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Chip Amps Amplifiers based on integrated circuits

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Old 3rd March 2009, 09:52 PM   #321
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Quote:
Originally posted by ClaveFremen


here it's the same and not only for electronic components.

If you want something that it's not mainstream you must buy online...

Surely GB are interesting, particularly those like this one, for components you can buy online.

Peter and Uriah obviously deserves our gratitude



I've tried.

with tones is quite impossible...

With bass notes (AC/DC - Ride On and Bublé - Fever) at full volume (0db attenuation) at near field I would confirm my subjective impressions, differences are not night and day but audibles.

The 'body' of the note with R46 is not as big as DC coupled or PHE426, IMHO

You could try by yourself temporarily shorting C13 ( only if you're SURE your pre/cd has NO DC OFFSET!!!! Measure it! )

wich is the "Safe" DC Offset allowed fromPRE?
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Old 3rd March 2009, 10:10 PM   #322
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Quote:
Originally posted by samsagaz
wich is the "Safe" DC Offset allowed fromPRE?
It's easy, 0.0 mV

Or, if you prefer, pre/cd has output DC blocking caps (= NO DC OFFSET= 0.0 mV).
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Old 3rd March 2009, 10:34 PM   #323
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Quote:
Originally posted by ClaveFremen
You could try by yourself temporarily shorting C13 ( only if you're SURE your pre/cd has NO DC OFFSET!!!! Measure it! )
I've tried myself and simply shorting cap I can't hear any difference...

And it's right, a wire in parallel is like a cap of infinite value (circa), so the sonic signature of the real cap remain...

Only swapping caps or caps and wire differences are audible.

Sorry for the wrong information...
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Old 4th March 2009, 12:12 AM   #324
schro20 is offline schro20  United States
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Quote:
Originally posted by ClaveFremen
I've tried myself and simply shorting cap I can't hear any difference...

And it's right, a wire in parallel is like a cap of infinite value (circa), so the sonic signature of the real cap remain...
I am confused. While parallel capacitances are additive, shorting a capacitor takes it out, no? Just consider the fact that shorting it allows DC through, while otherwise DC would not go through. There is no chance for energy storage in the cap since the short keeps it from charging. What am I missing?

peter
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Old 4th March 2009, 01:15 AM   #325
troystg is offline troystg  United States
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Quote:
Originally posted by schro20

I am confused. While parallel capacitances are additive, shorting a capacitor takes it out, no? Just consider the fact that shorting it allows DC through, while otherwise DC would not go through. There is no chance for energy storage in the cap since the short keeps it from charging. What am I missing?

peter

You're not missing anything. Shorting across a cap effectively takes it out of the circuit.

It definitely has audible effects AND allows DC to pass.
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Old 4th March 2009, 10:08 AM   #326
AndrewT is offline AndrewT  Scotland
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having DC blocking caps in both the source and receiver is a complete waste.
You only need to block once.

Fit dual inputs to your power amp.
One RCA using the DC blocking cap, labeled AC input.
One RCA bypassing the DC blocker, labeled DC input.

The amp will still be AC coupled, due to the DC blocking cap in the NFB leg and the single DC blocking cap somewhere on the input.

This way you choose which is the better sounding cap, the one supplied as standard in your source (which can also be bypassed) or your very special and correctly sized one at your input.
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Old 4th March 2009, 02:50 PM   #327
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Quote:
Originally posted by schro20

I am confused. While parallel capacitances are additive, shorting a capacitor takes it out, no? Just consider the fact that shorting it allows DC through, while otherwise DC would not go through. There is no chance for energy storage in the cap since the short keeps it from charging. What am I missing?
Quote:
Originally posted by troystg
You're not missing anything. Shorting across a cap effectively takes it out of the circuit.

It definitely has audible effects AND allows DC to pass.
I'm confused too but I've tryed to short with a wire cap's leads on the breadboard and no difference were audible.

Putting wires from boards in the same breadboard line (no cap involved so) and difference from cap was audible.

I've explained that to myself in this way:

A (ideal) cap in signal path is a high-pass filter so, under the cutoff frequency is an open circuit and over a short circuit.

When you put a cap and a wire in parallel the wire let pass all the signal and the cap only the part over the cutoff frequency. The quantity of signal (over the cutoff frequency) is proportional to the esr of the cap and wire resistance.

In other words part of the signal pass through the shorted cap and so has its sound signature.

It could be right or I'm drunk?
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Old 4th March 2009, 03:13 PM   #328
troystg is offline troystg  United States
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Not a personal comment, please do not take it as anything directed personally.

Something must be amiss.

I still can't think of any frequency that a cap would have a lower resistance than a direct short. Therefore the majority of the signal (proportional to resistance of both paths) would take the short.
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Old 4th March 2009, 04:06 PM   #329
schro20 is offline schro20  United States
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Quote:
Originally posted by troystg
I still can't think of any frequency that a cap would have a lower resistance than a direct short. Therefore the majority of the signal (proportional to resistance of both paths) would take the short.
There is an interesting article by Rod Elliott (surprise...) on caps. In particular he looks at all the parasitic effects just from soldering something and having longer leads and such and they dwarf everything else. That may well be what's going on in Dario's setup, since, as you point out, the behavior of a shorted capacitor with no other effects taking into account is unambiguous.

peter
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Old 4th March 2009, 04:27 PM   #330
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Quote:
Originally posted by troystg
Not a personal comment, please do not take it as anything directed personally.

Something must be amiss.

I still can't think of any frequency that a cap would have a lower resistance than a direct short. Therefore the majority of the signal (proportional to resistance of both paths) would take the short.
Troy, no problems at all.

apart how much of the signal passes through the cap one thing is sure:

a shorted cap is different from a wire...

Let's collect some data:

8 cm of 30AWG wire has a resistance of 0.0268 Ohms (my shorting cable was ca 8cm) (calculator)

I've found a CDE polypropilene cap that has a ESR of 0,012 Ohm...
A Panasonic FM Elco has ESRs as low as 0,012 Ohm...

With these values ca 2/3 of signal passes through the cap...
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