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Old 29th November 2007, 12:47 PM   #1
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Default diy resistor , or not

hello people,

there is always a discussion going on about parts, well here is my question. i have red that a tantalium resistor on my dac will sound much much better.
but i red an article, where a guy makes his own resistor from resitor wire.

he uses isotan,
http://www.isabellenhuette.de/pdf/WI...ENHUETTE-R.pdf

(but constatan could also be used).

i want to know your opion.

1)i need to make a 5k resistor, and because i don't wanna end up winding to much, i'll take 500 omh/m wire, or even more (like 1k/m) the wire is getting very thin; for 500 ohm: 0.035mm ; 1k= 0.025mm diameter; is this a problem that the wire is getting extremely thin ?

2)what about the winding, it is non magnetic wire, but what about the mH, cause it gonna looks like a coil.
you can use other winding techniques, but is that gonna resolve all the problems?

3)what to use: higher ohm, thinner wire : so less turns; or thicker ,lower ohm wire with more turns ?

thanx
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Old 29th November 2007, 01:01 PM   #2
Electrons are yellow and more is better!
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Never heard about the inductance in a resistor?
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Old 29th November 2007, 01:37 PM   #3
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well if you have to wind them on something, then you are actually making a coil. so there could be some inductance involved
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Old 29th November 2007, 02:33 PM   #4
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I do this all the time. My wire of choice is Manganin because you can solder it, it's rock stable, and it doesn't generate any significant thermal emf against copper. It's what NIST uses for their working standards of resistance. Those are then checked against a quantum standard (I think), but that's too inconvenient for daily calibration use. Things like Constantan can be soldered with difficulty, and have good properties, but generate a huge thermal emf against copper by comparison. That's why they also use if for thermocouple wire. Good for power circuits and heaters, but not for low level DC circuits. There are also excellent alloys like RO-800 that have every possible good property except one- they can't be soldered, but have to be welded to a solderable lead. I know nothing about tantalum resistors, but can't imagine they'd be as good as Manganin.

There are various strategies for winding resistors with minimum inductance. The easiest is to fold the length of wire in half, making a bite (or byte or some other spelling!), then hook the loop on a thread or pin, and wind the paralleled strand together around the form. The form can be various materials, depending on ones purpose.

IMO, none of this will be as good as a good bulk metal foil resistor for low inductance or size, nor is it good for high resistance values- the wire gage gets too small and the finished size too big. I won't comment on sound, since I think all resistance materials sound the same. IMO it's only the physical configuration and dielectric materials that matter. Others disagree, usually strongly
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Old 29th November 2007, 02:46 PM   #5
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aha, that is very usefull information.
how thick is your wire you use ?
and how much ohm is the highest you wire ?
i need something around 5k. is that already to much ?

and where can you get it ?

thanx a lot
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Old 29th November 2007, 02:48 PM   #6
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It's a hopeless case to make a really good resistor, small AND with good resistive properties AND more than milliohms.
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Old 29th November 2007, 03:01 PM   #7
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that's not what i have red,

indeed they are big, very big, and cannot have a lot of power. but soundwise, they beat everything. at least that's what i have red at a guys site, and i believe him, he's not a noob.

here you have hist site, and project
http://www.dhtrob.com/projecten/dhz_weerstand_en.htm
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Old 29th November 2007, 03:26 PM   #8
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IMO peranders is absolutely right, though I wind up to a few hundred ohms with excellent AC performance. For resistance standards, there's no problem up to 10K and higher. The problem is, they're huge and never have zero inductance. Now, I've seen a company offering resistors wound out of a huge length of copper wire, and the claim is they sound great. The dilemma here is that what peranders and I consider excellent specifications have to do with basic electrical parameters like stability, inductance, voltage coefficient, self resonance, aging, temperature coefficient, and thermal emf against copper ( hop right in peranders if that's not your criteria!). Once you start talking about the sound of a resistor, all hope is lost, unless you can decide what measurable parameter is attached to that sound. As for a wire source, you can try Kanthal Palm Coast. You'll have to buy a reasonable amount, and it's not cheap, but they can supply almost any alloy. As for gage, you'll have to decide on how big you want the resistor, how small a wire you can handle comfortably (I draw the line at about 40ga), then get the resistance table and work out the length. If I can get it scanned, I'll try to post some tables and winding diagrams later.
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Old 29th November 2007, 03:32 PM   #9
AndrewT is offline AndrewT  Scotland
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Hi,
if you were winding <=10r then I think you stand a chance, but 5k0?

The wind in one direction and reverse it, works to reduce winding inductance.
Conrad's dual wire method brings the two ends together at the PCB and this makes the inductance even lower.
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Old 29th November 2007, 04:44 PM   #10
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Very high precision wire-wound resistors can be bought here:
http://www.rhopointcomponents.com/pr...(through+hole)

No need to bother making them DIY!
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