# Carbon comp vs. other types



## GuitarG. (Apr 1, 2010)

I have a question concerning carbon comp resistors. First I'll say I'm not a seasoned tech. I do understand alot of electronic theory and have some hands on experience, but lack alot of experience that some here have. In saying that, I have gained information from different techs/builders, some of which have differing opinions. For me it's a matter of testing alot of the information I have picked up and drawing my own opinions/conclusions. Oh yes, and I still have alot too learn. Not trying too come off sounding like I understand all theory either.
When it comes to carbon comp resistors some techs/builders swear by them and some would not even consider using them. So, it leaves the question, why differing opinions of them? And I'm not talking manufacturers trying to push their product. This is amongst techs. One fact that all techs/builders agree on, whether for or against them, is the reliability factor. Carbon comps are the most prone to malfunction or breakdown. they can't take excessive heat like other resistor types ie. metal film, metal oxide. Another fact is they are the most noisy.
Where the opinions differ between the use of different resistor types is the sound factor. Some techs say despite the added noise they sound better than other resistor types. Other techs say they dont make a bit of difference. Some techs state that they sound more "musical" and that metal films for expample, while quieter, sound more sterile.
Personally I question the quality of carbon comps made today. Also considering that they are 2 too 3 times more expensive than other resistor types, "boutique hype" i guess you could say, these factors have turned me off from even considering using them. As an experiment though I'd like to try building a simple circuit with strictly one type then swapping all resistors with another type just too test this "difference in sound" theory. I'm not talking about noise, just too see if there is a difference in the overall sound.
I know you have a ton of experience as a tech WildBill and appreciate your knowledge of electronics and amps. Same goes for other techs on here. As for other techs on here, are most of the opinion/conclusion that there are no differences in sound between different resistor types? Just wondering what your experiences are. I think it's a fair question being that I've heard both sides of the issue. Just wondering what the general opinion is here on GC.

thanks,

GuitarG.


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## greco (Jul 15, 2007)

GuitarG...I am not a tech, but I am interested in electronics as a hobby. 

The one thing that (I think) you missed is that the values of carbon comps drift significantly. Maybe, to some extent, that is what you were describing when you said they were prone to "malfunction"?

Your "experiment" idea _sounds_ (pun is intended) interesting. Were you thinking of testing this by building a simple pedal?
If so, *mhammer *, GC member in Ottawa, might have some interesting comments...possibly he might even be able to tell you what to expect (he has years of experience in the area).

We have an old local electronics store that sells CC resistors for very little (at least they used to have quite a few in packages)..I can get some for you and save you from having to pay "boutique" prices and expensive shipping.

Cool thread....BTW.

Cheers

Dave

P.S. I just read in a catalog (Antique Electronics Supply, Tempe, Arizona) that carbon comp resistors have *"Better pulse endurance characteristics than film type resistors"*...I have no clue what that means, or if it is all that important/significant.


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## keeperofthegood (Apr 30, 2008)

Read: http://www.c-c-i.com/sites/default/files/vse-an00.pdf

OH and, there are techs out there that will look at an amp with 6BQ6's, stick a 6L6 in its place, cut off the cap wire and tell you the amp isn't repairable. Some "techs" are just beer drinkers with signs out their front doors. Between such people and the people that either went and spent 5 years in Honors Engineering at University, or did a 4 year technical college when it comes to opinions on things like make of capacitors and if a resistor is good or bad in a circuit. 

Like they say, when you go online for medical advice.....


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## Wild Bill (May 3, 2006)

GuitarG. said:


