[Tuomaster]

Hi,

I'm a long time reader and a first time writer ;DDD


OK, let's get to the point. I'm planning to build Kevin Gilmore's Solid State amp. Money is a problem so I'm not going to make KG's PSU for it. Every part costs about twice as much here in Finland than it costs in the US.

I like Welborne Labs' PS1-design BUT my budget is so tight that I'm planning to make some changes.
PS1 Homepage

1) Hexfreds -> Regular rectifiers (1N4007 for example)
2) LT1085/1033 -> LM337/317
3) Just one 3300uF electrolytic between rectifiers and regulators instead of two 2200uF in Welbornes design
4) Trimpot instead of fixed resistors

Is this "el cheapo PS1" still OK?

 

[kevin gilmore]

Yes the "el cheapo" power supply will definitely work.

 

[Tuomaster]

I just made a layout of of the PSU: Layout alpha 1.0

And here's the original: PS1 layout

Just wondering why the original layout looks so complicated. All grounds are drawed separatedly. Is there some reason for that? I think that they are just trying to sell those PCBs for people who think that it's more difficult to DIY than it really is ;D

Any comments?

 

[jamont]

I don't think you would hear any audible difference between your "el cheapo" PS1 and the Welborne version. Go for it!

 

[eric343]

It's called star grounding. There's a reason for it; use it for maximum performance... depending on the p/s design it might be necessary.

Incidentally, 'KGSS' generally refers to Kevin's electrostatic amplifier; the dynamic amp (which I'm assuming you're talking about, since the electrostatic runs off +/-350V) is more generally referred to as the KGCA, class A, or dynamic amp.

 

[Tuomaster]

It's 8:46 am and I am still selecting parts for the amp and psu

Have to make a proper layout for the psu after I get some sleep. I made that alpha 1.0-layout with paint shop pro.. Took about 2 hours and it looks like crap, I know

Sorry about that "KGSS" mixup..

 

[Tuomaster]

Jeah, I spent some time with the layout and I expect that RC1 is out soon

Layout beta 3.0

It's almost identical with the WL's design. I just concentrated on details. I prolly have to add more space for the cooling; LM3x7 will get hotter than LT1xxx.

 

[Jupiter]

Tuomaster,

Welborne has some PS1 PCBs (old version) for $5: http://www.welbornelabs.com/stuff.htm

 

[Tuomaster]

Jupiter:
I knew about that sale but it would be like $50 when I order it to Europe

My layout almost ready.. I made some more space for the trimpot and rounded the corners. PSP is way better than Eagle ;D
Layout RC1

Board's size is about 5.5" x 3" (that gif is only 1/3 of the real image so it looks bad because of the pixel resizing)

 

[Tuomaster]

PS1 Value Edition has been ready for ages and it works fine.

Today I made one channel for the amp and it doesn't work at all. Dunno where the problem is. I used Kevin Gilmore's own layout for the pcb. When I hook it up, leds turn on but I get no sound. Well, lots of debugging to do =)

 

[eric343]

You put the transistors in right way round, right? The datasheets often show them from the *bottom*...

 

[Tuomaster]

I've checked them too many times and they should be right way round.

I built this amp just for testing so I can avoid stupid problems with the 2ch version. Glad I did

 

[Tuomaster]

I measured the voltage between legs of a led and result was 1.85V. I don't know if this is ok. What happens if the DC-servo doesn't work; will the amp be dead silent?


BTW. If some moderator happens to read this post, would you change the topic to KGCA Amp and Welborne Labs' PS1