Thanks Andrew, Bob.
I figured since the Zeners were there to limit the voltage to 40vdc, that a regulator would be better, and would be easy to insert. Alternative?
Boards are the 6 transistor version, and I wonder, how low can you go with VCC/VSS before you need to start changing component values? Is 52VDC useable for this circuit (what about 50vdc)?
My transformer is one of a pair, I planned to use one per PCB, if possible.
-Chas
I figured since the Zeners were there to limit the voltage to 40vdc, that a regulator would be better, and would be easy to insert. Alternative?
Boards are the 6 transistor version, and I wonder, how low can you go with VCC/VSS before you need to start changing component values? Is 52VDC useable for this circuit (what about 50vdc)?
My transformer is one of a pair, I planned to use one per PCB, if possible.
-Chas
The Zeners are not there to limit the voltage to 40Vdc.
Download Leach's papers on the Lo Tim and read what he says about the design in general, each stage in detail and includes a useful build guide.
Download Leach's papers on the Lo Tim and read what he says about the design in general, each stage in detail and includes a useful build guide.
Your transformers will give you 56V. That's a good operating point. When you understand how the VAS and output stages work you'll see why the VAS needs to operate in the vicinity of the output rails.
Front end regulation is an interesting exercise, but providing the required raw voltages can be a challenge with an uncertain benefit. Why not try your amps without regulation, but leave room for regulators and their PSU. You may well find that your Leach amps leave little to be desired.
Front end regulation is an interesting exercise, but providing the required raw voltages can be a challenge with an uncertain benefit. Why not try your amps without regulation, but leave room for regulators and their PSU. You may well find that your Leach amps leave little to be desired.
About some components..
Hello forum,
It been a very long time that i had bought the 10 version transistor - Leach Amplifier from Jens / Delta Audio (that time).
Now i try to get the components for the amplifier as on the pdf manual.
Since now i choose metal film Beayschlag Resistors (both for 0.6 and 1W) and Nichicon KZ & ES for the electrolytic capacitors.
Now i'm searching about the emmiter resistors 0R47/5W and i would like to ask if someone have any experience of Mills MRA-5 and Ohmite Audio Series ?
Any other suggestion for those resistors?
Thanks a lot!
Regards.
P.S. Because i was now following the subject for years, is there any change at the components list for the 10 transistor version ?
Hello forum,
It been a very long time that i had bought the 10 version transistor - Leach Amplifier from Jens / Delta Audio (that time).
Now i try to get the components for the amplifier as on the pdf manual.
Since now i choose metal film Beayschlag Resistors (both for 0.6 and 1W) and Nichicon KZ & ES for the electrolytic capacitors.
Now i'm searching about the emmiter resistors 0R47/5W and i would like to ask if someone have any experience of Mills MRA-5 and Ohmite Audio Series ?
Any other suggestion for those resistors?
Thanks a lot!
Regards.
P.S. Because i was now following the subject for years, is there any change at the components list for the 10 transistor version ?
Attachments
Mot on/off
I used the Mills resistors in my first set of Leach boards and was extremely pleased with them. I am not overly critical of components if they in some way work.
My set of Leach amps is better than any commercial offering I have ever owned. You will be extremely pleased with the outcome. Be very careful dialing in the the pots on each leg of each channel and the bass will just come alive.
I have several sets of these boards up and running and a pair of twelve output boards which have not made it yet.
Shop wisely for components and you can get some very good deals. I chose to use the Rifa film caps in my amp and like them very much. I could not fit the Dale resistors in the holes on the board and used whatever Mouser had in that range.
Build a very robust power supply and it will serve you for many many years.
Tad
I used the Mills resistors in my first set of Leach boards and was extremely pleased with them. I am not overly critical of components if they in some way work.
My set of Leach amps is better than any commercial offering I have ever owned. You will be extremely pleased with the outcome. Be very careful dialing in the the pots on each leg of each channel and the bass will just come alive.
I have several sets of these boards up and running and a pair of twelve output boards which have not made it yet.
Shop wisely for components and you can get some very good deals. I chose to use the Rifa film caps in my amp and like them very much. I could not fit the Dale resistors in the holes on the board and used whatever Mouser had in that range.
Build a very robust power supply and it will serve you for many many years.
Tad
I have two boards for sale. if you are interested, please contact me at ipolykov at pacbell.net.
Thanks,
Igor
Thanks,
Igor
I sold almost two hundred of these boards. Has anyone built one yet? Did they get the protection circuit figured out?
The ten transistor amps turned out flawlessly I cannot figure out why the twelve device amp did not respond as well. I have yet to get one up and running. Please let me know how any of yours turned out.
Tad
The ten transistor amps turned out flawlessly I cannot figure out why the twelve device amp did not respond as well. I have yet to get one up and running. Please let me know how any of yours turned out.
Tad
hey Tad,
after all the discussions about the merit of routing the feedback path to make it shorter......what was the issue about?
i am in the process of building still, very very slowly as i am deep into tubes right now...
Tony, you would need to discuss this with Jens and Andrew. I believe this discussion came about in the initial design of the 6 output boards. I became involved with this project as a means to acquire boards for my own builds.
I too have gotten into the tube amp area, though rather slowly, acquiring everything for a nice GU-50 amp. I have yet to get the pcb's layed out. The rest is pretty much done. I have hand wound the transformers and cut out most of the material for the chassis/case. Winding these transformers is a very tedious job. If you go to the christl ludwig site in Denmark or Germany you can see the base of my design. This guy is quite good. Just google 160 watt tube amp. Very nice. He has done all of his homework and much more.
Tad
I too have gotten into the tube amp area, though rather slowly, acquiring everything for a nice GU-50 amp. I have yet to get the pcb's layed out. The rest is pretty much done. I have hand wound the transformers and cut out most of the material for the chassis/case. Winding these transformers is a very tedious job. If you go to the christl ludwig site in Denmark or Germany you can see the base of my design. This guy is quite good. Just google 160 watt tube amp. Very nice. He has done all of his homework and much more.
Tad
Hey Tony, I remember back then you mentioned you did some work on the double barrel. Did you have any luck on that?
Hi Igor,
I got it, thanks a lot.
remarkable quality boards and professionally made.
BR,
Junie
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some guy in Manila was able to build 4 channels, unfortunately his hardrive crashed and lost all the files.....
