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Paul[_13_] Paul[_13_] is offline
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On 2/16/2017 7:23 PM, PStamler wrote:
On Thursday, February 16, 2017 at 2:43:15 PM UTC-6, Paul wrote:
On 2/16/2017 12:21 PM, PStamler wrote:
On Thursday, February 16, 2017 at 1:07:31 AM UTC-6, Paul wrote:
On 2/15/2017 10:13 PM, PStamler wrote:
At the risk of incurring a personal attack, I wish to report that I have tested common commercially-available capacitors, looking for the resonant frequency (frequency at which the device's impedance bottoms out; the cap stops behaving like a capacitor above this frequency and starts behaving like an inductor). The lowest resonant frequency I found was 5.3kHz, well within the audio range.


What was the capacitor value for that measurement?

It was a 3,300µF/50V Panasonic Series NHG electrolytic.




http://www.murata.com/~/media/webren...ow/12to14.ashx

So resonant freq f=1/(2*Pi*(L*C)**0.5)

So L=273nH.

So you had 273nH of parasitic/lead inductance? BULL****.

Also, where in the **** would you need such a large cap
in a speaker crossover?


I never said you would. A 3,300µF cap would more likely be found in a power supply, or perhaps in series with Rin in a noninverting opamp circuit.

IF DON'T WANT PERSONAL ATTACKS, DON'T MAKE STUPID **** UP!!!


I am making nothing up; I'm simply reporting the result of aome tests I ran, no counter the assertion that inductance isn't an issue with electrolytic capacitors.


But you still haven't addressed why you had such a high
parasitic/lead inductance.

Typical values are around 15nH for a leaded component....

????

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PStamler PStamler is offline
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On Thursday, February 16, 2017 at 8:39:44 PM UTC-6, Paul wrote:
On 2/16/2017 7:23 PM, PStamler wrote:
On Thursday, February 16, 2017 at 2:43:15 PM UTC-6, Paul wrote:
On 2/16/2017 12:21 PM, PStamler wrote:
On Thursday, February 16, 2017 at 1:07:31 AM UTC-6, Paul wrote:
On 2/15/2017 10:13 PM, PStamler wrote:
At the risk of incurring a personal attack, I wish to report that I have tested common commercially-available capacitors, looking for the resonant frequency (frequency at which the device's impedance bottoms out; the cap stops behaving like a capacitor above this frequency and starts behaving like an inductor). The lowest resonant frequency I found was 5.3kHz, well within the audio range.


What was the capacitor value for that measurement?

It was a 3,300µF/50V Panasonic Series NHG electrolytic.




http://www.murata.com/~/media/webren...ow/12to14.ashx

So resonant freq f=1/(2*Pi*(L*C)**0.5)

So L=273nH.

So you had 273nH of parasitic/lead inductance? BULL****.

Also, where in the **** would you need such a large cap
in a speaker crossover?


I never said you would. A 3,300µF cap would more likely be found in a power supply, or perhaps in series with Rin in a noninverting opamp circuit.

IF DON'T WANT PERSONAL ATTACKS, DON'T MAKE STUPID **** UP!!!


I am making nothing up; I'm simply reporting the result of aome tests I ran, no counter the assertion that inductance isn't an issue with electrolytic capacitors.


But you still haven't addressed why you had such a high
parasitic/lead inductance.

Typical values are around 15nH for a leaded component....

????


I can only report what I measured; I don't know why the caps measured that way. Incidentally, I also found, when I measured other values of cap:

100µF - 27.9kHz - 34kHz resonance
330µF - 16.2kHz - 17.8kHz "
1,000µF - 9.3kHz - 12.8kHz "
3,300µF - 5.3kHz - 8.6kHz "

So there's a clear correlation -- resonance frequency goes down as capacitance value goes up, broadly speaking. Within a given capacitance value, however, there seemed to be no correlation between physical size and resonance frequency (I confess that I expected to find one, but didn't).

This experiment was done as part of a power supply design project, so most of the capacitors I tested were ones you'd expect to find in power supplies..

Peace,
The Other Paul
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On 2/16/2017 8:12 PM, PStamler wrote:
On Thursday, February 16, 2017 at 8:39:44 PM UTC-6, Paul wrote:
On 2/16/2017 7:23 PM, PStamler wrote:
On Thursday, February 16, 2017 at 2:43:15 PM UTC-6, Paul wrote:
On 2/16/2017 12:21 PM, PStamler wrote:
On Thursday, February 16, 2017 at 1:07:31 AM UTC-6, Paul wrote:
On 2/15/2017 10:13 PM, PStamler wrote:
At the risk of incurring a personal attack, I wish to report that I have tested common commercially-available capacitors, looking for the resonant frequency (frequency at which the device's impedance bottoms out; the cap stops behaving like a capacitor above this frequency and starts behaving like an inductor). The lowest resonant frequency I found was 5.3kHz, well within the audio range.


What was the capacitor value for that measurement?

It was a 3,300µF/50V Panasonic Series NHG electrolytic.




http://www.murata.com/~/media/webren...ow/12to14.ashx

So resonant freq f=1/(2*Pi*(L*C)**0.5)

So L=273nH.

So you had 273nH of parasitic/lead inductance? BULL****.

Also, where in the **** would you need such a large cap
in a speaker crossover?

I never said you would. A 3,300µF cap would more likely be found in a power supply, or perhaps in series with Rin in a noninverting opamp circuit.

IF DON'T WANT PERSONAL ATTACKS, DON'T MAKE STUPID **** UP!!!

I am making nothing up; I'm simply reporting the result of aome tests I ran, no counter the assertion that inductance isn't an issue with electrolytic capacitors.


But you still haven't addressed why you had such a high
parasitic/lead inductance.

Typical values are around 15nH for a leaded component....

????


