Symasym - the sequel - Page 27 - diyAudio
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Old 11th February 2007, 04:21 PM   #261
Ryssen is offline Ryssen  Sweden
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Quote:
Hi,no readme.txt as per our web template,no soldermask files - note that our process is immersion gold and if no soldermask massive gold deposit on the track will be made which will increase the price of panel x3
Thanks
Olimex
Funny Olimex didn´t find it,I sent the whole zip file to them.
But Cogra Pro AB,didn´t say anything that is whas missing,maybee thay found i...
Is it allrigt if whe set the date for last signup to 28/2 2007?
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Old 11th February 2007, 04:49 PM   #262
AAK is offline AAK  United States
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My mistake. In the knew SA50D.zip the .msk file is the solder mask. The .slk is the silk file that labels each part and goes above the solder mask. Sorry about that. If there are any other problems let me know.

Al
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Old 11th February 2007, 06:57 PM   #263
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Originally posted by Ryssen
Myself 2
Sigurd 2
Sheldon 2 ?
SteveA 2 ?
Colescuttle 2
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Ahhh! Symasum boards

Four PCB`s for me please Thanks!
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Old 11th February 2007, 08:13 PM   #264
Ryssen is offline Ryssen  Sweden
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Myself 2
Sigurd 2
Sheldon 2 ?
SteveA 2 ?
Colescuttle 2
Peter M. 4
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Old 14th February 2007, 08:01 PM   #265
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Default Question for Al, or maybe Mike.

Hi, Al:

Was there a reason you chose 4700 uF caps for your power supply? Would 1000 or 2200 work as well (sound as good), or better? The reason being, of course, I have some 1000 and 2200uF caps left over from another project.

Mike, if you catch this post and there's a design issue involved, please jump in.

Thanks.

George
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Old 15th February 2007, 04:14 AM   #266
AAK is offline AAK  United States
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Hi Colescuttle,

The rule thumb for determining PS capacitor values is 1000uF for every 10watts of amplifier power. I run symasym at +/-50V rails to generate 100 watts rms into 8ohms, and for that reason I selected two 4700uF caps in parallel per rail (9400uF total). But, in the first symasym I built I used two 3300uF instead and couldn't tell a difference in sound or bass performance.

Symasym PSRR is very good, and for that reason SNR remains nearly the same for both cases, I'd imagine with two 2200uF per rail it would still be pretty good. My guess is that if you run the amp below 50 watts it's performance should be fine, above 50 watts you may hear some low frequency deterioration.

The amount of reservoir capacitance remains controversial. Some prefer loads of it, and others don't. I'd rather stick to the rule thumb, it's worked great for me. Give the smaller caps a shot, maybe do some experimentation. Just make sure your caps are rated at least 10% above the rail voltage.

Regards,

Al
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Old 15th February 2007, 06:59 AM   #267
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Default Thanks, Al.

George
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Old 15th February 2007, 09:11 AM   #268
roender is offline roender  Romania
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After countless hours of simulation and practical tests, I came to this version of power amplifier, inspired by symasym.
The main goal was crystal clear trebles, very good dumping factor - bass control and 4ohm stable in any output condition.
What do you think about output and thermal compensation stage, 2x1n4148 for CFP drivers plus 2xNJL diodes for power BJT's?
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Old 15th February 2007, 09:13 AM   #269
roender is offline roender  Romania
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PCB top view
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Old 15th February 2007, 09:14 AM   #270
roender is offline roender  Romania
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PCB top view whitout components
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