Modifying Crossovers

My cautionary tale is to be careful in doing too much.  Tweeter and mid-cap upgrades are simple and easy. 

If you have a 1980's - 1990's vintage speaker though, it's worth doing a complete analysis before doing much work.  The issue is the tools and effort it took to get a good crossover back then to work across both frequency and impedance.  There's plenty of examples of speakers in this vintage that need different crossover designs. 

Be extremely careful replacing caps that go to ground, their effects on the impedance curve is unexpected, so measure and compensate for ESR changes. 

Best,

E

Thanks everyone for this very interesting and informative discussion. Let’s close this out. 

Cheers

This used to be a VERY sore point for me. I got so tired of seeing SO Called High End Brand Names using something similar to Cat5 wire and a single off the shelf Radio Shack quality capacitor inside. I sincerely hope that this is a thing of the past. I might say that I do believe that most of the really quality speaker manufacturers have real science backing them up when they design their crossovers. I still try to have faith in the educated human mind.
I must remind the folks that there are so many components to chose from and different ideas behind how they go about creating a particular crossover. A Particular driver may have some inherent oddity that requires something that you are not aware of and can’t predict.
Also lets just look at one component, the capacitor. And even at that, One Brand, MUNDORF. They make so many different caps for any given value that it would be insurmountable for the average user to pick one and say that just because it is a Mundorf; it will give my speaker a better sound. You might hit on the right one but if you miss yo just wasted a bunch of spare change and time. and at the same time probably gained a slanted opinion of Mundorf when they really don’t disserve it.
Looking at Inductors, I would love to brag about continuous ribbon wound inductors over wire wound inductors but even then this could blow up in my fact just because I don’t know something about the coil in the speaker’s driver that would necessitate the wire wound over the ribbon wound.
And just to show you that I can screw up a speaker as well as the next guy. I took one of my own designs where I originally used Chartreuse caps in and always liked them, but thought I could do better so I spent a couple hundred dollars on some Mundorf caps. I have regretted that decision every day since.

I'm a big believer in the effect of using quality components in the crossover. I've done a modest amount of experimentation and have found that high quality parts can make a significant effect on tonal richness, dynamics, microdetails, and soundstage. 

Besides the obvious issues of resale value, warranty, etc., there are a few things to keep in mind:

Esoteric components, particularly capacitors, can add a tonal flavor that is different than the original design. This might be preferred by the listener or might not be, so just because a component is well regarded and much more expensive than the original part, it doesn't necessarily mean that it will be an improvement since we all have different preferences. 

Many of the higher quality parts are bigger (sometimes considerably so) than the original parts. IT may be challenging to actually get the new parts to fit in your speaker. I use some capacitors in my speakers that are 50% bigger than a 12oz can. 

Some of these parts, particularly esoteric film capacitors, can take hundreds of hours to "break in". During this time, the sound can change considerably - sometimes for the better and sometimes for the worse. So you can't really make a judgement when you first install the parts.

A classic example of the sanity of a) knowing the relative quality of your speaker’s crossovers and b) improving them if their quality is not to the level that you would like is the B&W Matrix 801 Series 2 speaker. Although widely regarded as one of the finest speakers that existed at the time of it’s introduction in 1995, it’s crossover was highly compromised due to the space limitations of the underside of the bass cabinet where it was placed in the interest of the speaker being highly moveable for it’s anticipated, and actual, use in recording studios...famously at Abbey Road Studios.

George Short, the brilliant speaker designer and founder of North Creek Audio stated that this speaker "...has some of the lowest distortion, inherently linear drivers of any speaker ever produced in one of the most acoustically inert cabinets of any speaker ever produced, but some of the worst specified crossovers of any high end speaker ever produced." This fact made his crossovers for said speakers extremely popular for at least two decades before he closed his business several years ago.

Suffice it to say, anyone with one of these speakers systems with Mr. Short’s crossovers has left the speaker consumer market.