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Old 25th April 2003, 08:03 PM   #1
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Default Power supply inductors in Aleph

Hi,
It seems like alot of people are using CLC filters to clean up power supply ripple.

My understanding is that while its great to get rid of the power supply rails noise, adding the inductors to the supply will limit(compress) dynamics on the amp. My guru states that we should use a CRC filter instead to get rid of ripple.

Can anyone comment on the pros and cons of CLC vs CRC? Will it compress dynamics??

Thanks!!
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Old 25th April 2003, 09:14 PM   #2
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Default Inductors for Aleph

A good inductor should not limit dynamics as much as a resistor. The circuit is Class A, the current to drive the speakers is coming down through the power supply already.
But the proper inductor for an Aleph is big, expensive, heavy, and radiates EMF. An udersized inductor that saturates its core will be much worse than the proper resistor.
I think the reason most commercial designs do not have the inductors is both radiated noise and cost related. But I found a stash of good inductors for an Aleph X or something close. I may even try an L-C filter next time instead of a C-L-C.
I put a L-C filter on the heater of my 6080 linestage instead of the R-C used a couple of weekends ago. The sound improved a bunch. More warmth and depth.
I plan on trying the L-C-L-C on a buffer to check it against a 7815/7915 type regulated supply. Should be interesting. Chokes are fun, but hard to locate.

George
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Old 25th April 2003, 09:24 PM   #3
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I would imagine that an inducter, like a transformer, could be shielded to limit its EMF. Of course this would again add to the cost.
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Old 25th April 2003, 11:48 PM   #4
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My first atempt to clean the rails was the use of a CRC filter wich did a lot of good things to the amp but also decreased the rail voltage by about 6 V.

Since I thought it was still not good enough I added a fairly big iron core inductor EI type gapped por 3 Amps and not shielded to form a LCRC filter.

The result of this addition gave a tremendous advantage on the soundstage width and deepness I was very surprised by the results. No problems with EMF either.

Adding an input inductor also has the disadvantage of lowering the rail voltage quite a bit but since I have power to spare didn't care much, I now have 31 V rails from the initial 50V.

But if you plan in advance you can take this in consideration and add this losses to the trany secondary voltage.

One other very important factor, at least when you add an input inductor is that you get a very well regulated supply even more than one could imagine.

IMO this is a very good addition to any power amp. I'm now thinking of making a GC with input inductors in the PSU.
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Old 4th May 2003, 10:36 PM   #5
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Default Inductor in Audio Supplies

Inductors are deigned to limit the flow of current. What I have found in the lab was a large inductor in the power supply causes loss of dynamic range by decreasing the available current during transients. Also, if not design correctly you will move the ripple voltage up to another frequency dumped on the voltage rails. The other effect caused by the inductor is RF interference and voltage loss in the inductor.

There are much better ways to remove wide band noise, ferrite beads, feed through capacitors, RC's, and smaller inductors. However, I do believe it is possible to change the sound of an amp by using large inductors since they limit the current flow and could make the amp sound fat.

JW
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Old 5th May 2003, 12:49 AM   #6
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Quote:
Originally posted by apassgear
IMO this is a very good addition to any power amp. I'm now thinking of making a GC with input inductors in the PSU.
if you are using a choke input, there has to be a minimum amount of current draw or the field collapses and all of a sudden you have a cap input supply with its inherently higher rails. This makes choke input unsuitable for Class AB amps (unless you have a properly configured shunt regulator inbetween to keep current flowing)

dave
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Old 5th May 2003, 01:48 AM   #7
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Default Input inductors on PSU

Your right Dave,

Inductors are all right on class A apms when appropiate specs are used but no good for class AB or B.

Yesterday we dsicuss this on a GC thread but my memory fails and forgot about my post on this thread.

Thanks for noting this.
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