Speaker Crossover Questions - Again

If they're in good condition, there's no reason to replace them.

For reliability, all connections should be soldered, regardless of how the components are "anchored"..

It is my opinion that switching from electrolytic to Mylar caps will effect a noticeable improvement in the sound. Mylar caps are not horribly expensive, so it won't cost much to experiment. You can modify one speaker and compare it with the unmodified one to see if you agree. I will not discuss this issue further.

You should replace the caps directly, rather than paralleling them. (Your point is correct, at least in theory.) A 10uF electrolytic should be replaced by a 10uF Mylar, and so on.

Mylar caps should also last longer than electrolytics, as they won't dry out.

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Looking at the AR91 schematic here

I notice that the original caps are all non-polarised electros. While changing to film type caps (mylar MKT or polypropylene MKP) is thought by many to improve the sound quality, this may prove to be a moot point in reality. Those 24 uF and 40uF caps will take several paralleled MKT's or MKP's to get the right value and the cost won't be all that small. As suggested by William you might care to modify one unit and compare it with a standard x-over. Listening test will require a suitable speaker switchover arrangement.

post,

That sounds right to me, but whats the point ?

Electrolytics are always plagued by tolerance, ESR, aging, and voltage limits. A quality speaker will be voiced by careful planning, listening, and measuring. Anything you change can affect the sound, not necessarily for the better. Resistors should be Ok indefinitely, unless they are cooked or have mechanical fatigue. After years of fooling around with internal crossovers while making speakers, I got smart and put the crossover components on the outside of the cabinet, and any changes could be made without reopening the cabinet. You can make a change, and check for changes in response, polar patterns, etc.. Sometimes it could take days or weeks to determine if I was satisfied with the sound.

greg

Polypropylene is probably overkill.

Mylar caps aren't horribly expensive.

I would start by replacing only those caps in series with the drivers -- the

4uF and 24uF capacitors. You can then try replacing the two that are directly in parallel, the 8uF and 40uF. The 100uF cap seems to be part of a Zobel filter (don't ask) and probably doesn't need replacing, unless it's "bad", in which case you can use an electrolytic.

Not necessarily. Before modifying a speaker, listen to a mono source and try to get a sharp central image. Modify one speaker, and repeat the listening. If the caps have changed the sound, the mono image should be at least "different", and (hopefully) degraded, because the speakers no longer "sound alike".

Pink noise is the only way to go for immediate recognition. Of course. if the component can be changed instantly outside the cabinet, you only need one speaker to hear any change.

greg