Mills wire vs. ceramic power resistors

[Arty]

Originally Posted by Joachim Gerhard

Let`s do a DIY resistor !
I have an idea for a chaos resistor that is just a bundle of resistive, insulated wire caotically pushed together and then somehow laquered, sealed or potted.
There is one guy in Switzerland that winds resistors like coils in old radios. Very pretty.
Isabellenhütte also makes one variaty that is antimagnetic. I think it has exactly 1 Ohm per meter and could be usefull.

in electrics stores here you can find resistor wire. It has high resistance / meter, suposedly You can just cut it to size , then put it on a piece of wood, apply hair "lacquer" and beeeee happy. not sure about temperature stability, never had the idea to be intrested in that. Suposedly the freqvency dependant part of the impedance is influenced by how you place the wire on the piece of wood. Probably making a coil out of it is... not the best idea, on the otherhand it may have low enough inductance that it won't mather anyways.
This wire resistor is usualy used to match resistors better. When needed.

[Conrad Hoffman]

Jackinnj- Yeah, I've heard of that AP outfit, they probably use op-amps and software to get the answers- highly suspect methods ;-)

Still, no matter how trusted the equipment, I always like to do a reality check with physical artifacts. I've read about very flat response RF standard resistors that are basically sheet metal affairs, though I can't for the life of me figure out exactly how to build one from the diagrams and descriptions. They look sorta like a tapered stripline with a resistance wire bonded across.

FWIW, I've tested various well known winding patterns and found that the "non-inductive" patterns don't buy as much as one might hope. The old Julie technique where they divide a bobbin into sections and change the direction on each section isn't very good, so my guess is that combining resistors in any special physical orientation doesn't accomplish much either. Still, whatever inductance there is doesn't seem to matter (to my ears). It does bother me that the percentage "tilt" over the audio range is as much as your graphs show, as I could imagine hearing that.

CH

[tinitus]

if all power resistors are inductive, I as ask myself, do they interact if mounted close to each other
we know coils do that
could this be any issue

[pinkmouse]

Of course they will. The question is, does this interaction significantly affect the functioning of the circuit?

[AllenB]

tinitus, have you experienced the sound of inductor interaction? I found out by accident once. The values were large, connected to a woofer and at least one was iron cored. The sound was like electronic reverb, only less distinct...a little phasey if that's a word.

I cant imagine resistor inductive interaction (in a passive crossover) as having a significant enough effect to be a problem, or even audible.

[tinitus]

Originally Posted by AllenB

tinitus, have you experienced the sound of inductor interaction?

yes, and just right now, actually

in the two schematics you will see different orientation of a small paralel coil on tweeter
difference in sound is significant
no doubt about it
and phase issues are very clear too
maybe a different size inductor would change that to the opposite
but I have not tried, so I dont know
funny thing is that Troels Gravesen suggest the opposite orientation

now, all my power resistors measures about 0.025mH
some bigger ones even twice of that
considering that resistor inductance is about 10% of the coil, well....

but my thought was aimed at power amps where we often see multiple power resistors mounted very close to each other

well, we are in speaker forum

[a.wayne]

Originally Posted by Joachim Gerhard

I did not try the Mills but i also like wirewounds best in speakers.
For best results i use Mundorf Supreem. They are non inductive non magnetic and low inductance.
having measured and listened to a lot of resistors i found that inductance is not an issue at audio frequencies even when the resitor has no Aerton-Perry winding.
Other favourits of mine are Vishay-Sfernice RWM. They are awaillable in 7, 8 and 11W at Farnell and cost around 1€. The sound has a bit more sparkle in the treble and is ideal for a softdome tweeter. You can fake a non inductive by mounting two resistors of double value close together, inverting the leads of one and then paralleling them for half value. Welwyn-TT electronics makes the somewhat similar W22, W23 and W24 series giving an even brighter sound with a very "high" soundstage. I do not know where that effect comes from but it is very obvious on listening.
For ribbon tweeters i like to use Vishay RCH, TT-BCP or BRP, Tyco MPC thick film resistors. They sound neutral as if they whould not be there but the Mundorf has a liquidity that is hard to explain but easy to like.

I find wirewound to be the best my self, Lynk used to make a fantastic wire wound resistor, non-inductive, very inexpensive , better than the more expensive vishays, they had very good sonics , then they switched to metal ...

Meh ...

Originally Posted by Joachim Gerhard

Thank you for the kind words.
I agree with conrad that inductance of resistors is a non issue in loudspeakers.
i made some measurements that i will publish on the soon to be released Quantum Music website. i was quite surprised that even the cheepest zement resistor had no measurable inductance up to 200kHz with a 2.5 Ohm dummy load.
of cause i can measure inductance with a squarewave but in the audio range there is nothing to worry about. i disagree that they sound all the same. please visit me and i can show you. by the way Isabellenhütte that makes resistive wire for a lot of companies is only 60km from my place. the are experts in metalurgy and it forrunners must go back to the midleages being swordmakers. they make Manganin Resistors called Isaplan.
Concerning wattage i whould not go under 5W. Resistors with higher wattage also distort a little less (but only under -140dB) and temperature coefficient it not such an issue. i learde that resistors in impedance compesation circuits can get quite hot so go for 10 to 20W there.

"Use your ears as your eyes" - Gertrude Stein

What are your thoughts on this now , any changes ...?

Originally Posted by Joachim Gerhard

Let`s do a DIY resistor !
.

Sounds good, make mine wire wound with silver leads....