> I have a question concerning carbon comp resistors. First I'll say I'm not a seasoned tech. I do understand alot of electronic theory and have some hands on experience, but lack alot of experience that some here have. In saying that, I have gained information from different techs/builders, some of which have differing opinions. For me it's a matter of testing alot of the information I have picked up and drawing my own opinions/conclusions. Oh yes, and I still have alot too learn. Not trying too come off sounding like I understand all theory either.
> When it comes to carbon comp resistors some techs/builders swear by them and some would not even consider using them. So, it leaves the question, why differing opinions of them? And I'm not talking manufacturers trying to push their product. This is amongst techs. One fact that all techs/builders agree on, whether for or against them, is the reliability factor. Carbon comps are the most prone to malfunction or breakdown. they can't take excessive heat like other resistor types ie. metal film, metal oxide. Another fact is they are the most noisy.
> Where the opinions differ between the use of different resistor types is the sound factor. Some techs say despite the added noise they sound better than other resistor types. Other techs say they dont make a bit of difference. Some techs state that they sound more "musical" and that metal films for expample, while quieter, sound more sterile.
> Personally I question the quality of carbon comps made today. Also considering that they are 2 too 3 times more expensive than other resistor types, "boutique hype" i guess you could say, these factors have turned me off from even considering using them. As an experiment though I'd like to try building a simple circuit with strictly one type then swapping all resistors with another type just too test this "difference in sound" theory. I'm not talking about noise, just too see if there is a difference in the overall sound.
> ...


Actually GuitarG, you haven't likely heard both sides of the issue. There is only ONE side and that's the technical side!

The other side comes from people who have never cracked an electronics textbook. If they have, they may have read a sentence or two but never read an entire chapter that explains something. They instead make mystical claims of what they "hear", never actually doing scientific tests but simply what they "feel".

They are like astrologers who make predictions. Every New Years some magazine will publish their predictions. No one ever tracks the accuracy record of their LAST YEAR'S predictions!

A volt will shove an amp through an ohm of resistance. That can be measured. You will always get the same result on your meter. Anything else is just unscientific mojo.

There is no substitute for learning electronics theory. There is no substitute for learning to read schematic diagrams. In my opinion, it is impossible to become a good tech without these two factors.

Sometimes it may require a bit of research to understand what is going on with some mojo factor. That's because things can get complicated and the theory to explain things will also be complicated. Much mojo starts from a grain of truth but gets stretched beyond all recognition, usually by someone trying to sell you something and/or convince you that he's some kind of cosmic guru of knowledge.

Carbon comps are a good example. Most folks agree that they are the best hiss,noise and spit generators ever made but some guys claim they also have better "tone". In fact, they are hearing something but it's not at all what they think is going on!

First off, resistance in itself is NOT a tone factor! DC resistance is the same at all frequencies. It can make a signal stronger or weaker. This is a volume thing, not a tone one. To change tone you have to change the shape of the wave. In essence, by changing it you are affecting how it sounds. The signal has become distorted! THAT'S why it sounds different!

A very smart man and a REAL guru in guitar amp circles is named R G Keen and he has investigated tone properties of carbon comps. He found that under SPECIAL and EXTREME circumstances in only certain areas of a circuit a carbon comp resistor will break down and not operate as a pure or good resistance. It will actually change its value slightly under a heavy voltage swing. This change in value can affect the tone. However, the change is very slight and only at high volumes. It's doubtful if many human ears would ever notice. 

What's more, there's really only ONE spot in an amplifier circuit where this effect can happen! Forget all the grid, signal, cathode, screen and plate resistors in an amp. Only the plate resistors of the typical long tail phase inverter would or could show this slight difference if they were carbon comps!

This is a far cry from putting carbon comps in every spot in your amp! It's also not a big enough tone thing to impress anyone either. Still, it's enough to con lots of people into buying your carbon comps at ridiculous prices!

Here's a link to R G Keen's site:

New Page 1 When you get there, click on "Tube Guitar Amp Tech Pages" from the column on the left and then choose "Carbon Comp Resistors - Is the Mojo Factor Real?"

This is a fabulous article! It is scientific and makes sense! If you repeat what R G did you will get the same results!

One guy like R G is worth 10,000 phony mojo audiophile self-appointed gurus!

You will also find TONS of useful tech info on his site! It's a mandatory bookmark!

WB


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## greco (Jul 15, 2007)

Thanks for the link Wild Bill !!...and Yes, I did bookmark the site.

from RG KEEN: 

QUOTE *"I'm always amused at people who advertise putting carbon comp resistors in their 9V powered effects to give them some kind of magical vintage sound. Urban legend is tough to kill, though - and magic mojo always makes for dynamite advertising copy."* END OF QUOTE

So much for doing your experiment using a pedal/effects circuit....LOL

Cheers

Dave


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## Jean GODBOUT (Oct 31, 2009)

That a very interesting discussion. I'm not a tech either, just a passionate hobbyist and I build so far 6 tubes amps. So here is my humble opinion, carbon comp resistors are best to be use in the audio patch, input and so on, but carbon film (or metal film) have their place on the power section since they are more stable. Why do peoples pay a fortune to buy vintage amps ? Because they sound good and most of them use carbon comp resistors. I have build a Tweed Deluxe with four 6V6 power tubes call the 5E3X2 (in Weber site) and just for experience I tried a HiFi Jensen Paper & Oil capacitor and the tone was lacking of punch, then I came back to a ''cheap'' cap and the amp became back sensitive and reactive. I guess it's the same with carbon comp resistor, they have some drawback but this contribute to the raw power of a guitar amp oppose to a HiFi amp. 

