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Old 3rd March 2005, 12:24 AM   #111
fab is offline fab  Canada
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Default DH-200 cascode diff input stage

Rob

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Old 3rd March 2005, 12:34 AM   #112
Bogie is offline Bogie  United States
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DickW - did you do anything to that amp, beyond setting the bias?

YOW! Seems to be cleaner, and play lower, than my _previous_ favorite DH-200 amp...

(thus far only one test disk - Steely Dan 2 against nature...)
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Old 3rd March 2005, 01:59 AM   #113
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Bogie,

You are referring to the P-225? I agree, it does sound different than a stock DH-200 but these are two different amps with slightly different circuits. I thought the P-225 had a lot of punch and drive when I listened to it. Not much more I can say as I know nothing about your DH-200. All I did with the P-225 was set the bias at 270 mA.
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Old 3rd March 2005, 02:32 AM   #114
fab is offline fab  Canada
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Default DH-200 cascode diff input stage

Here is a picture of a symetric diff input cascode CFP stage using a cheap Radio-shack universal pcb #276-150A. Each 4 input bjts of the original mother board of the DH-200 are replaced with small wires (b,c,e) that go to the daughter board sitting on top of the pc-6 DH-200 mother board. The connectors shown on the daughter board for the wires are only for my first protoptype (except for the V+, V- and ground).
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Old 3rd March 2005, 02:35 AM   #115
fab is offline fab  Canada
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Default DH-200 cascode diff input stage

Here is the back of the daughter board including a post to secure the board into the mother board. Drill a hole in the mother board.
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Old 3rd March 2005, 02:37 AM   #116
fab is offline fab  Canada
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Default DH-200 cascode diff input stage

Here is the daughter board installed on the DH-200 mother board. This is my prototype DH-200 which had lots and lots of mods so it is a little bit damaged...
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Old 5th March 2005, 02:50 PM   #117
Bogie is offline Bogie  United States
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I feel really stupid...

Finally got around to installing the new caps in my 200... Figured I'd do one at a time.

Could someone confirm this to me? The neg on the right side one (as viewed from the front of the amp) is on the "inside," and the pos on the left side one is also on the inside, joined in the center by that bridge?

Didn't take a picture before I started, and I _think_ I got the left one in right, but...

Help?
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Old 5th March 2005, 03:18 PM   #118
fab is offline fab  Canada
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Quote:
Originally posted by Bogie
I feel really stupid...

Finally got around to installing the new caps in my 200... Figured I'd do one at a time.

Could someone confirm this to me? The neg on the right side one (as viewed from the front of the amp) is on the "inside," and the pos on the left side one is also on the inside, joined in the center by that bridge?

Didn't take a picture before I started, and I _think_ I got the left one in right, but...

Help?
Bogie

See http://www.hafler.com/techsupport/pd...00_amp_man.pdf for all info on the DH-200 manual.
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Old 5th March 2005, 03:25 PM   #119
Bogie is offline Bogie  United States
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Hey, thanks... Already checked that, but I had to wonder...

So, I pulled the top off a 225... Looks like the pos and negs on the caps are joined in the middle by this bridging wire - why is that? Why not two negs, or two pos? If possible, please use short words...

I'm gonna go hook everything else up. If you guys hear a loud noise, you know where it came from.
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Old 5th March 2005, 03:45 PM   #120
Bogie is offline Bogie  United States
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Oh, and yet another stupid question - if I'm gonna swap out the caps in these other amps...

Just looked at Digikey's web site... And did a search on capacitor... Came up with >30,000 hits... Which do I pick?
Or how do I narrow the search?
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