staxmale5.jpg

 

in case someone wants to have the Chinese make up a batch cheaper than I can

http://gilmore.chem.northwestern.edu/staxplug.pdf

[Kerry]

Looks great.

what material did you end up with?

[kevin gilmore]

white delrin.

 

turns out there is a .002 taper in the insides of the neutrik jack.

 

will make a couple out of Teflon anyway

[astrostar59]

ON-BOARD or OFF-BOARD?

He guys. I am not a tech, so bear with me. Is the design philosophy of the

on-board and off-board the same? I am thinking (in physical terms) the off-board

design should be able to shift more heat, which may allow more amps on the grid?

 

If this is true, does this in turn mean an off-board could sound better as it 'can/could' have more

dynamics, more effective head room.

 

My other theory, was, can one KGSShv sound better than another depending on parts

qualities? I have some 300B monoblocks, and they are at level 3, the level 5 versions

have better transformers, and do sound nicer, sweater.

 

If all this is true or possible, it would be really interesting to build an ultimate KGSShv with no

holes barred parts, where the design can be taken to the max. Has such an amp ever been built?

 

Fascinating subject. To my tiny exposure to the KGSShv it has really impressed me as being a classic

amp design that will around for years to come. it is also fantastic that it is available to the DIY community,

as some like to build for themselves, but it also allows those on a tight budget (me) to get a taste of the high end.

[Sherwood]

EDIT: KG gave a better answer than my uninformed answer.

Edited July 18, 2014 by Sherwood

[kevin gilmore]

The on board version can only handle so much power because of the heatsink size.

The default is 5ma, which at 450V is 9 watts total for the output stage which is

2.25 watts per output device.

 

The off board version is limited by only 2 things, the size of the heatsink and the

maximum amount of power the output devices can handle. So yours is 14ma

which is 25 watts per channel.

 

The effect of the higher current is to extend the high frequency response well

past 50khz. So the amp will definitely sound different.

 

The choice of resistors will likely not make a change that you can ever hear.

Except that a few of the trendy and expensive resistors cannot handle the voltage

and cause all sorts of trouble.

 

An lsk389 is going to be better than 2 x 2sk170 from an electrical drift standpoint.

Not going to make any difference in the sound.

 

Now the pot makes a big difference. RK50 and P&G are definitely the best of the

bunch, rk27 and tkd less so. Mainly in channel to channel matching.

dact will do better on matching. digital attenuators are even better.

Edited July 18, 2014 by kevin gilmore

[guzziguy]

The effect of the higher current is to extend the high frequency response well

past 50khz. So the amp will definitely sound different.

 

So bats are only interested in the off board version?

[spritzer]

I only sell them to bats.... it's a niche market

Edited July 18, 2014 by spritzer

[astrostar59]

The on board version can only handle so much power because of the heatsink size.

The default is 5ma, which at 450V is 9 watts total for the output stage which is

2.25 watts per output device.

 

The off board version is limited by only 2 things, the size of the heatsink and the

maximum amount of power the output devices can handle. So yours is 14ma

which is 25 watts per channel.

 

The effect of the higher current is to extend the high frequency response well

past 50khz. So the amp will definitely sound different.

 

The choice of resistors will likely not make a change that you can ever hear.

Except that a few of the trendy and expensive resistors cannot handle the voltage

and cause all sorts of trouble.

 

An lsk389 is going to be better than 2 x 2sk170 from an electrical drift standpoint.

Not going to make any difference in the sound.

 

Now the pot makes a big difference. RK50 and P&G are definitely the best of the

bunch, rk27 and tkd less so. Mainly in channel to channel matching.

dact will do better on matching. digital attenuators are even better.

Thanks Kevin, that is great to know.

[kh90123]

The on board version can only handle so much power because of the heatsink size.

The default is 5ma, which at 450V is 9 watts total for the output stage which is

2.25 watts per output device.

 

The off board version is limited by only 2 things, the size of the heatsink and the

maximum amount of power the output devices can handle. So yours is 14ma

which is 25 watts per channel.

 

The effect of the higher current is to extend the high frequency response well

past 50khz. So the amp will definitely sound different.

 

The choice of resistors will likely not make a change that you can ever hear.

Except that a few of the trendy and expensive resistors cannot handle the voltage

and cause all sorts of trouble.

 

An lsk389 is going to be better than 2 x 2sk170 from an electrical drift standpoint.

Not going to make any difference in the sound.

 

Now the pot makes a big difference. RK50 and P&G are definitely the best of the

bunch, rk27 and tkd less so. Mainly in channel to channel matching.

dact will do better on matching. digital attenuators are even better.

 

Default for onboard 450V version is 5mA, then what about the default for the 500V version?

 

Which resistors I need to change to increase the output current?

 

Also, where can I find LSK389/LSK170? Any alternative that's available at Mouser?

[eggil]

http://www.trendsetter.com/product-p/lsk389c%20to-71%206l.htm

[kevin gilmore]

default for 500v is the same 5ma. you change the emitter resistors at the bottom of the output stage.

and you want a lsk389B.

 

the lsk170B is available from diyaudio.com

[kh90123]

default for 500v is the same 5ma. you change the emitter resistors at the bottom of the output stage.

and you want a lsk389B.

 

the lsk170B is available from diyaudio.com

 

Thanks for the reply.

 

By the emitter resistors at the bottom of output stage, do you mean lowering R5 and R6 in this schematic: http://gilmore.chem.northwestern.edu/kgsshvproductiondual.pdf, which are both 180 ohm?

[kevin gilmore]

yep

120 ohms or even lower

Edited July 19, 2014 by kevin gilmore

[s_r]

Would LSK389A's work as well?

[kevin gilmore]

probably any of the lsk389 would work, but never tried it.

[s_r]

Well my huge hv uses the LSK389A's (the A is on ujamerstand's BOM too). Seems the only difference between the flavors is the Idss range.

 

Edit: Realized I answered my own question.

Edited July 20, 2014 by s_r

[astrostar59]

 

It's quite cramped, that's how.    Here is the latest version:

 

 

 

Only major change is the voltage selector PCB which makes the AC wiring all neat and tidy.  Nearly every centimeter is used now and I'm up to 9 pcb's per amp. 

 

The bigger changes are outside as I changed the layout a bit from the one above:

 

 

 

It's very hard to photograph the chassis as it's so reflective... 

 

Thanks for the offer but I do have a Wordpress site up and running but it appears to be down now.  My friend hosts it and he's been having some issues due to some of the other stuff being hosted there.  It's mjolnir-audio.com and .net when ever it is up again.  Haven't done a whole lot with it yet but I need to add all the DIY stuff and what stuff I have in stock. 

Let me know if I can help Birgir. I hosts quite a few WordPress sites. Call it FOC if you need help. I think it is good to help in the cause if I can.