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Old 12th December 2006, 06:23 PM   #1
Jonasa is offline Jonasa  Belgium
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Default Air or a steel core inductor

Saturation will make a steel core inductor in a crossover less good than an air coil.
But when happens the saturation?
Is this only at high currents? So then a steel core inductor gives alway good sounds at low volume levels.

When saturation is only dependend of the current then we can use an air coil in series with woofer because the current is highest. So there is no need to use air coils in notch filters and low current tweeter filters?

At what power or current will saturation be audible? And what is the effect on sound? Harmonic distortion only at high volume levels?
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Old 12th December 2006, 06:29 PM   #2
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If the core saturates, the inductor will loose the inductance. Compare a toroid transformer under startup conditions.

You should pick a core which can handle the current you'll have in mind. The other more obvious side effect is maybe unlinearity and hysteresis.

You choose iron core (of some kind) when you want high inductance and rather low resistance.
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Old 12th December 2006, 07:49 PM   #3
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Use air core if you can accept the higher cost or resistance. It will have less distortion.

Use cored if you have to have low resistance.
Larger cores will handle more current before saturation. Cores for inductors usually have large air-gaps, like rod cores and such. The will saturate gradually, gradually increasing distortion.
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Old 12th December 2006, 08:12 PM   #4
Jonasa is offline Jonasa  Belgium
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Thanks for the aswers.
But at what power or current has saturation effect?
Is the distortion bad?
Many people use tube amplifiers to create some kind of distortion.
When saturation creates second and third harmonic distortion it will be good? Tube amps create also distortion and sound more natural.
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Old 12th December 2006, 08:31 PM   #5
lndm is offline lndm  Australia
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Quote:
Originally posted by Jonasa
But at what power or current has saturation effect?
Typical budget iron cores will begin to saturate during normal to slightly loud listening.
Quote:
Is the distortion bad?
It can be. By losing the inductance you may hear parts of a driver's range that sound bad. By using two saturating iron cored inductors you may notice interactions between them.

My point is that the distortion is not consistent.
Quote:
Many people use tube amplifiers to create some kind of distortion.
.No.
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Old 12th December 2006, 08:36 PM   #6
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Quote:
Originally posted by lndm
.No.
Where do you think the warmth comes from?
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Old 12th December 2006, 08:44 PM   #7
adason is offline adason  United States
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Quote:
Air or a steel core inductor
if you listen to rock music, you should use rock core inductor
sorry, could not resist....
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Old 13th December 2006, 05:35 PM   #8
Jonasa is offline Jonasa  Belgium
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Does anybody know what the difference in sound is between air and non air inductors.
What is the effect on woofer, tweeter or in case of notch filters?
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Old 13th December 2006, 10:21 PM   #9
Klimon is offline Klimon  Belgium
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Oh-oh!!!!

Quote:
Many people use tube amplifiers to create some kind of distortion.
If you're referring to guitar-amps you're right.

In home audio I would ascribe the subjective superiority (to some including me) of tube amps to the several benefits they could have; the higher harmonic distortion being a backdraw and NOT the reason for their good performance (besides, measured distortion patterns of tube and transistor amps do not necessarily differ much). Some benefits of a minimalistic set amp versus a typical commercial transistorised amp (push-pull) that come to mind:

- minimum component count in signal path
- much better phase behaviour due to the absence of negative feedback
- no crossover region distortion
- ??????

...which mainly translates into better midrange. Needless to say there are many backdraws much greater than the slightly higher harmonic distortion that go with sets.

To answer your original question :

The way I understand it is that the 'distortion' you'll get with a saturated X-over coil is simply that the crossover won't work as planned but e.g. in the case of a first order low-pass filter the woofer crossover point will shift upwards = subjectively more midrange + break-up resonances will come through with more bite (especially in the case of alu-cone // kevlar etc. woofers). Iron-cored coils are only used because they are cheap, small and have low DCR for a given price.

Groets -- Simon
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Old 13th December 2006, 11:35 PM   #10
Ron E is offline Ron E  United States
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Quote:
Originally posted by Jonasa
Does anybody know what the difference in sound is between air and non air inductors.
What is the effect on woofer, tweeter or in case of notch filters?

There isn't any until the iron core saturates. With good iron core or ferrite this will not hapen until the speaker is so stressed you wouldn't notice anyway. Buy cored inductors when they are more than 1mH, it only makes sense. Cored inductors have lower DCR, better "Q".
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