Here is a picture of my latest build (JTM45 clone) and you will see a mixture of carbon comp resistors and carbon film on the power section, as suggest by Metro-Amp guys.


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## greco (Jul 15, 2007)

Jean GODBOUT said:


> .......just for experience I tried a HiFi Jensen Paper & Oil capacitor and the tone was lacking of punch, then I came back to a ''cheap'' cap and the amp became back sensitive and reactive.
> I *guess* it's the same with carbon comp resistor, they have some drawback but this contribute to the raw power of a guitar amp oppose to a HiFi amp.


Beautiful work Jean !!

Not wanting to upset you in any way, but you say that you *"guess"* that changing to carbon comp (CC) resistors makes a difference (as you compared this to the change of caps that you did). However, have you ever changed any of the CC resistors for other types and heard any difference? 

Cheers

Dave


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## GuitarG. (Apr 1, 2010)

greco said:


> However, have you ever changed any of the CC resistors for other types and heard any difference?


And THAT is exactly what I am getting at. This is where some techs and builders have had differing views on the subject of what they HEAR as differences. I understand WildBill's side of the arguement speaking of it technically and with what he may hear as it being a non-difference. Thanks for the response WildBill and others that responded. I respect what you're saying. I've talked too a few techs/builders that claim there is a difference. Obviously Metroamps seems too think, or have concluded, that there is judging by the above post as well as a few other established builders. I've heard other builders and techs say the same thing in other articles and forums. And others that say there is'nt. So yes there seems to be two general consensus on the issue. What do I think? I don't know. I have not put together an amp or rebuilt one experimenting with various brands and all types all in one amp.
As far as experimenting, yes I meant a simple amp circuit not a pedal Greco. Mabe I'll try it on a low wattage kit or rebuild. Not something I'd want to try on a "red-knob" Fender Twin. 
Keeper and WildBill, like I said I am not an experienced tech. I have taken a college electronics course. The problem with electronics is that it is so wide with various branches of fields that a course cannot cover all of the various fields in detail. Hell if you can point me too any college that deals strictly with tube circuitry or more specifically with tube radios and amplifiers I'd give it a go. Best I can do is take whatever I've learned as far as just general electronics and try too apply it too my interest in tube amplifiers. I'd say the Radiotron book probably has more information on tube circuitry than anything anybody would hope to learn on that subject through a college course today. Have I absorbed all the information from a 1500+ page technical book? I'd need to seek mental help after trying such an attempt LOL. But seriously it is a great reference book of course and a good read. Deffinately recommend anyone interested whether for hobby or learning to have this book.
Anyway, back too the subject of CC's, it's something I'll have to try sometime and see what my ears tell me. I guess the fairest way of experimenting would be too have two exact circuits, one with CC's and one without.
BTW thanks for the links. I've added them too my favourites list.

GuitarG.


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## nonreverb (Sep 19, 2006)

GuitarG. said:


