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Old 9th November 2004, 08:49 AM   #1
Ralph is offline Ralph  Netherlands
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Default Should I use a cathode capacitor in my SE amp?

Hi all,

Currently I'm listening to my DIY SE and I am very happy with it. In this amp I'm building an active filter for my new loudspeakersystem, so it's time to strip and rebuild the amp (not as much work as it seems).

In the driver circuit C22 is in the signal path. I was wondering if there are any cons to remove it completely. The interstage's load should be high enough for C22 to be removed, or am I overlooking something?

Ralph
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Old 9th November 2004, 09:07 AM   #2
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C22 is there to bypass R24 so that under AC conditions (music) the cathode of V4 appears to be connected to ground. If you remove it, you will be adding local feedback to the stage.
This might sound better or worse although the gain will be slightly reduced.
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Old 9th November 2004, 05:59 PM   #3
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Default Re: Should I use a cathode capacitor in my SE amp?

Quote:
Originally posted by Ralph
In the driver circuit C22 is in the signal path. I was wondering if there are any cons to remove it completely.
Well, if you are sweating over a capacitor, let me assure you, any logical response on the actual functions of the capacitor are moot.

Tim
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Old 9th November 2004, 06:12 PM   #4
Ralph is offline Ralph  Netherlands
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Hi Tim,

May be the best and only answer
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Old 10th November 2004, 06:32 AM   #5
Blue is offline Blue  Cayman Islands
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Ralph

You have overlooked a few things:

C22 could go but so would all that distortion that makes the amp sound the way it does and nobody likes SE for its neutral sound :-) Is R22 really 62k should it not be 6k (6k2) or is this a magic interstage 1:1 ?? Is there a capacitor somewhere down the line before R23 ? if not there should be; make its value such that the bass rolls off to suit the interstage transformer or preferably the output, my guess is the output is only good for about 40Hz so why push it lower or do you like the TID ? What are R1-R21 and C1-C21 doing ??
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Old 10th November 2004, 08:21 AM   #6
Ralph is offline Ralph  Netherlands
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Quote:
C22 could go but so would all that distortion that makes the amp sound the way it does and nobody likes SE for its neutral sound :-)
point taken

Quote:
Is R22 really 62k should it not be 6k (6k2) or is this a magic interstage 1:1 ??
R22 is really 62K and the interstage is indeed a magic 1:1. I might remove it alltogether.

Quote:
What are R1-R21 and C1-C21 doing ??
There are used in my powersupply.
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