I can only report what I measured; I don't know why the caps measured that way. Incidentally, I also found, when I measured other values of cap:

100µF - 27.9kHz - 34kHz resonance
330µF - 16.2kHz - 17.8kHz "
1,000µF - 9.3kHz - 12.8kHz "
3,300µF - 5.3kHz - 8.6kHz "

So there's a clear correlation -- resonance frequency goes down as capacitance value goes up, broadly speaking. Within a given capacitance value, however, there seemed to be no correlation between physical size and resonance frequency (I confess that I expected to find one, but didn't).

This experiment was done as part of a power supply design project, so most of the capacitors I tested were ones you'd expect to find in power supplies.


Maybe you used long leads with alligator clips to do this test?
That would explain the abnormally high parasitic inductance.

And it would make your measurements useless, if you ended up
mounting the caps properly for the power supply.

But again, you don't use these kind of values in the actual audio
chain, or a crossover, so it doesn't matter anyways!



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PStamler wrote:


I can only report what I measured;


** But how no idea of how to measure.


100µF - 27.9kHz - 34kHz resonance
330µF - 16.2kHz - 17.8kHz "
1,000µF - 9.3kHz - 12.8kHz "
3,300µF - 5.3kHz - 8.6kHz "


** All the resonance values are wrong because you included connection lead inductance in the tests.

There is a good reason most electro cap ESR meters work at 100kHz - it is the frequency where electro impedance is at its very lowest over a wide range of values.

The true readings for your 3,300Uf cap are Fo at 19kHz with impedance rising above the ESR value only beyond 250kHz.

The inductance is the same as* 1 inch of wire * and you did not take that fact into account.

The ESR is higher in value until the frequency is in the long wave RF range..



....... Phil


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On 2/16/2017 8:12 PM, PStamler wrote:
On Thursday, February 16, 2017 at 8:39:44 PM UTC-6, Paul wrote:
On 2/16/2017 7:23 PM, PStamler wrote:
On Thursday, February 16, 2017 at 2:43:15 PM UTC-6, Paul wrote:
On 2/16/2017 12:21 PM, PStamler wrote:
On Thursday, February 16, 2017 at 1:07:31 AM UTC-6, Paul wrote:
On 2/15/2017 10:13 PM, PStamler wrote:
At the risk of incurring a personal attack, I wish to report that I have tested common commercially-available capacitors, looking for the resonant frequency (frequency at which the device's impedance bottoms out; the cap stops behaving like a capacitor above this frequency and starts behaving like an inductor). The lowest resonant frequency I found was 5.3kHz, well within the audio range.


What was the capacitor value for that measurement?

It was a 3,300µF/50V Panasonic Series NHG electrolytic.




http://www.murata.com/~/media/webren...ow/12to14.ashx

So resonant freq f=1/(2*Pi*(L*C)**0.5)

So L=273nH.

So you had 273nH of parasitic/lead inductance? BULL****.

Also, where in the **** would you need such a large cap
in a speaker crossover?

I never said you would. A 3,300µF cap would more likely be found in a power supply, or perhaps in series with Rin in a noninverting opamp circuit.

IF DON'T WANT PERSONAL ATTACKS, DON'T MAKE STUPID **** UP!!!

I am making nothing up; I'm simply reporting the result of aome tests I ran, no counter the assertion that inductance isn't an issue with electrolytic capacitors.


But you still haven't addressed why you had such a high
parasitic/lead inductance.

Typical values are around 15nH for a leaded component....

????


I can only report what I measured; I don't know why the caps measured that way. Incidentally, I also found, when I measured other values of cap:

100µF - 27.9kHz - 34kHz resonance
330µF - 16.2kHz - 17.8kHz "
1,000µF - 9.3kHz - 12.8kHz "
3,300µF - 5.3kHz - 8.6kHz "

So there's a clear correlation -- resonance frequency goes down as capacitance value goes up, broadly speaking. Within a given capacitance value, however, there seemed to be no correlation between physical size and resonance frequency (I confess that I expected to find one, but didn't).

This experiment was done as part of a power supply design project, so most of the capacitors I tested were ones you'd expect to find in power supplies.


Actually, you have to watch your ESR and ESL on switching power
supplies even MORE! They will typically use a switching frequency
of 100kHz to several MHz:

http://cds.linear.com/docs/en/applic...te/AN140fa.pdf

And from he

http://www.ti.com/lit/an/slta055/slta055.pdf

For input caps: "Ceramic capacitors placed right at the input of the
regulator reduce ripple voltage amplitude. Only
ceramics have the extremely low ESR that is needed to reduce the ripple
voltage amplitude. These
capacitors must be placed close to the regulator input pins to be
effective. Even a few nanohenries of
stray inductance in the capacitor current path raises the impedance at
the switching frequency to levels
that negate their effectiveness.
Large bulk capacitors do not reduce ripple voltage. The ESR of aluminum
electrolytics and most tantalums
are too high to allow for effective ripple reduction. Large input ripple
voltage can cause large amounts of
ripple current to flow in the bulk capacitors, causing excessive power
dissipation in the ESR parasitic."

For output caps: "The self resonant frequency is considered to be the
maximum usable frequency for a capacitor. Above
this frequency the impedance of the capacitor begins to rise as the ESL
of the capacitor begins to
dominate. Note that each capacitor type has a specific frequency band
over which it is most effective.
Therefore, a capacitor network of multiple capacitor types is more
effective in reducing impedance than
just one type."

Figure 5 and 7 and VERY interesting, and show how you have to design
around the resonant frequency of the caps.

COOL ****!










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PStamler PStamler is offline
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On Thursday, February 16, 2017 at 11:31:35 PM UTC-6, Phil Allison wrote:

** All the resonance values are wrong because you included connection lead inductance in the tests.



The inductance is the same as* 1 inch of wire * and you did not take that fact into account.


I offer the following results in rebuttal. All were obtained with the same test setup, including the samw test leads. From the resonaance figures I calculated the inductaance. These figures are for 3,300µF capacitors.

