unwinding a 1mh. steel laminate inductor into .8mh, good idea or not? - diyAudio
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Old 14th February 2008, 03:28 PM   #1
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Default unwinding a 1mh. steel laminate inductor into .8mh, good idea or not?

Dear all,

I have a need for a low DCR .8mh inductor for my project.

I have a list of options.

#1. madisound .82mh w/ .19 DCR perfect lay inductor, unwound to .8mh. costing about $17-

#2. Goertz 12 guage .82mh w/ .111 DCR foil inductor, But cannot be unwound . costing about $34-

#3. Madisound 1mh w/ .1 DCR steel laminate inductor, unwound to .8mh. costing about $8.65-.


I'm thinking that my best option is to go for option # 3. As I already have an LCR meter.

But the question is , Is there anything wrong with unwinding the 1mh steel laminate to .8 mh? Would'nt that steel cored inductor suffer in performance with values lower than 1mh?

And , Is this really the best option?
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Old 14th February 2008, 03:39 PM   #2
hermanv is offline hermanv  United States
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There is nothing wrong with removing turns on a laminated core inductor.

Steel core inductors could saturate (especially in woofer circuits). Removing turns reduces the chance of saturation. Take the I max ratings seriously, if they are below any current likely to flow in your circuit go for it.

If an inductor in a series woofer circuit saturates, the inductance drops to near zero causing a loud bang from the woofer with at least a potential for driver damage.
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Old 14th February 2008, 04:18 PM   #3
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Thank you.

But I dont know any current rating on that inductor. All I know is that, It uses #15 AWG magnet wire and it's supposed to be used for high power application. LINK .

The maximum possible amp. power I'll use for my project is 250watts/pc rms amp. and the load that will pass through the inductor is 4 ohms. ( two 8 ohms 7" woofers)

Do you think the inductor would be adequate for the job?
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Old 14th February 2008, 05:17 PM   #4
hermanv is offline hermanv  United States
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I have used one of those at 6mH in a woofer circuit, it worked fine.

A very similar part is available from Parts Express, it is 1.5mH, so even more turns would have to be removed.

http://www.partsexpress.com/erse-16-gauge-inductors.cfm
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Old 14th February 2008, 07:36 PM   #5
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You could get even lower DCR with one of the 14AWG Erse Inductors at Zalytron . $12.53 for a 14AWG 1.5mH. Even less than Parts-Express's 16AWG version!

Regards,
David
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Old 14th February 2008, 10:37 PM   #6
Jay_WJ is offline Jay_WJ  United States
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marchel,

Go with whatever you can get cheap. I'd even consider Madisound Sidewinder 16 AWG air core .8 mH. You won't notice an audible effect of a .2 ohm DCR difference.

And don't worry about a steel core inductor's saturation. It won't happen in your case (2.5 way with 7" woofers).
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Old 15th February 2008, 04:02 PM   #7
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Many thanks to all,

I'm going for the mad. steel laminate inductor.
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Old 16th February 2008, 09:52 AM   #8
Thawach is offline Thawach  Thailand
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Hi marchel


The low DCR coil does not means s good sound. steel core
i had ever used it. Now i only use air core. marchel i had ever
known before that the steel core when it gets the high current.
The impedance of it that it's not correct linear. I often see the speaker to sell in the store. sometime a good speaker use the air cores are too much. Yes! you may be lose a damping factor just a little. But it does not means that you will get a good sound from it.

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Old 16th February 2008, 12:08 PM   #9
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Hello Thawach,

So you're saying that air cored inductors might have better subjective sound quality than steel laminate cored inductors?




You might be right though, Cause , As I remember, There were 2 versions of B&W 800 ( not the D series), There was a plain version and a signature version. The plain version uses iron core coils and bipolar caps on strategic locations, The signature version uses air core coils and poly caps all the way. Of coarse the reviews favor the signature version in terms of sound quality, But wether the difference is true or not, I wonder how much the air core coils and poly caps contributed to the supposed improvement in SQ.
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Old 17th February 2008, 11:55 PM   #10
Thawach is offline Thawach  Thailand
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Hi marchel


i think that you must come back to a hi-school again.And learn
about english+distortion language. you will be better. sometime
I cannot understand my words that i write but you can translate
some words of mine.i think "oh my god" marchel you are good.lol

About steel laminate coil that i can remember a little.i had ever
heard it from the thai producers.they has a company to build the
speaker and sell in the stores. A speaker of them had ever shown in
the CHICAGO hi-fi festival and change the brand was song audio.
The speaker of them never use the steel laminate coil(the pic the use).

they told me about the flux of steel laminate coil. it has a problem.
the flux is easy to full when it gets the current.(this word i don't know)

marchel i understand you. you have a rcl meter.Why don't you wire the
coil by yourself? here is the pic that i wire by myself. i spend my
money about 5 dollars to buy a wire about 1 kg. i wire it 1 mh=4 coils
i use a little tool. 80 per i use my hand. and check it again by lcr meter.
1 mh i spend the times about 15 minutes.is it cheaper? marchel your home
is far from me.i would like to wire it for you but i can't.


marchel i send the graph about bobbin.about 10 years ago i had ever used
i used the bobin 1" 2" and lower than 1"(x) 3 coils had value about 0.6 mh.
i used 16 awg(3 coils) i listen each of it to used. the low freguency was
difference. marchel i used order 1 for the woofer.i knew the best coil
is i"(diameter)for 0.6 mh. and i had ever wired it for passive sub.
i used 11 mh. The bobbin(air core)is the best=2" Marchel you see the
graph x=bobbin. r=ohms below=mh


regards



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