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Old 28th August 2012, 12:19 PM   #2811
mikelm is offline mikelm  England
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Hi Christophe,

In your experience, how long does it take for an electrolytic in the signal or FB path to "run in"

cheers

mike
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Old 28th August 2012, 12:21 PM   #2812
a.wayne is offline a.wayne  United States
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From listening experience , amp with multiple caps (16x 5000uf ) don't have as good a bass as (4x20000) , sounds weaker or put another way , everytime I have heard an amplifier that has exceptional bass , slam and control , it is never with large quantity of small caps , in the PSU...
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Old 28th August 2012, 12:56 PM   #2813
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Quote:
Originally Posted by a.wayne View Post
From listening experience , amp with multiple caps (16x 5000uf ) don't have as good a bass as (4x20000) , sounds weaker or put another way , everytime I have heard an amplifier that has exceptional bass , slam and control , it is never with large quantity of small caps , in the PSU...
It depends on the cabling; wires and CI tracks thickness, distances etc...I used to feel the same than you, then, i tried to sold my caps on big copper bars...
Of course, if the wires between the PSU and amp are long, because of the self of the wires, you will lose any benefit using several caps instead of big ones, and, if you add an extra filter on the amp ...
I believe the best is to use big caps in the PSU, and several (4 on each side) little caps as extra filtering on the amp board (total value=1/10 of the value of the PSU ones) ? And big big wires to carry the power between boards.
Quote:
Originally Posted by mikelm
In your experience, how long does it take for an electrolytic in the signal or FB path to "run in"
Did-you mean "breaking time" ? I found that, letting an amp during a night on a generator and charged by a resistance at near full power is enough ? Like for breaking loudspeaker suspension.
If you means heating time at each listening seance ? It depends of your life time ;-). Half an hour is enough to stabilize the temps, i think, but i feel be better to listen to music during half an hour than to loose my time waiting for some kind of perfection ? ;-)

Regarding those psu choices, many audiophile prefer to use 2 mono amps instead of a stereo one. The difference is each one use his own PSU. I use to feel the stereo image less stable with mono amps.
Easy to undestand: each amp will vary its efficiency during big power transients, not at the same value on each side, and intruments will move on stereo localization. A common PSU for both chanels will reduce the phenomena. Reason why i recommend a 1/10 value for the amp board power filtering caps.
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Old 28th August 2012, 01:15 PM   #2814
a.wayne is offline a.wayne  United States
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ESP,

I'm inclined to agree on big in the PSU and then smaller as close as possible to the outputs.

I was looking at FMA , Newest and greatest amp , the FMA118 and suprised to see Manny favoring one large transformer over 2smaller ones for the PSU. Supposedly one large is superior to 2 small ...!

Thoughts ...?
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Old 28th August 2012, 01:18 PM   #2815
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About breaking amps, each of us do not always have big 50w 8 ohms resistances.
A tip i used in the manufacture i worked in long time ago:

We used to break each amps, before to 'pass them" charged by a 50w 24v truck headlight bulb at 50w of output power
.
It is low priced, and, if you see an bulb not lighting in the morning, you know in one sight that the amp has failed (or the bulb).
And, if, when you bring the source to 0V, if a bulb is still lighting, that the amp oscillate, or one side of the push pull is in short circuit.
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Old 28th August 2012, 01:28 PM   #2816
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Quote:
Originally Posted by a.wayne View Post
Supposedly one large is superior to 2 small ...!
Thoughts ...?
Agree. For the same reason: Using a single transformer help keeping the both rails symmetrical during transients.
This said, X3 the required VA seems a good compromise: i use a 1000 VA for my 2X150w amps. I use > X2 with SMPS.

ps: One more advantage, using paralleled caps, is to linearize their value: Electolitics caps have great value disparities, paralleled them help to randomly equal the total value on both rails. (Is this understandable, despite of my poor English ;-)
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Old 28th August 2012, 01:30 PM   #2817
shaan is offline shaan  India
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I prefer film type caps for input coupling. In my short ~10 years life with audio diy electrolytics has always failed me here. I have been using 1uF Siemens MKT polyester with my DOZ amps with 100k input impedance for the last 2 years for their apparently better HF response, placing an electro in its place makes the sound dull. I have placed order for a dozen of 10uF 630v rated large cylindrical polypropylene things. Hoping magix. Will update when they arrive.

Anyways the 10uF electro is on fire with SSA right now with the following, each of which has challenging HF content:

Keith don't go - Neils Lofgren
After hours - Ronny Jordan
Red dust and spanish lace - Acoustic Alchemy
The brightness of these days - Kyoto Jazz Massive
Time - Stella Starlight Trio
Flying, part 2 - Keith Jarrett
Glass room - Speak (synth dnb track, but great for both bass and treble test, if you have not tried it yet I suggest you do so ASAP)

and many more...
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Old 28th August 2012, 01:34 PM   #2818
a.wayne is offline a.wayne  United States
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My preference is no cap , nada , zero, zilch .....
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Old 28th August 2012, 02:11 PM   #2819
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Quote:
Originally Posted by a.wayne View Post
My preference is no cap , nada , zero, zilch .....
No doubt.
And a protecting circuit is less expensive than golden diamond audiophile caps ;-)
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Old 28th August 2012, 02:42 PM   #2820
Jay is offline Jay  Indonesia
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No doubt.
And a protecting circuit is less expensive than golden diamond audiophile caps ;-)
Your speaker protection idea is the most complex one I have seen on this planet, but it fails to eliminate a (cheap?) relay at the amp output.

I have checked big names high end amps, and yes, almost all of them use relay at output. Different approach (such as used by Pioneer if I'm not mistaken) is to ground the input and output of the amp when DC is detected at output. I don't know if this approach is effective enough but why not?
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