resistor types

[baddog]

do different types of resistors effect the sound of a guitar amp. I have a Crate VC50 3x10 amp and it has metal oxide resistors in the power amp section. How would it change the sound if i installed carbon composite resistors like Allen Bradleys?

thanks
keith

[tubeswell]

I don't know about the tone, but metal film resistors are good for reducing (or virtually eliminating) hiss when you use them as plate resistors. I think they come in 0.6W, so if you want more power you can put a couple in parallel for each plate resistor.

RG Keen's website has a blurb about the mojo of carbon comp resistors.

[Paul P]

Mouser (in the US) sells metal film resistors up to 10w (at 5$ each).

Paul P

[d95err]

I'm guessing (just speculation) that to get the "mojo" out of carbon comp, you need them in a stage that is driven really hard. I.e. if you put them in a typical master volume amp that doesn't drive the poweramp hard, all you get is more hiss.

[PRNDL]

The general rule is carbon comps have better tone and are noisier than metal film, which are much less expensive.

Many vintage Fender amps builders often use carbon comps exclusively, although some may use metal films in specific places to reduce hiss.

Modern mass production amps often use metal films to reduce costs.

Some boutique amp builders use them to get a certain type of clean sound (carbon comps have a more blues sound). For example, Dumble amps use metal films.

Of course, all of these statements are generalizations.

[Rick Erickson]

The general rule is carbon comps have better tone and are noisier than metal film, which are much less expensive.

I've never used carbon comp resistors in my builds, rebuilds or repairs. No one has ever demonstrated to me that carbon comp resistors sound better than any other type. There seems to be a LOT of "botique" builders who want to justify their existence and high prices by continuing this myth, or they don't really know - so they just put their finger in the air and say - "this is what's selling today". Metal film resistors are less expensive (now) because of supply & demand economics. There are a LOT more metal film resistors sold these days than Carbon Comps. In the 50's and 60's 1% metal film resistors were less plentiful and much more expensive than the generic common Carbon Comp. CC resistors were not selected by amp manufacturers for tone - they were selected because they were cheap and easy to find. Now they are much more expensive so in order to justify the cost in a "clone" amp there has to be some mystical, magical tonal quality attributed to them.

Many vintage Fender amps builders often use carbon comps exclusively, although some may use metal films in specific places to reduce hiss.

No need to repeat myself here....

Modern mass production amps often use metal films to reduce costs.

Metal films are more expensive than Carbon Film, which is used by most major manufacturers. Metal film resistors are used to control variances in production, often by high-end high-gain builders like Mesa, Soldano or Bogner. Most MF's are 1% tolerance. Using tight tolerance components makes for more consistent tone from one amp to another. The low noise factor is an added plus.

Some boutique amp builders use them to get a certain type of clean sound (carbon comps have a more blues sound). For example, Dumble amps use metal films.

And Dumbles aren't played by any Bluesy players???

Of course, all of these statements are generalizations.

Understood - I just wanted to share my take on this subject.

RE

[Steve A.]

The general rule is carbon comps have better tone and are noisier than metal film, which are much less expensive.

I've never used carbon comp resistors in my builds, rebuilds or repairs. No one has ever demonstrated to me that carbon comp resistors sound better than any other type...

Okay, throw out the word "better"... I know a lot of roots players who prefer carbon comp resistors because they are noisier. They also seem to prefer single coil pickups because they are noisier, too. Go figure...

When you add up the noise from the single coil pickups to the noise from the CC resistors, you probably aren't going to crank up the gain of your rig to heavy metal extremes.

I was listening to Jimi Hendrix one night (this was a recording, not the man! ) and it occurred to me that part of his sound was due to the noise coming from the single coil pickups. Namely, if you were to put Kinmans in his guitar, it just wouldn't have sounded the same...

Of course after that night my doctor changed my meds so I have had not any further revelations about Jimi Hendrix or single coil noise.

Steve Ahola

P.S. I only buy metal film resistors these days- who needs more noise? They are dependable and accurate- although pricier than carbon films if I were to buy them in bulk. And I've read a few posts here that say that carbon film resistors are almost as quiet as metal film ones, although you might want to use metal film for plate resistors... Thanks for your very informative posts!

[Enzo]

ANd I would think the application makes a difference. The high gain input stages where the signal level starts out tiny will be a lot more sensitive to noise from a resistor than something like the cathode resistor in the output stage. I don't worry much about noise in the power amp coming from resistors.

[Pedro Vecino]

Mesa uses a big quantity of carbon comp resistors in the Lonestar.
Regards

[Ben N]

Here is the whole subject, scientifically treated and wrapped with a bow.

http://www.aikenamps.com/ResistorNoise.htm
http://www.geofex.com/article_folder...carboncomp.htm

AFAIAC, any anecdotal, subjective, mojo-ridden discussion about the tone of CCs beyond the above two sources is almost guaranteed to be largely BS.

[Rick Erickson]

They also seem to prefer single coil pickups because they are noisier, too. Go figure...

I use single coils in my Strats & Tele's, but they have reverse-wound Center (Strat) & Neck (Tele) pu's in them.

I was listening to Jimi Hendrix one night...

I was talking to Randy Hansen a few weeks ago. That's about as close to Jimi as we can get around here since Al passed away.

RE

[jrfrond]

I didn't believe all of the CC hype until I took two identical amps I built and swapped in CC resistors in crucial places. Man, was THAT an eye-opener! It's not hype. CC resistors DEFINITELY give the amp more feel. And I just did the preamp! I left the PI alone with CF resistors. Can't say that I noticed any more noise. CC's are noise-prone as the carbon block ages and takes on moisture from the surrounding environment.

Critical places for CC are signal path and load. This encompasses series signal resistors (including grid stoppers), cathode resistors and plate resistors.

Here at our shop in NYC, we stock CC's to use in vintage repairs. If a CC comes out, a CC goes in. I'm convinced it's real.

[Tubis]

Metalfilm is more transparent and carbon is not.
In high gain amps the carbon hizzes lika a f... snake.
I love metafilm because i lets all the colour of the guitar and the tubes through.
The same for polypropylen caps.
But carbon and polyester is colouring the sound more, that is true.

[HTH]

My AC20 build sounded quite flat and lacking sparkle until I replaced the 1w CFs with CCs.

I wouldn't use CCs for everything, but it's worth trying them out and deciding for yourself.

[bulldogguitars]

What about the carbon film resistors. Wouldnt this be the best of both worlds. Just askin.