Incidentally, the inductance of 1" of wire, if it's 22 AWG, is 0.022µH; if it's 12AWG the inductance is 0.0162µH.

Capacitor Inductance
1 0.273µH
2 0.213µH
3 0.213µH
4 0.206µH
5 0.200µH
6 0.161µH
7 0.157µH
8 0.148µH
9 0.148µH
10 0.133µH
11 0.133µH
12 0.104µH

I submit that a ratio of 2.05:1 in inductances suggests that I'm measuring something besides the test leads' inductances.

Peace,
The Other Paul
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On 17/02/2017 12:41 PM, Scott Dorsey wrote:
In article , Trevor wrote:
On 16/02/2017 3:57 PM, PStamler wrote:
At the risk of attracting one of Mr. Allison's personal attacks,I
have measured the rise in capacitors' impedance at high frequencies
-- in some cases they switch from being capacitative to inductive
well within the audio band.


If you often use power supply filter caps etc. for audio coupling
purposes, that's definitely something you'd would want to take into
account I guess. :-) There is a reason why one selects components for
purpose of course.


Sadly, that was the technology of the 1970s. People were designing with
transistors but they were still thinking about tubes in their heads, so
everything was capacitively coupled and electrolytics were needed in order
to deal with the high values required due to the low impedances.


Name ONE item that used a 3,300uF cap (as mentioned elsewhere) for
coupling? I never saw one.


I was at a mastering facility a few years back with some audiophile label
guys who were looking at having some LPs cut. They asked the mastering
engineer if there were any electrolytic capacitors in the signal path of
the Neumann lathe amplifier and he about spit himself. "Millions of them!"
he said. "Millions!"


Well hundreds anyway, and perfectly adequate for the purpose. Least of
your worries with vinyl!


And so, because we live with a lot of older equipment designed in this
regime, we have to deal with it and we have to find capacitors appropriate
for the application.


Exactly. Not 3,300uF filter caps for coupling purposes.

Trevor.


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On 17/02/2017 2:12 PM, PStamler wrote:
On Thursday, February 16, 2017 at 8:39:44 PM UTC-6, Paul wrote:
On 2/16/2017 7:23 PM, PStamler wrote:
On Thursday, February 16, 2017 at 2:43:15 PM UTC-6, Paul wrote:
On 2/16/2017 12:21 PM, PStamler wrote:
On Thursday, February 16, 2017 at 1:07:31 AM UTC-6, Paul
wrote:
On 2/15/2017 10:13 PM, PStamler wrote:
At the risk of incurring a personal attack, I wish to
report that I have tested common commercially-available
capacitors, looking for the resonant frequency (frequency
at which the device's impedance bottoms out; the cap
stops behaving like a capacitor above this frequency and
starts behaving like an inductor). The lowest resonant
frequency I found was 5.3kHz, well within the audio
range.


What was the capacitor value for that measurement?

It was a 3,300µF/50V Panasonic Series NHG electrolytic.




http://www.murata.com/~/media/webren...ow/12to14.ashx



So resonant freq f=1/(2*Pi*(L*C)**0.5)

So L=273nH.

So you had 273nH of parasitic/lead inductance? BULL****.

Also, where in the **** would you need such a large cap in a
speaker crossover?

I never said you would. A 3,300µF cap would more likely be found
in a power supply, or perhaps in series with Rin in a
noninverting opamp circuit.

IF DON'T WANT PERSONAL ATTACKS, DON'T MAKE STUPID **** UP!!!

I am making nothing up; I'm simply reporting the result of aome
tests I ran, no counter the assertion that inductance isn't an
issue with electrolytic capacitors.


But you still haven't addressed why you had such a high
parasitic/lead inductance.

Typical values are around 15nH for a leaded component....

????


I can only report what I measured; I don't know why the caps measured
that way. Incidentally, I also found, when I measured other values of
cap:

100µF - 27.9kHz - 34kHz resonance 330µF - 16.2kHz - 17.8kHz "
1,000µF - 9.3kHz - 12.8kHz " 3,300µF - 5.3kHz - 8.6kHz "

So there's a clear correlation -- resonance frequency goes down as
capacitance value goes up, broadly speaking. Within a given
capacitance value, however, there seemed to be no correlation between
physical size and resonance frequency (I confess that I expected to
find one, but didn't).

This experiment was done as part of a power supply design project, so
most of the capacitors I tested were ones you'd expect to find in
power supplies.


Exactly, and those resonances are hardly a problem at 50-120Hz. People
do often worry about which caps they choose in the 100uF range for
coupling purposes however.

Trevor.



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On 17/02/2017 5:47 PM, PStamler wrote:
I offer the following results in rebuttal. All were obtained with the
same test setup, including the samw test leads. From the resonaance
figures I calculated the inductaance. These figures are for 3,300µF
capacitors.

Incidentally, the inductance of 1" of wire, if it's 22 AWG, is
0.022µH; if it's 12AWG the inductance is 0.0162µH.

Capacitor Inductance 1 0.273µH 2 0.213µH 3
0.213µH 4 0.206µH 5 0.200µH 6 0.161µH 7
0.157µH 8 0.148µH 9 0.148µH 10 0.133µH 11
0.133µH 12 0.104µH

I submit that a ratio of 2.05:1 in inductances suggests that I'm
measuring something besides the test leads' inductances.


According to your own figures, a foot of test lead (*2), will be in the
same ball park as your readings, or more!

Trevor.


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On Friday, February 17, 2017 at 1:28:00 AM UTC-6, Trevor wrote:
On 17/02/2017 5:47 PM, PStamler wrote:
I offer the following results in rebuttal. All were obtained with the
same test setup, including the samw test leads. From the resonaance
figures I calculated the inductaance. These figures are for 3,300µF
capacitors.

Incidentally, the inductance of 1" of wire, if it's 22 AWG, is
0.022µH; if it's 12AWG the inductance is 0.0162µH.

