The definitive answer: do "boutique" capacitors affect tone in bass wiring?

[12bass]

Some interesting info: http://diyaudioprojects.com/mirror/m...h102/caps.html

[dmusic148]

Originally Posted by 12bass

And by implication that would mean that they can pass a little more of the extreme highs to ground when used in a passive tone control circuit. Another capacitor type might leave a bit more of the upper treble in the signal rather than shorting it to ground.

Doesn't happen. The highest-highs will always go through. Google 'capacitor time constant.'

[uOpt]

Originally Posted by SGD Lutherie

With your tone knob set where? On zero? That will never be more open sounding. On 10 the cap has no affect on the tone.

You are just hopeless.

The tone pot on 10 is a resistor and a capacitor in series. That is a first order low pass filter. At "10" the pot has 500 or 250 Kohm, respectively, not zero Ohm.

What the hell are you doing here? Do you have any idea what damage you do to your "Lutherie" business?

[SGD Lutherie]

Originally Posted by 12bass

Oh... wasn't too clear there. I meant that polypropylene/polystyrene caps sound more open when passing a signal through them, as is the case when they are used a coupling capacitors between parts of a circuit. If they are more open sounding, that suggests that they are just a little bit better at passing high frequencies than other types. And by implication that would mean that they can pass a little more of the extreme highs to ground when used in a passive tone control circuit. Another capacitor type might leave a bit more of the upper treble in the signal rather than shorting it to ground.

Oh I see. I always try to use polypropylene/polystyrene caps. I use them in my preamps. I use them because they are good quality caps. I also use tantalum, as much as people seem to think they sound bad. They sound fine to me.

[SGD Lutherie]

Originally Posted by uOpt

You are just hopeless.

The tone pot on 10 is a resistor and a capacitor in series. That is a first order low pass filter. At "10" the pot has 500 or 250 Kohm, respectively, not zero Ohm.

What the hell are you doing here? Do you have any idea what damage you do to your "Lutherie" business?

Excuse me? It actually forms a resonant low pass filter along with the pickup. But you are forgetting the impedance of the cap and the pickup.

Earlier I posted this:

As you turn down the tone control pot from ten, the major effect is changing the resistive loading on the resonant circuit. This is because the impedance of the capacitor in the range of the resonance is a lot less than the pot value. As the pot gets closer to zero, the capacitor becomes important, but the initial effect is just resistive loading.

Show me where I said the pot is zero ohms?

So, once again, when the pot is on 10, the cap's impedance is less than the pot, so all that is happening is the resistive load of the pot on the pickup. As you turn down the tone control the cap starts to come into play. But not on 10. On 10 the cap has no affect on the tone, but the pot does.

So before you get your snorts in a knot, make sure you know what you are talking about, or you will do some damage to your reputation.

Sorry buddy, but I have been doing this a long time and know what I'm talking about. How about you?

[Meddle]

At the risk of rehashing statements already made in this thread, I believe "boutique" capacitors have no impact on tone. Those offering up their psuedo-science may have their bonehead mates convinced down the pub, but they are typically talking rubbish, and I wager they spend too much time wasting money on stuff they imagine will make them sound better as musicians, when infact they should be taking some lessons and actually improving their musicality. I guess it is the mentality of "if I pay enough money I want to see instant results!" which does not work in any artistic field.

The deal with old capacitors is that their tollerances drift by up to 50% or so, and can be influenced by the weather.

Say you buy an old paper 'n' oil cap rated at 0.047uF, it might only be 0.022uF or it could be 0.1uF or anywhere in between. If it is actually sitting at 0.022uF the corksniffers would say "unlike all other cheap (Chinese) 0.046uF capacitors this one has so much more sparkle and top end!". Conversely, a paper 'n' oil 0.047uF cap that is actually rated at 0.1uF would make the corksniffers say "woa! Vintage tone! This cap is so much warmer than cheap (Chinese) 0.047uF capacitors!!!".