> And THAT is exactly what I am getting at. This is where some techs and builders have had differing views on the subject of what they HEAR as differences. I understand WildBill's side of the arguement speaking of it technically and with what he may hear as it being a non-difference. Thanks for the response WildBill and others that responded. I respect what you're saying. I've talked too a few techs/builders that claim there is a difference. Obviously Metroamps seems too think, or have concluded, that there is judging by the above post as well as a few other established builders. I've heard other builders and techs say the same thing in other articles and forums. And others that say there is'nt. So yes there seems to be two general consensus on the issue. What do I think? I don't know. I have not put together an amp or rebuilt one experimenting with various brands and all types all in one amp.
> As far as experimenting, yes I meant a simple amp circuit not a pedal Greco. Mabe I'll try it on a low wattage kit or rebuild. Not something I'd want to try on a "red-knob" Fender Twin.
> Keeper and WildBill, like I said I am not an experienced tech. I have taken a college electronics course. The problem with electronics is that it is so wide with various branches of fields that a course cannot cover all of the various fields in detail. Hell if you can point me too any college that deals strictly with tube circuitry or more specifically with tube radios and amplifiers I'd give it a go. Best I can do is take whatever I've learned as far as just general electronics and try too apply it too my interest in tube amplifiers. I'd say the Radiotron book probably has more information on tube circuitry than anything anybody would hope to learn on that subject through a college course today. Have I absorbed all the information from a 1500+ page technical book? I'd need to seek mental help after trying such an attempt LOL. But seriously it is a great reference book of course and a good read. Deffinately recommend anyone interested whether for hobby or learning to have this book.
> Anyway, back too the subject of CC's, it's something I'll have to try sometime and see what my ears tell me. I guess the fairest way of experimenting would be too have two exact circuits, one with CC's and one without.
> ...


I remember talking to someone about a related subject which could be applied here. The test was done with a few audiophile guys who were of the belief that the expensive speaker cable made an audible difference in the quality of the sound. So to test this theory out the subjects were blind folded and played pieces of music from two identical systems. One using expensive speaker cable., one using coat hangers twisted together. The conclusion was, after the test was complete, that none could really tell the difference.
So here we are talking about CC vs. metal film resistors. Take two identical amps, one with newer resistors and one with CC's and see who can tell the difference. My bet is that the overall data would show that there's no audible difference that could be detected...IMO


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## keeperofthegood (Apr 30, 2008)

LOL Could be. You know, would make a good fun thing to do at a get-together actually. Having now read as much as I have (thank you Wild Bill for getting me on that road) what I have found is, the higher the voltage (or was that current, different effects one to the other) or the higher the resistance then the higher the noise factor. In tube amps, I think the higher resistance is a bigger factor, and the stage of the amp that resistance is in too. This is speculation, but does present ideas for setting up the "experiment. I would set up a dual tetrode, resistance coupled and biased mid-stage, I think in this that the resistance values would be high enough, and early enough in the amp to have a bigger sound effect on the output of the amp.

OK TUBES are still taught at the University level. Just, finding the courses are not as easy as phoning up the local outfit. Tubes are still widely used in industry, many broadcasters still use tube transmitters.

University of Denver 

PRINT THIS OFF, it is 50 pages when printed, and well worth the read. This is written from the point of view "I don't really know what these tubes are about, so lets set them up and test them to find out".

Electronics 27

This long but informative article is wriiten by (quoting)


> *Dr Elizabeth R. Tuttle*
> 
> _ Professor of Engineering, University of Denver
> Registered Professional Engineer, State of Colorado No. 12480 _


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## Wild Bill (May 3, 2006)

GuitarG. said:


> And THAT is exactly what I am getting at. This is where some techs and builders have had differing views on the subject of what they HEAR as differences. I understand WildBill's side of the arguement speaking of it technically and with what he may hear as it being a non-difference. Thanks for the response WildBill and others that responded. I respect what you're saying. I've talked too a few techs/builders that claim there is a difference. Obviously Metroamps seems too think, or have concluded, that there is judging by the above post as well as a few other established builders. I've heard other builders and techs say the same thing in other articles and forums. And others that say there is'nt. So yes there seems to be two general consensus on the issue. What do I think? I don't know. I have not put together an amp or rebuilt one experimenting with various brands and all types all in one amp.
> As far as experimenting, yes I meant a simple amp circuit not a pedal Greco. Mabe I'll try it on a low wattage kit or rebuild. Not something I'd want to try on a "red-knob" Fender Twin.
> Keeper and WildBill, like I said I am not an experienced tech. I have taken a college electronics course. The problem with electronics is that it is so wide with various branches of fields that a course cannot cover all of the various fields in detail. Hell if you can point me too any college that deals strictly with tube circuitry or more specifically with tube radios and amplifiers I'd give it a go. Best I can do is take whatever I've learned as far as just general electronics and try too apply it too my interest in tube amplifiers. I'd say the Radiotron book probably has more information on tube circuitry than anything anybody would hope to learn on that subject through a college course today. Have I absorbed all the information from a 1500+ page technical book? I'd need to seek mental help after trying such an attempt LOL. But seriously it is a great reference book of course and a good read. Deffinately recommend anyone interested whether for hobby or learning to have this book.
> Anyway, back too the subject of CC's, it's something I'll have to try sometime and see what my ears tell me. I guess the fairest way of experimenting would be too have two exact circuits, one with CC's and one without.
> ...


