# Carbon Film vs Metal Film revisited



## dsavitsk

Looking through old posts, there seems to be a consensus around here (with the exception of rick, perhaps) that metal film resistors are neutral and good, and that carbon film resistors behave badly (especially with heat), that they are inconsistent, that they are noisy, and that they are to be avoided except perhaps in power supplies where they don't matter so much.

 I recently built two versions of the same circuit one with carbon film Kiwame resistors, the other with a combination of PRP and Holco metal films. This is a buffer and is being used as a buffered passive pre. The Carbon version has a modified velleman with a tle2426 as a PS while the metal film has a modified welborne PS1 (that is, the metal film version has the arguably better PS.) The source is a Cary cdp, the power amp is a sumo, and the speakers are B&W (I mention this as the source, power amp, and speakers are all decidedly warm.)

 Listening to these two circuits, it is true that the metal film version has lower noise, is more detailed, has more extension, images better, and sounds alltogether more clear. However, the carbon film version is clearly better. The difference, moreover, is not subtle in the least (i.e., this is not last 1%, but more like last 20%). The metal film version is harsh and tinny and foreward sounding -- even with all of the associated equipment being on the warm side. 

 The carbon version is warm and musical -- this was the case even when paired with a Non inverting gain clone which can sound a lbit on the sterile side itself. The sounds are round -- almost bloomy. Bass is deep and defined, but is visceral -- my wife described it as embracing.

 Now, it may be that there is too much noise with the carbons for a headphone amp. In places where thay can be used, however, I am going to try them more often.

 -d


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## Daroid

Very interesting! I also agree that carbon resistors might not be very tolerable for headphone amps because of the noise. But one other thing: The Kiwame is not just a simple "carbon" resistor - it's a boutique marked for audio applications - and it is assumedly better for that appliaction than radio shack carbon resistors or other cheap carbon film. i always read it as metal film was more desireable when it was cheaper metal film vs. cheap carbon film.


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## kevin gilmore

There is a big difference between carbon film and standard bulk carbon
 resistors. Furthermore many metal film resistors are actually spiral cut,
 typically with a laser and are more inductive than one might expect.


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## dsavitsk

Quote:


  Originally Posted by *Daroid* 
_The Kiwame is not just a simple "carbon" resistor - it's a boutique marked for audio applications - and it is assumedly better for that appliaction than radio shack carbon resistors or other cheap carbon film. i always read it as metal film was more desireable when it was cheaper metal film vs. cheap carbon film._

 

That's a good point that I should have mentioned. It is worth adding to it that the metal film resistors in the comparison are also boutique ones. So, cheap metal and carbon are both left out of the experiment.


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## multibit16

Riken is my favourite carbon resistor, they are also specced at 1% tol


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## Garbz

I'd like to add my opinions about Holco resistors which to my ear sound noticably brighter then the Vishey Dales. But that could just be placebo effect. I did have 2 gilmore amps one used Holco's on the output the other visheys.

 Btw what B&W speakers do you have?


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## Emon

Don't mean to hijack here, but I have a quick question...I threw together a 75 ohm adapter for my KSC-75 for whenever I get around to building an amp, and I used some unknown resistors I found in my stash. I matched them, they were within 0.1 ohms before I started soldering. After...well let's just say I was using slim Calrad jacks and these are (presumably) carbon resistors and a little bigger than more modern carbon or metal film...ended up heating them way too much, now they're off by like 1.5 ohms. Bah. Anyway, would there be any noticable difference between those (presumable carbon) and metal film? I never thought there would be much of a difference in sound, as resistance is just resistance (in theory anyway)...I doubt there would for my KSC-75, but I figured it's worth asking. I thought the main reason people used metal film was because of the price and the low tolerance at said price.


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## dsavitsk

Quote:


  Originally Posted by *Garbz* 
_Btw what B&W speakers do you have?_

 

old DM630's. They are pre kevlar drivers, so while they have the B&W sound, they don't quite have the detail. Also, not being matrix construction they lack a bit of bass punch. For what they cost, however, they're pretty good. They are the only things (other than my Linn table) that have been in my system since the beginning 12 years ago.

 As a side note (and an opportunity to say something nice about a manufacturer,) a couple of years ago -- long after the warranty had ended -- the rubber rings around the cones started to deteriorate. I contacted B&W to see if I could buy new ones, and they sent me a new set for free.

 -d


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