I've read a bit about capacitor microphonics being a problem and have read that some have zip tied caps to the board or used hot glue. About ten years ago, when I built my first outboard, I put the caps on thin sheet rubber and secured them tightly to the board with zip ties. But now I wonder if the vibrations causing microphonics are within the capacitor and securing them to the board doesn't eliminate the problem. Is that the real problem or are zip ties/hot glue the cure?
Capacitor "microphonics" would not be a problem in a passive crossover. Any noise a properly functioning capacitor would pick up and pass on would be so far below the electrical signal passing through it as to be inconsequential.
"Whining" or "singing" capacitors, coils and resistors could be audible if the crossover was in a room totally soundproofed from the loudspeaker, and damping the parts with rubber or caulk, or encasing the crossover in a soundproof box would eliminate the noise.
"Whining" or "singing" capacitors, coils and resistors could be audible if the crossover was in a room totally soundproofed from the loudspeaker, and damping the parts with rubber or caulk, or encasing the crossover in a soundproof box would eliminate the noise.
There is a difference between physically possible ( it is) and of any actual concern ( I doubt it) . Do you have a reference to any objective testing that shows they are a problem in a speaker? Which technology, as caps can me made from a lot of things and constructions.
Now, especially in a crossover where the caps are physically large, sound mechanical securing is wise. Some ultra high end speakers pot their crossovers and some folks put them in their own chamber. In my view, there are hundreds of details I would worry about first.
Now, especially in a crossover where the caps are physically large, sound mechanical securing is wise. Some ultra high end speakers pot their crossovers and some folks put them in their own chamber. In my view, there are hundreds of details I would worry about first.
It's not BS, any component or bit of wire can act as an antenna. Resistors above a Meg Ohms are good examples. What @weltersys was saying is that the induced noise picked up in a passive crossover is going to so far below the output signal of the amplifier it will have no effect on the sound, the only caveat on this is that the system is well shielded so induced noise would not be an issue.
Also his suggestion of calking all components is a widly used practice by manufactures of electronic components.
Also his suggestion of calking all components is a widly used practice by manufactures of electronic components.
Having worked in the electronics industry for 45 years potting was used to hide circuits to make reverse engineering more difficult. There are other valid reasons for potting like moisture resistance, environmental and hazardous area use. I would just add mechanical damping to the components with silicone sealant.
Depends on the circuit talked about- yes, one can tap on a ceramic disc capacitor in a tube preamp circuit with a stick and hear a "clunk" after amplification in a loudspeaker, but that is several orders of magnitude different than tapping or vibrating a decent capacitor in a passive crossover circuit.
So, yes, I'd put the talk in a similar BS bin as putting speaker cords on little crutches, "cable elevators" or "cable lifts" for "huge improvements in detail, focus and dynamics, creating an instantly noticeable and undeniable audible improvement".
And I've read that one of the reasons Wilson potted their XOs was to avoid reverse engineering. And I'm amazed that their XO desgin hasn't been determined. I would love to see the watt5 layout.
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There newer Wilsons are a lot better. I heard some Alexia. The SabrinaX is not even too ugly like their big monstrosities and only a mere $18k.
Knowing Wilson crossovers is meaningless without knowing their drivers and cabinet. There is no wisdom gained to copy a crossover.
Another reason some circuits are potted is to hide that they are using cheap crappy parts.
A reason not to pot is heat dissipation.
A DSP generated frequency response is not the same as the passive implementation. If it were, every AVR on $200 K-mart speakers would be "perfect"
Besides "stealth", a reason to glue or pot crossover components is they are big and heavy, so it is wise to have good mechanical support. That way vibration over time will not cause a physical connection failure. i.e. a broken solder joint.
Go look at how big an old school spring reverb was and then consider what effect a single tightly wound cap could have.
I HAVE experienced a poorly mounted crossover board vibrate in the cabinet and be audible in pure sine test sweeps. Always fun to find out what resonates in your room.
But hey, it costs almost nothing to secure parts and if it makes one feel better, great. A few zip-ties or hot glue are far cheaper than one boutique cap.
Wouldn't capacitor microphonics be easy to test? Have someone tap the cap - or smack it with a hammer. Anything coming out of the speaker? If you have a soundcard with inputs, you could probably record it directly.
As a follow up to some talk about potentiometer microphonics I did a test by biasing the pot with a 9V batter and taking the signal from the wiper (via DC blocking cap). Even hitting it with a hammer gave no signal. But it was a fancy $50 pot. Just saying that these things are not difficult to test.
As a follow up to some talk about potentiometer microphonics I did a test by biasing the pot with a 9V batter and taking the signal from the wiper (via DC blocking cap). Even hitting it with a hammer gave no signal. But it was a fancy $50 pot. Just saying that these things are not difficult to test.
I like to use motor run " ceiling fan " caps, not only are they cheap, but thet often have a plastic lug with hole for mounting. There is a tread somewhere about the right type of glue for caps, it was as heated as a thread about wire, some people DON'T like silicon sealant, some said hot melt glue absorbs water and becomes unstuck. One speaker manufacturer has the crossover in a separate box and fills it with sand, at least it can be tipped out for repair.
this certainly the microphonic effect inside the film cap due to the behavior between the dielectric and the polarized sheet when the current flow that is a concern, not so much external one ! You can do nothing for the first but some film and dielectric are better than others, e.g. tin foil; but it doesn't say all, there are some more important to choose a cap in a speaker filter than inherent microphonics imho, so it is not BS, to worry too much about is !