Capacitor Inductance 1 0.273µH 2 0.213µH 3
0.213µH 4 0.206µH 5 0.200µH 6 0.161µH 7
0.157µH 8 0.148µH 9 0.148µH 10 0.133µH 11
0.133µH 12 0.104µH

I submit that a ratio of 2.05:1 in inductances suggests that I'm
measuring something besides the test leads' inductances.


According to your own figures, a foot of test lead (*2), will be in the
same ball park as your readings, or more!


Actually just 1 foot; my clip leads were 6" long.

But you make a good point.

Peace,
The Other Paul


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On 2/17/2017 1:18 AM, PStamler wrote:
On Friday, February 17, 2017 at 1:28:00 AM UTC-6, Trevor wrote:
On 17/02/2017 5:47 PM, PStamler wrote:
I offer the following results in rebuttal. All were obtained with the
same test setup, including the samw test leads. From the resonaance
figures I calculated the inductaance. These figures are for 3,300µF
capacitors.

Incidentally, the inductance of 1" of wire, if it's 22 AWG, is
0.022µH; if it's 12AWG the inductance is 0.0162µH.

Capacitor Inductance 1 0.273µH 2 0.213µH 3
0.213µH 4 0.206µH 5 0.200µH 6 0.161µH 7
0.157µH 8 0.148µH 9 0.148µH 10 0.133µH 11
0.133µH 12 0.104µH

I submit that a ratio of 2.05:1 in inductances suggests that I'm
measuring something besides the test leads' inductances.


According to your own figures, a foot of test lead (*2), will be in the
same ball park as your readings, or more!


Actually just 1 foot; my clip leads were 6" long.

But you make a good point.


Redo the test, without the test leads.

The resonant frequency should go up...

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Don Pearce[_3_] Don Pearce[_3_] is offline
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On Fri, 17 Feb 2017 03:25:18 -0700, Paul wrote:

On 2/17/2017 1:18 AM, PStamler wrote:
On Friday, February 17, 2017 at 1:28:00 AM UTC-6, Trevor wrote:
On 17/02/2017 5:47 PM, PStamler wrote:
I offer the following results in rebuttal. All were obtained with the
same test setup, including the samw test leads. From the resonaance
figures I calculated the inductaance. These figures are for 3,300µF
capacitors.

Incidentally, the inductance of 1" of wire, if it's 22 AWG, is
0.022µH; if it's 12AWG the inductance is 0.0162µH.

Capacitor Inductance 1 0.273µH 2 0.213µH 3
0.213µH 4 0.206µH 5 0.200µH 6 0.161µH 7
0.157µH 8 0.148µH 9 0.148µH 10 0.133µH 11
0.133µH 12 0.104µH

I submit that a ratio of 2.05:1 in inductances suggests that I'm
measuring something besides the test leads' inductances.

According to your own figures, a foot of test lead (*2), will be in the
same ball park as your readings, or more!


Actually just 1 foot; my clip leads were 6" long.

But you make a good point.


Redo the test, without the test leads.

The resonant frequency should go up...


Easier way. Just calibrate by connecting the test leads together.
Measure the inductance and subtract it from whatever is later
measured.

d

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On 17/02/2017 7:47 PM, PStamler wrote:
On Thursday, February 16, 2017 at 11:31:35 PM UTC-6, Phil Allison wrote:

** All the resonance values are wrong because you included connection lead inductance in the tests.



The inductance is the same as* 1 inch of wire * and you did not take that fact into account.


I offer the following results in rebuttal. All were obtained with the same test setup, including the samw test leads. From the resonaance figures I calculated the inductaance. These figures are for 3,300µF capacitors.

Incidentally, the inductance of 1" of wire, if it's 22 AWG, is 0.022µH; if it's 12AWG the inductance is 0.0162µH.

Capacitor Inductance
1 0.273µH
2 0.213µH
3 0.213µH
4 0.206µH
5 0.200µH
6 0.161µH
7 0.157µH
8 0.148µH
9 0.148µH
10 0.133µH
11 0.133µH
12 0.104µH

I submit that a ratio of 2.05:1 in inductances suggests that I'm measuring something besides the test leads' inductances.

Peace,
The Other Paul


Why not actually test capacitors that are likely to be found in series
in a signal path, rather than used in their designed application as
reservoir capacitors in a power supply (and maybe in one model
audiophool valve/tube power amp) ?

And on input to my old KEF R105 crossovers (but I'm sure that was a
designed-in factor)

geoff

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On Sat, 18 Feb 2017 00:39:04 +1300, geoff
wrote:

On 17/02/2017 7:47 PM, PStamler wrote:
On Thursday, February 16, 2017 at 11:31:35 PM UTC-6, Phil Allison wrote:

** All the resonance values are wrong because you included connection lead inductance in the tests.



The inductance is the same as* 1 inch of wire * and you did not take that fact into account.


I offer the following results in rebuttal. All were obtained with the same test setup, including the samw test leads. From the resonaance figures I calculated the inductaance. These figures are for 3,300µF capacitors.

Incidentally, the inductance of 1" of wire, if it's 22 AWG, is 0.022µH; if it's 12AWG the inductance is 0.0162µH.

Capacitor Inductance
1 0.273µH
2 0.213µH
3 0.213µH
4 0.206µH
5 0.200µH
6 0.161µH
7 0.157µH
8 0.148µH
9 0.148µH
10 0.133µH
11 0.133µH
12 0.104µH

I submit that a ratio of 2.05:1 in inductances suggests that I'm measuring something besides the test leads' inductances.

Peace,
The Other Paul


Why not actually test capacitors that are likely to be found in series
in a signal path, rather than used in their designed application as
reservoir capacitors in a power supply (and maybe in one model
audiophool valve/tube power amp) ?

And on input to my old KEF R105 crossovers (but I'm sure that was a
designed-in factor)


Hang on there. Power supply capacitors absolutely are in the signal
path. The alternating speaker current flows through them as a series
element.

d

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david gourley wrote:
(Scott Dorsey) said...news
david gourley wrote:

My Dynaco ST120 channels use that value for output coupling to the speaker.


