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?
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
Al
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
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
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
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
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?
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?
Attachments
Roender, some advice for when you use EAGLE to print to Press-n-Peel.
It is far better to not have the holes etched out. To do this, type the command "SET DISPLAY_MODE NODRILL" into the EAGLE command line at the top of the editor window. You will see on screen that all the drill holes now become solid. To get back to normal, type "SET DISPLAY_MODE REAL"
Admittedly, drilling the holes becomes a bit more difficult 🙂 but you can activate layer 44 (Drills) and deactivate everything else except 20 (Dimension), print that out, and use it as a drill template.
It is far better to not have the holes etched out. To do this, type the command "SET DISPLAY_MODE NODRILL" into the EAGLE command line at the top of the editor window. You will see on screen that all the drill holes now become solid. To get back to normal, type "SET DISPLAY_MODE REAL"
Admittedly, drilling the holes becomes a bit more difficult 🙂 but you can activate layer 44 (Drills) and deactivate everything else except 20 (Dimension), print that out, and use it as a drill template.
Two reasons.
One is that the acid can etch under the pads. This can lead to the pads coming off when you heat them up to solder them. Admittedly, this is only likely if you leave it in the acid too long.
Two, and the more importan one, is that if you don't drill exactly where the hole is etched, you end up with a hole, and part of the pad with no copper on to attach to. If you leave the pad filled, then the hole is wherever you drill it, so if you're a bit off, it wont affect solderability.
One is that the acid can etch under the pads. This can lead to the pads coming off when you heat them up to solder them. Admittedly, this is only likely if you leave it in the acid too long.
Two, and the more importan one, is that if you don't drill exactly where the hole is etched, you end up with a hole, and part of the pad with no copper on to attach to. If you leave the pad filled, then the hole is wherever you drill it, so if you're a bit off, it wont affect solderability.
Hello,
I always etch with holes-never had a problem.
Problems in diy echting do happen if the etchant is old, or your copy (i alway work with photo-positive material).
Very nice Board!
🙂
Black
I always etch with holes-never had a problem.
Problems in diy echting do happen if the etchant is old, or your copy (i alway work with photo-positive material).
Very nice Board!
🙂
Black
A Symasomething Amp for Dummy
Six months ago I carried my not-currently-working-for-the-last-time SETs out to the street and turned my attention to building a reliable, great sounding amp. I’d heard about the sym-a-sym on the chip amp forum, and was impressed to learn that in comparison to a chip amp there was no contest. So, after successfully building a chip amp I decided to give a sym-a-sym a try. However, now that Al’s boards will be ready soon and I have all the other components, it’s time to come out of the closet.
I am an ee-dummy. When reading what you have posted on this forum, and I mean what virtually all of you have posted, I get the same slightly panicky, glazed-eye feeling I get when talking to academic sociologists.
There. That wasn’t so bad. I feel much better.
Please consider my presence on this forum a social experiment. Can you, as experts, convey complicated and esoteric concepts in such a manner that a six month old cocker spaniel can understand them, and can you do so without rancor or spiritual deterioration? I know you don’t know me, but I’m not a seriously bad person and I didn’t vote for George Bush and I’m old and won’t be around much longer (cough, cough) and I love music and it would be good for your karma. Please?
Before I ask questions I will do at least fifteen minutes of serious research. (Hey, I told you I was old. Time is passing.) Further, I will flag all of my posts with questions with a “DUMMY WARNING!” in the subject field. That way you can roll your eyes and move on if you choose. If, on the other hand, you accommodate me, I will write your name in Wonder Solder on my forearms until there’s no space left or I run out of Vicodin. Finally, when the amps are done, I will provide Stilton, pears and Peyrot every time you visit for a listen.
I thank you in advance for your patience.
Six months ago I carried my not-currently-working-for-the-last-time SETs out to the street and turned my attention to building a reliable, great sounding amp. I’d heard about the sym-a-sym on the chip amp forum, and was impressed to learn that in comparison to a chip amp there was no contest. So, after successfully building a chip amp I decided to give a sym-a-sym a try. However, now that Al’s boards will be ready soon and I have all the other components, it’s time to come out of the closet.
I am an ee-dummy. When reading what you have posted on this forum, and I mean what virtually all of you have posted, I get the same slightly panicky, glazed-eye feeling I get when talking to academic sociologists.
There. That wasn’t so bad. I feel much better.
Please consider my presence on this forum a social experiment. Can you, as experts, convey complicated and esoteric concepts in such a manner that a six month old cocker spaniel can understand them, and can you do so without rancor or spiritual deterioration? I know you don’t know me, but I’m not a seriously bad person and I didn’t vote for George Bush and I’m old and won’t be around much longer (cough, cough) and I love music and it would be good for your karma. Please?
Before I ask questions I will do at least fifteen minutes of serious research. (Hey, I told you I was old. Time is passing.) Further, I will flag all of my posts with questions with a “DUMMY WARNING!” in the subject field. That way you can roll your eyes and move on if you choose. If, on the other hand, you accommodate me, I will write your name in Wonder Solder on my forearms until there’s no space left or I run out of Vicodin. Finally, when the amps are done, I will provide Stilton, pears and Peyrot every time you visit for a listen.
I thank you in advance for your patience.
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