on bass-pass 250Hz 12db which is preferable Jantzen C-Coil with 0.05 ohm or Wax-coil with 0.47 ohm?
at listening tests what the differences will be ?
i think that +0.42 ohm are a big value against to 0.05 ohm.
i've seen someone (very rare) who add a resistor in series to woofer crossover but i don't understand why .
thank you very much
at listening tests what the differences will be ?
i think that +0.42 ohm are a big value against to 0.05 ohm.
i've seen someone (very rare) who add a resistor in series to woofer crossover but i don't understand why .
thank you very much
Adding a resistor will reduce the damping factor, try adding a 1 ohm resistor bypassed with a 1 uf cap in series with a speaker, it will give quite a different sound. 0.42 ohm and 0.05 ohm is the kind of difference between speaker cables, generally to lower impedance sound better; the best thing on the subject I could find was a test done by stereophile. Can of worms opened. I prefer low impedance chokes, and have used three ( I could afford four at the time ) laminated iron chokes in parallel to achieve this and intend on using a transformer from a microwave to make an E core choke to make super low impedance chokes; but others on this forum have much more knowledge on this, I'm just the first to chime in.
Maybe a bit of theory would help your understanding of the subject: not that I have all the answers!
Air cored inductors are generally the first choice for audio applications as they do not exhibit non linear distortions such as caused by core saturation. Magnetic saturation is a bit analogous to signal clipping in an amplifier.
The incentive to use laminated iron or other core materials is that they have a permeability several times that of air. The permeability figure (Ue) is an inductance multiplier. If we put a core in an air cored winding its inductance multiplies by the Ue figure.
We thus achieve our inductance with a lot less turns, allowing lower DC resistance in a smaller package. I get the impression that cored inductors for crossover use start at values around 5 mH and above.
Your mention of ferrite cores surprises me a bit. While ferrites can have high permeability I believe it is hard to control this aspect in the manufacturing process. This means that if an inductor manufacturer was trying to make n mH inductors by winding (say) 50 turns of wire on every core the reject rate could be rather high.
Keith
Air cored inductors are generally the first choice for audio applications as they do not exhibit non linear distortions such as caused by core saturation. Magnetic saturation is a bit analogous to signal clipping in an amplifier.
The incentive to use laminated iron or other core materials is that they have a permeability several times that of air. The permeability figure (Ue) is an inductance multiplier. If we put a core in an air cored winding its inductance multiplies by the Ue figure.
We thus achieve our inductance with a lot less turns, allowing lower DC resistance in a smaller package. I get the impression that cored inductors for crossover use start at values around 5 mH and above.
Your mention of ferrite cores surprises me a bit. While ferrites can have high permeability I believe it is hard to control this aspect in the manufacturing process. This means that if an inductor manufacturer was trying to make n mH inductors by winding (say) 50 turns of wire on every core the reject rate could be rather high.
Keith
Just another point, I would be very reluctant to have an non air core anywhere near a speaker driver magnet, if you have an iron or ferrite core near a magnet it could saturate the core. It is also possible ( but this is only an idea, I have NO proof ) that a driver in use could give of variations in it's magnetic flux, turning any nearby coil into a ac generator; perhaps someone with more knowledge would like to comment on this.
The tradeoffs on inductors are basically: aircore if higher series resistance (higher SPL loss in series) is tolerable, and that resistance is extremely linear (doesn't change with current through the inductors). Ironcore if lower resistance is needed, but poorer linearity and distortion from the inductance can be tolerated. Ferrite core if the very lowest series resistance is desired, but the inductance and resistance will be quite nonlinear and can get ugly on current peaks. Powdered Iron core is usually a good compromise, but expensive. It's a good reason to simulate crossovers in software to let you see how badly the current peaks up on inductors.
Note that it's AMPERES, not Watts that causes problems on cored inductors -- ideally, an inductor doesn't dissipate power/watts, that's not a meaningful spec. If the current stays reasonable, then huge 'Watts' from an amplifier are handled ok. But if the inductor forms a resonance with other components or drivers, the current can get high with relatively little power.
Note that it's AMPERES, not Watts that causes problems on cored inductors -- ideally, an inductor doesn't dissipate power/watts, that's not a meaningful spec. If the current stays reasonable, then huge 'Watts' from an amplifier are handled ok. But if the inductor forms a resonance with other components or drivers, the current can get high with relatively little power.
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If the core is large enough for the amount you drive your speakers, you might be able to make use of the lower resistance. Rarely are different sized core options offered or discussed in terms of what they can do. Higher efficiency speakers or lower listening levels can make this decision easier.
