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Old 11th April 2010, 09:12 PM   #1291
ra7 is offline ra7  United States
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Cool idea for the transparent cover... nicely shows off the led!

Great build!
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Old 11th April 2010, 09:14 PM   #1292
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Williams,
First, congratulations for your great build. It maybe one, if not the most, complete integrated DCB1 with all those connection options, nice volume control, LED indicator, and demostrating wonderful constructor skills. Amazing mesh cover
I have some questions about it:
-How does the orange led works? I am interested in this display for the LDR range, haven't ever heard of such a thing...I am going to implement an LDR volume control soon.

-For he CCS, I have heard that the sweet spot could be between 200ma and 250ma because of some characteristic of the MOSFETs at this values. Maybe Salas can give us more info about that.
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Old 11th April 2010, 09:32 PM   #1293
Salas is offline Salas  Greece
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william2001:

Wow! Thanks for showing. Happy listening.
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Old 11th April 2010, 09:37 PM   #1294
Salas is offline Salas  Greece
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Quote:
Originally Posted by regiregi22 View Post
-For he CCS, I have heard that the sweet spot could be between 200ma and 250ma because of some characteristic of the MOSFETs at this values. Maybe Salas can give us more info about that.
You remember well, I have wrote before that for the particular MOSFETS they pick up some transconductance around 200mA. Where they really pick up, you don't wanna hear. They are current beasts.
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Old 11th April 2010, 09:49 PM   #1295
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Thank you guys, I worked hard on this. A drill press sure would have been nice to have, ha! Metal was ordered online cut to size, birch ply side panels cut at a relatives house where I had access to a table saw, and compound miter. Sanded and stained it a nice dark ebony (Minwax #2718) then "clear satin" polyurethane when I got home. The mesh was left over from my diy ESL's, cuts easily with scissors.

The orange LED is really just a "power on" indicator that's there mainly to sort of balance out the look of the front panel, add some interest, and with 40 something LED's already, how about 1 more.... I've read the LDR's will receive the least amount of wear if you keep the volume at 50% if you're leaving this thing on all the time, which I mostly do. So, it made sense to me to put the LED there.

The high CCS seems desirable, but my FETs are not sinked to handle that much. I think it's great even at stock values, the bump up to 100mA was subtle to me, maybe it "needs" more? Maybe not. It really sounds great and I'm super impressed as is.
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Old 11th April 2010, 09:51 PM   #1296
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Quote:
Originally Posted by Salas View Post
You remember well, I have wrote before that for the particular MOSFETS they pick up some transconductance around 200mA. Where they really pick up, you don't wanna hear. They are current beasts.
So...time for running a heatsinks group buy?
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Old 11th April 2010, 09:53 PM   #1297
ra7 is offline ra7  United States
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Where'd you find thos nice-looking knobs?
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Old 11th April 2010, 10:02 PM   #1298
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Mouser p/n 450-3000

"aluminum 1.00"D
Eagle Metal Knobs"

Great quality, duel setscrews, $6.05 each
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Old 11th April 2010, 10:12 PM   #1299
Salas is offline Salas  Greece
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At 100mA you get some of the benefit. If you can get some MKP 1837 Vishay 10n or FT-1 22nF CCCP Teflon, just bypass the 5 string shunt 100uF lytics underneath pcb, keeping short legs. But not the output lytics. That one you may hear easy and decide, without hacking or altering visually the nice build.
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Old 11th April 2010, 10:18 PM   #1300
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Forgot to mention something important, this preamp is as silent as the grave. With the volume almost maxed, and my ear almost touching the speaker cone, I can not tell if the preamp is on or off, absolute silence. The trick was to tie the two main power supply ground points of the two buffers together underneath with a short run of wire (maybe 18ga? can't remember). Also, the ground of the LDR power supply (and front panel LED's) is in no way connected to the ground of the DCB1's.
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