One point, when I comment, "Can I follow the same order as in the original circuit (39w) by inverting only the zener diode?"
I am referring to the order starting from the top, V121(1N4148), H121(led red clipping) and V122(2.7v zener).
Regards
I am referring to the order starting from the top, V121(1N4148), H121(led red clipping) and V122(2.7v zener).
Regards
Today the tests continued with resistance 0.18Ω ~ 2A and 0.12Ω ~3A. The ripple with 2A bias before the multiplier 60mv and after about 1mv. The ripple with 3A bias before the multiplier 120-130mv and after about 4-6mv.
The temperature from the lower side of the copper is approximately above 45C, from the upper side around 52-54C.
The temperature from the lower side of the copper is approximately above 45C, from the upper side around 52-54C.
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Looking good.
How hot do your cap multipliers get? Mine were getting too hot. I'm going to try a normal CRC ,33mf,0.1r,33mf per rail per channel so 240mf total. It will raise my rail voltage a little also so need to keep my eye on that. How much rail voltage are you loosing with your multiplier.?
How hot do your cap multipliers get? Mine were getting too hot. I'm going to try a normal CRC ,33mf,0.1r,33mf per rail per channel so 240mf total. It will raise my rail voltage a little also so need to keep my eye on that. How much rail voltage are you loosing with your multiplier.?
Today i have put a trimmer 500Ω instead 200Ω and ajust the offset from 3.5 mv to 0.2mv .....
The only problem i have is ... with version of 3A bias the voltage rail goes on spot about 20.20- 20.45V but the voltage on 3.32k goes down to 7.80V from 8.30V
It seems i have the problem and before with voltage rails at 21.80 then i measure low voltage 8.30-8.50 little lower before spot 8.63V.
Αlso on 33.2Ω i measure 287mv.
On 825Ω at negative rail i measure 6.200V
Any advice? How to raise at 2.6 ma ?
The only problem i have is ... with version of 3A bias the voltage rail goes on spot about 20.20- 20.45V but the voltage on 3.32k goes down to 7.80V from 8.30V
It seems i have the problem and before with voltage rails at 21.80 then i measure low voltage 8.30-8.50 little lower before spot 8.63V.
Αlso on 33.2Ω i measure 287mv.
On 825Ω at negative rail i measure 6.200V
Any advice? How to raise at 2.6 ma ?
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Here we are .....job done......
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Nikos,
Thanks for the schematic.
I would play only with R112/5k.
Use a 5k pot and then measure the offset against ground, adjusting R112 with no signal until you measure an offset if less than 5mV.
Warm up the amp for 20mins before setting the offset.
Nice build and lovely moniker - my favourite restaurant in Melbourne is also NIKOS with the best spanakopita in Victoria.... As you may know Melbourne is the home of 350k Greeks, second only to Athens. Sadly they do not speak good Greek however....
Hugh
Thanks for the schematic.
I would play only with R112/5k.
Use a 5k pot and then measure the offset against ground, adjusting R112 with no signal until you measure an offset if less than 5mV.
Warm up the amp for 20mins before setting the offset.
Nice build and lovely moniker - my favourite restaurant in Melbourne is also NIKOS with the best spanakopita in Victoria.... As you may know Melbourne is the home of 350k Greeks, second only to Athens. Sadly they do not speak good Greek however....
Hugh
Μr Hugh.
Thank you very much for the help and your kind words., I will do it, I will install a 5k trimmer . My mother used to make spinach pie, now I make it myself..... Here in Epirus, in Arta, we don't call it spanakopita hahaha, that's what those from the capital call , we call it vegetable pie, it is a combination of various vegetables, including spinach and feta cheese .
Here is ....
https://www.gastronomos.gr/syntagh/ipeirotiki-lachanopita-me-aromatika-chorta/52943/
Thank you very much for the help and your kind words., I will do it, I will install a 5k trimmer . My mother used to make spinach pie, now I make it myself..... Here in Epirus, in Arta, we don't call it spanakopita hahaha, that's what those from the capital call , we call it vegetable pie, it is a combination of various vegetables, including spinach and feta cheese .
Here is ....
https://www.gastronomos.gr/syntagh/ipeirotiki-lachanopita-me-aromatika-chorta/52943/
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What impresses me about this amplifier and the thread is that I have not seen any post or almost none with a test of the amplifier with a generator and an oscilloscope ..... or even from him Χrk 971.. or did I miss something?
And i wonder the C134 2200pf installed or not at version 4Ω ?
https://www.diyaudio.com/community/threads/alpha-nirvana-39w-8ohm-class-a-amp.344540/post-6900892
And i wonder the C134 2200pf installed or not at version 4Ω ?
https://www.diyaudio.com/community/threads/alpha-nirvana-39w-8ohm-class-a-amp.344540/post-6900892
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Everything go very well with 2N5401 not matched at all i pick randomly one couple ..about 4R version with 5k resistor zero offset and 2.37ma-7.80-.7.90 voltage on 3.32k ........same measurements with gen and scope.....
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But when i put 4.3k to raise the bias ata 2.6 ma ~8.63V at 3.32k the offset with 2N5401 goes up to 35 mV instead to ksa992 to 15mv.
I think i must match better the ksa 992....but i leave them as well....
I think i must match better the ksa 992....but i leave them as well....
Temp air 20C
3A bias 42C.....upper copper.. aluminium
Body temp mosfets 35C.... THE ..... solution.
I have also this with largest copper surface.....but im very pleased.
The active fan doesn't work properly with air flow down to upper.
Strange box hahaha.
Only vertical as the photos.
My little advice.....
3A bias 42C.....upper copper.. aluminium
Body temp mosfets 35C.... THE ..... solution.
I have also this with largest copper surface.....but im very pleased.
The active fan doesn't work properly with air flow down to upper.
Strange box hahaha.
Only vertical as the photos.
My little advice.....
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After experiments i will stay with 5K and 500Ω pot with zero offset -0.2 -0.4mv at 2.35ma for ksa992.
Amazing amp a lot of bass and details...first impressions....
Thanks Mr Hugh.
Amazing amp a lot of bass and details...first impressions....
Thanks Mr Hugh.