Interesting concept. I'm not certain the effect would be significant, pole pieces are typically near saturation and etc. I think someone has done measurements, I just can't remember where just now.cracked case said:
One reason, to match a replacement inductor in sound, as when using the one it's replacing.
Another reason, to reduce the damping factor to tailor the bass response.
Hi,
The series resistance in front of the woofer has an influence on your box alignment. Personally I prefer lowest resistance possible to have the loss of damping factor minimized. In a highly resolving OB bass (with AE 18 in this case), differences in series resistance are easy to hear. Having the bass driver working up to app. 300Hz, than being filtered 2nd order, quality differences of inductors are easy to hear. By the way, quality differences of parallel caps as well...
The Jantzen C-Coils are very good in the bass range and have very low series resistances. Normal home use, even with high levels, shouldn´t bring them even near core saturation.
I do like foil inductors better than wire inductors - depends on how much mids your bass driver really reproduces (and don´t believe that if you´re filtering at 300Hz or whatever, the bass driver won´t have any influence above that) and how high your general level of quality is.
I would suggest to have a look at the Mundorf I-core foil inductors as well. They have quite a low resistance and provide the foil advantage, and were my final choice (as they performed SLIGHTLY better in the lower mids). They come at a price, and I´m not hesitating to use C-Coils in other applications.
And this will be the decision element, as usual: what´s the intended application???
All the best
Mattes
The series resistance in front of the woofer has an influence on your box alignment. Personally I prefer lowest resistance possible to have the loss of damping factor minimized. In a highly resolving OB bass (with AE 18 in this case), differences in series resistance are easy to hear. Having the bass driver working up to app. 300Hz, than being filtered 2nd order, quality differences of inductors are easy to hear. By the way, quality differences of parallel caps as well...
The Jantzen C-Coils are very good in the bass range and have very low series resistances. Normal home use, even with high levels, shouldn´t bring them even near core saturation.
I do like foil inductors better than wire inductors - depends on how much mids your bass driver really reproduces (and don´t believe that if you´re filtering at 300Hz or whatever, the bass driver won´t have any influence above that) and how high your general level of quality is.
I would suggest to have a look at the Mundorf I-core foil inductors as well. They have quite a low resistance and provide the foil advantage, and were my final choice (as they performed SLIGHTLY better in the lower mids). They come at a price, and I´m not hesitating to use C-Coils in other applications.
And this will be the decision element, as usual: what´s the intended application???
All the best
Mattes
thank you mattes.
my application is 4ways and the cutoff frequency of bass pass for the woofers is 200/250 hz 12db
my application is 4ways and the cutoff frequency of bass pass for the woofers is 200/250 hz 12db
better compared to c-Coil ?
please specify
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where you read this ?...i've seen on data sheet but nothing...
i'm using tha jantzen C-Coil 12AWG
In subwoofers i add series resistor of 0.5 to 3 ohms.
For several reasons..
Tuning of Qts (higher) often more "extended" bass.
Back EMF dampening and less modulation of midrange.
The dampening is also affecting all power amps with output feedback.
Adding a small resistor sounds more pleasant and less noisy.
It has less effect if you drive the subwoofer with a tube amp.
I did fft distortion measurement on a dipole woofer and what happend was that the 2nd harmonic increased slightly and maybe even 3d by a fraction of a % close to the fs where the higher orders where not affected!
That is a good sign... the 2nd harmonic masks higher orders of distortion making it more pleasant for the ear. This is all psycoacoustic phenonoma and well known in the mp3 compression literature. But it is still valid knowledge for us interested in high end!
What i´m doing right now is transconductance amplifier with 400ohms outoput impedance, and motional feedback. reducing all distortion with approx 22dB. Yes that is absolutely noticable!
For several reasons..
Tuning of Qts (higher) often more "extended" bass.
Back EMF dampening and less modulation of midrange.
The dampening is also affecting all power amps with output feedback.
Adding a small resistor sounds more pleasant and less noisy.
It has less effect if you drive the subwoofer with a tube amp.
I did fft distortion measurement on a dipole woofer and what happend was that the 2nd harmonic increased slightly and maybe even 3d by a fraction of a % close to the fs where the higher orders where not affected!
That is a good sign... the 2nd harmonic masks higher orders of distortion making it more pleasant for the ear. This is all psycoacoustic phenonoma and well known in the mp3 compression literature. But it is still valid knowledge for us interested in high end!
What i´m doing right now is transconductance amplifier with 400ohms outoput impedance, and motional feedback. reducing all distortion with approx 22dB. Yes that is absolutely noticable!
Again, we have all this info very nicely tested and explaining at hificompas, I dont think there is any other such a great resource for speaker builders! Test of a couple of iron core inductors | HiFiCompass
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