Leach Super Amp Pcb Re-Design (LSAPRD)

[JensRasmussen]

Hello all.

There has been a lot of talk about redesigning both the Leach amp and Leach super amp to fit flat pack transistors in the output section of the amp. I have started this thread to find out if there is enough interest in the DIY community to make this a project.

I feel the need emphasize that this will be a NON PROFIT project (As most other projects here at diyaudio.com) I have had some experiences earlier where I was accused of profiteering from a project I got involved with here. I’m sure the outcome of the project has proven that delta-audio is for our (Jan and I) personal fun of DIY and nothing else. Jan Dupont and I share an interest for making small projects in our spare time, and I humbly offer to make the PCB layout for this project, should there be enough interested.

Now let’s get this project going. Please give your input to the following:

1)Overall component choice (I prefer standard non exotic parts)
2)Layout of the PCB
3)What should be included on the PCB other than the amp components
4)Technology (Double sided, single sided, Surface mount devises etc.)
5)Target price for the boards (to find out how many we need to order)

Keep the ideas coming

\Jens

[tiroth]

In case anyone has somehow missed this fact, Jens is a very skilled designer and an eminently honest individual. And since he already has experience in designing Leach amp boards, I am sure that this project will be very successful.

[tool49]

Hi Jens,

I have participated in the Mox Group buy and was very satisfied with your layout.

I support the idea of using non exotic part because I can hardly justify the cost increase over the regular parts. When my ears and my wallet get into a fight, my wallet or wife almost always win...

I have a terrible problem soldering surface mount components so through hole would be best for me.

As for the technology, I'd suggest that the simpler the board, the lower the cost and the lower the cost, the most chances it'll get attention. So single or double sided being often very close in price, I would suggest double sided if the layout can be made smaller this way.

In terms of design I don't really know the Leach Amp or the Leach Super Amp, but by the names, I'd say I'm more likely to be interested by the Super Amp

As for the flat pack transistors, would the MJL4281A (NPN) and MJL4302A (PNP) be useable? (I have a bunch of those left over).

If so, I'd be in for 2 or 5 boards depending on the price. Speaking of which, I think a price between $15US and $30US would be acceptable.

Hope this helps!
Sébastien

EDIT: I second tiroth on that!

[still4given]

1)Overall component choice (I prefer standard non exotic parts)

Non exotic sounds good to me.

2)Layout of the PCB

I would prefer if the PCB' didn't get too much larger than the originals. I know they have to become larger to accommodate the flatpacks but I would prefer if they didn't need huge heatsinks to accommodate them.

3)What should be included on the PCB other than the amp components.

I would like to see the flatpacks included but I rather have the PSU separate to keep the size down.

4)Technology (Double sided, single sided, Surface mount devises etc.)

For me, single sided with no surface mounts. Those little suckers are tough to solder. with single sided, it would be easier for someone to make their own boards if they choose.

5)Target price for the boards (to find out how many we need to order)

I have no idea on this. I am interested in buying some though.

I want to thanks you Jens for taking this on. I will be keeping a close eye on this thread.

Blessings, Terry

[jacco vermeulen]

Considering how much time and effort Jan and you are investing in a pcb design i'd think you'd have a poor return even if the design was made on a profit basis, Jens.

I'd say any profit interested pcb company is more than welcome to offer high quality PCB's for building Krell's , Leach amplifiers, and the like.

1 Standard, please
2 single channel pcb, with a flexible layout that allows varying
parts size.
3 besides front end and power stage enough space for small PS
caps(electrolytics and several foil types)
I am hoping for enough space to mount wide flatpacks(mt200)
with an option for type of high power source and emitter R's.
4 Double-sided, and regular parts( smd is no diy fun), but i go
with the crowd
i desire 2 at the rate for the number you have made.

Thanks for offering your time, Jens
I loved the pcb work on Delta-Audio

[BrianDonegan]

1) Standard
2) I tihk seperate driver/power boards would be nice to allow more flexible mounting options. The flatpaks can take up a lot of room. If seperate, a standard connector scheme would be good, like .1" spaced pins, so a variety of connectors could be used.
3) As little as possible. I am all for a seperate power board.
4) I agree with still4given on single to make it easier to self-make the boards, but 2-sided would likely make them much smaller. Torn on this.
5) Free (ha ha). I guess up to $30USD (?).

Again, Jens is great. He puts a lot of time, effort, and expertise into his work, and expects nothing in return (other than fun, I suppose).

[acenovelty]

Here is the published board from Prof. Leach.
Measures approx. 6"x4". All components fit easily on one side and none of them is difficult to find.

Prosit

[acenovelty]

Flat pack/plastic transistors are no problem.
This by member maxhawk published elsewhere on the forum.

[acenovelty]

And parts placement layout on the board. The Super Amp takes 8 transistors per side.

[acenovelty]

Driver transistors on the heatsinks wired with computer power connectors.