Pay atttention to NonReverb's post, GuitarG. Simply building two indentical circuits with and without CCs is worthless by itself. You have to have a blindfold test to eliminate any chance of a "psychological" preference. If you don't know what amp is being played because someone else is making changes (or no changes, as long as you can't see him do it) then you might get a valid result.

As for MetaAmps, they are entitled to their opinion but you should not forget, just because you form a company does not make you an expert. Lots of guys can copy old circuits and make a few minor mods without any real deep understanding of electronic theory. With MetaAmps, obviously they are trying to compete with a LOT of other boutique amp makers! Using carbon comps is a marketing move. If they can convince a customer that carbon comps sound better then he's more likely to buy THEIR amp!

What's more, they can be perfectly sincere and believe their own stuff, yet still be totally wrong! I guarantee that if you ask them for a technical explanation as to WHY carbon comps sound better you will not get a good one! Certainly not one as technically accurate as what we can read from R G Keen or someone like him. R G makes sense and most important, he's not trying to sell me something!

Why is it that if you do a google you won't find hundreds of blindfold tests showing that carbon comps sound better, or that a certain brand of guitar cable has better tone than another one? Try it! Virtually everything you find is either just talk on a discussion forum or else something on a site run by someone with a vested interest in selling you the product.

The reason blindfold, scientific tests are so rare is that people WANT to believe! Mojo is easier to swallow than actual book learning. It's like sugar water for a baby. You think you've learned something but it's just fluff, just as the baby gets a sweet taste but no nutrition, along with a rotten first set of teeth.

Why does no one check out the astrologer's predictions from LAST year? Because it's comforting to believe in him.

Here's the link to the coat-hanger wire test:

Audiophile Deathmatch: Monster Cables vs. a Coat Hanger - Audio - Gizmodo


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## keeperofthegood (Apr 30, 2008)

HAHAHAHAHA Wild Bill..... As I said, Beer Drinkers with a Sign on there porches. Also, as I said, when you go online to find medical advice ...

You do have to know your sources. The two articles I have linked are 1) Vishay the manufacture of the producs, and 2) a University of Denver professor of Engineering. These people are a lot more in the know than some company started by some guy with a few dollars to his name and a circuit out of a magazine (LIKE ME  which is why I am only slamming others that are uneducated LIKE ME because I know my limitations and I am not the one to speak). 

That is how a lot of the amp companies started out from all the history of amp companies discussions that have floated about. Someone gets a schematic, builds it, put his personal stink of a shiny case and skull knobs on it, and it sells and then 10 years later that person is still at it, but is now in the "if I did it any other way I would go out of business" rut. So they put out the 8 x 10 colour glossy photos with the circles and the arrows and the writing on the back TOUTING that they use "Vitamin Q" capacitors and "Carbon Comp" resistors and "My Babies Foreskin" Speakers... it is just advertising blather. Point of fact, when you pull up many of the original works of the pioneers of audio, you will see things like "1500 ohms 3watt" and not "1500 ohms, NOT wire wound, 3 watts if made on a Sunday of the Full moon, only made in countries that do not end in a Vowel."


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## greco (Jul 15, 2007)

*Keeps*...thanks for the "Electronics 27" (University of Denver) link. Much appreciated

How on earth do you find all this stuff? (meant as a joke...you don't need to tell me)

*GuitarG*...be sure to have a look at the Electronics 27 link.

*Wild Bill*...your comment re: "psychological preference" ...this is certainly a paramount factor.


Enjoying the thread...

