Jens Rasmussen Leach clone group buy

[jacco vermeulen]

Snob-Bob Fancypants can invest another 75 cents per board, for 250Vac higher voltage rating and 8 times lower DF.
Exactly fits the 6mmx13mm footprint on the board : Siemens/Epcos B32921

Personally, i just like 'm cause they're Blue and had enough of them for the two 10-er boards i got from Jens.

 

[tryonziess]

What is wrong Jacco? You do not like the nice white Rifa's that Jens used in his boards. I had to get mine from RS in England. With freight I think they cost about a buck fifty each. Will not do that again. Tad

 

[kpmadden]

Next, the fuse clips...

Hi all,

Can anyone recommend a source for the fuse clips used on the pcbs??

Thanks,
Keith

 

[BobEllis]

IIRC, http://www.mouser.com/Search/ProductDetail.aspx?qs=qOqV1E1P08Qnk025MRBEEA== should work - check the data sheets and measure the board - I think the lead spacing is ~22 mm which this one would fit. I used a different one from Digikey which doesn't seem to be availble anymore.

 

[Carl_Huff]

Jacco's recommendation for bypass caps is a better choice than what I have been using. I recommend going with the Digi-Key Part #495-2318-ND that he offered up.

 

[clm811]

pair of PCB's needed!

Hi.

Anyone here have an extra pair of these boards that I can buy, or trade for(I've got 4pcs of 7.5"x5.25"x1.25" heat sinks I would gladly trade)??

Please let me know via email.

Thanks and Merry Christmas to all!

-Chas

 

[TonyTecson]

Merry Christmass to all Leach amp afficionados!!!

and thanks to Bob Ellis, i got those parts i ordered.....😀

 

[BobEllis]

Geez, that took a long time Tony. I'm glad they finally made it.

 

[TonyTecson]

oh, i got it more than 2 months back, i only acknowledged it now, you know i have been away from home, am back in russia where the temperature is -24* in the morning, as i type this, its -12*C and it's 30 past 12 noon here.....😀

 

[kpmadden]

Happy Holidays to all!

Hi everyone,

I just wanted to send my holiday greetings to my friends in this group. Merry Christmas and a joyous New Year to all!

Best wishes,
Keith

P.S. Chas, I hope that your procedure went well for you! -K.

 

[rob3262]

Re: searching components for best quality/price rate

While I waited for the arrival of the pcbs, I am searching the components, so I have prepared a datasheet that could be useful to others.
Ciao, Giuseppe.

Giuseppe, your resistor values in the front end (R6 R7 R9 R10 etc) stray from Jens posted BOM, where you have specified 300R instead of 330R. Please explain this discrepancy.

As I'm ready to build up my first PCB, I need to know what effect (however marginal) this will have on function of the build.

Regards, Rob

 

[rob3262]

P.S. Merry Chrismas to Keith / et all

 

[AndrewT]

Re: Re: searching components for best quality/price rate

Giuseppe, your resistor values in the front end (R6 R7 R9 R10 etc) stray from Jens posted BOM, where you have specified 300R instead of 330R. Please explain this discrepancy.

300r is specified by Leach and discussed in detail in the section covering linearity of the input stage and how degeneration influences this.

 

[JensRasmussen]

Re: Re: Re: searching components for best quality/price rate

300r is specified by Leach and discussed in detail in the section covering linearity of the input stage and how degeneration influences this.

Merry X-mas....

I chose the 330 Ohm value as this is a standard E12 type.... 300 Ohm may not be as easy to get....

\\\Jens

 

[AndrewT]

Hi Jens, Rob & AudioG,
There's nothing wrong with adopting 330r for 300r in the input stage, It's only 10% after all.

Rob asked, why AG reverted to 300r and it appeared that Rob had not bothered to read up on the Leach. Prof Leach gave us all this good design info for free and yet some refuse to read it.

 

[clm811]

Merry Christmas!

Hi All!

Just wanted to say I'm now home recuperating and everything is fine(except I have to stay off my foot for a few weeks-darned crutches!).
Thanks for the kind wishes.

Also, I got another pair of PCB's(since I'd already started soldering components on mine, I didn't have an empty board to use for indexing the heat sinks!), and all the heat sinks in the current order are spoken for.

I wish all my friends* here a Merry Christmas/Hanukkah, etc, and a Happy New Year!!

-Chas

*special greetings and thanks to Jens, Tad, Ray, Carl, Fred and Bill

 

[rob3262]

Hi Jens, Rob & AudioG,
There's nothing wrong with adopting 330r for 300r in the input stage, It's only 10% after all.

Rob asked, why AG reverted to 300r and it appeared that Rob had not bothered to read up on the Leach. Prof Leach gave us all this good design info for free and yet some refuse to read it.

There's a lot of information to absorb on this project, and many sources for reference material. I will re-read Mr. Leach's documentation, thank you Andrew for pointing me back to this source.
With regards,

 

[rob3262]

thermal track pcb

I noticed that the Thermal tracking diode PCB's in this latest group buy are plated thru-hole to unmasked pads on the bottom side.

As seen in the PCB photo on Jens' Delta-Audio website, the pads should have been omitted. These bottom side pads can short out to the heatsink when mounted.

So, best way to remove the pad? Take Exacto knife and scrape 'em off, or hit it with a hot iron until the pads lift?

 

[fredlock]

rob3262,

Based on post 662 and 666, Tad and Bob mentioned that as long as the diode lead doesn't protrude, it should be fine. They didn't mention about the pads. See picture attached from Delta-Audio website. I hope that helps.

 

[BobEllis]

The first batch of boards did not have pads on the bottom of the diode boards. It sounds like a manufacturing error since Tad just reordered - the first I've heard of from Advanced. Maybe they'll give us a break on the next buy.

I'll grind the pads off with a Dremel. If you have a sheet of mica or some Kapton tape, you can just insulate them.