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Old 28th March 2006, 03:26 PM   #11
Magura is offline Magura  Denmark
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One way to improve things would be to go air core for the inductor.

Magura
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Old 28th March 2006, 09:03 PM   #12
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Default Thanks for the response.

117033201 is the Plitorn part number for the transformer serving time in my amplifer as a center tapped choke.

It does sound excellent. I just thought that the correct audio choke might sound better. Wouldn't an air-core choke have more resistance?

The bass in this amplifer is truly wonderful. The cello in "Bare Naked Ladies" sounds warm and chilling. It sends tingles up my spine just thinking about it.

I'm discovering that I want to leave the power house tri-amped 2000 watt speaker system I currently have and move towards simpler, passively crossed speakers. This amp has changed how I view sound and its reproduction. Funny how things go... in an odd way, Nelson is the yen and the yang, a curse and a blessing at the same time. I mean this in the sweetest way. I've come to understand more about the beauty of simplicity from Nelson than any other person on this planet. A portion of the "curse" I refer to is being coaxed into realizing that bigger isn't better, less is sometimes more.

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Old 29th March 2006, 05:58 AM   #13
Magura is offline Magura  Denmark
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Default Re: Thanks for the response.

Quote:
Originally posted by carpenter
Wouldn't an air-core choke have more resistance?

I have made 80mH inductors with about 2.4R, so resistance in an air core is no big deal if made right. All it takes is a lot of copper.

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Old 29th March 2006, 12:40 PM   #14
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Default Copper I have.

Several years ago I purchased an eighty pound spool of 11 gage magnet wire.

If there's 2 or 3 ohms of resistance in the choke, will this require changing other values in the amp?

Thanks for the reply. BTW, how does an air core inductor make the amp sound better? Just curious.

John
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Old 29th March 2006, 07:46 PM   #15
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Air core does not suffer from the non-linear magnetic character
of iron, so all other things being equal, it's better.

A couple of ohms resistance in the coil is fine in my experience.

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Old 29th March 2006, 07:55 PM   #16
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Default Just the man I want to see!

I'll explore air-core inductors. I can have them wound with a center tap.

Is there optimum size in wire gauge and in mH? My wire guy doesn't wind below 14 gauge. 16 is more cost effective...

Please, please. If you have a moment, can you please explain what adjustments you make to the ZV7-T amp when looking at your distortion analyzer? I can't figure out which pot to turn without altering dc offset or bias.

Many thanks,

John Inlow
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Old 29th March 2006, 09:55 PM   #17
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If you have an air core transformer, the adjustments are a lot
easier, since a small DC imbalance will not be much of a problem.
With an iron core transformer, a small imbalance gives are very
much larger distortion due to core saturation.

Essentially, you want about the same amount of current flowing
through the two halves, and you also want to watch the total.
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Old 29th March 2006, 11:03 PM   #18
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Default What is the sound of one hand scratching a head?

Quote:
Essentially, you want about the same amount of current flowing

Where does using a distortion analyzer to locate magnetic center fit in? I paid two hundred bucks to find what I thought was magnetic center which would create lower distortion. Finding balanced current--isn't that done indirectly with a voltage reading and ohm's law?

I'm a bit perplexed. The upshot is that the amp sounds excellent. Better than chocolate and peanut-butter. I love the design!

John
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Old 29th March 2006, 11:42 PM   #19
Zen Mod is offline Zen Mod  Serbia
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Default Re: What is the sound of one hand scratching a head?

Quote:
Originally posted by carpenter



Where does using a distortion analyzer to locate magnetic center fit in? I paid two hundred bucks to find what I thought was magnetic center which would create lower distortion. Finding balanced current--isn't that done indirectly with a voltage reading and ohm's law?

I'm a bit perplexed. The upshot is that the amp sounds excellent. Better than chocolate and peanut-butter. I love the design!

John

yep
but you must do both - DC and AC measurements of voltage reading...
ant that's somewhat easier with dist. analyzer
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Old 30th March 2006, 12:24 AM   #20
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Default DC and AC?

I've only been working with DC...

Oh My Gosh...


So. I've never owned a distortion analyzer. I tried to measure the distortion on my signal generator. Quite difficult and tedious. Never did get it nailed. Unless of course, that old clap-trap tone generator is noisier than a long-tailed cat in a room full of rocking chairs. Thought I'd try it out on something cleaner.

I'm still groping in the dark--but at least the amp sounds good.

John
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