Hello
I'm interested on these amplifier , any idea about the two diode I marked with 2 arrow.
There is no value there , probably not sender diode because I see for Sender they use different symbol .
If you have any idea please let me know !
Thanks
Kaneta method's all FET power amplifier
"I recommend this amplifier as a best choice, considering quality,accessibility and stability.
This one is a masterpiece of Kaneda method's amplifiers."
I'm interested on these amplifier , any idea about the two diode I marked with 2 arrow.
There is no value there , probably not sender diode because I see for Sender they use different symbol .
If you have any idea please let me know !
Thanks
Kaneta method's all FET power amplifier
"I recommend this amplifier as a best choice, considering quality,accessibility and stability.
This one is a masterpiece of Kaneda method's amplifiers."
Attachments
Hello
I see the image not so cear I tought better to post the website .
http://www.geocities.jp/mutsu562000/root/amps1/htm/e/hp004e.htm
Thanks
Regards
I see the image not so cear I tought better to post the website .
http://www.geocities.jp/mutsu562000/root/amps1/htm/e/hp004e.htm
Thanks
Regards
Hi,
There are a couple of reasons Kaneta didn't use resistors there. The first reason is rather a historical one. He used to use pile of D battery cells as power source for a while (before he switched to R core transformer based power supply circuit). He was in need of reducing the idling current for the output pair, thus the output pair idle current was set in the region where it has positive temperature coefficient. He used diodes to set the idle current and glued the diode to output FET for stabilization of the idle current. He didn't care much about the variation of the idle current itself.
The second reason is related to the 5.6Kohm resistor to the ground. If you use a variable resistor in the place of diodes, I'm not sure from where you may want to connect that 5.6Kohm to ground... The discussion whether you want that 5.6Kohm resistor there or not is a separate issue. So, if I'd want to replace diodes with variable resistor, I'd remove the 5.6 Kohm and give the output pair large enough idle current (with large enough heat sink, of course!).
Good luck and enjoy!
Satoru
There are a couple of reasons Kaneta didn't use resistors there. The first reason is rather a historical one. He used to use pile of D battery cells as power source for a while (before he switched to R core transformer based power supply circuit). He was in need of reducing the idling current for the output pair, thus the output pair idle current was set in the region where it has positive temperature coefficient. He used diodes to set the idle current and glued the diode to output FET for stabilization of the idle current. He didn't care much about the variation of the idle current itself.
The second reason is related to the 5.6Kohm resistor to the ground. If you use a variable resistor in the place of diodes, I'm not sure from where you may want to connect that 5.6Kohm to ground... The discussion whether you want that 5.6Kohm resistor there or not is a separate issue. So, if I'd want to replace diodes with variable resistor, I'd remove the 5.6 Kohm and give the output pair large enough idle current (with large enough heat sink, of course!).
Good luck and enjoy!
Satoru
Hi,
The release of this amplifier circuit overlaps with a period I tracked most of Kaneta's articles. Kaneta does weird stuff on a belief that "it sounds better". I'm not defending his designs at all. I agree that a simple resistor would be a better solution (granted that you remove the 5.6Kohm resistor, which doesn't make much sense to be there either). I'm just describing what I think the reason behind of the two diodes sitting there.
The owner of a small parts shop in Kyoto told me once: "Kaneta's amplifiers sounds very good. But I don't like him since he says so nasty things about amplifiers designed by others". He was a very nice old men who listened patiently to many questions from a beginner (me
).
Oh, the current going through the diodes depends on the Idss of two 2SJ72 which is rather difficult to know before hand. Of course, you can measure it and calculate the value of the bias resistor. But it won't be too good for a design to be published in a DIY journal where you cannot assume much about the skill level of the readers... Yes, I agree with you that a fixed resistor would be the best!! Actually, if I'm going to make this amp now, I'd do exactly as you suggested.
Thanks!
Satoru
The release of this amplifier circuit overlaps with a period I tracked most of Kaneta's articles. Kaneta does weird stuff on a belief that "it sounds better". I'm not defending his designs at all. I agree that a simple resistor would be a better solution (granted that you remove the 5.6Kohm resistor, which doesn't make much sense to be there either). I'm just describing what I think the reason behind of the two diodes sitting there.
The owner of a small parts shop in Kyoto told me once: "Kaneta's amplifiers sounds very good. But I don't like him since he says so nasty things about amplifiers designed by others". He was a very nice old men who listened patiently to many questions from a beginner (me
). Oh, the current going through the diodes depends on the Idss of two 2SJ72 which is rather difficult to know before hand. Of course, you can measure it and calculate the value of the bias resistor. But it won't be too good for a design to be published in a DIY journal where you cannot assume much about the skill level of the readers... Yes, I agree with you that a fixed resistor would be the best!! Actually, if I'm going to make this amp now, I'd do exactly as you suggested.
Thanks!
Satoru
Hello Satoru
You mentioned to use 1N4148 instead what is in the Kaneda schematic .
You also wrote you have some of the orig Diode . If I can use the 1N4148 with any sound degradation that would be also OK to me !
How much would be 4 pc?
These is an interesting am .
I did tried the Kaneta preamp , but I used cheap parts and not bad at all .
Now I purchased Dale resistors and re build it using better quality components .
Lumba Orig
Yes I did found trim pot which sounded much better than the Dale or RPM resistors in the M Hiraga amplifier .
Hard to believe ? For me to !
But I tested many time and after I left the trim pot inside the PC board rather one of the resistors mentioned above .
Satoru if you build these amp before me , probably yes because I'm busy with another project , these week I will meet the spine surgeon probably I need lo back surgery .
Please let me know the result if you done with the amp at first .
Thank
Regards
You mentioned to use 1N4148 instead what is in the Kaneda schematic .
You also wrote you have some of the orig Diode . If I can use the 1N4148 with any sound degradation that would be also OK to me !
How much would be 4 pc?
These is an interesting am .
I did tried the Kaneta preamp , but I used cheap parts and not bad at all .
Now I purchased Dale resistors and re build it using better quality components .
Lumba Orig
Yes I did found trim pot which sounded much better than the Dale or RPM resistors in the M Hiraga amplifier .
Hard to believe ? For me to !
But I tested many time and after I left the trim pot inside the PC board rather one of the resistors mentioned above .
Satoru if you build these amp before me , probably yes because I'm busy with another project , these week I will meet the spine surgeon probably I need lo back surgery .
Please let me know the result if you done with the amp at first .
Thank
Regards
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