Is mentioning an ST120 like mentioning Hitler? Is this thread closed now?


Wow, sorry didn't know it was THAT bad. I've used it for a guitar and bass
amp.


It has some interesting issues. It's slew-limited, which was typical of
amps back then, but in part because of single supply rail and the
non-complementary output stage, the slew limiting is asymmetric.

On top of all that it has that huge blocking capacitor on the output which
isn't helping anything... and then they wind the output choke around the
blocking capacitor which is not exactly a linear core... that becomes a
really remarkable source of distortion.

Probably make a perfectly fine bass amp, though. Because of all that DC
blocking and that huge choke on the output to move all the poles to the
left, the thing is much more stable than many of the amps from that era.

But, when I think about why solid state electronics had such a bad reputation
for sound quality in the seventies, the ST120 is one of the first things I
think about.
--scott

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In article , Paul wrote:

But you still haven't addressed why you had such a high
parasitic/lead inductance.


He hasn't, but that doesn't mean it's not there. And it's not the lead
inductance at all, it's the inductance of the foil wrap. We're talking
some hundreds of turns in many capacitors.

If all this bothers you, use a stacked film cap and don't worry.
--scott
--
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On Friday, February 17, 2017 at 9:26:38 AM UTC-5, Scott Dorsey wrote:
In article , Paul wrote:

But you still haven't addressed why you had such a high
parasitic/lead inductance.


He hasn't, but that doesn't mean it's not there. And it's not the lead
inductance at all, it's the inductance of the foil wrap. We're talking
some hundreds of turns in many capacitors.

If all this bothers you, use a stacked film cap and don't worry.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."


yes.... and regardless of what the cause of that inductance that the OP is seeing, the value of that inductance and the value of the Z at audio is sooo looow that it is of no concern.

m

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(Scott Dorsey) said...news
david gourley wrote:
(Scott Dorsey) said...news85ked$gqe$1

@panix2.panix.com:

david gourley wrote:

My Dynaco ST120 channels use that value for output coupling to the

speaker.

Is mentioning an ST120 like mentioning Hitler? Is this thread closed

now?

Wow, sorry didn't know it was THAT bad. I've used it for a guitar and

bass
amp.


It has some interesting issues. It's slew-limited, which was typical of
amps back then, but in part because of single supply rail and the
non-complementary output stage, the slew limiting is asymmetric.

On top of all that it has that huge blocking capacitor on the output

which
isn't helping anything... and then they wind the output choke around the
blocking capacitor which is not exactly a linear core... that becomes a
really remarkable source of distortion.

Probably make a perfectly fine bass amp, though. Because of all that DC
blocking and that huge choke on the output to move all the poles to the
left, the thing is much more stable than many of the amps from that era.

But, when I think about why solid state electronics had such a bad

reputation
for sound quality in the seventies, the ST120 is one of the first things

I
think about.
--scott


Surely those Southwest Tiger amps fit in some place near the top ? g

david

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On 17 Feb 2017 09:26:36 -0500, Scott Dorsey wrote:

In article , Paul wrote:

But you still haven't addressed why you had such a high
parasitic/lead inductance.


He hasn't, but that doesn't mean it's not there. And it's not the lead
inductance at all, it's the inductance of the foil wrap. We're talking
some hundreds of turns in many capacitors.

If all this bothers you, use a stacked film cap and don't worry.


The capacity of some capacitors (especially multi layer ceramic) is
dependent on the voltage across them; in some cases the value gets
halved! You don't want such in an audio path if the audio voltage is
a significant part of the blocking voltage (if any). See
http://www.eetimes.com/author.asp?se...oc_id=1330877& .

Also
http://www.intersil.com/content/dam/...n13/an1325.pdf
has a nice table of different capacitor types and their trade-offs.

Mat Nieuwenhoven


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david gourley wrote:

Surely those Southwest Tiger amps fit in some place near the top ? g


They have some stability issues, to say the least. But as far as exploding
into flames go, they are no match for the Phase Linears.
--scott

--
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On 2/17/2017 7:26 AM, Scott Dorsey wrote:
In article , Paul wrote:

But you still haven't addressed why you had such a high
parasitic/lead inductance.


He hasn't, but that doesn't mean it's not there. And it's not the lead
inductance at all, it's the inductance of the foil wrap. We're talking
some hundreds of turns in many capacitors.

If all this bothers you, use a stacked film cap and don't worry.
--scott


So let's assume the leaded capacitor has about 15nH of self
inductance.

270-15= 255 nH.

And let's guesstimate 6nH of inductance per cm of lead length.

42.5 cm of added lead length???

THAT WOULD BE SLOPPY ENGINEERING!!!!

:/

http://sound.whsites.net/articles/capacitors.htm

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..

The capacity of some capacitors (especially multi layer ceramic) is
dependent on the voltage across them; in some cases the value gets
halved! You don't want such in an audio path if the audio voltage is
a significant part of the blocking voltage (if any). See
http://www.eetimes.com/author.asp?se...oc_id=1330877& .

Also
http://www.intersil.com/content/dam/...n13/an1325.pdf
has a nice table of different capacitor types and their trade-offs.

Mat Nieuwenhoven


no it's not that bad

if the cap "in the audio path" is a coupling cap
then it's job is to have as little as possible audio voltage drop
across it... and it will be sized accordingly.

So then only at very high amplitude and very low frequency bass, i.e. below the - 3 dB point, will there be any significant voltage drop ACROSS the cap.

In that special case, there may be added distortion.

The other case is when the cap is used as part of a filter and there is
large audio voltage ACROSS (not through) the cap.

