# Are resistors directional?



## skaelin

I know this is probably a dumb question for a lot of you, but I really don't know. I'm about to do the resistor mod on a pair of KSC35s. 

 Thanks, 

 Steve


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## perfectturmoil

Nope :- ]


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## whiz

I don't know to which mod your reffer...but if your are talking about resistors in general...they don't have specific way we aply them to a cirquit!


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## jarthel

there is no direction BUT

 it seems paralleling them on the opposite directions could lower inductance? (not sure if it only applies to metal oxide though)

http://www.audiodesignguide.com/my/n...004/schem2.jpg

 it's a design by Andrea Ciuffoli.

 ps. no I haven't not tried it myself and I have no way of measuring inductance. But Andrea has built lots of amps, he probably knows what he is doing.


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## motherone

Well, there are plenty of audionuts that will tell you resistors are directional, but I doubt it


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## Garbz

Quote:


  Originally Posted by *jarthel* 
_there is no direction BUT
 it seems paralleling them on the opposite directions could lower inductance? (not sure if it only applies to metal oxide though)_

 

Inductors are non-directional. Parallelling them will lower inductance by the inverse of the sum of the inverses just like resistors, but this is irrespective of their alignment.

 Could just be another marketing trick. Mention torroids and run before music_man gets here!


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## jarthel

Quote:


  Originally Posted by *motherone* 
_Well, there are plenty of audionuts that will tell you resistors are directional, but I doubt it 
	

	
	
		
		

		
		
	


	


_

 

andrea ciuffoli is a respected figure in the DIY community. He didn't acquire such respect by designing "snake oil" amps.

 you on the other hand... 
	

	
	
		
		

		
		
	


	




 ps. I do not think paralleling them means they have direction. Maybe it was something to do with the construction of resistors which makes them less inductive by paralleling them.

 from my limited knowledge, inductances in series increases while paralleling them would decrease them.


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## jarthel

Quote:


  Originally Posted by *Garbz* 
_Inductors are non-directional. Parallelling them will lower inductance by the inverse of the sum of the inverses just like resistors, but this is irrespective of their alignment.

 Could just be another marketing trick. Mention torroids and run before music_man gets here! 
	

	
	
		
		

		
		
	


	


_

 

andrea does not sell any amps nor he said to use a specific brand of resistors to use.

 maybe he know something about metal oxide resistors that others don't? his suggestion even be limited to metal oxide. 

 who knows? I surely don't but I just posted a suggestion/recommendation by someone who knows what he is doing.


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## nikongod

paralleling resistors to make them "more ideal" (less inductive, or generally noisy) has been done for ages, and its benefits are not limited to metal oxide resistors.


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## jarthel

Quote:


  Originally Posted by *nikongod* 
_paralleling resistors to make them "more ideal" (less inductive, or generally noisy) has been done for ages, and its benefits are not limited to metal oxide resistors._

 

I think what people is arguing is the way of paralleling the resistors as andrea has recommended

 I assume you looked at the link I provided above?


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## marvin

Metal oxide resistors are decidedly not directional.

 A metal oxide resistor is just a ceramic tube with metal oxide stuffed in it and a lead coming off of each end. There is no way you could make one that's directional and still have it be a resistor.


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## nikongod

i am torn on this subject.

 on the one hand to argue aganst it, it is an inductor but inductors are non directional. 

 on the other, the way resistors are "cut" makes them SOMETIMES have a more resistive side than the other, sort of like soldering a 100&50 ohm resistor in series to get 150ohms. measuring "1 resistor" from one side gets 50 ohms, and measuring 1 resistor from the other gets 100 ohms. i dont think that this is as much a problem with newer reisitors, but it could be.

 on the next hand from there, is there a guarantee that a particular manufacturer will label their product consistently? will the "less resistive side" allways be on the "tollerance band" end (for example) or does it vary from batch to batch? does it vary WITHIN batches?

 i still say if you care enough to parallel, throw a carbon in the mix with a bunch of metals.