Basically I think the whole thing is cooked up by rich old dudes with too much time and too much money trying to make something out of a very cheap component. I don't believe these corksniffers are actually musically gifted enough to either be able to really hear these supposed differences (I file audophiles in the same category, if you are tone deaf don't try and tell me you can hear the difference in quality between speaker cables).... Also I find it hard to believe corksniffers even use their tone controls on their instruments.

I'm surprised this is allowed to be an issue, as the stupidity in boutique capacitors is so absurd. At least with the (relatively stupid) concept of relic guitars, the sandpaper 'n' rasps crowd, who try and make dented poly look like aged nitro, seem to get some level of protection. In the case of capacitor cork sniffers they need saving from themselves! A fool and his money are easily parted, etc etc etc...

[SGD Lutherie]

Originally Posted by Meddle

The deal with old capacitors is that their tollerances drift by up to 50% or so, and can be influenced by the weather.

+1

They coated them in wax for a reason! They are often hydroscopic.

[Meddle]

To be even more obtuse than my original post, why don't these corksniffers keep the old swollen, leaky, dried out filter caps in their amps?

[khutch]

Originally Posted by uOpt

The tone pot on 10 is a resistor and a capacitor in series. That is a first order low pass filter. At "10" the pot has 500 or 250 Kohm, respectively, not zero Ohm.

It does not form a low pass filiter because the pot resistance is not in series with the signal path. It would only be a low pass filter if you take the signal output from the junction between the tone pot and the tone cap. The pot is in series with the cap and that series combination is in parallel with the signal path. As David says when the pot is on 10 the capacitor is basically out of the circuit because its impedance is so much smaller than the pot's. At 31 Hz a 47nF tone cap has about 11k impedance compared to 250k or more for the tone pot and the cap impedance drops by ten for every decade increase in frequency.

Ken

[khutch]

Originally Posted by 12bass

Some interesting info: http://diyaudioprojects.com/mirror/m...h102/caps.html

Interesting but I fail to see any curvature in any of those plots except the ones for the ceramic caps. And then we have to wonder if his paper/oil caps aren't just plastic caps in packages meant to look like paper/oil to extract more $$$ from audiophiles!? Also, if you are going to test ceramic caps you need to tell us the dielectric in addition to the voltage rating. Ceramic dielectrics vary hugely in performance under the test that he ran.

It would have been a far better test to put these caps in a circuit where the capacitor nonlinearities would produce a distorted output and then show us the spectrum of the output signals. Distortion is all anyone cares about and as I have said when it comes to bass guitar applications the right kind of distortion can be a Good Thing. Those ceramic caps look a bit "tubey"....

Ken

[Handyman]

Originally Posted by khutch

Interesting but I fail to see any curvature in any of those plots except the ones for the ceramic caps. And then we have to wonder if his paper/oil caps aren't just plastic caps in packages meant to look like paper/oil to extract more $$$ from audiophiles!? Also, if you are going to test ceramic caps you need to tell us the dielectric in addition to the voltage rating. Ceramic dielectrics vary hugely in performance under the test that he ran.

It would have been a far better test to put these caps in a circuit where the capacitor nonlinearities would produce a distorted output and then show us the spectrum of the output signals. Distortion is all anyone cares about and as I have said when it comes to bass guitar applications the right kind of distortion can be a Good Thing. Those ceramic caps look a bit "tubey"....

Ken

It's was still interesting to see the astoundingly large nonlinearity on his ceramic cap, even if we have no idea which dialectic material it used. Even that awful thing doesn't look too bad if you restrict yourself to the +/- 1V range you'd from a bass pickup's output. (The plots were done with a 60V AC input, for those who didn't read the fine print).

My favorite capacitor non-ideality to plot is effective capacitance vs frequency (essentially showing the effect of ESR, which itself can be frequency dependent). I think lots of people would worry less about the capacitor in their bass's tone control if they saw the really nasty effects of electrolytic caps used as output coupling capacitors on lots of stomp boxes.

Aside from awful high frequency response, those darned things are polarized!

[SGD Lutherie]

Originally Posted by Handyman

I think lots of people would worry less about the capacitor in their bass's tone control if they saw the really nasty effects of electrolytic caps used as output coupling capacitors on lots of stomp boxes.

