Centralab pots make a difference, WOW.

Sterling # Sound

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There a few fences people stand behind in these types of arguments - similar to pickup changes, magnets, strings, hardware material - those who believe that changes can be heard, and those (often electricians!) who are certain that resistance is resistance.

I am dead certain that old Centralabs sound different to today’s pots. Why there is a change is speculation but I’m guessing that material properties were different , like carbon, metals which influence not just resistance but also magnetic properties, frequency spectrum, acting as filters to the sound.

The signal is so incredibly low to begin with, once you wack up an amplifier you will hear all the difference. If you blew up a minuscule ant to the size of an elephant you would notice that not all ants are the same ?
 

spitfire

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There a few fences people stand behind in these types of arguments - similar to pickup changes, magnets, strings, hardware material - those who believe that changes can be heard, and those (often electricians!) who are certain that resistance is resistance.

I am dead certain that old Centralabs sound different to today’s pots. Why there is a change is speculation but I’m guessing that material properties were different , like carbon, metals which influence not just resistance but also magnetic properties, frequency spectrum, acting as filters to the sound.

The signal is so incredibly low to begin with, once you wack up an amplifier you will hear all the difference. If you blew up a minuscule ant to the size of an elephant you would notice that not all ants are the same ?

The small signal effect is actually the opposite of what you described. With the very low voltages and currents involved, the component behaves more like an ideal resistance not less. And guitar signals are very low level by just about any standard.

The amplification argument is a bit of a red herring. You wouldn't hear anything at all without the amplification. All that matters is the relative levels of the signal and the artifact in question.
 

spitfire

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Makes total sense! Thanks!

I guess what I'm wondering is that I personally found a difference in wiring my guitars using a super low capacitance cable like the inner portion of a George L's cable, and using a seperate grounding wire... as opposed to using a braided shielded cable to wire the cavity for example.

I dont know why it sounds slightly better... more open and clearer... but it does.

When I posted about it I got trolled that because of the small signal in a guitar there was no way I could hear the difference.

But I did hear a difference... so I was wondering if I could because a good tube amp was amplifying the small signal so therefore I could hear the difference.

Does that make sense?

Jason

Sorry, I did not see this response until now (months later). The cabling or wire in a guitar can matter. Doesn't always, but often can. The more wiring the bigger the difference. Cabling has capacitance and the more cabling the more capacitance. This is like a very small tone cap going directly from the signal to ground. But, keep in mind that you often have 10-20 ft of guitar cable from your guitar to your amp which could easily overwhelm the effects of cabling in the guitar.

Also, less capacitance is not necessarily better. True that with lower capacitance more of the original guitar signal gets to the amp. But rolling off a bit of highs may sound better. Also, all these incapacitates interact with the inductance of the pickup to create a frequency peak. So it isn't even as simple as increasing or decreasing the high frequency.

But, bottom line, it is very possible you made an audible difference using different cable in the guitar.
 

grayd8

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I rarely take my 550k pots above 9, unless it’s a bass heavy riff like sunshine of your love.
 

jwinger

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Hesitatent to say this and let too many in on this hidden gem, but gotta say old centralabs made nearly as much difference to one of my guitars as a change of pickups. Couldn't believe my ears either but the clarity went through the roof despite the fact they were around 500k and I had 550k CTS in there before. Can't explain it but not imagining it!
 

zoork_1

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I've been using old Centralabs for some years now. I don't know if they sound different to today’s pots. To me, the magic is in the taper/ratio. They operate so precise and smooth, best I've tried so far, and I have tried a lot of pots...
 
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tonemonster58

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This has been beaten to death but I have to chime in. First I have tremendous respect for highly skilled/experienced engineers. They have much to add and all of it is relevant. However for some reason they seem to suffer from a bit of tunnel vision. Not everything can be quantified and accounted for mathematically for something as subjective as tone. While I agree with the concept that resistance is resistance, it does not take into consideration what might not be measurable scientifically in the course of transmission.

I for one have noticed significant night and day differences in tone from changing pots of equal values. As an FYI the pots replaced were vintage centralab, go figure. I tried several pots and Hamer's won out, they are really good.

I would like to make an analogy that might be more relatable. You can take 3 glasses of water from 3 different sources that all have exactly the same chemical makeup and ratios, but will all taste differently. By every measure possible they can be identical but people will have favorites that will be repeatable. Just sayin'...
 

yamariv

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I've been following this thread and find the topic crazy interesting as I just rewired my 15 Junior with a 1962 P90 and a full 1956 Gibson wiring harness from an ES125. I was a bit skeptical that I would notice any difference because I already had top of the line 500k CTS pots, a vintage Russian PIO cap (with 50's wiring) and a handwound P90 in the guitar and it sounded great but I had a little extra cash and a hot soldering iron and figured why not.. I'll be keeping the vintage harness and pickup even if I sell the Junior so why not experiment a little....

The 56 wiring harness came with a Grey Tiger Cap (.02uf) that read a little high at .032uf, the volume pot is a IRC 500k which reads high at 717k and a 250k Centralab tone (which read 250k exactly, to my surprise) I cleaned both pots with Deoxit and they both work absolutely perfect and quiet after all these years.. very impressive!

