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Geoff Moss's JLH-2005 design files
Geoff Moss's JLH-2005 design files
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Old 13th March 2021, 06:46 PM   #1
paulb is offline paulb  Canada
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Join Date: Jun 2001
Location: Calgary
Default Geoff Moss's JLH-2005 design files

Many of you are familiar with The Class-A Amplifier Site (TCAAS), now hosted as part of Rod Elliott's ESP website (Elliott Sound Products - The Audio Pages (Main Index)). Geoff Moss is the creator of the TCAAS and was of great help to me when I built my version of the JLH. I built the amp in 2005 and it has been my main amplifier ever since, driving the midrange/tweeter in a biamped system.
I have not communicated with Geoff for several years now, and he has not been active on diyaudio for about the same period (his health was deteriorating at the time). With the continued interest in the JLH, I thought it would be good to post the PCB design files that Geoff gave me. I have had several enquiries over the years and at least one forum member (Mamak) has built a version.
The design is based on the schematic "Fig 3 The Higher Power Circuit" on the "JLH Class-A Update" page at
The Class-A Amplifier Site - JLH Class-A Update
(with the addition of a "Zobel network" on the output).

Rod has placed Geoff's design files including schematics and PCB fabrication files on the main TCAAS page:
The Class-A Amplifier Site
with a link having the heading
Geoff Moss Construction Information

This provides a zip file with the various required files and more background information from both Geoff and myself.

I highly recommend that any who are interested read the entire article "JLH Class-A Update" that explains the modifications to the original JLH design.

Schematic and picture of my completed PCB are attached.

By the way, if you have not already done so, I recommend checking out the rest of Rod's ESP website. There is an incredible amount of design information at this site, for all levels of audience. Thanks Rod!
Attached Images
File Type: jpg PCB JLH 2006 jan29.jpg (74.3 KB, 803 views)
File Type: gif JLH-2005-AMP-schematic-v1.gif (13.5 KB, 795 views)
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Old 13th March 2021, 06:59 PM   #2
EUVL is offline EUVL  Europe
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That is very kind of you.

But PCB shops these days charge essentially the same for 1 or 2 layer 35Ám copper.
They charge a lot more for 70Ám, even single layer.
Would it not be an idea to duplicate the power tracks on the top layer for better conductivity ?


Cheers,
Patrick
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Old 13th March 2021, 07:05 PM   #3
paulb is offline paulb  Canada
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Location: Calgary
As I noted, Geoff Moss did this layout. I have no way to modify it. I just posted the Gerbers so others could have it built.
Yes, somebody could certainly create a top layer to add parallel tracks by editing the bottom layer. One of the free Gerber tools would probably work for this.
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Old 13th March 2021, 07:09 PM   #4
EUVL is offline EUVL  Europe
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Also the PSU PCB Gerber files seem to be missing ?


Patrick
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Old 13th March 2021, 08:01 PM   #5
paulb is offline paulb  Canada
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Yes, I did not build the Power supply PCB so Geoff did not generate Gerbers for me. My power supply has huge capacitors and Geoff thought I did not need a capacitance multiplier. I made one for another project and just handwired it.
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Old 14th March 2021, 08:49 PM   #6
EUVL is offline EUVL  Europe
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I tried to import the Gerber files and the drill later in the given link above.
But I had no success with multiple software for Gerber viewing.
I did manage to load the Gerber files into a CAD software.
As a tribute to Geoff Moss, I decided to refresh those Gerber files and the drill files.
Hopefully they could be more compatible to today’s PCB shop settings.

I tried my best not to change anything, including layout, component placement, etc.
But there are a couple of changes which I consider beneficial.

1) The high current tracks are repeated on both top and bottom layer.
This not only double the copper cross-section, but also the surface area.

2) The pins of all TO92 devices are placed on a triangle and marked with E,B,C,
so that devices with different pin assignments can still be used (e.g. BD560, KSA992, 2SA970BL, ….., etc.)

3) Some signal tracks running parallel to neighbouring ones are moved to the top layer to reduce cross coupling.

4) The power devices in the original layout are TO3 metal case, remotely connected to the PCB by flying leads.
The revised PCB has a minor revision to allow the direct soldering of TO247 or TO3P devices onto the PCB.
TO3 metal case can still be wired with flying leads without problems.


To complete refreshing Geoff’s work, I also made a set of Gerber files for his power supply PCB.
Unfortunately, no Gerber files are available.
So I had to import the graphics image of the PCB and trace that with a CAD software.
The position of components might not be accurate to the last 0.1mm.
But I hope I have been able to retain the original overall layout.
The enhancement changes mentioned above have also been implemented on the PSU PCB.

Hopefully someone skilled in PCB layout can double checked my revision before realising them in hardware.
I find it very difficult to find my own mistakes, but it is quite likely that there might be some.

My highest respect to Geoff for his exceptional work which makes thing easy for all of us.



Patrick

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Attached Images
File Type: png GMJLH2005.png (108.8 KB, 732 views)
File Type: png GMJLH05PS.png (104.0 KB, 699 views)
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Old 14th March 2021, 08:50 PM   #7
EUVL is offline EUVL  Europe
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Here the original files from Geoff in graphic format.


Patrick

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Attached Images
File Type: jpg JLH-2005-AMP-PCB.jpg (65.9 KB, 687 views)
File Type: jpg JLH-2005-PSU-PCB.jpg (61.0 KB, 189 views)
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Old 14th March 2021, 08:53 PM   #8
EUVL is offline EUVL  Europe
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And finally the Gerbers in zip files.
As stated above I have double checked but cannot guarantee 100% free of error.


Patrick

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Attached Files
File Type: zip GMJLH2005.zip (216.2 KB, 79 views)
File Type: zip GMJLH05PS.zip (150.7 KB, 70 views)
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Old 14th March 2021, 10:45 PM   #9
paulb is offline paulb  Canada
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That's pretty awesome, Patrick. I will load a Gerber viewer and have a look at your files.
I'd consider asking Rod to replace the old with your new files (or maybe include both), but it would be nice to know first that somebody has used the files successfully.
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Old 14th March 2021, 10:50 PM   #10
EUVL is offline EUVL  Europe
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Just wish to pay respect to Joh Linsley Hood and Goeff Moss for their contribution to DIY.


Patrick
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