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Old 7th April 2006, 05:45 AM   #41
Paper mache horn fabricator
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Default It's just so cool...

Nelson's ideas and articles just flame my brain. I just can't get enough. Talk about addiction! It's better than women, whiskey, and song, unless that song is playing through my amplifier. Gosh, I can't see how this baby is going to get any better, jfet of not. I can place my ear against my 110 db 1w1m horn and hear nothing but air. Nice, quite air. That's no joke! I think this inductor loading must also be doing double duty as a filter. I'm running an LCLC filter, but to be this quiet, there's got to be more to it than my simple filter. Oh yes, the amp design. It all works. I could never get my AX this quiet, sweet baby that it is.

flg, somewhere around here I posted a drawing of an inductor loaded version of Nelson's jfet amp in simple balanced mode. It's been given an ok from several members and Nelson has suggested it looks possible. I'm learning how to build the ZV7-T as a prelude to the jfet project. It'd be nice to have others on board to brainstorm with. Glad you're here, along with Choky, Maqura, apassgear, nobody special, Nelson and the rest of the viewing gang. I'm sorry if I missed anyone else.

John
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Old 7th April 2006, 07:20 AM   #42
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Default Re: inductance

Quote:
Originally posted by carpenter
That's really not so tough to transfer into air chokes. Is 4.66 ohms resistance per choke too much. I'm looking at 16 gauge wire. This yields a choke with the dimensions of 1" dia. core, 1" width, 6.89" outer dia. It will take two of these babies per mono-block. They could be placed side by side and connected like a center tapped plitron to cancel magnetics. Or is this totally unnecessary.

John,

I'm not quite sure but it seems to me that whatever coils you use should share the same magnetic path, this would mean that you will not be able to use two separate coils. Maybe a bifilar winding with center tap could be used and both sides should measure similar inductance as does your Piltron.

The way you mount the coil also has influence on the inductace. As an example if one side is near a ferromagnetic material it will show a higher inductance than the other side that could not be near a similar field.

Me thinks, for what you say, that you have gone far enough with your project and any improvement will have diminishing returns and maybe you will only hear some differences with no clear winner, or to be honest you will return to the Piltron. Time to move on to a new project?

A Pi filter as you describe on the PSU its realy good so is no surprise to hear your comments.

Excellent work John, congratulations!!!
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Old 7th April 2006, 11:30 AM   #43
Magura is offline Magura  Denmark
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For 20Hz you need 80mH, to keep things reasonably efficient you need less than 3ohm for the inductor. my air core 80mH inductors are around 2.4ohm as I recall it.

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Old 7th April 2006, 12:18 PM   #44
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hi!

I have used the secondary of a good tube output transformer (LL1627 PP) for a similar task with very good results. It has a c-core with a small air gap to give some dc current imbalance immunity. The dc resistance is in the range of 0.5 ohms.

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Anders
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Old 7th April 2006, 01:11 PM   #45
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Default 80mh?

Maguara, 80mH is so much easier. But, I thought your 2x80 weighed 20kg. Here's what I got off the net:

Inductance 160.36 mH
DC Resistance 2.16 Ohms
Wire Gauge 12 AWG
Wire Diameter 80.8 mils (1 mil = .001 in)
Coil Length 2 in
Coil Inner Diameter 1 in
Coil Outer Diameter 8.43 in
Average Turn Diameter 4.57 in
Wire Length 1336.32 feet
Copper Weight 26.41 pounds
Turns 1118
Levels 45.17
Turns/Level 24.75

At 26.41 pounds, I can do this. Isn't this about half the weight you mentioned?

Thanks for posting,

John

bappe,

That's just the kind of info I love to read. I'll check into that serial number you posted.

John

apassgear, thanks for the positive strokes. With regards to transformer strategy, I'm giving this experiment my all in order to prepare myself for the ZV9-T. If I'm going to make mistakes, it's probably easier to understand them with this simple little layout. The ZV9-T will be more confusing for me. That is, unless one of you fine gents build and debug it first. Ha ha ha, there's a muhaahaa in there somewhere...

love you guys, what an amazing group of explorers.

John
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Old 7th April 2006, 02:01 PM   #46
Magura is offline Magura  Denmark
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Your calculations are most likely right, but you will find that inner diameter of 25mm and 1.9mm wire does not add up. Besides that you don't need 160mH but 2*80mH. To actually wind a bifilar coil is pretty hard in the first place, you need a reasonable inner diameter to end up with something useful.
I am at my GF's place 400km from home at this moment, but when I get home Monday or Tuesday I will try if I can post a pic of my inductors, then you will see what I'm trying to explain.

Magura
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Old 7th April 2006, 02:03 PM   #47
Magura is offline Magura  Denmark
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BTW, the real deal would be a ZV7-TAXJ

Magura
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Old 7th April 2006, 02:06 PM   #48
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Default Zv7-taxj?

Oh, please do elaborate.


The 160 mH is a center tapped 2x80 choke.

John

For center tap, I'll be hand winding two strands onto one bobbin. Twelve gauge will just take a bit longer. I'll wear gloves!
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Old 7th April 2006, 02:36 PM   #49
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Default Re: Zv7-taxj?

Quote:
Originally posted by carpenter
Oh, please do elaborate.


I'll wear gloves!

You will find gloves to be a disadvantage, as they will cause you more trouble than you could possibly imagine when it comes to controlling the wires and pulling them hard enough to make a good quality inductor

T(inductor load) A(aleph current source) J(J-fet cascoded) X(super symmetry)

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Old 7th April 2006, 04:57 PM   #50
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I thought the transformer/inductor took the place of the aleph current source?
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