In most ordinary coupling cap applications, it is not a problem.

m





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On 2/17/17 11:58 AM, Mat Nieuwenhoven wrote:
On 17 Feb 2017 09:26:36 -0500, Scott Dorsey wrote:



The capacity of some capacitors (especially multi layer ceramic) is
dependent on the voltage across them; in some cases the value gets
halved! You don't want such in an audio path if the audio voltage is
a significant part of the blocking voltage (if any). See
http://www.eetimes.com/author.asp?se...oc_id=1330877& .

Also
http://www.intersil.com/content/dam/...n13/an1325.pdf
has a nice table of different capacitor types and their trade-offs.

Mat Nieuwenhoven


Both of those references seem to discuss the shortcomings of the
crappier ceramic capacitors, with just a passing reference to the
premium ceramic capacitors known as the "COG" or "NP0" types. The
COG/NP0 type deserves special consideration. If anyone is interested,
page 8 of my 990 data package describes some of the differences between
the three most common types of ceramic capacitors, the COG/NP0, X7R and Z5U.

http://www.johnhardyco.com/pdf/990.pdf

Thank you.

John Hardy
The John Hardy Co.
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Mat Nieuwenhoven wrote:
The capacity of some capacitors (especially multi layer ceramic) is
dependent on the voltage across them; in some cases the value gets
halved! You don't want such in an audio path if the audio voltage is
a significant part of the blocking voltage (if any). See
http://www.eetimes.com/author.asp?se...oc_id=1330877& .


Hey! I bet I could use that as a compressor!
--scott


--
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In article , Paul wrote:
So let's assume the leaded capacitor has about 15nH of self
inductance.

270-15= 255 nH.

And let's guesstimate 6nH of inductance per cm of lead length.

42.5 cm of added lead length???


Sounds about right, since you have more than a meter of foil wrapped up
inside that thing, and you have mutual coupling between winds.

THAT WOULD BE SLOPPY ENGINEERING!!!!


Don't like it? Use a stacked film type!
--scott
--
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PStamler wrote:

Phil Allison wrote:

** All the resonance values are wrong because you included connection lead inductance in the tests.



The inductance is the same as* 1 inch of wire * and you did not take that fact into account.



I offer the following results in rebuttal.





Incidentally, the inductance of 1" of wire, if it's 22 AWG, is 0.022µH;
if it's 12AWG the inductance is 0.0162µH.


** Correct - so ****ing what?

Consider that your fake results are CONTRADICTED by everyone else !!

BTW:

You snipped my info on electro ESR meters working at 100kHz.

It alone PROVES you are wrong.

You are one stubborn POS aren't you ?



..... Phil
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On Friday, February 17, 2017 at 7:44:12 PM UTC-6, Phil Allison wrote:
PStamler wrote:

Phil Allison wrote:

** All the resonance values are wrong because you included connection lead inductance in the tests.



The inductance is the same as* 1 inch of wire * and you did not take that fact into account.



I offer the following results in rebuttal.





Incidentally, the inductance of 1" of wire, if it's 22 AWG, is 0.022µH;
if it's 12AWG the inductance is 0.0162µH.


** Correct - so ****ing what?

Consider that your fake results are CONTRADICTED by everyone else !!


They weren't fake, just wrong, which I freely acknowledge.

BTW:

You snipped my info on electro ESR meters working at 100kHz.

It alone PROVES you are wrong.


It's actually a side issue.

You are one stubborn POS aren't you ?


Yes -- it's a useful survival skill.

Peace,
The Other Paul


.... Phil


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PStamler wrote:



Consider that your fake results are CONTRADICTED by everyone else !!


They weren't fake, just wrong, which I freely acknowledge.


** Really - when did that happen ??


BTW:

You snipped my info on electro ESR meters working at 100kHz.

It alone PROVES you are wrong.


It's actually a side issue.


** No, it proves how naïve and stubborn you are.

That electro ESR meters typically work at 100kHz *contradicts* all your mad assertions.

It PROVES that ESL has no effect on impedance until well above that frequency.

There are none so blind as those who will not see.


You are one stubborn POS aren't you ?


Yes -- it's a useful survival skill.



** No round here pal.




..... Phil




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On 18/02/2017 2:13 PM, Scott Dorsey wrote:
In article , Paul wrote:
So let's assume the leaded capacitor has about 15nH of self
inductance.

270-15= 255 nH.

And let's guesstimate 6nH of inductance per cm of lead length.

42.5 cm of added lead length???


Sounds about right, since you have more than a meter of foil wrapped up
inside that thing, and you have mutual coupling between winds.

THAT WOULD BE SLOPPY ENGINEERING!!!!


Don't like it? Use a stacked film type!
--scott



Isn't a wonder that one can hear anything vaguely coherent at all out of
nearly all audio gear ....

geoff


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geoff wrote:

Isn't a wonder that one can hear anything vaguely coherent at all out of
nearly all audio gear ....


Well, thats part of the problem with measurement. If you measure carefully
enough, you'll find all kinds of weird stuff going on. Whether it actually
matters or not is a different issue.
--scott
--
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On 2/17/2017 6:13 PM, Scott Dorsey wrote:
In article , Paul wrote:
So let's assume the leaded capacitor has about 15nH of self
inductance.

270-15= 255 nH.

And let's guesstimate 6nH of inductance per cm of lead length.

42.5 cm of added lead length???


Sounds about right, since you have more than a meter of foil wrapped up
inside that thing, and you have mutual coupling between winds.


Incorrect.

270nH would be a ridiculous amount of parasitic inductance.

The Other Paul admitted his leads were 6", so he added
about a foot of lead length!

And look here again:

http://www.ti.com/lit/an/slta055/slta055.pdf

Check plots 4, 5, and 7.

Calculate the ESL from the resonant frequencies.

You'll see most are in the tens of nH.


THAT WOULD BE SLOPPY ENGINEERING!!!!


Don't like it? Use a stacked film type!
--scott


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On Friday, February 17, 2017 at 8:00:45 PM UTC-6, Phil Allison wrote:
PStamler wrote:



Consider that your fake results are CONTRADICTED by everyone else !!


