Capacitors and Tone

[walterw]

An important point in one of the above videos—the cap is irrelevant for most of the pot’s travel.

yep, this also shows up in @Mechanical's chart; note how for tone pot settings above 5 the curves are the same regardless of which cap is used, they're literally on top of each other

I just watched RobbieK's video above - It was very interesting that with the tone pot at 50% there was almost no difference in EQ curves between caps of hugely different values!!

more than that, you could literally replace the cap with a straight bit of wire and for that first half of the tone pot sweep there would still be no difference.

the physics as i understand it is that for the first part of the tone pot's travel it's letting very little signal into the cap, not enough for it to "fill up" and start blocking lower frequencies. at this faint level the signal is going right through the cap unimpeded so it acts like a dead short and all we're hearing is the additional load of the tone pot itself bleeding signal to ground.

 

[soulstew]

look again:

those numbers are for the two different cap values at progressively lower tone pot settings. the black and blue curves on the right are for the tone pot on "8" or "10", while the red curves on the left are for the tone pot at "2" or "0".

Aha. I see it now. I was missing out on a whole dimension--wondered what those numbers before the slash were there for. Thank goodness I'm too old to get too embarrassed about how clueless I sometimes am. Thanks for clarifying

 

[walterw]

Aha. I see it now. I was missing out on a whole dimension--wondered what those numbers before the slash were there for. Thank goodness I'm too old to get too embarrassed about how clueless I sometimes am. Thanks for clarifying

ehh, i mostly knew it from having seen it before, it wasn't super clear:

(in this case "T-off" means a bypassed tone pot)

again, notice how at above "T-4" the curves are the same regardless of cap value

 

[soulstew]

ehh, i mostly knew it from having seen it before, it wasn't super clear:

View attachment 3664412

(in this case "T-off" means a bypassed tone pot)

again, notice how at above "T-4" the curves are the same regardless of cap value

Thanks! I'm a tiny bit smarter that I was yesterday

 

[eastcoasteddie]

These videos by TB member @RobbieK are informative:

These are awesome.
I like how Robbie mentioned that with overwound pickups like QP’s, you will have much different curves with each cap - as I have recently found out myself by swapping the .047 cap with a .022 cap. I would recommend anyone using QP’s to try the .022

 

[rojo412]

One of my favorite mods to do in any bass with passive tone is to swap the pot for a push/pull and have a cap select setup. Typically, I'll do .047/.1uf, making it so you can have your standard bass cap in push, but pull it for those times when you want that dub/classic rock wooliness.
It's cheap, it works great, and you can choose on the fly. You can also sub whichever cap values you want, depending on your needs.

 

[fig]

An important point in one of the above videos—the cap is irrelevant for most of the pot’s travel.

note how for tone pot settings above 5 the curves are the same regardless of which cap is used, they're literally on top of each other

Between a linear or log taper pot, would one give more useable rotational range? My knee jerk answer says 'no'. But that knee has been wrong before...

In a broader sense, are there any wiring/component solutions to broaden that useable range?

 

[non]

These videos by TB member @RobbieK are informative:

these vids are great.
in the first vid at 11:55 he explains what i am hearing and the reason i started this thread.
i have quarter pounders. the bass sounds awesome for the first 3/4 of the tone roll off. the tone roll off is smooth for the first 3/4. for the last quarter rotation the tone quickly goes to wet blanket to wet blanket under water. i was just curious as to why the roll off gets really extreme and now i know it is because of the quarter pounders. i have a .022 cap i can try instead of the .047 cap . i will try just to see if that counters the effects of the quarter pounders extreme roll off.
thanks everyone for the great info!

 

[fermata]

Between a linear or log taper pot, would one give more useable rotational range? My knee jerk answer says 'no'. But that knee has been wrong before...

In a broader sense, are there any wiring/component solutions to broaden that useable range?

Gotta be audio taper. To broaden the range, something like a Stellartone capacitor switch (or home brew equivalent).

 

[fig]

Gotta be audio taper.

Thanks for replying. Forgetting the Stellartone type (which I like) for a moment, will the audio taper pot broaden the useful rotational range of the standard cap/pot tone control?

As of now, the video and comments indicate 1/2 to about 3/4 of the rotational range is useless. Meaning only 1/4 to 1/2 is useful. Judging by your answer, the audio taper (as opposed to a linear taper) won't extend the useful range either. Is this correct?

