Is it a good way to build a Dirtbag deluxe with carbon resistors?
Carbon Comp? No.
Carbon Film is fine.
Jacob
Metal film: ideal.
Ok,
What kind of resistors was used in "old" DMM, Carbon film or metal film ?
did you mean OLD DMM?
(http://t1.gstatic.com/images?q=tbn:ANd9GcTCFwmg87DPjn3SQE27xmxCHxdd0LtNRbQq1ghIHriIZt6GNFOFead6hdyoeg)
Looks like carbon film to me
Yeah, there is nothing wrong with using carbon film. That's what I used. I only meant if you do have metal this type of effect does benefit from lowering its noise floor as much as possible.
Thank you ;)
Yes i suppose the metal film will lower the noise, but i thinked maybe the carbon film provide something good and more authentic in the sound.
I used to build many vintage clone FX, Fuzz face, Treble boost, wah, with carbon comp resistors.
But if i understand well it seem's to be too noisy for DMM.
Marc
The originals used a combo of Metal Film, Carbon Film & Carbon Comp... the EHX way :) A long with the majority of caps being Mylar with the odd paper 'n' oil & ceramic thrown in.
Any of them will be fine, your delay wont sound 'sterile' if you use all Metal Film resistors, it'd probably be a bit noisy with all Carbon Comps, but so would a 30 year old delay pedal with old electros and drifty resistors.
Basically... use whatever parts you can get your hands on in the right values, EHX were not a strict company regards components, there was always method, but they just used components that were cheap, available and would work happily IMO.
Personally, I tend to throw one or two mojo components in most builds strictly for the fun of it.
Quote from: madbean on January 27, 2012, 02:26:47 AM
Personally, I tend to throw one or two mojo components in most builds strictly for the fun of it.
If you look at old EHX boxes it seems like they did exactly that, there's always one, usually in a normal value used all over the pedal :D
I see no reason not to have a bit of mojo, as long as you don't go too crazy... so... Carbon Comp, Mullard Mustard Cap, Metal Can Op-Amp DMM!? :o
You have to consider the number o parts. The fuzz face has like 5 resistors. The Dirtbag has more than 50...
That's 10x the noise.
Jacob
Quote from: jkokura on January 27, 2012, 02:43:29 AM
You have to consider the number o parts. The fuzz face has like 5 resistors. The Dirtbag has more than 50...
That's 10x the noise.
Jacob
Noise doesn't add like that as far as i'm aware? Just as tollerance doesn't add? Or am I mistaken?
Not forgetting Gain adding to said noise though, the fuzz face being set up to produce gain and the DMM having a Compander to counteract noise.
Not saying it wont be noisey-er, just dunno if it quantifies like that.
That's an interesting point and I am admittedly kind of ignorant about it. How exactly does noise propagate through a circuit by virtue of component make-up? My gut feeling is that it is probably additive to a degree, IOW, if you use a lot of components prone to a higher noise floor, the resultant THD, or whatever, would be pretty close to a linear sum.
But, I'm no EE.
Quote from: Scruffie on January 27, 2012, 02:50:09 AM
Quote from: jkokura on January 27, 2012, 02:43:29 AM
You have to consider the number o parts. The fuzz face has like 5 resistors. The Dirtbag has more than 50...
That's 10x the noise.
Jacob
Noise doesn't add like that as far as i'm aware? Just as tollerance doesn't add? Or am I mistaken?
Not forgetting Gain adding to said noise though, the fuzz face being set up to produce gain and the DMM having a Compander to counteract noise.
Not saying it wont be noisey-er, just dunno if it quantifies like that.
Yeah, I was being somewhat silly in that comment.
I guess what I was saying was that in some cases the noise is fine. The bigger the circuit, the less noise tolerance there is/should be.
Jacob
Quote from: madbean on January 27, 2012, 02:26:47 AM
Personally, I tend to throw one or two mojo components in most builds strictly for the fun of it.
Love my LCR meter for this reason. Check it, solder it, rock it!
It could be interesting to know wich resistors was, carbon film, metal film and above all carbon comp in DMM.
I try to find some more infos about that but with no succes.
I' really think to put a poor specs componants at the good places participate to the vintage sound.
Same for rhe caps, Mylar, PIO, etc...
If someone know sometghing about it... :)
For exemple i built a 5E3 amp with Russian PIOs coupling caps, i already tried Mallory 150 series in this amp. But with PIOs it sound more open and have more clarity, the difference is convincing.
i think carbon comps on low voltage builds are nonsense.
i use metal films
why ?
let me quote geofx.com
Quote
The manufacturers also document that CC's have excess noise and bad drift with temperature and aging. That makes them a two-edged sword. Put everywhere in an amp, and they'll both sweeten the tone, and at the same time induce hiss. A little thought leads us to the following guidelines for using carbon comps for tone mojo:
1. high voltage across the resistor is necessary, in the range of 100V on up
2. large signal swings across the resistor are needed - ideally, a large fraction of the static DC voltage so you have signal swings of 50 to 100V too.
3. only positions in the amp that have both high DC voltage and wide signal swings as in 1 and 2 will give you enough resistor distortion to benefit from; other places should be chosen for low noise and/or economy.
4. resistor power rating should be the minimum needed to work for a reasonable life in the circuit to maximize resistor distortion. Maybe a good guideline is that the dissipation should be selected to be as close to two times the average dissipation as possible.
5. as a corollary to the power guideline, we should be prepared to replace CC's every few years as the life at high temp makes them drift and get noisy(-er).
I recently re- build two wah one with carbon comp and another with metal film, the one with carbon have a little more hiss, but i found the sound of the one with metal film less interesting.
(http://nsm07.casimages.com/img/2012/01/27//1201270937031310609352432.jpg) (http://www.casimages.com)
Just one resistor is metal film, and will be changed.
The other thing to consider is that the layout is very very tight. Component size will be a limiting factor in your choices.
Josh
Quote from: marcfrom on January 27, 2012, 07:55:29 AM
It could be interesting to know wich resistors was, carbon film, metal film and above all carbon comp in DMM.
I try to find some more infos about that but with no succes.
I' really think to put a poor specs componants at the good places participate to the vintage sound.
Same for rhe caps, Mylar, PIO, etc...
If someone know sometghing about it... :)
For exemple i built a 5E3 amp with Russian PIOs coupling caps, i already tried Mallory 150 series in this amp. But with PIOs it sound more open and have more clarity, the difference is convincing.
There was no designated Carbon comp places in the original, just stick a couple in if you wanna add some noise, the design is not a quiet one anyway, even if you use all metal film it'll still hiss because it uses BBDs. Use 4558s or 1458s in the audio path if you want more noise too.
I dunno why you want more noise but there ya go.