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## jarthel

Quote:


  Originally Posted by *nikongod* 
_i am torn on this subject.

 on the one hand to argue aganst it, it is an inductor but inductors are non directional. 

 on the other, the way resistors are "cut" makes them SOMETIMES have a more resistive side than the other, sort of like soldering a 100&50 ohm resistor in series to get 150ohms. measuring "1 resistor" from one side gets 50 ohms, and measuring 1 resistor from the other gets 100 ohms. i dont think that this is as much a problem with newer reisitors, but it could be.

 on the next hand from there, is there a guarantee that a particular manufacturer will label their product consistently? will the "less resistive side" allways be on the "tollerance band" end (for example) or does it vary from batch to batch? does it vary WITHIN batches?

 i still say if you care enough to parallel, throw a carbon in the mix with a bunch of metals._

 

from what more knowledgeable people have said (diyaudio), it could the way the resistor was cut. and then you have the problem on the labelling consistency.

 ps. sort of annowing how people dismissed an idea without providing an explanation/reason 
	

	
	
		
		

		
		
	


	




 another ps.

 with polypros (at least of the some expensive brands), they label the side where it's on the outer foil (not sure of this. but it has something to do with the cap construction). something akin to "direction" perhaps even though polypros are supposed to be non-polarized.


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## DaKi][er

Even if you got some 'directionality' to your resistance (which i am yet to see any plausible explanation) what effect will this have on our sounds AC signal that has no 'direction' as such?


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## motherone

Quote:


  Originally Posted by *jarthel* 
_andrea does not sell any amps nor he said to use a specific brand of resistors to use.

 maybe he know something about metal oxide resistors that others don't? his suggestion even be limited to metal oxide. 

 who knows? I surely don't but I just posted a suggestion/recommendation by someone who knows what he is doing. 
	

	
	
		
		

		
		
	


	


_

 

First off, my comment wasn't directed at you. It was directed at the topic in general. If you ever read diyaudio, you'll know that there's been conversations regarding the sound of resistors, along with whether or not they have directionality.

 Second, have you read Andrea's articles? He recommends plenty of brands, mainly Allen Bradly Carbon Comps and Caddocks. He almost always specifies them in every article I've seen him write.

 I think resistor directionality is snake oil. And while I may not design amps, that does not prevent me from having an opinion. If you beg to differ, you're more than welcome to, but please don't attempt to admonish my comments simply because I don't have designs published for others to look at. 

 I have actually tried many different types of resistors (Caddock, Vishay/Dale, Vishay S102 thick film, Corning Glassware Glass/Metal Film, CGW Glass/Carbon Comp, Allen Bradly and various other carbon comps, Carbon Film, and so on). I can't even tell the difference between the various types of metal film resistors in identical versions of a circuit, let alone whether any of them would have directionality.

 I also doubt that the inductance of a resistor would have an audible result in 99.999% of the designs out there. And if it did, I would contend that the design is most likely broken. If you're worried about the inductance of a metal film, wirewound, or metal oxide resistors, go back to using carbon comps!


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## jarthel

Yes I have read his ariticles in headwize and those in his own site.

 And yes Andrea does recommend various brands of resistors on his *other* designs. BUT not on the amp I linked.

 your opinion vs andrea's opinion in relation to audio DIY...


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## jarthel

let us not forget that the recommendation was for "paralleled resistors"


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## Born2bwire

Quote:


  Originally Posted by *jarthel* 
_let us not forget that the recommendation was for "paralleled resistors"_

 

The recommendation in question is to situate the parallel resistors in opposite directions in reference to the printed labels. The construction of a resistor should be symmetrical, as opposed to say an electrolytic capacitor which has a decided difference in its construction between the two leads. Even if there is a slight, systematic, and reproducible difference in the construction as seen from each lead, I doubt that the printing of the label on the resistor is done consistently in regards to this directionality.

 The idea of putting them in parallel to reduce inductance is a sound idea. All linear circuit elements in real life will have minute parasitic capacitances or inductances. Putting capacitance in series reduces the total capacitance. Placing inductors in parallel reduces inductance (provided that the mutual inductance between the two inductors is not significant in regards to their respective self-inductance, which is a very reasonable assumption here). Resistors are generally inductive because of how they are constructed. For example, they can be long resistive wire loops which lend towards inductive parasitics. For the most part though, with audio frequencies, the frequency is so low that the impact of the parasitics should be fairly insignificant. But there is no harm in using these tricks. Nothing wrong with going that extra mile.

 EDIT: Actually, there is another practical reason why you may want to do the parallelized resistors given that you can replace them with a single resistor of equivalent value. By using two resistors in parallel, the error in your final resistance value will be less than the error in the individual resistors provided that the two resistors are the same. Working it out real quickly, if the error in resistor 1 is E1 and the error in resistor 2 is E2, then the total error will be (1/E1+1/E2)^{-1}. So if you have a positive 10% error in your value for both resistors where both of them are supposed to be the same resistance, then the resulting error in your parallel configuration will be a positive 5%.


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## splaz

Quote:


 on the other, the way resistors are "cut" makes them SOMETIMES have a more resistive side than the other, sort of like soldering a 100&50 ohm resistor in series to get 150ohms. measuring "1 resistor" from one side gets 50 ohms, and measuring 1 resistor from the other gets 100 ohms. i dont think that this is as much a problem with newer reisitors, but it could be. 
 