And in your amplifier. Probably one of the first parts your signal reaches. Sure, let's have this "pure" signal ... until it hits your amp! Then all bets are off. Then you have people using a very non linear amp like an SVT where you have little chance of hearing what you bass actually sounds like. (sorry, couldn't resist!). But you are going to worry about a cap on a passive tone control?

In the end you either like your tone or you don't. Imperfection sounds better to human ears. Thats why we like distortion.

Personally I have never heard a problem with polarized caps used in most musical instrument settings.

[dmusic148]

The non-linearity is irrelevant in a passive tone control, because it all occurs above the cut-off frequency. The non-linear, distorted stuff all goes in the dumpster.

[joelb79]

Originally Posted by SGD Lutherie

So before you get your snorts in a knot, make sure you know what you are talking about, or you will do some damage to your reputation.

Sorry buddy, but I have been doing this a long time and know what I'm talking about. How about you?

Talkbass can be so harsh sometimes David. I've gotten in a lot of debates online where I knew what I was talking about; but when i chose to cap my "rebuttal" with statements like this I essentially lost the argument.

It's best to just present the facts as a debunk, state you disagree and move one. Nobody really wins in online contests where people throw credentials and experience at each other. I can tell that you know what your talking about; as you can explain it fully with normal words. No sense in making a contest out of it.

That said, I agree with what David is saying. I might get flamed, but I think the mini-disc type caps sound better than orange drops. I don't know if they have a tighter tolerance or something (even though the spec is still 10%) All IMO, without any facts to present to the case. Just something I've notices about tone caps... When I like them they are cheap. When I pay $1.50 and my bass sounds murky like the cutoff point is too low and the cap is orange, I'm upset.

[12bass]

FWIW, it seems important to make a distinction between suggesting that the type of capacitor material can make a difference in sound and the notion that one ought to buy expensive and possibly fraudulent components, like boutique wooden volume knobs and such....

[SGD Lutherie]

Originally Posted by joelb79

Talkbass can be so harsh sometimes David. I've gotten in a lot of debates online where I knew what I was talking about; but when i chose to cap my "rebuttal" with statements like this I essentially lost the argument.

I responded with the same tone as his post. If he doesn't want to take a moment and frame his (incorrect) post with at least some shade of decorum, then he gets what he gives.



Also, it had nothing to do with me being right or not, he misquoted what I had said, which is why I had to copy and past it. People with a little electronics know how often forget about things like impedance when it comes to a circuit like this. It looks like an RC filter, but it's really a little different (no series resistance and a complex impedance as a source).

[wcriley]

So.......
What you guys are saying is that I won't be able to retire by selling my box full of 50s and 60s vintage caps to knowledgeable bass players.

Dang it, guys, keep your knowledge to yourselves!

[joelb79]

Originally Posted by SGD Lutherie

I responded with the same tone as his post. If he doesn't want to take a moment and frame his (incorrect) post with at least some shade of decorum, then he gets what he gives.

I got you, but it's Christmas yo!

Perhaps the "tone" is all a mis-understanding. See that pun? See how I did that.

Merry Christmas everybody. And Good will to Talkbass!

[uOpt]

Now I'm tempted to build some kind of string-picking robot to get consistent enough "playing" to actually measure this and graph the output.

I can only repeat that the difference I hear was still there after I hand-picked a ceramic disk that had the same actual value on the multimeter as the orange drop I used to compare. This does of course have the difficulty of possibly inconsistent playing.

[khutch]

Originally Posted by dmusic148

The non-linearity is irrelevant in a passive tone control, because it all occurs above the cut-off frequency. The non-linear, distorted stuff all goes in the dumpster.

The nonlinearity occurs at every frequency, even DC. It doesn't go in the dumpster either, nonlinearities in the cap current produce nonlinear voltage drops across the signal path series impedance and the amplifier sees that. People who like fuzz and distortion will put a diode or diodes in where the tone cap goes. You can hear those nonlinearities quite well. Capacitor nonlinearities are more subtle than those of a diode but they pass through to the amplifier by the same mechanism.

Ken