Relation between RC time constant of psu cap and slew rate - Page 3 - diyAudio
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Old 11th February 2013, 04:15 AM   #21
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Default Epcos

Quote:
Originally Posted by JMFahey View Post
In fact, I use EPCOS exclusively, I use "regular" EPCOS,
But if you want to go for the best of the best, be my guest .
Certainly can't hurt
@ JMFahey

Can You point out which particular Epcos series are sound-wise Yours best choice ?

Thnx,

Andreas
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Old 11th February 2013, 05:39 AM   #22
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Quote:
Originally Posted by JMFahey View Post
Yes.
Truth is, and going to the bottom of the problem, that those Sikorel are very good.
No doubt about that.
In fact, I use EPCOS exclusively, they are the best available in my market, period.
It's just that some parameter, measured in V/uSec and referred to overheating , was mixed with Amplifier slew rate, which does use same units, but for a different purpose.
Nothing beyond that.

By the way, I use "regular" EPCOS, no need to approach "Computer Grade " capacitors or similar spec.
I'd have to order the full box through ARROW or AVNET.
But if you want to go for the best of the best, be my guest .
Certainly can't hurt
I believe its B41550 sikorel original version tech acquired by Epcos but there are two things..

1. On the reviews its said that Halcro has lean bass and not impressive in < 100Hz bass frequencies..

2. What is the option shall we go with 7 x 1500uf caps or one 10000uf cap ?

even im about to order the only prob is lead time of 12weeks..
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Old 11th February 2013, 10:33 AM   #23
JMFahey is offline JMFahey  Argentina
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Dear smiley09 and rhythmandsandy.
Being an Engineer with 43 years experience building amplifiers commercially, and with the feet firmly on the ground, I don't care much about uncontrolled "listening tests" and "Magazine Reviews".
I prefer EPCOS for the very good reason that they are a "serious" company, I've been using them for said 43 years (since February 1969 to be precise, when I cloned my first Fender Bassman), for so long that I witnessed their colour change: from original "S&H" silver to yellow to "Siemens" orange to EPCOS black, go figure.
Always consistent, solid, long lasting, reasonable price, what's not to like?
"Sound" ?????
They are reservoir caps, holding a certain voltage between charging pulses, and providing current on demand.
Nothing more, nothing less.
Sound is made by the amplifier, not the PSU.
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Old 11th February 2013, 10:40 AM   #24
DF96 is offline DF96  England
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Quote:
Originally Posted by JMFahey
Sound is made by the amplifier, not the PSU.
True, but only when both are properly designed by someone who can do both arithmetic and algebra.
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Old 11th February 2013, 11:33 AM   #25
JMFahey is offline JMFahey  Argentina
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Obviously
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Old 11th February 2013, 12:00 PM   #26
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I believe EPCOS B41505 series is very good. Low ESR, high rip current, long life, snap in minimum dimensions...
And ultrafast diodes, that's my plan for building PSU. Capacitance is not important.
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Old 11th February 2013, 02:52 PM   #27
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did anybody try Alcon the specs look even better than Epcos..
http://www.icd-sales.com/Manufacture...G6DI%20ICD.pdf
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Old 11th February 2013, 04:03 PM   #28
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Better?
Better at what?
Slightly better ESR or impedance?
I have capacitors of an "nonfamous" brands here with even better ESR, slightly poorer impedanse and actually better leakage currents. Where does this place my caps?
As Fahey states earlier here, the capacitors in the PSU are there to store some energy, for the amplifier to use from on demand. (Together with the energy actually provided by the transformer) There is not very much to it.
And it has an unbelieveable little influence to the amplifiers slewrate in the amp anyway.

I am willing to go so far that an amplifier and its PSU wich is engineered in an adequate proper manner would give no influence to either the slewrate neither the sound as for the capacitors in the powersupply. If the cap there is named Jenssen, Epcos, BC, Vishay or "FengPeng" would do the job regardless.
The timeconstant even gets worse as the capacitance increases. Guess where this leads? There should actually be no problem getting the same timeconstant on a bad ESR-cap, opposed to a fenomenal good ESR-cap. But really one should look at the impedance of the cap instead. And what curvature the cap can show us out of that parameter.
That would tell us much more of how fast the capacitor is able to deliver this peak in current (keeping its voltage at a certain level) at the frequencies in speak.

My PSUs contains sufficient capacitance to provide energy to the amp when the transformer is "on vacation" (Read, have its voltage on a level lower than the requiresd to present any voltage in speak on the amplifiers output.
If my PSU doesn't deliver this required voltage, I add some more.
Result: Better ESR, Better Impedance, Better PSU. And this regardless what vcapacitor I use. I like it.
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Old 11th February 2013, 04:39 PM   #29
gootee is offline gootee  United States
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Quote:
Originally Posted by JMFahey View Post
Sound is made by the amplifier, not the PSU.
I completely agree with everything you've said. The following is really nothing but semantics. But what "makes the sound" could be thought of in more than one way.

When a layman sees an amplifier, the PSU is included in the term "amplifier". And after all, the two must work together, to make any sound.

But the fact remains that the sound we actually hear is rather-directly created by the PSU current (which is merely "modulated" by the amplifier). The PSU is providing the energy to make the sound. So in that sense, the PSU is making the sound, but under the control of the amplifier portion.

Also, the large majority of the current that makes the sound comes from the reservoir and decoupling caps. See the attached image from an LT-Spice simulation. This was discussed more-thoroughly around the post at Power Supply Resevoir Size .

None of this makes much difference, except maybe in the way that people think about how an amplifier works. I have found it to be a useful construct to use in order to help clarify both my own and other people's understandings of how amplifiers work. (It's also sometimes amusing to use just to "tweak" certain electrolytic-hating people who pretend that "the signal path" does not include the PSU.)

I too do not see how, with a properly-engineered PSU, different makes or models of reservoir caps could affect the sound. I suspect that when differences have been heard, it was because the design or implementation was marginal in some way, which allowed the differences to affect the PSU performance.

Keep up the great work.

Cheers,

Tom
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Old 12th February 2013, 12:14 AM   #30
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if its just esr then why cant use 100 x 100uf caps in parallel to achieve in micro ohms thus more beneficial? isnt that a good solution? or having one or two big 20000uf in parallel along with them does do the job perfect..
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