Well, as I mentioned earlier, the 1000 uF, as well as the 100 uF capacitors bypassing the VCC and VEE power rails should be rated for 100V.
The bulk PSU electrolytic capacitors would have more options available if they supported 5-pin snap-in terminals as well as the 2-pin versions that you already have. This is a simple modification to your layout. The bulk capacitors should be rated for at least 75V or 80V, and some of these are available only in 3-pin or 5-pin versions.
The bulk PSU electrolytic capacitors would have more options available if they supported 5-pin snap-in terminals as well as the 2-pin versions that you already have. This is a simple modification to your layout. The bulk capacitors should be rated for at least 75V or 80V, and some of these are available only in 3-pin or 5-pin versions.
James: you are welcome!
Patrick: in his original design Prof. Leach used MJ15003/MJ15004 output transistors and 4 discrete diodes to do the temperature control / biasing.
I have replaced these items by the NJL0 transistors, which contain integrated thermal diodes.
Best regards - Rudi
P.S.: There is only 1 pair of PCBs left that I can offer you.
Patrick: in his original design Prof. Leach used MJ15003/MJ15004 output transistors and 4 discrete diodes to do the temperature control / biasing.
I have replaced these items by the NJL0 transistors, which contain integrated thermal diodes.
Best regards - Rudi
P.S.: There is only 1 pair of PCBs left that I can offer you.
Jose: you are the last one to have my Prof. Leach AMP PCBs / this beautifully sounding amplifier.
I will keep you informed about the progress of ordering ...
Best regards - Rudi
I will keep you informed about the progress of ordering ...
Best regards - Rudi
The reason 4 discrete diodes were used is to have the option of having the NPN and PNP on separate heat sinks and still be able to sense them. Can’t do that with a single vbe multiplier. (If the one not being sensed runs hotter it could run away). DIY builders often do this to use what is available in the way of heat sinks. Thermaltraks are even better for this purpose. Professor Leach would have used them if they were available when this was designed.
Patrick, I have followed Prof. Leach' design very closely - except for the output.
Prof. Leach uses MJ15 - TO3 output transistors and 1N4007 diodes for thermal tracking whereas I am using NJL0 - TO264 transistors
with integrated thermal track diodes.
So: "my" Leach-amplifier will give you as well about 120W output, if connected to a 8 Ohm speaker, about 250W output, if connected to a 4 Ohm speaker, ...
Eric, I have roughly measured the MPSA transistors (see image 1 and image 2) to be sure that they are no fakes.
I have then distributed them to your letters.
You are advised to match (!) the transistors yourself. This is part of "Do-it-Yourself". Prof. Leach tells you in his amplifier-articles how to do the matching.
I will definitely match (!) the NJL0 output transistors for you.
I will keep you informed about the progress - Rudi
Prof. Leach uses MJ15 - TO3 output transistors and 1N4007 diodes for thermal tracking whereas I am using NJL0 - TO264 transistors
with integrated thermal track diodes.
So: "my" Leach-amplifier will give you as well about 120W output, if connected to a 8 Ohm speaker, about 250W output, if connected to a 4 Ohm speaker, ...
Eric, I have roughly measured the MPSA transistors (see image 1 and image 2) to be sure that they are no fakes.
I have then distributed them to your letters.
You are advised to match (!) the transistors yourself. This is part of "Do-it-Yourself". Prof. Leach tells you in his amplifier-articles how to do the matching.
I will definitely match (!) the NJL0 output transistors for you.
I will keep you informed about the progress - Rudi
Attachments
it seems MJ TO-3 is a bit more powerful (250W vs 180) ... so a 4 ohm load for plastic transistors will be "heavier". but in general it all depends on the transformer - with 800VA 2x42VAC (2x 59 DC) output at 8 ohms is stable 35V RMS ... so 153W .... before clipping. That's pretty high for home use.
Greg: I have fixed this "error" a couple of days ago.
But: thank you very much for following my Leach_AMP - thread.
Best regards - Rudi
But: thank you very much for following my Leach_AMP - thread.
Best regards - Rudi
I constructed this amp and replaced the zeners with a 40 volts shunt regulator. What an improvement in the low level sounds.
gajanan phadte
gajanan phadte
Gentlemen, while I am looking for a new amplifier to build (since my designated case does not fit with the LEACH), I have begun with a „general“ ADDON-PCB.
The ADDON-PCB can be used with your LEACH-Amp, your Nelson Pass, your, ...
