Kofi Annan in: "Kofi Makes a 300b DRD... and You Get to Help!" - diyAudio
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Old 12th May 2007, 01:20 AM   #1
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Default Kofi Annan in: "Kofi Makes a 300b DRD... and You Get to Help!"

So, after years of gathering parts and convincing wives, the 300b DRD project appears a mere few weeks away from realization. And here's where you come in...

For your convenience, Kofi has attached the schematics for the circuit and the PSU along with a physical layout design from both the top and bottom perspective thanks to the fantastic Google Sketchup, six packs of Belgian beer and a modicum of child neglect.

I tried to annotate the different components-- the all-white thingees are the motor run caps, the yellow thingees are the tubes and the gray / brown thingees are the transformers.

Mostly, I need to know if the current layout is OK and maybe some ideas on the best star grounding concept. Actually, mostly what I need is some alcohol counseling, but the layout help would be good too.

Kofi
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Old 12th May 2007, 01:21 AM   #2
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Bottom....
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Old 12th May 2007, 01:22 AM   #3
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Circuit
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Old 12th May 2007, 01:23 AM   #4
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... and the PSU.
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Old 12th May 2007, 04:03 PM   #5
Sheldon is offline Sheldon  United States
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Default Re: Kofi Annan in: "Kofi Makes a 300b DRD... and You Get to Help!"

Quote:
Originally posted by Kofi Annan
Mostly, I need to know if the current layout is OK and maybe some ideas on the best star grounding concept. Actually, mostly what I need is some alcohol counseling, but the layout help would be good too.

Kofi
Don't see any big issues with the layout. Star grounding should be pretty simple if you lay it out much as in the schematics. You can connect the signal ground and grid resistor together, then a small resistor (10R or so) to lift it. Then separate leads for the cathode resistor connection, the speaker return, the filament lift divider ground, and the filament center tap. I like to make a big fat buss wire for the PS grounds, then make the main star at the quietest spot on the PS ground buss. Or bring all the PS grounds together along with the others for one main star.

As for alcohol, life is short, my counsel is drink the good stuff when you can.

Sheldon
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Old 13th May 2007, 04:12 AM   #6
arnoldc is offline arnoldc  Philippines
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Personally, I don't like the layout. It's a matter of taste...

I'm not fond of big capacitors sticking out the top of the chassis, I find them ugly. I have to admit though that my 45 amp has one Audio Professor dual 47uF/500V sticking out the chassis.. But just one..
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Old 13th May 2007, 03:17 PM   #7
rdf is offline rdf  Canada
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Hello Mr. Annan. Have you run that power supply through PSUD2 yet? My immediate sense is the combination of very low first two C and very high first H will ring like a UN session closing bell.
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Old 13th May 2007, 07:49 PM   #8
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Quote:
Don't see any big issues with the layout. Star grounding should be pretty simple if you lay it out much as in the schematics. You can connect the signal ground and grid resistor together, then a small resistor (10R or so) to lift it. Then separate leads for the cathode resistor connection, the speaker return, the filament lift divider ground, and the filament center tap. I like to make a big fat buss wire for the PS grounds, then make the main star at the quietest spot on the PS ground buss. Or bring all the PS grounds together along with the others for one main star.
So noted. Thanks for the advice. I'll post my version of the grounding scheme soon.

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[/b]Personally, I don't like the layout. It's a matter of taste...[/b]
Also noted. I have revised the drawing to only have the two round caps poking through the top. I crammed the rest in there and I think I'll be able to work with this, but I'd still like some comments on the layout and positioning of components.

Have a look:
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Old 13th May 2007, 07:50 PM   #9
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Another angle...
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Old 13th May 2007, 07:51 PM   #10
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And the guts...
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