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Re: CC vs CFvs MF/ Rambling


 :
7/29/2000 10:33 PM
Carl Z
Re: CC vs CFvs MF/ Rambling
Bruce;  
 
I'm starting to believe there is some difference in the sound of resistive components. I've been a cap proponent for a long time. Unless you're completely tone deaf you'll be able to hear changes in caps, but I never bought into the resistor argument.  
 
OK, story time...  
I've got a guy over here that I did some AB testing with some resistors and reverb tanks. What got me started with this guy was that he needed a new reverb tank. The original came with a Gibbs tank but I put in an equivalent Accutronics version. The guy came back saying he could hear the difference. So, I'm thinking, yeah whatever. If you say so. The customer is always right so I scrounged up an original tank and just for shits and giggles we did some blind testing. He was able to pick the original tank as well as component changes 100% of the time. So I'm starting to think that there might be more to some of these claims than most people are willing to believe.  
 
This is pretty much what got me thinking along these lines to begin with. Obviously there's something going on that's not easily quantifiable.  
 
Carl Z
 
7/30/2000 5:07 AM
Rebel420

quote:
"This is pretty much what got me thinking along these lines to begin with. Obviously there's something going on that's not easily quantifiable."
That is where I"m coming from, thery MAY be something going on that we are not looking at. AND ti may not be something that we cna measure on our Fluke meters. Ti may be something that is involved with heat... then again, it may be all voodoo. A resistor MAY be showing some inductance or capacitane, granted it may be negligible, BUT that would start making the 'resistance' (guess it woudl be called impedance here, eh?) WOULD vary at different frequencies. I personally cant tell a CC from a CF... nor a CF from a MF resistor, but I can hear minor differences between a CC and a MF.. very negligible, and it truely MAY be a factor of the summing of the noise with the audio signal. THAT is why I suggested someone doing some quantitative measurements, at different frequencies, and at different voltages. Things may become a bit mroe unstabel running at or near the rated voltage as well. I odnt know if I was clear in my post, but I meant not only AC signals at different voltages, but an ac signal, riding on top of a DC bias at or close to the rated working voltage. Who knows *laugh*  
I personally use Carbon Film resistors almost exclusively, why? they are MUCH quieter than CC resistors, sound the same, + they have the "C" word in the name, so from a marketing standpoint it's all good.  
 
"you can't sell a boutique amp unless you have a tube rectifier, have it covered in tweed, it's hand wired, you call cathode bias "class a" and the resistors have the word 'carbon' in them."
 
7/30/2000 4:01 PM
Gus

Carl I can test caps and get #'s that seem to follow the tone changes they even make sense to me. Lower ESR in the ps caps (Plate and Screen supply) louder puncher amp and less cap needed to reduce hum(maybe easer on a tube rec maybe not one day I will use a current clamp to check the current spikes). I am thinking it is the hiss adding to the signal that people are hearing at louder levels. So build the amp with CFs or MFs and add hiss controlled with a pot maybe at the Phase inverter stage( the other side like the matchless amp reverb)
 
7/30/2000 6:17 PM
Bruce

My brother Lew can hear many of these kinds of subtle differences too Carl.  
I built two identical Mission, 40 watt Crusader w/reverb amps and used all carbon comp resistors in one and a combination of carbon film and Mtl film resistors in the other.  
Using the same speaker cab, I was able to get them sounding exactly the same, yet Lew seemed to prefer the carbon comp amp every time in blind tests and to this day uses this amp in a single 12" combo cab as his personal favorite small gig amp.  
 
Yes, the amp did seem to have a very-very slightly more hissy tone with the carbon comp resistors, but this was not noisey hiss nor is it an objectionable hiss.  
If that very slight hiss, nebulously or subtley, adds somehow musically to the overall enjoyment of the tone, then I'd like to know how too and capitalize on it.  
 
I've built way many amps using Mtl film plate load resistors in contrast to gurus, like G.Webber, who insits that these all need to be carbon comp exclusivley, and almost with out exception the amps still sounded fabulous and get great reviews from all except a few of the players who are hard core late 50's tweed amp lovers, who thought these amps had a tiny bit too much clean sound just when driven into distortion!?  
Is that knee of crossing into distortion effected by the CC resistors?  
Sometimes I wonder if many players expect that tonal effect and convince themselves it's there, or not there, just because of the CC, Mtl-F or CF resistors used.  
 
I'm one who is not totally convinced the CC plate load resistors, or CC in general, add a certain musical blur or not. I simply don't know.  
Is it possible that the parallel lumped LCR of a CC resistor resonates at some frequency that causes a cut in the lower highs but pass the higher freqs causing some unusual notched bandpass?  
I don't really hear it that way myself but I am not building or tweaking amps just for myself and it should be obvious to all that do this, there are always a few people that can hear many things better or different then you or I do.  
 
Bruce
 
7/30/2000 9:05 PM
Steve A.

Bruce:  
 
Is it possible that the parallel lumped LCR of a CC resistor resonates at some frequency that causes a cut in the lower highs but pass the higher freqs causing some unusual notched bandpass?  
 
    I bet that a test circuit could be made up, with the output run into a scope for analysis... Something like this might settle for once and all these questions about cap and resistor types. As you suggest I think that it has to do with the other qualities of the caps and resistors (besides the capacitance and dc resitance). Like the ESR and inductance of the caps, and the inductance and capacitance of the resistors.  
 
Steve Ahola  
 
P.S. Does anybody still make carbon comp resistors anymore, or are we using up the NOS ones from Allen/Bradley, et al? (The guy at the local electronics parts house was telling me that it is illegal to use anything not flameproof; that is why they only stock the metal film resistors. He was also the same guy who told me that "caps are caps" and I got stuck with a bunch of "little greenies" that I don't use in anything except guitars. Peavey amps use carbon film resistors and they are UL listed so I think that he was selling me a load of goods (or at least a bag of lousy caps!) )
 
7/30/2000 9:20 PM
Troy

Steve, I guess Xicon (or whoever makes they're components) is still making CC resistors. Mouser stocks all of the typical values in 1/2W. Now 1W is a different story, I can't seem to find a source for those (maybe Allied has 'em, can't remember). I wonder where Matchless got all of they're 1W CC used in they're amps?  
 
The Xicon's are definitely different looking than AB resistors; shorter leads and lighter brown color.  
 
Troy
 
7/31/2000 8:33 AM
BWilliamson

quote:
"I wonder where Matchless got all of they're 1W CC used in they're amps?"
 
 
As I heard it--Matchless and Victoria pretty much bought up all the Allen-Bradley stock in the 1W CC in the sizes they needed.  
 
bw
 

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