But how does that make it directional ?

 It was my understanding two resistors in series will give the same resistance in whatever orientation and order. Same I'd imagine goes for a single flawed resistor. Overall it still provides a resistance that isn't directional. A less resistive side as far as I can imagine would only put the resistor slightly out of spec.

 If the order and orientation of those resistors make a difference I stand corrected.


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## jarthel

here's a thread I created in diyaudio:

http://www.diyaudio.com/forums/showt...threadid=84819

 more mature discussion IMO (not to say that every discussion there is mature)


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## creyc

C'mon guys!

 I don't like how everyone dispels snake oil like it doesn't do anything!


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## Born2bwire

Quote:


  Originally Posted by *jarthel* 
_here's a thread I created in diyaudio:

http://www.diyaudio.com/forums/showt...threadid=84819

 more mature discussion IMO (not to say that every discussion there is mature)_

 

And what do you know, they are saying the same things. Parallel resistors will reduce the total inductance in comparison to a single resistor (ignoring the added inductance of the additional traces). However, this introduces mutual inductance in addition to their self-inductance. But since the magnetic moment of the resistors are the same in either orientation, reversing the resistors has no effect on this. But we can make the safe assumption that the mutual inductance is negligible. In addition, there is no way to assume that the resistors are banded in a consistent orientation at the factory.


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## NeilR

Quote:


  Originally Posted by *Born2bwire* 
_ In addition, there is no way to assume that the resistors are banded in a consistent orientation at the factory._

 

Take it a step further.... if the manufacturers had a reason to make it consistent they would talk about it in their datasheets. It is probably a safe assumption that if they don't have a specific reason to maintain the orientation then if they do it is an accident of the specific manufacturing process. That could change with the next tweak or upgrade to the process. 

 I find it amusing that someone would put something in a schematic such as polarized resistors without a very complete explanation. Kind of goes along with the old saying "extraordinary claims require extraordinary evidence".


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## Garbz

Quote:


  Originally Posted by *creyc* 
_C'mon guys!

 I don't like how everyone dispels snake oil like it doesn't do anything! 
	

	
	
		
		

		
		
	


	


_

 

Other than making people sick if consumed.


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## motherone

Reducing whatever inductance exists in a resistor by paralleling two of them works because a paralleled pair of identical inductors will reduce the inductance by half (which I think is what born2bwire is trying to explain). Assuming the inductance of the two resistors is indentical, their combined inductance would then be halved. 

 There's nothing really mentioned about directionality in Andrea's article from what I can see. He marks the "orientation" of the resistors with the dot, but there's no explanation as to why, other than trying to reduce the inductance of the metal oxide resistors in his circuit. I have no idea how this has anything to do on the discussion of whether or not resistors are directional.

 My thought on it is similar to Neil's: If directionality in resistors actually existed and affected anything in a circuit, the manufacturers would spec it in the resistor's datasheet. We also would have probably heard about what circuits could be affected by said directionality.


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## vixr

I always put resistors in with the bands describing the first value "up" because it looks so cool... you guys should try snake oil on west indian manatee... it really softens up those endangered aquatic speedbump tags.


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## motherone

As do I, Vixr.. I generally try to make the look of the amp consistent for purely aesthetic reasons (i.e. bending the pins on the vishay/dale resistors so that you can read their value, and the text is oriented in the same direction on all parallel resistors).t


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## Uncle Erik

I'd recommend finding out for youself. Take your DMM and measure the resistor in both directions. If the value is the same on both readings, it's not directional. I've done this now and then... still have yet to find a "directional" resistor.


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## jarthel

...........................


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## Denim

Quote:


  Originally Posted by *Born2bwire* 
_EDIT: Actually, there is another practical reason why you may want to do the parallelized resistors given that you can replace them with a single resistor of equivalent value. By using two resistors in parallel, the error in your final resistance value will be less than the error in the individual resistors provided that the two resistors are the same. Working it out real quickly, if the error in resistor 1 is E1 and the error in resistor 2 is E2, then the total error will be (1/E1+1/E2)^{-1}. So if you have a positive 10% error in your value for both resistors where both of them are supposed to be the same resistance, then the resulting error in your parallel configuration will be a positive 5%._

 

You have the right idea here, but the explanation could use some additional info. It's possible that 2 resistors in parallel will achieve a final resistance closer to the desired value, but the errors need to cancel out each other. That is, one resistor having a higher reading, and the other having a lower reading. If they are both higher, or lower, then the total resistance can still be off as much as a single resistor. Here's the math --

 Desired resistance - 50 ohms

 Circuit 1: 100 ohm (measures 110 ohms) & 100 ohm (measures 110 ohms) in parallel = 55 ohms. Resistors off by 10%, circuit off by 10% also.

