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Old 15th September 2006, 05:49 PM   #11
traw is offline traw  United States
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from crtsurplus on da'bay... think another diyaudio member here had used them as well. sold in 12x12x4 piece, 30 bucks. i chopped so i could use up some left over bar stock. remaining peice, 7.5 inch, for another project... maybe aleph 5 depending on how these 4.5x12 sections work out for the aleph 30. each one uncut is about 20 pounds. 66 fins. they aren't extruded... the fins are cemented with some dark gray compound (?) to the base, 1/2" thick.

think about trying to make home made sinks similar to the pass styling - horizontal fins but bent upwards. would be much less tedious than trying make something like these with the vertical fins. if works out, will post results of that endeavor. any easy way to measure ballpark performance?
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Old 9th October 2006, 02:12 PM   #12
traw is offline traw  United States
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Default up and running

got it done now, just need to pick up some sheet metal for the top... it's just about right as after running overnight can touch for 3-5 seconds firmly. transformer gets warm. not worried, will beat into ground and replace if have too. should have used a bit bigger. i used a 400va 20x2. CRC uses 2x0.3ohm and get 23.5 volt rails.

it was running good for a few days, then a channel went out after running a few hours after completed rear plate. was freaking out thinking damaged output devices from heat. seems a solder bridge on Q1 (one of the input diff pair) started acting up. did some searching and inquired with a diyaudio member directly via email giving me some starting points helping to identify the culprit. thanks to netlist post that list voltage points for aleph 3 (similar) and email responses from bob ellis. reached in with wick and iron getting the excessive solder. phew... sounds great. had a small hum on this second version (same boards new chassis)... moved the board ground from the cap bank as star ground to a new star ground at the chassis and went away.

phew... aleph 30 really has some bottom end.

attaching slew of pics
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Old 9th October 2006, 02:13 PM   #13
traw is offline traw  United States
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rear... opted for jumpers as plan to use balanced pre eventually
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Old 9th October 2006, 02:15 PM   #14
traw is offline traw  United States
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another view .... 12 x 10000uf. 3x10000 - R - 3 x10000
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Old 9th October 2006, 02:16 PM   #15
traw is offline traw  United States
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and last one... in action.
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Old 30th March 2011, 09:26 AM   #16
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Smile Aleph 30 - Distorsion on higher frequencies

Hi DIY-ers,

Another build of A30 using Brian's board has been completed. It was really good fun and results were quite pleasing.

Off-course I couldn't just left it there, so I started testing, measuring, tuning ...

I've noticed, that on higher frequencies (10K and more) and signal levels there is certain distorsion quite visible on my DSO.

I attached couple of DSO screenshots. First one is output (4ohm dummy load) at 14.4Vrms and Second one is near clipping and 15Vrms. Area in question is circled red. Is this normal type of distorsion for Aleph 30 ?

I am running with 22V rails, total of 2.5A (Ch1) and 3A (Ch 2) total bias (just for test ) and AC gain of 45%-55%.

Any help would be very appreciated.

Regards, Boris
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File Type: jpeg Distorsion on high signals 10KHz.jpeg (192.5 KB, 392 views)
File Type: jpeg Distorsion near clipping 10KHz.jpeg (188.7 KB, 129 views)
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Old 30th March 2011, 11:09 AM   #17
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That is pretty lousy looking, isn't it. It looks like you are well into the area where it has run out of poop. 22V rails won't get you a clean 14Vrms output, you have to take the losses into account such as source R drop and Vgs of the fets. Also, the difference between 45% and 55% AC gain is pretty substantial. Just trying to be helpful.
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Old 30th March 2011, 12:37 PM   #18
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Quote:
Originally Posted by Bill Fuss View Post
That is pretty lousy looking, isn't it. It looks like you are well into the area where it has run out of poop. 22V rails won't get you a clean 14Vrms output, you have to take the losses into account such as source R drop and Vgs of the fets. Also, the difference between 45% and 55% AC gain is pretty substantial. Just trying to be helpful.
Thanks for your comment Bill. I am currently experimenting with different bias's so one channel is at 2.5A (total) with 55% ACG and second one is at 3A with 45% ACG - I still have to bump up that one. I am getting about 12Vrms without distortion - which should give me ~ 35W on my 4ohm Dali speakers. Enough for me .

My main concern was to see if there is anything else that I could do to improve distortion that occurs before clipping. ie do you guys have clean waveform before going into clipping or you are seeing similar behavior.

Cheers, Boris
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Old 30th March 2011, 01:26 PM   #19
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It is into clipping in your pics, just not hard clipping. It will start clipping at around 17V peak. The PS can't keep up with demand.
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Old 30th March 2011, 02:30 PM   #20
Zen Mod is offline Zen Mod  Serbia
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don't use force - use a bigger hammer



or just make bigger amp ..........

anyway - useful reading :

( worth chasing few related threads here on DiyA , but I'm lazy and I can't remember author's nick here ; http://www.pmeweb.co.uk/Audio/index.html )

ok ....... I'm lazy , but I'm also dumb : http://www.diyaudio.com/forums/searc...archid=2606682
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