Tone capacitor values..

BeardyAndy

I usually buy my harnesses pre-wired but decided to make use of all the odds n' end and make my own up. Thought i'd look into the finer points of tone cap' values and found this video helpful so thought i'd share, didn't realise quite how much difference the values would make.

https://www.youtube.com/watch?v=cXlek6mn4b0&t=287s

Funkfingers

Depending on the host circuit, the nominal values and production tolerances make a noticeable difference. Far more than the materials. [Ducks for cover.] 

ICBM

Funkfingers said:

Far more than the materials.
[Ducks for cover.] 

The materials make *no* difference. I'm quite happy to make it as black and white as that.

Yes, the nominal values make a noticeable difference. The tolerances might, but only just - if they're as wide as +/- 20% you'll probably be able to hear it, but not if they're 10% or better. There is a reason component tolerances are chosen as they are.

To test it properly and avoid any possible differences in playing technique making a difference, you really need to be able to switch the values on the fly - that way you can hear if there is a change as you actually move the switch with a note or chord sustaining. This will show up tiny differences quite clearly - and also prove that there is none, if there's no change.

PeteC

try persuading the Dumble clone makers on the Amp Garage forum about that !!!  I built up a 50w Dumble-like amp using ordinary caps from places like RS and Farnell and it sounded just fine.   SO much smoke and mirrors regarding capacitors. 

ICBM said:

Funkfingers said:

Far more than the materials.
[Ducks for cover.] 

The materials make *no* difference.

sixstringsupplies

This article is great: http://zerocapcable.com/?page_id=224

RiftAmps

**opens can of worms**

I'm from the other end of the camp, arguing that the construction material can (and does) make a difference. I've come to this conclusion, not through confirmation bias, nor through the marketing hype, but from real-world ABCD testing of different capacitors in actual circuits, all measured and matched outside of the circuit to the nearest pF, and then hot-switched in a circuit whilst both a loop or a sine wave is played through the amplifier and results measured not just with my ears, but with an Oscilloscope and a Spectrum Analyzer, where any differences can clearly be seen.

The answer as to why material affects tone is not what I'd expected though, so here's what I discovered...

Firstly, the 'capacitance' of the capacitors nearly always changed when the circuit's working voltage is applied to it. For example, a 715P 600v Orange Drop with a measured value of 22nf (rounded up) increased to just over 25nf when 400v DC was applied across it - note, the same in-circuit capacitor tester was used for all measurements - whereas a Mallory 150 22nf dropped to 21nf. A change in value = a change in tone.

Admittedly, I didn't measure the change of capacitance across a wide range of voltages, that'll be something for next time.

Secondly, the value would change when heat is applied to the capacitor, simulating the hot, harsh environment that the capacitors have to operate in.

Here is a 1nf (1000pf) poly film cap measured at room temperature, after 60 seconds of being blasted by a hairdryer the capacitance increased by 49pf, or 4.5%.

Here is a 100pf Silver Mica cap, which after the same test dropped in value by .2pf, or 2%.

To summarise, the material that a capacitor is constructed from is affected by both the operating voltage and the localized temperature that the capacitor sits in. Therefore, when the capacitor is in use, the material can (indirectly) have an effect on the tone.

Interestingly, old adverts for caps don't talk about tone, but performance under temperature.

ICBM

 RiftAmps said:

I'm from the other end of the camp, arguing that the construction material can (and does) make a difference. I've come to this conclusion, not through confirmation bias, nor through the marketing hype, but from real-world ABCD testing of different capacitors in actual circuits, all measured and matched outside of the circuit to the nearest pF, and then hot-switched in a circuit whilst both a loop or a sine wave is played through the amplifier and results measured not just with my ears, but with an Oscilloscope and a Spectrum Analyzer, where any differences can clearly be seen.

The answer as to why material affects tone is not what I'd expected though, so here's what I discovered...

Firstly, the 'capacitance' of the capacitors nearly always changed when the circuit's working voltage is applied to it. For example, a 715P 600v Orange Drop with a measured value of 22nf (rounded up) increased to just over 25nf when 400v DC was applied across it - note, the same in-circuit capacitor tester was used for all measurements - whereas a Mallory 150 22nf dropped to 21nf. A change in value = a change in tone.

Admittedly, I didn't measure the change of capacitance across a wide range of voltages, that'll be something for next time.

Secondly, the value would change when heat is applied to the capacitor, simulating the hot, harsh environment that the capacitors have to operate in.

...

To summarise, the material that a capacitor is constructed from is affected by both the operating voltage and the localized temperature that the capacitor sits in. Therefore, when the capacitor is in use, the material can (indirectly) have an effect on the tone.

Interestingly, old adverts for caps don't talk about tone, but performance under temperature.

You're talking about amp circuits, where they very definitely do make a difference in some circuit positions.

In guitars they don't. There is no DC voltage, the AC voltage is usually no more than 1V, and the temperature variation is +/- about 10º at most.

RiftAmps

ICBM said:

 RiftAmps said:

I'm from the other end of the camp, arguing that the construction material can (and does) make a difference. I've come to this conclusion, not through confirmation bias, nor through the marketing hype, but from real-world ABCD testing of different capacitors in actual circuits, all measured and matched outside of the circuit to the nearest pF, and then hot-switched in a circuit whilst both a loop or a sine wave is played through the amplifier and results measured not just with my ears, but with an Oscilloscope and a Spectrum Analyzer, where any differences can clearly be seen.

The answer as to why material affects tone is not what I'd expected though, so here's what I discovered...

Firstly, the 'capacitance' of the capacitors nearly always changed when the circuit's working voltage is applied to it. For example, a 715P 600v Orange Drop with a measured value of 22nf (rounded up) increased to just over 25nf when 400v DC was applied across it - note, the same in-circuit capacitor tester was used for all measurements - whereas a Mallory 150 22nf dropped to 21nf. A change in value = a change in tone.

Admittedly, I didn't measure the change of capacitance across a wide range of voltages, that'll be something for next time.

Secondly, the value would change when heat is applied to the capacitor, simulating the hot, harsh environment that the capacitors have to operate in.

...

To summarise, the material that a capacitor is constructed from is affected by both the operating voltage and the localized temperature that the capacitor sits in. Therefore, when the capacitor is in use, the material can (indirectly) have an effect on the tone.

Interestingly, old adverts for caps don't talk about tone, but performance under temperature.

You're talking about amp circuits, where they very definitely do make a difference in some circuit positions.

In guitars they don't. There is no DC voltage, the AC voltage is usually no more than 1V, and the temperature variation is +/- about 10º at most.

Agreed 100% on caps in guitars.

I've often said that the tone cap in a guitar can be compared to the waste pipe on your toilet, the only thing that matters is the size of the pipe (capacitance) and not what it is made from.

BeardyAndy

RiftAmps said:

ICBM said:

 RiftAmps said:

I'm from the other end of the camp, arguing that the construction material can (and does) make a difference. I've come to this conclusion, not through confirmation bias, nor through the marketing hype, but from real-world ABCD testing of different capacitors in actual circuits, all measured and matched outside of the circuit to the nearest pF, and then hot-switched in a circuit whilst both a loop or a sine wave is played through the amplifier and results measured not just with my ears, but with an Oscilloscope and a Spectrum Analyzer, where any differences can clearly be seen.

The answer as to why material affects tone is not what I'd expected though, so here's what I discovered...

Firstly, the 'capacitance' of the capacitors nearly always changed when the circuit's working voltage is applied to it. For example, a 715P 600v Orange Drop with a measured value of 22nf (rounded up) increased to just over 25nf when 400v DC was applied across it - note, the same in-circuit capacitor tester was used for all measurements - whereas a Mallory 150 22nf dropped to 21nf. A change in value = a change in tone.

Admittedly, I didn't measure the change of capacitance across a wide range of voltages, that'll be something for next time.

Secondly, the value would change when heat is applied to the capacitor, simulating the hot, harsh environment that the capacitors have to operate in.

...

To summarise, the material that a capacitor is constructed from is affected by both the operating voltage and the localized temperature that the capacitor sits in. Therefore, when the capacitor is in use, the material can (indirectly) have an effect on the tone.

Interestingly, old adverts for caps don't talk about tone, but performance under temperature.

You're talking about amp circuits, where they very definitely do make a difference in some circuit positions.

In guitars they don't. There is no DC voltage, the AC voltage is usually no more than 1V, and the temperature variation is +/- about 10º at most.

Agreed 100% on caps in guitars.

I've often said that the tone cap in a guitar can be compared to the waste pipe on your toilet, the only thing that matters is the size of the pipe (capacitance) and not what it is made from.

Tell that to the fella that fitted cardboard waste pipes!

thermionic

I suspect that any differences are not due to the material per se, but other properties (ESR, inductance) that may differ between caps of the same capacitance value but different materials and construction. Might be noticeable at valve amp voltages, but unlikely imho at the levels produced by the average electromagnetic pickup.

ICBM

thermionic said:

I suspect that any differences are not due to the material per se, but other properties (ESR, inductance) that may differ between caps of the same capacitance value but different materials and construction. Might be noticeable at valve amp voltages, but unlikely imho at the levels produced by the average electromagnetic pickup.

Exactly. It’s the self-distortion characteristics of different materials and construction which are the big factor, I think. These only apply at fairly high voltages, and relative to the cap rating. The lowest-rated (non-electrolytic) caps still have a rating around 100 times greater than any voltage in a passive electric guitar, so there’s really no way it’s a factor.

axisus

I have to admit that I give them no thought at all. I grab one out of the box and solder it on without even looking at the value.