 Circuit 2: 100 ohm (measures 110 ohms) & 100 ohm (measures 90 ohms) in parallel = 50 ohms. Resistors off by 10%, circuit achieves desired resistance because the offsetting differences cancel each other out. 

 As for resistors being polarity sensitive, I haven't seen one yet.


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## Born2bwire

Quote:


  Originally Posted by *Denim* 
_You have the right idea here, but the explanation could use some additional info. It's possible that 2 resistors in parallel will achieve a final resistance closer to the desired value, but the errors need to cancel out each other. That is, one resistor having a higher reading, and the other having a lower reading. If they are both higher, or lower, then the total resistance can still be off as much as a single resistor. Here's the math --

 Desired resistance - 50 ohms

 Circuit 1: 100 ohm (measures 110 ohms) & 100 ohm (measures 110 ohms) in parallel = 55 ohms. Resistors off by 10%, circuit off by 10% also.

 Circuit 2: 100 ohm (measures 110 ohms) & 100 ohm (measures 90 ohms) in parallel = 50 ohms. Resistors off by 10%, circuit achieves desired resistance because the offsetting differences cancel each other out. 

 As for resistors being polarity sensitive, I haven't seen one yet._

 

Whoops, made a mistake in the math. The error should be:
 abs(1+2*(E1*E2-1)/(2+E1+E2)).
 So it would appear that the final error is going to be equal to or less than the larger error of the two resistors. In your second circuit though there still is an error of 1%.

 Another reason to go parallel that I thought of is that you split the current running through each resistor by half while increasing the resistance by 2. So the power dissipated will reduce by a factor of two. So theoretically, you could use cheaper parts. For example, instead of a 1K 1/2 W 5% resistor, you could use a 2K 1/4 W 1% and a 2K 1/4 W 10% and achieve the same power specs with a maximum error of 5.7% Though in real life I doubt there is any such combination of two resistors that would actually be cheaper than the single resistor that you are replacing.


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## NeilR

Quote:


  Originally Posted by *Denim* 
_You have the right idea here, but the explanation could use some additional info. It's possible that 2 resistors in parallel will achieve a final resistance closer to the desired value, but the errors need to cancel out each other. That is, one resistor having a higher reading, and the other having a lower reading. If they are both higher, or lower, then the total resistance can still be off as much as a single resistor. Here's the math --

 Desired resistance - 50 ohms

 Circuit 1: 100 ohm (measures 110 ohms) & 100 ohm (measures 110 ohms) in parallel = 55 ohms. Resistors off by 10%, circuit off by 10% also.

 Circuit 2: 100 ohm (measures 110 ohms) & 100 ohm (measures 90 ohms) in parallel = 50 ohms. Resistors off by 10%, circuit achieves desired resistance because the offsetting differences cancel each other out. 

 As for resistors being polarity sensitive, I haven't seen one yet._

 

The problem with this is that resistors within a batch tend to match each other much closer than their spec'd tolerances. This is great for matching but not helpful for absolute tolerance to the specified value. Within a random lot it would probably be easier to find a single very close match to the specified value than to find two that are relatively close in absolute error, on opposite sides of the intended value.

 Then again, there aren't many circuits that care about absolute values below 5% or so and most have much higher tolerances.


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## Denim

Quote:


  Originally Posted by *NeilR* 
_The problem with this is that resistors within a batch tend to match each other much closer than their spec'd tolerances. This is great for matching but not helpful for absolute tolerance to the specified value. Within a random lot it would probably be easier to find a single very close match to the specified value than to find two that are relatively close in absolute error, on opposite sides of the intended value.

 Then again, there aren't many circuits that care about absolute values below 5% or so and most have much higher tolerances._

 

I hear what you are saying. I was running with the idea that Born2wire submitted and stayed with the theory. This sounds like the problem I constantly run up against. Just because you can put it on paper, it doesn't mean you can go to the parts bins and wire it up. I have enough trouble just finding the right components.


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## NeilR

Quote:


  Originally Posted by *Denim* 
_I hear what you are saying. I was running with the idea that Born2wire submitted and stayed with the theory. This sounds like the problem I constantly run up against. Just because you can put it on paper, it doesn't mean you can go to the parts bins and wire it up. I have enough trouble just finding the right components._

 

You were working through a theory. Theory and practice are often two different animals


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