crossover upgrade

[kingfisher]

To answer the question of how to test..... I would recomend the W3 Woofer tester... Well worth the small $.. and while you are shopping you may consider the OmniMic as well.. I have just puchesed this and all of my guess work has been corrected! I believe many of the questions you posted will be answered through testing! Hey after this Test your other gear also....

[system7]

Considering the amount people spend on capacitors at the high-end, it's really quite amazing we pay so little attention to Coils, which are WAYY more imperfect!

A typical coil has a DCR resistance of 10% of the loudspeaker resistance and often include highly non-linear cores like ferrite and soft iron. By their nature they are microphonic too, which combined with inclusion in rattling speaker cabinets makes it even worse.

You can spend an awful lot on exotic low resistance coils, but the main thing is to go AIR-CORE and get rid of the non-linear magnetic material. How much improvement can you expect? Well, probably only 50%, after all speakers include iron and ferrite in construction. Here's a very good coil supplier based in Germany, Strassacker:
Strassacker: Speaker - kits - do it yourself

Troels Gravesen explains how to choose:
COILS FOR DIY LOUDSPEAKERS

You'd expect huge improvement from moving the crossover out of the cabinet to reduce microphonics. If money is no object, avoid iron and ferrite cores which will suffer non-linearity and saturation. Actually choosing a coil for the job might take into account the crossover details. Because things like damping changes caused by DCR resistance can be happily allowed for in cabinet and crossover design. So don't expect the moon from a coil change. But it's worth considering.

[leonm12]

The core in the picture I have posted is called "IRON BARS"
Is it considered good?

[system7]

leonm12, I can only say that adding a magnetic core to an inductor, while reducing the DCR resistance per Henry in practise, adds an effect called magnetic hysteresis, which is lossy and non-linear:
Hysteresis - Wikipedia, the free encyclopedia

It's one for the physicists really, but ideally you should use air-core with heavier copper windings. That's about as good as it gets. But before you spend huge bucks on passive crossovers, it's gotta be worth considering an active scheme for filtering, which, at the high end, will work better.

[weltersys]

Originally Posted by leonm12

The core in the picture I have posted is called "IRON BARS"
Is it considered good?

Choose your poison: Air core eliminates saturation effects which cause distortion at high power levels.
Iron core allows less length of copper to be used, increasing damping factor compared to an air core using the same wire gauge, giving a "tighter" bass sound.

At 4.7 mH either air core or ferrite core can be used with large wire gauge and work well, when values of 10 mH are needed, the length of heavy gauge wire (and reduction of damping factor) is such that an iron core would be preferable to me.

[system7]

No, I've gotta pick some holes in that. Just to clarify an often misunderstood issue about damping factor.

Ferrite and iron core coils are a cheaper solution. They confer no benefit beyond cost saving. Lowering DCR is a good thing, because resistance increases with temperature, so you are reducing a non-linear effect to some extent. But you'd be better applying some cooling, no?

Damping factor, within reason, is not important. You can design a tight sounding loudspeaker for ANY source impedance. If you lose 10% of damping factor to a 1 ohm coil, the answer, broadly speaking, is to make the cabinet 10% bigger!

[strawberry]

Save your money. Take your girlfriend some where, like around the world on a cruise ship. For the 22 uF, go with elna silmic 50-63V, bypassed with a polyester 0.5 uf or so. Most polypropylene or bypassed polyesters sound good for a 2.2 uF. You will see a better upgrade in tweaking the crossover to other values, but not all can do that.

[garrettba03]

Personally I would leave the coil alone. If you must really change it to air core...make sure you have plenty of space to mount that low dcr thick guage 4.7mh coil...cause its gonna be big and id be very suprised if you fit it on the crossover board (its in a car isnt it?)
As you have to match (or at least get very close to) the original DCR of the iron core low pass to the new air core DCR...if you dont it will change the frequency response (this is as a higher dcr your adding resistance in series to the woofer circuit).
It is for this reason...I wouldnt touch ANY coils. The caps you can change however with the noise floor in a car I believe you would notice 0 difference.

[leonm12]

when upgrdaing the coils in the crossover (serial and parallel coils), is it improtant to use same dcr coils on the new coils ?

what is the problem on high resistance coils? (1.0 -ohm resistance).

currently I have 4.7mH IRON BARS , 1.0 ohm resistance coil for the low pass of the woffer and I would like to upgrade it to new coil.
I need to know if it improtant to use same dcr value on the new coil.
the crossover is 3 way for woffer mid and tw.( no Bi-amping and no Three-amping)

please give accurate info if you really have understanding on this.

Thanks