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Old 3rd June 2011, 06:03 PM   #1801
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Quote:
Originally Posted by ByronInLawrence View Post
Very nice build, and without a PCB! I'm curious: why do you have capacitors across the filtering caps instead of bleeder resistors?
I would guess for the same reason I do it. Using a smaller high quality cap in parallel with larger "ordinary" electrolytics is a highly desirable configuration. Consider Texas Instruments similar suggestions for improved amplifier performance when they suggest parallel plastic caps on the power buss close to the power pins ... Reasons for this abound, including making TI specs look their best.

Yes, a nice build that will make for great cocktail party conversation. Wood rules!
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Old 3rd June 2011, 06:57 PM   #1802
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Default High Frequencies and ESR

Quote:
Originally Posted by FastEddy View Post
I would guess for the same reason I do it. Using a smaller high quality cap in parallel with larger "ordinary" electrolytics is a highly desirable configuration. Consider Texas Instruments similar suggestions for improved amplifier performance when they suggest parallel plastic caps on the power buss close to the power pins ... Reasons for this abound, including making TI specs look their best.

Yes, a nice build that will make for great cocktail party conversation. Wood rules!
Many electrolytics are ineffective above 20Khz or so and a small non-electrolytic in parallel substantially improves high frequency filtering and stability in a power supply. I've even used the technique to "help" non-polar crossover capacitors with some success.
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Old 3rd June 2011, 08:13 PM   #1803
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Originally Posted by imfree707 View Post
Many electrolytics are ineffective above 20Khz or so and a small non-electrolytic in parallel substantially improves high frequency filtering and stability in a power supply. I've even used the technique to "help" non-polar crossover capacitors with some success.
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Old 3rd June 2011, 09:10 PM   #1804
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Default I'll Raise You...

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Originally Posted by FastEddy View Post
Thanks for the kind emoticons.

Over compression is a problem with modern CD recordings

I see your great quote/link and raise you "has destroyed" to your "is a problem"

Scratchy vinyl sounds better than CD's. Vinyl, properly ripped and burned to CD, sounds great. I think some modern recording engineers really don't have any feel or love for music.
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Old 3rd June 2011, 09:22 PM   #1805
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Originally Posted by imfree707 View Post
... I see your great quote/link and raise you "has destroyed" to your "is a problem". ... Scratchy vinyl sounds better than CD's. Vinyl, properly ripped and burned to CD, sounds great. ...
Mmmmm ... Yes, and I would raise your "properly ripped" to "properly ripped from the original masters".

A benchmark for ripping good quality of transfer to digital media:

Click the image to open in full size.

This HD-DVD-Audio is as good as it gets.

Last edited by FastEddy; 3rd June 2011 at 09:27 PM.
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Old 3rd June 2011, 09:27 PM   #1806
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Good to know. I would guess this is only a problem in large electrolytics with a lot of leakage, so my more modest pair of 10,000uf 50V filter caps would not benefit? I've also noticed many PS come with multiple (6 or 8) smaller caps instead of a pair of monsters. Is this the reason why? His caps are overkill, but they look cool!
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Old 4th June 2011, 12:46 AM   #1807
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Default Chip Amp Photo Gallery

There are my amp using STK audio modules, I think that sounds very well.
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Old 6th June 2011, 04:19 PM   #1808
frank1 is offline frank1  United Kingdom
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Quote:
Originally Posted by imfree707 View Post
Many electrolytics are ineffective above 20Khz or so and a small non-electrolytic in parallel substantially improves high frequency filtering and stability in a power supply. I've even used the technique to "help" non-polar crossover capacitors with some success.
I would dispute this.
I repair a lot of audio gear. and test the smoothing electrolytics with an ESR meter which measures the impedance at 100kHz.
Good ones all measure between 0.1 and 0.3 Ohms.
Smaller values have higher ESR values (e.g 100uF typically 0.5 Ohms @ 100kHz)
Thus no problems with anything remotely audible and probably no point in multiple capacitors?
Frank
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Old 6th June 2011, 04:24 PM   #1809
AndrewT is offline AndrewT  Scotland
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Originally Posted by frank1 View Post
......and test the smoothing electrolytics with an ESR meter which measures the impedance at 100kHz.
Good ones all measure between 0.1 and 0.3 Ohms
Does obtaining an ESR value tell us that the capacitor is not behaving as an inductor at the test frequency?
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Old 6th June 2011, 04:34 PM   #1810
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Default Old Info...

Quote:
Originally Posted by frank1 View Post
I would dispute this.
I repair a lot of audio gear. and test the smoothing electrolytics with an ESR meter which measures the impedance at 100kHz.
Good ones all measure between 0.1 and 0.3 Ohms.
Smaller values have higher ESR values (e.g 100uF typically 0.5 Ohms @ 100kHz)
Thus no problems with anything remotely audible and probably no point in multiple capacitors?
Frank
Capacitors have changed since I was told about that, back in the early 70's. I would think the small caps would still be needed on the amp board if its not very near the filter caps.
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