Hello -
I live in Brisbane, Australia.
Whilst looking for information on the Leach Amplifier, and now also learning of Prof. Marshall Leach's recent passing in 2010 ( since he supplied the PCBs) -
I am now wondering if any one knows where I can buy predrilled fibreglass PCB's for the Leach Amp design - probably the version 4.5 that is shown on the Leach Amp Website ? A local supplier of these boards would be ideal.
Additional to this - the original 1976/77 Audio Magazine articles showed the board as having an earth ground plane on the component side - so I don't know if new boards come with this feature still ?
I'm also interested in the same Leach Amplifier design, but with a higher power output > say from 250-500 watts into 4 ohms ( since I will bridge 2 modules to get even more power @ 8 ohms)< if anyone knows of PCBs being available for this.
Any assistance is greatly appreciated.
I live in Brisbane, Australia.
Whilst looking for information on the Leach Amplifier, and now also learning of Prof. Marshall Leach's recent passing in 2010 ( since he supplied the PCBs) -
I am now wondering if any one knows where I can buy predrilled fibreglass PCB's for the Leach Amp design - probably the version 4.5 that is shown on the Leach Amp Website ? A local supplier of these boards would be ideal.
Additional to this - the original 1976/77 Audio Magazine articles showed the board as having an earth ground plane on the component side - so I don't know if new boards come with this feature still ?
I'm also interested in the same Leach Amplifier design, but with a higher power output > say from 250-500 watts into 4 ohms ( since I will bridge 2 modules to get even more power @ 8 ohms)< if anyone knows of PCBs being available for this.
Any assistance is greatly appreciated.
a 2pr output stage, the standard Lo Tim implementation will struggle, to do that reliably.
You will probably have to go to one of the clones to implement a 3pr to 5pr output stage.
2pair of MJ15003/4 or MJ21193/4 can do ~200W into 8r and possibly 250W into 4r, if kept cooler.
4pr of MJ21193/4 or MJ21195/6 can do ~400W into 8r0 and probably around 500W into 4r, again if kept cooler.
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About your Leach boards
Hi WT;
Thanks for the reply. Could you kindly send me a picture or two of your PCBs and advise if they have the ground plane on the component side.
From that I'm happy to make an offer.
My email is - kimbalsummers@hotmail.com
Regards -
Kimbal Summers ( Brisbane - Australia ).
Hi WT;
Thanks for the reply. Could you kindly send me a picture or two of your PCBs and advise if they have the ground plane on the component side.
From that I'm happy to make an offer.
My email is - kimbalsummers@hotmail.com
Regards -
Kimbal Summers ( Brisbane - Australia ).
Ground-Plane On Leach Amplifier PCB's
So clarifying your statement -
The ground plane made quite an improvement to the overall quality of the sound ?
The boards on offer to me, have no ground plane, though being sold to their former owner through Prof Leach.
Hence, I might add aluminium foil ( or better still, see if I can bond some copper sheet-shim with drilled out oversized holes ) to the top of the PCB.
Possibly a lot of extra work for maybe very little improvement !
What have others experienced regarding this ?
So clarifying your statement -
The ground plane made quite an improvement to the overall quality of the sound ?
The boards on offer to me, have no ground plane, though being sold to their former owner through Prof Leach.
Hence, I might add aluminium foil ( or better still, see if I can bond some copper sheet-shim with drilled out oversized holes ) to the top of the PCB.
Possibly a lot of extra work for maybe very little improvement !
What have others experienced regarding this ?
"The ground plane made quite an improvement to the overall quality of the sound ?"
No, the new boards without the ground plane sound better than the old one with the ground plane.
The 4.5 sounds better because it uses more local feedback on the diff inputs, cascodes the diff inputs, and takes another feedback loop from the driver stage.
No, the new boards without the ground plane sound better than the old one with the ground plane.
The 4.5 sounds better because it uses more local feedback on the diff inputs, cascodes the diff inputs, and takes another feedback loop from the driver stage.
I'll try contacting GT. I'm hoping to find a board(s) that support off-board output devices. I have a recently rebuilt but now defunct AR D100 I want to try to refresh. Great chassis, massive PS, but 35 yr old circuit that will cost more to repair than I am willing to risk.
If there is indeed interest in a GB for this board I'd be willing to participate- I may even be able to convince a former colleague to generate new artwork and G code in Eagle
J
If there is indeed interest in a GB for this board I'd be willing to participate- I may even be able to convince a former colleague to generate new artwork and G code in Eagle
J
As far as I can tell, Delta only provides CAD files or .pdf files of the art. They do not sell boards, and the boards they do have info on have plastic packaged output devices on the main board- not what I am looking for.
I am looking for the board that fed the output devices off board on a separate heatsink-
Thanks for your suggestion, however
J
I am looking for the board that fed the output devices off board on a separate heatsink-
Thanks for your suggestion, however
J
I didn't build it, but it's a Super Leach option...
Although it's a strange mounting.
Diy 280W super leach double barrel power amp. pcb set | eBay
Although it's a strange mounting.
Diy 280W super leach double barrel power amp. pcb set | eBay
Attachments
I just looked at Farjon's (thank you, by the way) fleabay link, and I must say it is tempting. The price is reasonable, and the board quality described seems very good. At this moment there was only one set left, but my guess is they will make more available.
They will knock off just about anything over there (Hong Kong)
HOWEVER- I can't be sure that the topology is the same as the original Leach board. There is a link to the schematic, but it requires a somewhat pricey subscription to view.
DJK very kindly provided a link to Leach's site which contains information on the original work, which I am more inclined to pursue.
Lastly, I am under specific mechanical restraints which require the output devices to be socket mounted on an exsisting heatsink. I think this configuration may appeal to more builders as it allows much more flexibility in chassis/heatsink layout, although it requires a little more wiring complexity.
So, the research will go on, probably on the original Leach "double barrel" design. I am very close to breaking down and doing an Eagle CAD work-up on the original board, in which case I will see about pricing for a group buy if there is enough interest.
This will take a while, as I have to generate all of the files in order to get a price quote. If I can find exsisting files that conform to Prof. Leach's original work, it will speed things up considerably.
J
J
They will knock off just about anything over there (Hong Kong)
HOWEVER- I can't be sure that the topology is the same as the original Leach board. There is a link to the schematic, but it requires a somewhat pricey subscription to view.
DJK very kindly provided a link to Leach's site which contains information on the original work, which I am more inclined to pursue.
Lastly, I am under specific mechanical restraints which require the output devices to be socket mounted on an exsisting heatsink. I think this configuration may appeal to more builders as it allows much more flexibility in chassis/heatsink layout, although it requires a little more wiring complexity.
So, the research will go on, probably on the original Leach "double barrel" design. I am very close to breaking down and doing an Eagle CAD work-up on the original board, in which case I will see about pricing for a group buy if there is enough interest.
This will take a while, as I have to generate all of the files in order to get a price quote. If I can find exsisting files that conform to Prof. Leach's original work, it will speed things up considerably.
J
J
Gerber files for the 4.5 board are here:
http://users.ece.gatech.edu/~mleach/lowtim/LowTIMGerber.zip
I'd considered making a batch of boards for resale, but harsh economic reality makes that impossible. For those who want the original board layout, a group buy shouldn't be too expensive.
http://users.ece.gatech.edu/~mleach/lowtim/LowTIMGerber.zip
I'd considered making a batch of boards for resale, but harsh economic reality makes that impossible. For those who want the original board layout, a group buy shouldn't be too expensive.
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