They weren't fake, just wrong, which I freely acknowledge.


** Really - when did that happen ??


Just now -- see above.

Peace,
The Other Paul
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On Fri, 17 Feb 2017 13:11:59 -0800 (PST), wrote:

..

The capacity of some capacitors (especially multi layer ceramic) is
dependent on the voltage across them; in some cases the value gets
halved! You don't want such in an audio path if the audio voltage is
a significant part of the blocking voltage (if any). See
http://www.eetimes.com/author.asp?se...oc_id=1330877& .

Also
http://www.intersil.com/content/dam/...n13/an1325.pdf
has a nice table of different capacitor types and their trade-offs.

Mat Nieuwenhoven


no it's not that bad

if the cap "in the audio path" is a coupling cap
then it's job is to have as little as possible audio voltage drop
across it... and it will be sized accordingly.


In general yes, but with non-pro equipment cost is an important issue
and even coupling caps are likely to be as small as possible.
Fortunately, they are unlike to be the multilayer ceramics.
Electrolytics are much better in this respect.

So then only at very high amplitude and very low frequency bass, i.e. below the - 3 dB point, will there be any significant voltage drop ACROSS the cap.

In that special case, there may be added distortion.


It's not just the voltage. If the cap is voltage dependent, then the
current through it as result of an AC voltage will be distorted. See
for instance
http://www.cliftonlaboratories.com/c...age_change.htm , a
little bit down you see a plot of 922 Hz voltage / current
over/through a Y5U type cap (about the worst case) . Even though it's
not so real-life, I found this shocking.
The same page also shows that electrolytic and tantalum caps are much
better in this respect.

The other case is when the cap is used as part of a filter and there is
large audio voltage ACROSS (not through) the cap.

In most ordinary coupling cap applications, it is not a problem.


True. Most higher audio voltages, with apologies to our
thermionic-loving friends :-) , will nowadays be found in internal
passive loudspeaker filters, and there high-quality caps are
typically used.

Mat Nieuwenhoven


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On 17 Feb 2017 20:11:57 -0500, Scott Dorsey wrote:

Mat Nieuwenhoven wrote:
The capacity of some capacitors (especially multi layer ceramic) is
dependent on the voltage across them; in some cases the value gets
halved! You don't want such in an audio path if the audio voltage is
a significant part of the blocking voltage (if any). See
http://www.eetimes.com/author.asp?se...oc_id=1330877& .


Hey! I bet I could use that as a compressor!


:-) As a distortion thingy, more likely, albeit frequency and volume
dependent. See
http://www.cliftonlaboratories.com/c...age_change.htm ,
where a sine voltage across the cap results in a more or less
triangular current through it. The distortion would be more if the AC
was higher. The graph show the tops more or less OK, but the flanks
are distorted. I bet this would sound very different from
top-limiting, such as in guitar amps or overdriven tubes.

Mat Nieuwenhoven




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On Fri, 17 Feb 2017 17:24:55 -0600, John Hardy wrote:

On 2/17/17 11:58 AM, Mat Nieuwenhoven wrote:
On 17 Feb 2017 09:26:36 -0500, Scott Dorsey wrote:



The capacity of some capacitors (especially multi layer ceramic) is
dependent on the voltage across them; in some cases the value gets
halved! You don't want such in an audio path if the audio voltage is
a significant part of the blocking voltage (if any). See
http://www.eetimes.com/author.asp?se...oc_id=1330877& .

Also
http://www.intersil.com/content/dam/...n13/an1325.pdf
has a nice table of different capacitor types and their trade-offs.

Mat Nieuwenhoven


Both of those references seem to discuss the shortcomings of the
crappier ceramic capacitors, with just a passing reference to the
premium ceramic capacitors known as the "COG" or "NP0" types. The
COG/NP0 type deserves special consideration. If anyone is interested,
page 8 of my 990 data package describes some of the differences between
the three most common types of ceramic capacitors, the COG/NP0, X7R and Z5U.

http://www.johnhardyco.com/pdf/990.pdf


Very interesting document, thanks. Indeed, the COG/NP0 caps are fine
in this respect.

Are transformer-based mic amps still used? I can see that a
transformer-based gain is essentially noise-free, but aren't they
sensitive to microphone impedance?

One question about the MPC-1 mic pre-amp schematic, if I may. For the
+/- 15V the 78L15/79L15 regulators are used. I thought that these
were quite noisy? I've seen recommenations to use adjustable
regulators ones instead.

Mat Nieuwenhoven




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On Sat, 18 Feb 2017 20:45:19 GMT, Don Pearce wrote:

snip

Both of those references seem to discuss the shortcomings of the
crappier ceramic capacitors, with just a passing reference to the
premium ceramic capacitors known as the "COG" or "NP0" types. The
COG/NP0 type deserves special consideration. If anyone is interested,
page 8 of my 990 data package describes some of the differences between
the three most common types of ceramic capacitors, the COG/NP0, X7R and Z5U.

http://www.johnhardyco.com/pdf/990.pdf


Very interesting document, thanks. Indeed, the COG/NP0 caps are fine
in this respect.

Are transformer-based mic amps still used? I can see that a
transformer-based gain is essentially noise-free, but aren't they
sensitive to microphone impedance?

One question about the MPC-1 mic pre-amp schematic, if I may. For the
+/- 15V the 78L15/79L15 regulators are used. I thought that these
were quite noisy? I've seen recommenations to use adjustable
regulators ones instead.

Mat Nieuwenhoven



Transformer based gain? It isn't gain - it is just impedance
transformation.

Yes, but at the same time transforming voltage. And because the gain
stages after that are only interested in voltage, not power, why
wouldn't it be a noise-free voltage gain?

And most transformers have a loss about 1dB, which
equates to a 1dB added noise figure.

The 990 opamp pdf lists a transformer gain of 5.6 dB.

