Check with Mike over at AmpsLab. He most likely has L-Mosfets you are looking for....
Audio Power Mosfets - Buy OnLine @ AmpsLab
Brad
Audio Power Mosfets - Buy OnLine @ AmpsLab
Brad
Ray,
No p or n conjugate pair of outputs is identical electrically. One has a bigger gate capacitance than the other, and dissimilar gate resistors reflect this in an attempt to equalise the charge durations.
You can of course use identical gate resistors if you wish and I doubt you will hear much difference, BUT, we like to cross our tees and dot our eyes with precision in this parts!!
Andrew,
Wenceslas was either Hungarian or Czech, don't remember which, what's the Aussie connection here? I'm lost???
Cheers,
Hugh
No p or n conjugate pair of outputs is identical electrically. One has a bigger gate capacitance than the other, and dissimilar gate resistors reflect this in an attempt to equalise the charge durations.
You can of course use identical gate resistors if you wish and I doubt you will hear much difference, BUT, we like to cross our tees and dot our eyes with precision in this parts!!
Andrew,
Wenceslas was either Hungarian or Czech, don't remember which, what's the Aussie connection here? I'm lost???
Cheers,
Hugh
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Thanks Hugh. That was interesting. Now you've really got me curious as to how you came up with those resistance values.
I looked up the datasheets for ECX10N20 and ECX10P20 and I see the gate capacitances are 500pf and 700 pf. That's a different ratio than 150R to 270R. Is the calculation non linear?
Besides, I am using a 2SK1058 and @SJ162 (600 pf and 900pf). Should the resistance values be different.
And of course, as you say, I probably won't hear the difference.
And since I grew up in Maryborough, QLD, I always enjoyed looking out at the snow on Xmas Eve, deep and crisp and even. I think that song always goes well when you are boozed.
ray
I looked up the datasheets for ECX10N20 and ECX10P20 and I see the gate capacitances are 500pf and 700 pf. That's a different ratio than 150R to 270R. Is the calculation non linear?
Besides, I am using a 2SK1058 and @SJ162 (600 pf and 900pf). Should the resistance values be different.
And of course, as you say, I probably won't hear the difference.
And since I grew up in Maryborough, QLD, I always enjoyed looking out at the snow on Xmas Eve, deep and crisp and even. I think that song always goes well when you are boozed.
ray
Ray,
The 'calculation' as you put it was empirical; Greg futzed around until he had what he thought was the 'best sound'. Now you know, this is a painting, not a photograph..... ho ho!!
Maryborough, huh? Lovely spot, some heavy industry there, too. Fancy that, did you get a US job, or marry a US girl? Wish I had the guts to go to the US as a young man, it might have been a better choice, who knows?
Hugh
The 'calculation' as you put it was empirical; Greg futzed around until he had what he thought was the 'best sound'. Now you know, this is a painting, not a photograph..... ho ho!!
Maryborough, huh? Lovely spot, some heavy industry there, too. Fancy that, did you get a US job, or marry a US girl? Wish I had the guts to go to the US as a young man, it might have been a better choice, who knows?
Hugh
Hi Ray,
I'm also going to use 2SK1058 and 2SJ162, please let me know your findings, if you tweaked anything on those resistors.
Thanks
Do
I met a girl from southern New Jersey back in 1974 in Spain. We actually got married in Melbourne when we were living in Prahran. The US and Australia each has its good points and some not so good ones. I try to get back to Oz every year for a dose of what I call 'real civilization', or meat pies and violent rumbles.
Maryborough is one of those hidden gems that the main road bypasses. Time has stood still there since the 60's so there are still lots of nice old buildings.
Do, I'll let you know what develops on these gate resistors. I'm going to be away for a week so it will be a couple of weeks before I get the amp working. In the past I've mostly played around with tubes / valves and typically I would use a 1K carbon composition resistor as a grid stopper. From Hugh's answer I now know I can play around with these which is very helpful.
ray
Maryborough is one of those hidden gems that the main road bypasses. Time has stood still there since the 60's so there are still lots of nice old buildings.
Do, I'll let you know what develops on these gate resistors. I'm going to be away for a week so it will be a couple of weeks before I get the amp working. In the past I've mostly played around with tubes / valves and typically I would use a 1K carbon composition resistor as a grid stopper. From Hugh's answer I now know I can play around with these which is very helpful.
ray
Hi Syklab,
You can use a separate trafo for each channel, yes, that works fine.
Each trafo should be rated to 150VA at least - between 150VA and 225VA is fine.
If you use one trafo, then you will need one 300VA. 24Vac windings are fine, but 25Vac is better again - the design spec.
Thanks for the post, this will be helpful to others too,
Cheers,
Hugh
You can use a separate trafo for each channel, yes, that works fine.
Each trafo should be rated to 150VA at least - between 150VA and 225VA is fine.
If you use one trafo, then you will need one 300VA. 24Vac windings are fine, but 25Vac is better again - the design spec.
Thanks for the post, this will be helpful to others too,
Cheers,
Hugh
Hi NCC,
yes, correct indeed. These resistors separate the pins of the rail caps, and because those caps are on the component side, they MUST be placed under the pcb. But they are very thin, only around 3mm, so it's never a problem as the output devices, with two suitable washers between them and the pcb, leave a 7mm space, just over 1/4", between heatsink surface and pcb surface.
Hope this is clear!
Cheers,
Hugh
yes, correct indeed. These resistors separate the pins of the rail caps, and because those caps are on the component side, they MUST be placed under the pcb. But they are very thin, only around 3mm, so it's never a problem as the output devices, with two suitable washers between them and the pcb, leave a 7mm space, just over 1/4", between heatsink surface and pcb surface.
Hope this is clear!
Cheers,
Hugh
Hi Mkie,
The 470uf is that the C8 that you are replacing with 22,000uf? where do you mount the 22,000uF cap? Is it off board? The place that was originally design for C8 is quite small for such big cap. What brand of cap you have selected for this 22,000uF cap?
Thanks
Hi Skylab, I did not replace the 470uF but rather bypassed it with the 22,000uF cap thus maintaining the nice high frequency qualities of the rubycon ZL 470uF and boosting the bass & midrange filtration with the 22,000uF cap.
I think it was a BHC aerovox cap - quite good but nothing fancy and as you suggest, mounted offboard via twisted pairs.
Generally speaking I am really delighted with the quality of this amp - it's the best I have heard - being both delightfully detailed but also very soft and natural sounding. The vivid textures of different instruments still sometimes surprise me. It is rythmic and quite exciting and images nicely.
All in all - I would warmly recommend this design to anyone.
The more you put into it the more it rewards you
good luck
mike
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