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Old 24th October 2006, 06:39 PM   #21
dinu is offline dinu  United States
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SORRY EVERYONE!!
I can't seem to get the resolution up on this. Hope this is better.
http://i125.photobucket.com/albums/p...RSCHEMATIC.jpg
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Old 7th November 2006, 12:59 PM   #22
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Default getting ready to order

Not much interest here I guess. I'm getting ready to order front end and output boards. The output boards will hold up ro 6 TO247 devices each. I made a simple board for the output power supply to connect all the AC side components but am still looking for a nice psu for the front end. I'm working on the chassis right now. Bob, you were right; the transformers are 25 kilo each. I got the caps from apex JR. They're really nice but big. All said and done it probably will weigh about 150 pounds. Once it's in the living room, it ain't going nowhere.
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Old 7th November 2006, 01:15 PM   #23
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I guess its that "old design" syndrome. Alain and I are very happy with our amps. I'm sure that you will be, too.

Have you looked into Advanced Circuits 3 for $33 each special? For $50 extra you could have them panelize your input and output boards, maybe even repeating them so you could get 3-6 sets with soldermask and silkscreen for $149. Turn time is quick and they do a design rules check (always good to have a second set of eyes checking)
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Old 7th November 2006, 01:24 PM   #24
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If it's old design syndrome, what are all those tube guys talking about?
I haven't priced any board houses yet. I was waiting to see what kind of quantity I'll need. I guess 1. I'm also not too sure about the gerber file process and how to specify things like the copper thickness, plating options, mask color, through hole options, board thickness etc. I guess I'll need to talk to someone at Advanced Circuits. Do you have any contact info for them?
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Old 7th November 2006, 01:45 PM   #25
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www.4pcb.com

Check the EAGLE tutorial and manual for instructions on creating gerbers. Use a gerber viewer to verify that you have something that makes sense.
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Old 7th November 2006, 04:25 PM   #26
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Default Boards

Dinu,

I may be interested in a set of the boards. I have not read through the whole thread, but I imagine that the boards can be used to build the standard 75 watt amp?

I had built the A75 long ago, it is the oldest picture under the A75 amps on Passdiy gallery.

Let me know how much the boards will cost so I can decide.

Thanks.

Vinay
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Old 7th November 2006, 05:14 PM   #27
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Vinay,
The boards are essentially the same as the original. The real reason I had to make a new board was to give me a way of mounting the fets to a large heat sink. The switch for R81 and the DC servo is an add on that you can choose to use or not. I also added some filtering that the original lacked ie. bypass caps for power rails, and gate protection diodes which was an addendum to the original design made by Nelson. Also, because each board houses a single channel, you have more flexibility in placing it in the chassis. I'll be ready with pricing soon. I want to finish one more board which will be a filter network for high current PSU that will be mounted close to the output stage. Of course, you can get whatever you'd like.

BOB,
Any news on your PSU ?
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Old 7th November 2006, 05:55 PM   #28
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I am down to three PSU boards/Kits leftover. Jens had 10 or so available in his garage sale, but I don't know if he still has any.

I haven’t had a chance to hook it up and listen to a high voltage version yet.

The circuit on your boards is basically the same, but aren't you using IRF610/9610 for the input pairs, have added an optional DC servo and each board is a single channel?
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Old 7th November 2006, 05:58 PM   #29
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Are you willing to sell one of your boards?
I bought 640's. Don't ask me why. They should be sturdier and I bet sound different.
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Old 7th November 2006, 06:32 PM   #30
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They'll sound different alright - The 649 has ten times the input capacitance of the 610.
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