So overall after playing it for a couple weeks the biggest thing I notice is the interaction between the volume and tone knobs and how they work together.. It's hard to explain but they are so interactive compared to the 500k/500k setup I previously had. The vintage Centralab Tone not only has a ridiculously even taper as you roll off, it even takes away some distortion like the volume does when you roll down which I did not expect!. Overall, the clarity, taper and sensitivity of the whole rig is just leaps and bounds over what it was before with the modern components with 50's wiring.

Now is all of this simply due to a 250k tone pot vs the previous 500k?? I'm sure it has a big difference but the clarity and how the taper on both the vintage volume and the tone knob is very noticeable!! I can's say exactly what it is but they sure did something right when they built these vintage pickups and pots! :hmm::naughty:

On another note, geez the vintage P90's are an amazing pickup!! (Mine reads at 8.15k) If I roll down the volume knob to 5 and the Tone knob to about 3, I get a completely crisp, arcticulate clean sound on my DSL's distortion channel. Roll the volume and tone back up to 10 and this thing is a distortion animal!! What other pickup do you know can do this?? I've tried it with my HSS Strat, won't clean up much at all, tried it with my 50's Wired LP Standard, it's better but not spanky clean though.. All hail the P90 pickup!!!! :dude::dude:
 
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the great waldo

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You got it right, bro. :thumb: The carbon traces in the pots drift higher in resistance over time, just like carbon comp resistors.
There's a bit of difference between drift (the carbon material getting old and crumbly ) and wearing out which is usually what happens to old pots as the wiper wears on the carbon track. Those RS pots were usually pretty crappy even when new but were all we could get in England in the 60's I don't know if they've got any better .
Cheers
Andrew
 

cooljuk

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There's a bit of difference between drift (the carbon material getting old and crumbly ) and wearing out which is usually what happens to old pots as the wiper wears on the carbon track. Those RS pots were usually pretty crappy even when new but were all we could get in England in the 60's I don't know if they've got any better .
Cheers
Andrew


FWIW - I have a few hundred 1950s NOS Centralab pots from different times and sources and they all read high, out of spec. They are unused wafers so there is zero use or wear on the thick carbon traces. They are mostly in the 700-900k range but a few even go above 1.2M.

Interestingly, the 1960s Centralab pots I’ve tested tend to read low, rarely even at 500k. The construction looks similar but perhaps the formula of the traces was improved to prevent the drift? Maybe they aimed at a lower nominal value to compensate for drift (but they haven’t actually drifted so…?)?They are definitely still come carbon based trace, not PVC.
 

cooljuk

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The top three rows are 1960s wafers. You can see they have a different color/look. If you look on the left you can see some numbers on a piece of white vertical tape. Those are the ranges the wafers are sorted into.

Granted, this isn’t an all-inclusive photo. Still, it’s fairly accurate to what I tend to find.
 

jlee

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Crazy and eye opening info @cooljuk ! I’ve read of so many accounts of heavy drifting with vintage Centralabs. Any idea, how far well used 50s/60s Centralabs actually drifted? I suppose there’s no way to really know, without having known the specific value of the pots when new…
 

cooljuk

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Crazy and eye opening info @cooljuk ! I’ve read of so many accounts of heavy drifting with vintage Centralabs. Any idea, how far well used 50s/60s Centralabs actually drifted? I suppose there’s no way to really know, without having known the specific value of the pots when new…

There's no way Centralab was shipping all the pots reading out of spec, when new.

When new, they would read the correct 500k +/- 20% their literature states.

What we see in the high readings now is drift, not manufacturing error.
 

jlee

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Ah…misread some of the above posts differentiating drift from the traces aging and the traces wearing from use…
 

GBLEV

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There's no way Centralab was shipping all the pots reading out of spec, when new.

When new, they would read the correct 500k +/- 20% their literature states.

What we see in the high readings now is drift, not manufacturing error.
You're right about the drifting. I've had many N.O.S. 500k Centralabs from the 50's, 60's, 70's, and 80's over the years, and most of them started out somewhere in the 490k range when they are new. I have one set from the 70's I put in one of my guitars 5 years ago, and every year the resistance goes up a little. Because the carbon element is thicker than what you see in pots today, overtime with use, the wiper slowly scrapes some of that carbon off causing the resistance to drift upwards.

I'll add this towards the sound debate of Centralabs in this thread. From my experience, I too have notice quite the difference in sound with a Centralab pot compared to a modern CTS pot of the same value. They are much more open sounding, with less mud, which gives you the impression that they are brighter sounding. And, from a certain standpoint, they just might be. From my understanding, Centralabs were constructed with Lead, which before it was regulated it had the most pleasing sonic qualities and sound of all metals, including gold and silver. Which is why it was used in a lot of studio analog recording gear from the golden era.

*EDIT* I should say that it was probably used first because it was cheaper than gold and silver, but once they realized it's sonic capabilities, it quickly became the favorite.
 

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