|
Audio Asylum Thread Printer Get a view of an entire thread on one page |
For Sale Ads |
I would assume so, since the inductance would impede it out as the foil spirals inward, but don't know & thought I'd ask.
Since such inductors are used in loudspeakers and loudspeakers are 'floating' devices, there will be no difference in the way they are connected. Same as crossover caps. It is important to realise that louspeakers hadle AC currents only. There are no DC polarising Voltages, which may then require specific orientation of some components.Trevor
... if not to isolate the driver from RF? Would not the same apply here, where the outer part of the colied copper-foil pick up the RF & the inductance would progressively impede it out (instead of electricly insolating it with a dielectric like a cap). In the other direction, would it not act as an antena & acquire the RF only to send it to the midrange.
In the case of electrolytics they are directional because of the dielectric used to isolate (insulate) between the conductive charged layers. When wired the wrong way the dielectric can break down and with high voltages the capacitor can and will explode...I've witnessed it.
As far as I know it has nothing to do with RF.
Since we are talking about loudspeakers, then it is best to confine our analogy to audio, in general and speakers, specifically.Speakers are (or should) only be subjected to AC signals. AC suggests that any component must be capable of dealing with AC. This excludes such devices as: Diodes, polarised capacitors and the like. In fact, connecting a polarised capacitor in a speaker crossover, will ensure it's destruction.
Because a speaker is a 'floating' system, it has no ground reference, until it is connected to an item which is grounded. Consider the aspect of an amplifier with no grounded output terminal. Such amps may be: Bridged amps, of any technology, some SS amps and some tube amps. If there was any possibility that capacitors 'preferred' to be connected in a certain way, then by using any of the above-mentioned amps, would be useless.
Since loudspeakers are low impedance devices, pick up of external energy is unlikely to effect them, except under extreme (really extreme) circumstances. It is likely that the voice coil of the driver and wiring, itself, would be more likely to contribute than a simple crossover component, under such (extreme) circumstances, anyway. Shielding the entire loudspeaker and speaker cables would be mandatory, under such conditions, anyway. In any case, as discussed, earlier, speakers are 'balanced' devices. As such, there is no ground reference, until it is connected to a ground reference.
Coupling caps (AFIK) can be connected in any orientation. Decoupling and bypass caps MAY benefit from specific orientation. Speakers do not fit these categories.
By all means use the foil type inductors (they are excellent, BTW), but don't worry about orientation.
Trevor
I've found that 12ga CFAC as quite nice in the past.Plus, I'm truly aware of AC, diode, polarized electrolytic caps & the like. I was trying to convey that politely with the "understood" statement.
So if I ubderstand your POV, what you're saying is that you don't hear a prefered orientation in film&foil caps in XOs. The odd part is that I do. In fact, I'm torn between the low noise-floor in conventional design & the balanced simple beauty of dual half-value caps (both w/ bypass non-L caps) in opposing directions.
Mart, Trever, Dave,I just had an experience with the foil issue that made a believer in
"inner foil to out" or for coupling caps inner foil to grid of output tube.
The difference in my Mac 225 was less than subtle when I switched the direction of the coupling caps. I then did this for my series tweeter caps.
I think I heard a difference but I will not swear to it! In the case of the amp the sound was smoother and the hard edge I had went away. Go Figure! AC and just AF not RF, so whats the issue? I did not expect a difference so I can't say I was prepared to hear one! I've been told that Vacuum Tube Valley issue #11 has an article about this very issue. I need to get a copy to see what the story is. Now I'm really curious!
In a high impedance, DC polarised circuit, I could accept the possibility of a small difference. In a low impedance, non polarised circuit (loudspeakers), nope.Trevor
Well Dave, I'm not sure a film and foil coupling cap working with a DC bias on a very high impedance circuit is quite the same. Film and foil capacitors can have definite advantages when oriented in a way that shields the inner windings, especially with high impedance circuits. Speaker crossovers are not this type of circuit and metallized capacitors do not have near the potential to shield. This is only one possible explanation though. There could also be proximity effects to the chassis, etc.Dave
I am unaware of any technical mechanism which would explain a sound difference between the orientation of caps or inductors in a crossover. As to whether I can hear any difference, well I've never tried it. I have tried it on several clients, with very high grade systems and excellent listening acuity. In single blind tests, they were unable to hear a difference, either. BTW: these same clients COULD readily hear the difference between BRANDS of polyprop caps.It may be instructive for you to have someone wrap the caps in black tape, so you could not identify which end was which, then perform some random swaps, to see if the effect was real, or not.
Trevor
I think you will find Mart that smaller caps in parallel nearly always sound better than a bigger cap. There are less windings and they are tighter. Much more solid sound. This is especially true in the larger film caps used in crossovers. You want ot hear about overkill, listen to this. In my tweeter circuit I am using twenty Rifa 0.22uF vacuum epoxy impregnated paper film capacitors in parallel for the series capacitor. Possibly the best 4.4uF capacitor in the world!Dave
This post is made possible by the generous support of people like you and our sponsors: