I am in the process of modelling my 3 way crossover, and will be needing a few large inductors for woofer section. I recently recieved Parts Express new catalog, and they are offering Toroidal C Coils. Does anyone here have any experience with these, or information about them ? What are the upsides, or downsides to them. How do they compare to iron cores, performance wise, distortion wise, etc. Any information you all may have to share is greatly appreciated................Thank You.........Omni
I bought a pair of 4.7's to try out on my 2.5 MTMWW's.
They're nice and heavy for one thing, another might be less heat and less hysterisis loss than iron cores.
I went for less heat production.
I would notice air cores and some iron cores getting warm and even hot during loud sessions on my speakers. These C-cores never even warmed up.
A site on core types;
http://www.butlerwinding.com/core-types/index.html#ccore
They're nice and heavy for one thing, another might be less heat and less hysterisis loss than iron cores.
I went for less heat production.
I would notice air cores and some iron cores getting warm and even hot during loud sessions on my speakers. These C-cores never even warmed up.
A site on core types;
http://www.butlerwinding.com/core-types/index.html#ccore
RJ Thanks for your input and the link. I read a lot of it and must admit much of it was "Greek to me", however it does suggest an improved performance with these type inductors. What are the dimensions of the coil you bought? How did you mount them? Also, I have read debates on wiring the leads to + or - on the driver to the inside wire or outside wire of the inductor.{I think it was a thread on this forum}...........Is there a specific wiring direction you took with these inductors?....................Respectfully............Omni
Orientation is less of an issue with doughnut-shaped inductors, as there is little flux leakage. The series resistance should be quite low, resulting in less power loss (the heating referred to above). Inductor polarity does not matter, unless you're trying to use the electromagnetic coupling effect with another inductor (effectively making a transformer). But this application has no use in passive loudspeaker filters.
omni said:
He's referring to the "electromagnetic coupling effect" which is what is used in transformers to change AC voltages. This is is a completely different application than an audio filter network in which there is no desired coupling effect between inductors, and they are specifically oriented to minimize this effect. Because of that, the polarity of the inductor is of no concern in these filters.
omni said:
Well, transformers have been used in loudspeakers before (usually autotransformers) for impedance matching, and sometimes for attentuation. But it is poor practise (rather arbitrary) to use two separate inductors to achieve coupling, as the coupling will be very weak, with minimal power transfer. It is this arrangement that is of little use in passive crossovers: usually one tries to overcome any power losses, rather than introduce them (except, of course when attenuating a tweeter or mid).
Thank you for your replies, So, do you think these toroidal coils present a good use for a low end crossover value, in a passive crossover, say around 300Hz? And how do you think they would perform, compared to a basic iron core inductor like, for example, the ones available from Madisound { I think they call them Sledgehammer Steel Laminate }........Respectfully...........Omni
The C-core should be better mainly in terms of lower magnetic flux leakage. Coils should be used within their intended operating range, i.e., not close to saturation. Usually, current-carrying capability is specified. If this principle is observed, there should not really be much difference, apart from the series resistance. IIRC, the C-core inductors have generally lower resistance (but I speak under correction, so please check this).
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