 

[walterw]

As of now, the video and comments indicate 1/2 to about 3/4 of the rotational range is useless. Meaning only 1/4 to 1/2 is useful.

not at all (and yes it's gotta be an audio taper tone).

you still hear a usable tonal change at every increment, starting at "10". all kinds of useful variations can be had between "10" and "5" on the tone knob, that's where you shave off brightness without otherwise changing the character.

the point is just that those tonal changes aren't coming from the cap, they're coming from the tone pot itself.

 

[walterw]

In a broader sense, are there any wiring/component solutions to broaden that useable range?

if you go with a higher-value tone pot it'll broaden the range in the other direction, meaning that "10" will be brighter than before.

for example a 500k audio tone turned down to about "7" will be the same as a 250k audio tone on "10". from there ("7" to "0" on the 500k pot) the sounds will be the same.

 

[fermata]

Thanks for replying. Forgetting the Stellartone type (which I like) for a moment, will the audio taper pot broaden the useful rotational range of the standard cap/pot tone control?

As of now, the video and comments indicate 1/2 to about 3/4 of the rotational range is useless. Meaning only 1/4 to 1/2 is useful. Judging by your answer, the audio taper (as opposed to a linear taper) won't extend the useful range either. Is this correct?

As @walterw said above, the tone pot is useful across its full sweep; a linear pot would bunch up the entire sweep into a small part of the pot’s rotation.

 

[Killed_by_Death]

the last quarter rotation the tone quickly goes to wet blanket to wet blanket under water

A lower-value treble-cut capacitor will help with that, so the 22 nF cap should do the job.

 

[fig]

Thanks walterw and fermata for your time and sharing your experience. Just helped my understanding alot.

Spent the last hour or so re-reading and checking the two charts. Finally realized there were two things I had wrong in my understanding. That's now cleared up. Made the thread even more interesting to me.

Now that it's straightened in my head, it's time for a rum and coke to celebrate LOL.

Thanks again.

 

[BAG]

Thanks for this.
The main thing I get from this is that for anything above about 3 or 4 on the tone pot, which I would guess equates to something like 95% of playing by 95% of bass players, the value of the cap makes very little or no difference, particularly in a mix and that the different type of cap of the same value makes no difference whatsoever in the real world when playing music.

 

[Michael Jewels]

Ok, absolutely excellent thread, and I think I've learned a lot, but now I have a question.

Many of you have heard me raving about my Empress Para EQ, which I've been using since last April.

It's got a long learning curve, (at least for me) but I feel this unit can make any bass sound its best.

It can't make a P-bass sound like a different bass, but can make a P-bass yield its full potential of tones.

By fooling with the Q (starting point) then slowly going through the lows, mids and highs, then playing with the gain of each frequency I can make my Jack Casady bass sound as woody as it can be, or as Metal-ish as it can be and anywhere in between.

This unit really is amazing.

Then, when you get a tone you really like, by just slightly moving the tone controls on the amp, you seem to get even more variations of that sound.

So, my question is: If installing different pots and capacitors in the same instrument will yield different tones at the end of the EQ line, is my Para EQ doing the same thing at the start of the EQ line?

That's what it seems like it's doing to me.

Mike

 

[fermata]

Active and passive systems are very different in a variety of ways, so they're only "doing the same thing" insofar as they affect the instrument's tonal character. But how--and to what degree-they affect that tonal character is quite different.

An active EQ like yours gives predictable pinpoint control over specific frequencies/bands (and other parameters). By comparison, a passive tone control is a pretty blunt tool that's dependent on/affected by all the other LCR components of a particular bass--even the length of the cord! Speaking of the cord, the bass end of the cord is the beginning of the line, the stuff at the other end--pedals, amp, and such--is the end of the line. (The signal starts at the bass.)

 

[MustangWally]

Likewise audiophiles. I don't think audiophiles actually feel anything when they listen to music.

Agree totally - I have a friend who has an insanely expensive hifi setup in his house. Anthem amps, with a 9,000 watt subwoofer (yes, really) and God knows how many watts to the other speakers, conditioned power supplies, and in general every possible super-expensive thing that he can lay his hands on and yet he has not the faintest idea about music and even less interest as far as I can gather. This is just a 'thing' that gives him bragging rights and allows him to play very loud movies with shoot-em-up scenes and rattle the house. Shudder....

 

[Killed_by_Death]

I used to know a guy who had a kick-ass home cinema setup like that, he seemed to bring it up in conversations a LOT, LOL!
What was really odd to me was that he was watching pirated media on it, which is notorious for not being high-quality. So the whole point was lost, until he threw in a legit blu-ray!