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Tursiops_G
Technoid
MVM
join:2002-02-06
Brooksville, FL
ARRIS TM1602

Tursiops_G to iknow_t

MVM

to iknow_t

Re: Looking forward to some Brand of ELNA Aluminum Electrolytic Capacitors

said by iknow_t:

here's a guy that did a lot of real world testing on these and other caps. »tech.juaneda.com/en/arti ··· ors.html

Let me understand this... He's checking Perceived Audio performance of different Electrolytic Caps used in the Power Supply input, that ONLY see 120Hz Ripple current (AC Full Wave rectifier), behind a neutralized, 3-point DC Regulator, NOT anywhere in the Audio Signal Path itself...?

Just What has that guy been smoking?

Let's See what an Oscilloscope shows across the cap banks under test...

-Tursiops_G.
iknow_t
join:2012-05-03

iknow_t

Member

said by Tursiops_G:

said by iknow_t:

here's a guy that did a lot of real world testing on these and other caps. »tech.juaneda.com/en/arti ··· ors.html

Let me understand this... He's checking Perceived Audio performance of different Electrolytic Caps used in the Power Supply input, that ONLY see 120Hz Ripple current (AC Full Wave rectifier), behind a neutralized, 3-point DC Regulator, NOT anywhere in the Audio Signal Path itself...?

Just What has that guy been smoking?

Let's See what an Oscilloscope shows across the cap banks under test...

-Tursiops_G.

actually, the caps see the full audio spectrum drawn from the amp. even though they are in the power supply!. think about it.

aurgathor
join:2002-12-01
Lynnwood, WA

2 recommendations

aurgathor

Member

said by iknow_t:

actually, the caps see the full audio spectrum drawn from the amp. even though they are in the power supply!. think about it.

No, it does not. See attached.
iknow_t
join:2012-05-03

iknow_t

Member

said by aurgathor:

said by iknow_t:

actually, the caps see the full audio spectrum drawn from the amp. even though they are in the power supply!. think about it.

No, it does not. See attached.

this would reduce the AMPLITUDE of the ripple from the audio signal appearing across the caps. if the caps didn't see the load attached, then you could put a parallel resonant circuit tuned for 15khz in series with input of this, and not see any effect on the audio quality at 15khz!. with an audio amp, the frequency drawn from the power supply varies between say 15hz and 15 kHz. so for the caps not to see that would take a whole new realm of design.

aurgathor
join:2002-12-01
Lynnwood, WA

aurgathor

Member

The load on the caps is the voltage regulator, and while that's not a perfect isolator, it's a actually a fairly good one.

As per »www.fairchildsemi.com/ds ··· M317.pdf the typical ripple rejection @120 Hz is between 60 - 75 db, and while that doesn't say anything about other frequencies, I'd expect to see comparable numbers over 100 Hz.

Furthermore, take a look at his preamp at: »tech.juaneda.com/en/proj ··· mp3.html
My analog is a little rusty, but looks to me that thing is operating in class A so there won't be a whole lot of audio going out to the caps on the Vcc line.

He does make some very interesting design choices like bypassing the voltage regulator with a 220 ohm resistor. And the input section (50k pot, 1M, 33.2k, 6.2k) is a rather significant voltage divider adding some extra noise.

SmokChsr
Who let the magic smoke out?
Premium Member
join:2006-03-17
Saint Augustine, FL

1 edit

SmokChsr to iknow_t

Premium Member

to iknow_t
said by iknow_t:

the caps see the full audio spectrum drawn from the amp. even though they are in the power supply!. think about it.

Yes the caps will audio draw, but the audio will not see any difference in the power source as long as the caps are good enough to keep the voltage about above the Vmin of the regulator, the DC will still be DC.