i'm on a roll... the kgsshv

[MASantos]

They look legit, but the amp PCB is not set up for these; it is set up for the Linear Systems version in the TO-71 package, or pairs of 2SK170 singles.

http://www.linearsystems.com/datasheets/LSK389.pdf

Is there any way to bend the pins to fit the pcb? The 2sk170 with the little heatsinks could be much better matched tough with enough quantities and patience.

[spritzer]

You might be able to bend the 2SK pins to fit but the LSK389 is reasonably easy to find.

[MASantos]

I read 2SK389 on the BOM and have just wasted half an hour looking for it!

Any ideas or tips as where to find the other trannies?

Bdent doesn't have much, Counterpointe apparently doesn't ship to Europe...

[spritzer]

Mouser can order the output transistors for you but they won't sell the the 10m90 any longer outside the US. Dalbani might carry all of them (except the LSK389), I haven't checked but they are in the UK.

[Craig Sawyers]

I'm sure this has been discussed, but the trafo from SumR will have dual primaries for us 220v guys right?

The frequency is also a problem. In the US 60Hz but in Europe 50 Hz. The lower frequency needs a different transformer optimisation. The only way to ensure trouble-free operation at 50Hz is if the transformer is specified to be dual frequency. 60Hz transformers operated at 50Hz invariably hum because the core is driven higher up the induction curve of the core.

[Craig Sawyers]

Mouser can order the output transistors for you but they won't sell the the 10m90 any longer outside the US. Dalbani might carry all of them (except the LSK389), I haven't checked but they are in the UK.

Future Electronics have 60 in stock. No problems with where they are supplied to.

Craig

[livewire]

You might be able to bend the 2SK pins to fit but the LSK389 is reasonably easy to find.

Yes you can, I've done it. Very difficult to do, I dont recommend it.

(mouse-over or click pic to enlarge)

Get the LSK389 with a top hat heatsink. Much more purdy![ATTACH=CONFIG]4002[/ATTACH]

[livewire]

Are we still going ahead with the transformer group buy?

See post #337:

There will be no toroid group buy and any form of kits done by me aren't likely to happen.

[livewire]

I'll fix the led quantity thing much later today. There were 7 or 8 other errors i found and

fixed yesterday as i was ordering parts.

I've ordered all the parts i can from mouser, should be in by friday.

Will order the rest of the parts from digikey.

Those are the latest schematics, the only part that does not show up should be the 5 pf caps.

Something else i will fix later.

FWIW, There is also a pair of .47uf/50v caps on each amp board that are not shown on the BOM or the schematic.

Sorry if this may be construed as nit picking, the 2K pot silkscreened legend is missing on the amp boards.

[Lil' Knight]

FWIW, There is also a pair of .47uf/50v caps on each amp board that are not shown on the BOM or the schematic.

That's also what I saw.

In the PSU, this

2 C5,C10 .1uF

4 C17-C20 .1uF/1000v

should be 6 C5,C10,C17-C20 .1uf/1000v ,right?

[spritzer]

I think all SumR transformers can handle 50/60Hz as will most others. In a truly global market and step up/down transformers it is the only thing that makes sense.

Future Electronics have 60 in stock. No problems with where they are supplied to.

Craig

Future it is. Dalbani should have 1486's and most of the others.

[Craig Sawyers]

I think all SumR transformers can handle 50/60Hz as will most others. In a truly global market and step up/down transformers it is the only thing that makes sense.

That is not what I said - 60Hz transformers will always work with 50Hz.

The problem arises because the primary inductance is fixed, so the primary current has a 1/f dependence. If you are trying to design a transformer that effectively utilises the core at 60Hz, you push the core with 20% more flux when using it at 50Hz. So a 50Hz transformer needs either more primary turns (to keep the NI product the same) or 20% more core.

Which means that a 60Hz optimised transformer (doesn't matter whether EI or toroid) invariably hums when the primaries are connected for use on a 50Hz supply.

My supplier for the T2 transformers, Paul Houlden, can and will specifically redesign and optimise the toroid for 50Hz (if he knows the spec). He also uses oversize cores (within space constraints) to reduce mechanical noise to imperceptible levels.

[kevin gilmore]

FWIW, There is also a pair of .47uf/50v caps on each amp board that are not shown on the BOM or the schematic.

Sorry if this may be construed as nit picking, the 2K pot silkscreened legend is missing on the amp boards.

Just noticed the silkscreen legend is missing... Will fix that later today.

Will add the .47 caps to the bom later too.

Had to stop by the car dealer for a new battery yesterday. 4.5 years is way more than most people get.

And had the serpentine belts replaced because they were squeeking.

[spritzer]

Indeed, it is a matter of a larger core. The only transformers I've had a problem with here are the truly over sized Victoria Magnetics but they must have been something very wrong.

Had to stop by the car dealer for a new battery yesterday. 4.5 years is way more than most people get.

And had the serpentine belts replaced because they were squeeking.

That's not bad at all. Mine is starting to become weak after 5.5 years but only yesterday I had to jump start by dad's Range which is only 3 years old. The acid in the battery measures just fine though which is quite odd...

[kevin gilmore]

Trouble with corvettes is all the standby current used by the alarm and onstar, so batteries don't last as long as they should.

updated bom

http://gilmore.chem.northwestern.edu/kgsshv.xlsx

[livewire]

I just noticed that the amp board R8 and R9 are shown as 500 ohms on the BOM and the schematic.

The silkscreen on the amp pcb shows R8 and R9 as 600 ohms.

Which R value is correct?

[kevin gilmore]

500 ohms is the correct value. Actually either one works, 500 ohms puts a bit more current

into the 3rd stage.

[livewire]

Thank you sir.

And I thought that the Vette's battery's "early" demise was due to excessively cold winters.

[Lil' Knight]

I couldn't find a distributor for the LSK389. Any suggestion where to find them?

Just in case, could I just replace them with these? 4 X RARE MATCHED 2SK170 2SK170V FET - eBay (item 380269420276 end time Dec-14-10 04:58:05 PST)

How closely match for the 2SK170 should I look for?

[luvdunhill]

Trendsetter

How close? At least what the LSK389 specs as max diffference.

[justin]

Indeed, it is a matter of a larger core. The only transformers I've had a problem with here are the truly over sized Victoria Magnetics but they must have been something very wrong.

That's not bad at all. Mine is starting to become weak after 5.5 years but only yesterday I had to jump start by dad's Range which is only 3 years old. The acid in the battery measures just fine though which is quite odd...

i drove my first car for 8 years and never replaced the battery. no idea if the previous owner had ever replaced it. was 7 years old when i got it.

[ujamerstand]

I couldn't find a distributor for the LSK389. Any suggestion where to find them?

Just in case, could I just replace them with these? 4 X RARE MATCHED 2SK170 2SK170V FET - eBay (item 380269420276 end time Dec-14-10 04:58:05 PST)

How closely match for the 2SK170 should I look for?

I've got some. Want me to send you a pair?

[Lil' Knight]

I've got some. Want me to send you a pair?

Yes, please.

I must have missed it, but what is the peak-to-peak voltage of this amp? The original KGSS has 1200V p-p if I don't mistaken.

[kevin gilmore]

more than 1600V p-p probably closer to 1700V p-p

even more if you use the ixys parts for the current sources.

[ujamerstand]

Correct me if I'm wrong; since the input stage runs in current mode, jfet matching across the channel is not really necessary, is this correct?