The ADDON- PCB contains:
- Soft Power On
- Mains DC elimination
- Temperature sensor and display
- Selection of a 2-way input-source (f.e.: CDP, ADC, ...) and MUTE
- Attenuation of a motorized potentiometer (f.e. ALPS Velvet)
- Remote control of the fuctions mentioned above
The ADDON-PCB can be used with your LEACH, your Nelson Pass, your, ...
It contains a PIC 16F1827 8-bit µC to control all of the functions.
The attached image shows my assembled ADDON-PCB on top.
It shows a PCB (on the bottom) that contains a Tamura transformer (currently adjusted to 230 VAC/50Hz – can be easily changed to 110 VAC/60Hz),
a 6VDC PSU for the potentiometer's L293–motor-bridge and a 5VDC PSU for the logic components, relays, the processor, connectors, ...
It also shows a PICKIT3 (absolutely new, on the bottom right side) and cable to connect to a USB port of your PC, running the MPLAB software.
The reason why I am telling you:
I have a „rudimentary“ firmware-code, written in C, that does its job and has been approved in a former project of mine.
I have so far used a very old version of the HiTech – C – compiler and MPLAB IDE. I want to change to the MPLAB XC compiler and MPLAB X now.
If somebody of you is interested to do this together with me and has the time to program the firmware for the ADDON PCB together with me:
I will sell him the image2 – components for 25€ (Europe) resp. 30€ (worldwide).
Give me a PM if you are interested to gain some knowledge programming the ADDON - PCB.
I will give you my existing C-code, schematic of the ADDON, its layout, ...
Best regards - Rudi_Ratlos
The ADDON-PCB can be used with your LEACH-Amp, your Nelson Pass, your, ...
The ADDON- PCB contains:
- Soft Power On
- Mains DC elimination
- Temperature sensor and display
- Selection of a 2-way input-source (f.e.: CDP, ADC, ...) and MUTE
- Attenuation of a motorized potentiometer (f.e. ALPS Velvet)
- Remote control of the fuctions mentioned above
The ADDON-PCB can be used with your LEACH, your Nelson Pass, your, ...
It contains a PIC 16F1827 8-bit µC to control all of the functions.
The attached image shows my assembled ADDON-PCB on top.
It shows a PCB (on the bottom) that contains a Tamura transformer (currently adjusted to 230 VAC/50Hz – can be easily changed to 110 VAC/60Hz),
a 6VDC PSU for the potentiometer's L293–motor-bridge and a 5VDC PSU for the logic components, relays, the processor, connectors, ...
It also shows a PICKIT3 (absolutely new, on the bottom right side) and cable to connect to a USB port of your PC, running the MPLAB software.
The reason why I am telling you:
I have a „rudimentary“ firmware-code, written in C, that does its job and has been approved in a former project of mine.
I have so far used a very old version of the HiTech – C – compiler and MPLAB IDE. I want to change to the MPLAB XC compiler and MPLAB X now.
If somebody of you is interested to do this together with me and has the time to program the firmware for the ADDON PCB together with me:
I will sell him the image2 – components for 25€ (Europe) resp. 30€ (worldwide).
Give me a PM if you are interested to gain some knowledge programming the ADDON - PCB.
I will give you my existing C-code, schematic of the ADDON, its layout, ...
Best regards - Rudi_Ratlos
Attachments
Gentlemen, I intended to build the LEACH amplifier myself, because all of the feedbacks that I have read,
praised the Leach amplifier for his beautiful sound. But something has come up against this project.
So far I have collected:
1) a case
2) 8 capacitors Nichicon 10.000µF / 80V
3) 10 transistors, very (!) well matched NJL0281DG/NJL0302DG
4) small transistors: 12xMPSA06, 10xMPSA56, 4x2N3439, 4x2N5416
5) 2 PCBs
I would like and sell the whole bunch for 199€, delivery is within Europe.
If you are interested to have: give me a PM.
I will of course send you: the schematics, BoM, ...
Best regards - Rudi_Ratlos
praised the Leach amplifier for his beautiful sound. But something has come up against this project.
So far I have collected:
1) a case
2) 8 capacitors Nichicon 10.000µF / 80V
3) 10 transistors, very (!) well matched NJL0281DG/NJL0302DG
4) small transistors: 12xMPSA06, 10xMPSA56, 4x2N3439, 4x2N5416
5) 2 PCBs
I would like and sell the whole bunch for 199€, delivery is within Europe.
If you are interested to have: give me a PM.
I will of course send you: the schematics, BoM, ...
Best regards - Rudi_Ratlos
Attachments
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