Cheers

Dave


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## Rugburn (Jan 14, 2009)

I'll add that some of the "mojo" attributed to carbon comps may have a lot to do with their instability, or tendency to drift in value. The Victoria amp guy pulled apart more than a few old tweed Fender amps to look specificly at the resistor values and how far they drifted from their intended values. What a player likes may not be what old Leo originally specified in his circuits. I recall a recent post where Wild Bill mentioned measuring his customers' amps prior to repairs, and replacing resistors with the values they'd drifted to in an effort to maintain the exact tone of a clent's amp. This has little to do with function of the CC resistors themselves, but rather the value of the component and how it alters the tone of the amp. Which brings us back to the *value *of the component, rather than composition of the component. 

Shawn


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## Emohawk (Feb 3, 2006)

Awesome thread!

I'm not a tech or an EE either. I'm a hobbyist who's build a bunch of amps, but I'm also a systems analyst by trade & perhaps by nature, so I tend to take these "mojo" arguments with a grain of salt.

When it comes to vintage amps, one thing I've come to realize is no two of the same amp sound quite the same - even if manufactured with the same components. Why? My guess is the instability/inconsistency of the components used, especially as they age, is a big factor in the "mojo" people claim to hear. Maybe the instability/inconsistency itself is the "mojo".

Now that's all well & good, and vintage amps are certainly cool, but for myself if I can build an amp that has the core tone of the original but is more reliable, stable, consistent, and has a lower noise floor, I see no reason not to do it. Just my opinion.


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## greco (Jul 15, 2007)

Rugburn said:


> ....... I recall a recent post where Wild Bill mentioned measuring his customers' amps prior to repairs, and *replacing resistors with the values they'd drifted to in an effort to maintain the exact tone of a clent's amp*. This has little to do with function of the CC resistors themselves, but rather the value of the component and how it alters the tone of the amp. Which brings us back to the *value *of the component, rather than composition of the component.
> 
> Shawn


Wild Bill has a great concept to offer customers......"new, stable, *drifted value *resistor replacement"....I'm 100% serious with this !

Dave


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## nonreverb (Sep 19, 2006)

Just remember gents...old Traynor amps sound awesome AND didn't use CC resistors....maybe that's part of their mojo


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## greco (Jul 15, 2007)

nonreverb said:


> Just remember gents...old Traynor amps sound awesome AND didn't use CC resistors....maybe that's part of their mojo


Good one !!

Dave


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## GuitarG. (Apr 1, 2010)

nonreverb said:


> Just remember gents...old Traynor amps sound awesome AND didn't use CC resistors....maybe that's part of their mojo


I just bought a bassmaster that i think sounds great.....so far. Havent had much time with it though. And yes its all carbon film. I have a couple of Fenders which are all carbon comp. I would'nt say they lack mojo either because of the use of carbon comps. I see no reason too change them as they havent acted up in 40+ years. I will say again when I repair or modify an amp though I don't use carbon comp personally. Technically speaking there are too many drawbacks as has already been discussed here in this thread. However my reason for this thread was that I have read enough times the arguement of sound differences in using different types. And yes I already knew that values are prone to drift with the use of carbon comp. I forgot too add that in my OP. I guess this drifting could add to the arguement for or against. The drifting could add an element of mojo or it could sound worse.
In terms of sound, I'm not argueing for or against the use of carbon comps. My purpose with this thread was just too see what peoples opinions are for or against their use. 
There is sometimes mojo in what people hear it as and then there is sometimes hype being sold under the guise of mojo. This was the reason i started this thread with reference too carbon comps.
Thanks for your replies.

GuitarG.


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## GuitarG. (Apr 1, 2010)

And BTW I'm not on here necessarily for an education. sometimes for a bit of help and sometimes just too find opinions. I do find some of it educational though.

Thanks again, 

GuitarG.


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## analogteletube (Jan 26, 2011)

MY BABIES FORESKIN SPEAKERS!!! HAHAHAHAHA LOL!!!!! Awesome thread guys!!


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## gtone (Nov 1, 2009)

This is a great thread - very interesting and illuminating for us "non-tech" types.

I get that a resistor in/of itself does not affect the tone directly, all other things being equal. If CC resistors are more prone to "drift" over time, would that factor not have some potential effect on an older amp's tone as the drift from original tolerances made itself felt on a circuit? I remember reading how Chicago Blues Box reverse-engineered Buddy Guy's Bassman in an attempt to capture the exact tone of his amp, part of that process involving measuring/matching the drift of all resistors in the amp. Is this simply another example of "voodoo" marketing hype or could there be something to that aspect?

Thanks guys!


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