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Old 27th January 2007, 02:58 PM   #11
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Once you start building cages for the coils, build one more for the Tripath chip - if not done yet!

Backgroundnoise and distortions will drop!

Cheers.
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Old 28th January 2007, 03:59 PM   #12
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Quote:
Originally posted by theAnonymous1


If I can manage to get a hold of a pair I plan on trying them out on my AMP1-B. I also plan on making little grounded RF cages to fit around them.

Hi

I own 41Hz AMP5, and have just got a set of air-core inductors form Yeo (diyparadise), and I'm planing to try these out on th AMP5.

These RF cages sound interesting, could you post a few links on how to make these?
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Old 29th January 2007, 08:53 AM   #13
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I replaced the Charlize Air Cores with the Mundorf Coils 6 month
ago! And I won't step back.
Resolution clearly increased in the upper range.

The only problem with the Mundorfs: They are bigger than the
air cores of DIY-paradise.
That's why I mounted them underneath the board!

Cheers
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Old 29th January 2007, 09:56 AM   #14
icebear is offline icebear  Norway
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Quote:
Originally posted by soundcheck
Once you start building cages for the coils, build one more for the Tripath chip - if not done yet!

Backgroundnoise and distortions will drop!

Cheers.

Hi

Do you earth the cage in any way?
Do you have any pictures to show how you have done it?

Cheers
bjorn
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Old 29th January 2007, 12:55 PM   #15
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Quote:
Originally posted by soundcheck
I replaced the Charlize Air Cores with the Mundorf Coils 6 month
ago! And I won't step back.
Resolution clearly increased in the upper range.

The only problem with the Mundorfs: They are bigger than the
air cores of DIY-paradise.
That's why I mounted them underneath the board!

Cheers

So what size do these foils end up at Soundcheck?
Did you order from Mundorf direct?
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Old 29th January 2007, 01:33 PM   #16
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Quote:
Originally posted by Lostcause



So what size do these foils end up at Soundcheck?
Did you order from Mundorf direct?
25mm in diameter and 40mm tall.
I ordered directly from Mundorf.
Just tell them that you'll use them as output filter for a digital
amp. They'll know what you're talking about.

The coil comes with a wooden core. The foil sits extremely tight
on a wooden body.
I think that is one reason why it's better then the other air-cores around. It is much less sensitive to vibrations.

Cheers
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Old 29th January 2007, 03:20 PM   #17
ypasco is offline ypasco  Canada
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OK,

what i understand is :

- An air inductor is linear because the core itself is linear (the air) vs a solid core (hysteresis).

- The air coils is working quite well for low power amplifier (2-10W) but need to be shielded in a faraday enclosure to avoid EMI troubles in the case of 50W amplifiers.

- The chip itself needs to be shielded too (reduction of distorsion and background noise) in high power applications.

The output coils are then the critical part of the Class D amplifier and there are no immediate answer to all applications. I read that some of you don't have any troubles with 50W amplifiers and air coils : the way to go is maybe to enclose the entire board and connect the coil in another enclosure as close as possible of the first one.

am I right ?
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Old 29th January 2007, 05:53 PM   #18
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Quote:
Originally posted by ypasco
OK,

what i understand is :

- An air inductor is linear because the core itself is linear (the air) vs a solid core (hysteresis).

- The air coils is working quite well for low power amplifier (2-10W) but need to be shielded in a faraday enclosure to avoid EMI troubles in the case of 50W amplifiers.

- The chip itself needs to be shielded too (reduction of distorsion and background noise) in high power applications.

The output coils are then the critical part of the Class D amplifier and there are no immediate answer to all applications. I read that some of you don't have any troubles with 50W amplifiers and air coils : the way to go is maybe to enclose the entire board and connect the coil in another enclosure as close as possible of the first one.

am I right ?
I'd say so!

But don't overdo things here with shielding asf!
It is IMO a nice tweak to squezze the last out of it.
I would first give it a try without it.
What I did -- I had some of this ERS paper around, which I wrapped around the coils und the chip.

Cheers
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Old 29th January 2007, 06:20 PM   #19
cotdt is offline cotdt  United States
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Commercial Tripath amps with 300W per channel somehow get away with using air coils, so I don't know how serious the problem is. Not a problem in my case, though. Hysterisis isn't really a problem with the officially specified iron-core inductor, but for some unknown reason it sounds bad. I haven't read any good explanations as to why using better inductors can make the sound better, but it does. Maybe the extremely high frequencies involved have effects that are not easy to predict. The difference is massive, bigger than changing capacitors.

The Jantzen copper foils and Mundorfs look to be about the same. They have similar designs and both use a wood center core. So take your pick, and go with the cheapest. The 14GA Jantzen is $6.88 each from parts express.
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Old 29th January 2007, 11:20 PM   #20
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Default Response to the availability of the 11uH Jantzens......

Quote:
Hello,
Thanks for choosing Parts Express. Unfortunately this value is not currently available. I will pass this along to our product managers so they know that there is some demand for such an item.

If there is anything else I can do to assist you please let me know.

Chris Frechette
Technical Advisor


I guess I'll have to buy the 50uH and unwind...... which means I need to buy an inductance meter also.
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