If you want a quiet preamp you do
away with the transformer and design the front end to present a noise
match to the mic.

Understood, so such a preamp will have a recommended mic impedance?

This will also provide the lowest distortion, which
transformers won't manage at the low end.

I didn't know transformers have more distortion at low levels. Do
current top-of-the line mic preamps in mixers use discrete or
integrated circruitry?

As for regulator noise, if your preamp has even a half-way decent
PSRR, it simply isn't a factor.


Unless it's set to a high gain, which it isn't here.

Mat Nieuwenhoven




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On Sat, 18 Feb 2017 20:36:32 +0100 (CET), "Mat Nieuwenhoven"
wrote:

On Fri, 17 Feb 2017 17:24:55 -0600, John Hardy wrote:

On 2/17/17 11:58 AM, Mat Nieuwenhoven wrote:
On 17 Feb 2017 09:26:36 -0500, Scott Dorsey wrote:



The capacity of some capacitors (especially multi layer ceramic) is
dependent on the voltage across them; in some cases the value gets
halved! You don't want such in an audio path if the audio voltage is
a significant part of the blocking voltage (if any). See
http://www.eetimes.com/author.asp?se...oc_id=1330877& .

Also
http://www.intersil.com/content/dam/...n13/an1325.pdf
has a nice table of different capacitor types and their trade-offs.

Mat Nieuwenhoven


Both of those references seem to discuss the shortcomings of the
crappier ceramic capacitors, with just a passing reference to the
premium ceramic capacitors known as the "COG" or "NP0" types. The
COG/NP0 type deserves special consideration. If anyone is interested,
page 8 of my 990 data package describes some of the differences between
the three most common types of ceramic capacitors, the COG/NP0, X7R and Z5U.

http://www.johnhardyco.com/pdf/990.pdf


Very interesting document, thanks. Indeed, the COG/NP0 caps are fine
in this respect.

Are transformer-based mic amps still used? I can see that a
transformer-based gain is essentially noise-free, but aren't they
sensitive to microphone impedance?

One question about the MPC-1 mic pre-amp schematic, if I may. For the
+/- 15V the 78L15/79L15 regulators are used. I thought that these
were quite noisy? I've seen recommenations to use adjustable
regulators ones instead.

Mat Nieuwenhoven



Transformer based gain? It isn't gain - it is just impedance
transformation. And most transformers have a loss about 1dB, which
equates to a 1dB added noise figure. If you want a quiet preamp you do
away with the transformer and design the front end to present a noise
match to the mic. This will also provide the lowest distortion, which
transformers won't manage at the low end.

As for regulator noise, if your preamp has even a half-way decent
PSRR, it simply isn't a factor.
d

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Mat Nieuwenhoven wrote:

:-) As a distortion thingy, more likely, albeit frequency and volume
dependent. See
http://www.cliftonlaboratories.com/c...age_change.htm ,
where a sine voltage across the cap results in a more or less
triangular current through it. The distortion would be more if the AC
was higher. The graph show the tops more or less OK, but the flanks
are distorted. I bet this would sound very different from
top-limiting, such as in guitar amps or overdriven tubes.


Sure, but more interestingly I could put a large DC bias voltage across
them, and a small AC signal voltage. As I adjust the DC bias, the low
frequency corner moves up and down.

A little like the whole magnetic amplifier trick.
--scott

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Don Pearce[_3_] Don Pearce[_3_] is offline
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Default APOLOGIES TO ALL: PIEZO TWEETERS DO SOUND LIKE ****!!!!

On Sat, 18 Feb 2017 21:26:05 +0100 (CET), "Mat Nieuwenhoven"
wrote:

On Sat, 18 Feb 2017 20:45:19 GMT, Don Pearce wrote:

snip

Both of those references seem to discuss the shortcomings of the
crappier ceramic capacitors, with just a passing reference to the
premium ceramic capacitors known as the "COG" or "NP0" types. The
COG/NP0 type deserves special consideration. If anyone is interested,
page 8 of my 990 data package describes some of the differences between
the three most common types of ceramic capacitors, the COG/NP0, X7R and Z5U.

http://www.johnhardyco.com/pdf/990.pdf

Very interesting document, thanks. Indeed, the COG/NP0 caps are fine
in this respect.

Are transformer-based mic amps still used? I can see that a
transformer-based gain is essentially noise-free, but aren't they
sensitive to microphone impedance?

One question about the MPC-1 mic pre-amp schematic, if I may. For the
+/- 15V the 78L15/79L15 regulators are used. I thought that these
were quite noisy? I've seen recommenations to use adjustable
regulators ones instead.

Mat Nieuwenhoven



Transformer based gain? It isn't gain - it is just impedance
transformation.

Yes, but at the same time transforming voltage. And because the gain
stages after that are only interested in voltage, not power, why
wouldn't it be a noise-free voltage gain?


No, not noise free. Transformers have a loss figure, which translates
directly into noise.


And most transformers have a loss about 1dB, which
equates to a 1dB added noise figure.

The 990 opamp pdf lists a transformer gain of 5.6 dB.


That is the transformation ratio they recommend to bring the mic
impedance up to the optimum noise match impedance. You still have to
add the transformer loss though.

If you want a quiet preamp you do
away with the transformer and design the front end to present a noise
match to the mic.

Understood, so such a preamp will have a recommended mic impedance?

Yes, although it is a fairly broad peak.

This will also provide the lowest distortion, which
transformers won't manage at the low end.

I didn't know transformers have more distortion at low levels. Do
current top-of-the line mic preamps in mixers use discrete or
integrated circruitry?

Not low levels, low frequencies.

As for regulator noise, if your preamp has even a half-way decent
PSRR, it simply isn't a factor.


Unless it's set to a high gain, which it isn't here.

The gain shouldn't change the PSRR, but it does imply a low signal
level, so proportionately the effect will be greater. A resistor and a
fat electrolytic will kill the noise.

d

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