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Old 18th October 2009, 07:44 AM   #5211
fff0 is offline fff0  Singapore
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Hi Zen,

If I dont rem wrongly, you actually preferred LC*** as the filter, inductor being the input of the PSU filter. Can I confirm with you this is a safe method as I cant seems to simulate in PSUD2 due to some time step error? If my calculation is right, a 0.5ohm (DC resistance) inductor will consume ~5w (assuming 10A), is this too much for an air core inductor?
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Old 18th October 2009, 07:45 AM   #5212
fff0 is offline fff0  Singapore
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Hi Zen,

If I don't remember wrongly, you actually preferred LC*** as the filter, inductor being the input of the PSU filter. Can I confirm with you this is a safe method as I cant seems to simulate in PSUD2 due to some time step error? If my calculation is right, a 0.5ohm (DC resistance) inductor will consume ~5w (assuming 10A), is this too much for an air core inductor?
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Old 18th October 2009, 08:08 AM   #5213
Zen Mod is offline Zen Mod  Serbia
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0.5R inductor - it's on high side for that purpose ;

anyway - if big chunk of copper is used , 5W isn't too much

edit: LC filter is absolutely appropriate for pure A class amps (think SE) - without excursion in B class

so - use it only if you don't think to drive F5 hard
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Last edited by Zen Mod; 18th October 2009 at 08:17 AM.
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Old 18th October 2009, 09:18 AM   #5214
Magura is offline Magura  Denmark
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Quote:
Originally Posted by fff0 View Post
Hi Zen,

If I don't remember wrongly, you actually preferred LC*** as the filter, inductor being the input of the PSU filter. Can I confirm with you this is a safe method as I cant seems to simulate in PSUD2 due to some time step error? If my calculation is right, a 0.5ohm (DC resistance) inductor will consume ~5w (assuming 10A), is this too much for an air core inductor?
It's fairly easy to get a 2mH inductor below 0R3 (1.9mm magnet wire). A LC filter may not be the right solution, but a CLC filter sure is. I helped a friend making a F5 some time ago, and we used a 20.000uF 2mH 20.000uF filter.

No nasties what so ever survived that treatment

But as Zmuck stated above, it's only good for class A operation. We tried pushing it into AB, just to see what happened. That didn't sound good, or look good for that kind of matter.


Magura
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Old 18th October 2009, 10:24 AM   #5215
Zen Mod is offline Zen Mod  Serbia
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ZMetaldanske - try sometimes LC filter .......

20mF-2mH-20mF is enough for preamp ....... not for serious amp

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Old 18th October 2009, 10:55 AM   #5216
Magura is offline Magura  Denmark
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The 20.000uF figure was not to my liking either, I usually multiply that number by a factor of 10. In this case, it just wasn't up to me.

LC filters just don't seem to be as versatile. CLC is just a run of the mill.

Pick up the usual caps on the shelf, pick up the usual inductors on the shelf, good to go


LC needs something that fits whatever it's supplying, to work proper, so it takes a new inductor every time


Magura
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Old 18th October 2009, 11:43 AM   #5217
sekess is offline sekess  United States
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Quote:
Originally Posted by Magura View Post
It's fairly easy to get a 2mH inductor below 0R3 (1.9mm magnet wire). A LC filter may not be the right solution, but a CLC filter sure is. I helped a friend making a F5 some time ago, and we used a 20.000uF 2mH 20.000uF filter.

No nasties what so ever survived that treatment

But as Zmuck stated above, it's only good for class A operation. We tried pushing it into AB, just to see what happened. That didn't sound good, or look good for that kind of matter.


Magura
Hey Magura,

2 questions:

1. How far away from the amp circuitry did you mount the inductors? I am setting up a similar configuration and currently wrestling with the layout.

2. Do you think the ppor performance when the amp was pushed into AB was because of the inductors or the lowish capacitance or a combination of both?

Thanks,
Steve
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Old 18th October 2009, 11:52 AM   #5218
Magura is offline Magura  Denmark
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Quote:
Originally Posted by sekess View Post
Hey Magura,

2 questions:

1. How far away from the amp circuitry did you mount the inductors? I am setting up a similar configuration and currently wrestling with the layout.

2. Do you think the ppor performance when the amp was pushed into AB was because of the inductors or the lowish capacitance or a combination of both?

Thanks,
Steve
1) I usually make the layout like this, starting from the face-plate:

Transformer, rectifiers, first caps, inductors, second caps, a couple of hefty film caps, and on the rear panel, I mount the amp boards.

This way there is usually no issues.

2) The issue diminished, when taking the inductors out of the circuit, so yes. The cap bank size thing, was more like an insider joke, as I usually do the overkill thing in this respect. 2 x 20.000uF is not that little actually.

I bet that the original F5 didn't sport more than 40.000uF per channel (not that I've checked).


Magura
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Old 18th October 2009, 12:02 PM   #5219
sekess is offline sekess  United States
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Hey Magura,

You used iron-core or air core chokes? Do you think they were saturating at the higher currents? Or maybe the chokes just didn't like the extra modualtion they were seeing at the higher currents?

When finally get it all together, I think I'll try CLC and then CRC as well and see if hear a difference at highet output.

Thanks again,
Steve
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Old 18th October 2009, 12:05 PM   #5220
Magura is offline Magura  Denmark
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Quote:
Originally Posted by sekess View Post
Hey Magura,

You used iron-core or air core chokes? Do you think they were saturating at the higher currents?
I always make air core inductors, so that should answer your second question

Inductors are though only working well, at relatively constant current draw, which you don't have running the amp in AB.

Magura

EDIT: Just checked the original schematic. It sports 4 x 15.000uF per rail, as in 60.000uF.
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Last edited by Magura; 18th October 2009 at 12:07 PM.
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