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Old 22nd March 2007, 01:39 AM   #21
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" Take out the R and insert L? ..."

Yes. Why not, this is after all a power supply and you are trying to cut down on cross talk as well as noise in the rails. " ... you might wind your own resistor / inductor and put 'er there."

Figure out what the current you want flowing through that "Low R" resistor ... cut off a bunch of resistance wire ~= to that value of R and wind it around a wooden dowel, as many turns as are practical / possible = a nice inductor. ... the exact inductance value is not the issue, but the fact of an inductor's existance is = smack between two fat caps = lots of effect, just like you might find an those commercial power line filters that knock EMF off the power lines = squishes that ol' ripple down to a managabubble level = down a few db
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Old 22nd March 2007, 08:01 AM   #22
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Any amp which needs more than a simple CRC rail filter is not going to be much cop in the output impedance stakes at LF, for it will most definitely be a "Low Note Flapper"
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Old 22nd March 2007, 08:03 AM   #23
AndrewT is offline AndrewT  Scotland
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Why buy resistance wire?
just buy a 500gram reel of 1mm enamelled copper wire.
Leave it on it's plastic bobbin and solder the ends between the two caps. Job done.
Aircored inductor for about $10.

If you want to adjust resistance buy 0.9mm or 1.2mm wire. Or for super duty 1kg of 1.6mm wire.
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Old 22nd March 2007, 08:39 AM   #24
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Hi Andrew,

Yes, and stick a piece of ferrite rod down the reel centre for up to 40dB of 100Hz reduction.
This would be heavier however, and have lower total C reserve that two RC stages in series.
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Old 22nd March 2007, 07:19 PM   #25
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" ... just buy a 500gram reel of 1mm enamelled copper wire. Leave it on it's plastic bobbin and solder the ends between the two caps. Job done. ..." " ... tick a piece of ferrite rod down the reel centre for up to 40dB of 100Hz reduction ..."

Now that's DIY ...

(Wow !! 40 db !! ... down from the previous noise floor, right ... he, he, he)
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Old 22nd March 2007, 07:45 PM   #26
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transformer should have about 900W,
3x200W, AB class amp have efficiency max 67%, in practice about 50%, in this case one 200W amp takes 300W, 100W goes to the heat
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Old 17th August 2010, 09:35 PM   #27
badman is offline badman  United States
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This is why I love this place. I just ordered a bunch of BIG power resistors (10ohm 95W) from the bay, and am going to parallel 4 per rail on my UCD amps (one built, one pending). I was worried about the increasing voltage drop under load, but the diode trick oughta work real trick. I'll bypass them with a small cap to kill the HF noise and use quiet diodes (HexFreds).
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Old 17th August 2010, 11:17 PM   #28
pjpoes is offline pjpoes  United States
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Wow this is such an old posting. I ended up buying a bunch of Surplus inductors, and have been using them in various amp builds. To this day, regardless of the amplifier design afterwards, the CLC power supplies have made the best sounding amps with the lowest noise floor I've ever heard or owned. The inductors are potted in shielding cans which helps as well.

I recently finished an amp that used a switching supply. The ripple and regulation is about as low as it gets with these regulated supplies, so I thought I would give it a shot. Kept the supply well isolated, shielded, etc, but it just doesn't compare with the CLC supply. I finally after over a year of futzing got it so that its as quiet as my other amplifier. The amplifier modules themselves are of a better design, so its an overall better amp, but I still feel like I like the old amp better. I'm tempted to try making a CLC supply.

Another option I've toyed with would be to remove the filter inductor's at the output stage of the switching supply, then insert an inductor and capacitor set of much higher inductance and lower ESR at the caps. My understanding is it would likely kill the regulation, but would probably further improve the noise floor, and improve the power supplies ability to react to quick dynamic swings. As is there is already 18700uf's of capacitance. The designer of the supply is telling me I need to add more capacitance to the front end, not the back end, but I think they are more focused on the regulation. I'm not sure the regulation is that important here. Its probably more beneficial for the front end stages of the amplifier, but the amplifier has regulation onboard for that, so I'm not sure its buying much (its good regulation too). The problem you have is building a power supply for rail voltages in excess of 70 volts gets tricky. Parts are readily available for less than that, but I have rail voltages on one amp at 75 volts, and this amp is 106 volts. Findings caps with enough headroom to handle either is tricky. Transformers get huge, expensive, and heavy. On paper these switching supplies look like a god send, but I'm still up in the air. I do think its working quite well right now, and things sound great, but I literally just fixed the last problem this past weekend.
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Old 18th August 2010, 04:35 PM   #29
badman is offline badman  United States
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Quote:
Originally Posted by pjpoes View Post
Wow this is such an old posting. I ended up buying a bunch of Surplus inductors, and have been using them in various amp builds. To this day, regardless of the amplifier design afterwards, the CLC power supplies have made the best sounding amps with the lowest noise floor I've ever heard or owned. The inductors are potted in shielding cans which helps as well.

I recently finished an amp that used a switching supply. The ripple and regulation is about as low as it gets with these regulated supplies, so I thought I would give it a shot. Kept the supply well isolated, shielded, etc, but it just doesn't compare with the CLC supply. I finally after over a year of futzing got it so that its as quiet as my other amplifier. The amplifier modules themselves are of a better design, so its an overall better amp, but I still feel like I like the old amp better. I'm tempted to try making a CLC supply.

Another option I've toyed with would be to remove the filter inductor's at the output stage of the switching supply, then insert an inductor and capacitor set of much higher inductance and lower ESR at the caps. My understanding is it would likely kill the regulation, but would probably further improve the noise floor, and improve the power supplies ability to react to quick dynamic swings. As is there is already 18700uf's of capacitance. The designer of the supply is telling me I need to add more capacitance to the front end, not the back end, but I think they are more focused on the regulation. I'm not sure the regulation is that important here. Its probably more beneficial for the front end stages of the amplifier, but the amplifier has regulation onboard for that, so I'm not sure its buying much (its good regulation too). The problem you have is building a power supply for rail voltages in excess of 70 volts gets tricky. Parts are readily available for less than that, but I have rail voltages on one amp at 75 volts, and this amp is 106 volts. Findings caps with enough headroom to handle either is tricky. Transformers get huge, expensive, and heavy. On paper these switching supplies look like a god send, but I'm still up in the air. I do think its working quite well right now, and things sound great, but I literally just fixed the last problem this past weekend.
Inductors for the power level I have are very large and pricey, so I found the cheapest huge power resistors I could and Whoo-bam, done. I agree with you on SMPS, I think regulation for home power amps is not so much of an issue so long as there's plenty of cap in the supply. Proamps would naturally be a different story.

I'll include a diode string with some low-noise Hexfreds or the like and bypass each of them with a small cap.
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Old 18th August 2010, 10:57 PM   #30
pjpoes is offline pjpoes  United States
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They would have been for me too. My amps are 200 watts per channel. The inductors I have are capable of passing 8 amps rms each and are good for 120 mh. These were more than enough for my amps. I have enough of them I could do mono power supplies, but for these amps, it was more than enough to have one. I know I know, reduced cross talk, but it was a lot of work to build two.

The reason I didn't do it for the better amp was that they were 300 watts per channel at 8 ohms, 600 at 4 ohms given a sufficient power supply, and I couldn't create a big enough supply with those inductors, even in mono operation. It was just easier to use a 1200 watt SMPS.
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