[adydula]

Well, there are many types of components and I have always wanted to know what components are used in the crossovers and why....I am not looking for trade secrets or the actual designs, schematics etc...although I would think it would be very interesting from an engineering standpoint.

For example there are many types of capacitors:

Ceramic, Electrolytic, Tantalum, Silver Mica, Polyester Film, Metallised Polyster Film, Polycarbonate, Polypropylene, etc....such a wide variety indeed.

If the wrong type of component is used in a circuit it could result in not so good results.

So as far as you can it would be very interesting to understand what goes into a good crossover, parts, design etc...without spilling the beans exactly..

Maybe the famous Dennis Murphey can chime in or Jim.

All the best
Alex

[DMurphy]

I just posted  in the last thread concerning crossover component offerings.  We all have our biases, and mine is a strong bias against expensive crossover components.  That's based partly on personal experience, and partly on my background in enforcing advertising statutes at the FTC.  If someone is offering a capacitor (inductor, resistor) at a super premium price, and claiming it will sound better, then they have a responsibility to substantiate the claim with some kind of scientific evidence.  I rarely see that.  This is a kind of fringe market, and it's not likely that the FTC will come crashing down on sellers in this market segment, but I think you as buyers should expect tht kind of substantiation.  If you don't see it, be cautious.

[adydula]

Hello Dennis,

I started this thread here so it would not hijack the ribbon vs dome tweeter comparision thread.

That said I undertstand the low cost. Its like the old speaker wire stuff...and I do like to see facts and oscilloscope traces of circuit signals etc...show me the money etc.

If you can get world class performance using low cost parts great...as long as they hold their specs over time. I think most of us wouldnt mind paying a small increase in parts if they were justified etc...sonically etc.

I remember when I was 'auditioning' speaker cables I was almost sold when I opened up a really high dollar speaker to only see some really el cheapo, small gauge wiring with mechanical connectors on the inside.....with all that silver solder and gold connectors etc on the cables only to have el cheapo inside of the transducer. I would have thought these internal connectors would have been soldered etc....nope just mechanical push on's that will oxidize with age....

All the best
Alex

[fsimms]

If someone is offering a capacitor (inductor, resistor) at a super premium price, and claiming it will sound better, then they have a responsibility to substantiate the claim with some kind of scientific evidence.

I built a circuit in a simulator at NASA that depended on the accuracy of capacitors.  That was 30 years ago so I don't remember any details, but I had to use a very expensive capacitor as the cheaper ones were not linear.  I tested each of the caps on the bench with precision equipment and could easily measure the effects.  I don't know if the distortions would be strong enough to hear but they did add distortion!

Bob

[adydula]

fsimms,

Interesting, linear components and a NASA capacitor simulator! Neat.

I sure hope todays caps and the technology is better than those of 30yrs ago, but something tells me that their  is still cheap stuff out there that the values wander all over the place depending on the circuit its being used in and the frequency response etc.

In designing a crossover, I would think that to accurately build a crossover that 'crosses' over at a design frequency the parts tolerance needs to be up to spec to allow the crossover to work as designed...

What I dont know and am not an expert is how much variance means 'anything' or should we care? Is a filter circuit that has componets off the center of their values really mean anything to us at all?

If a circuit designed to allow frequencies above 60HZ (example) how far off does a component have to be that would change this frequency???

I guess you would have to hook up some resistor and cap decade boxes, a signal generator and a Oscope to actually see whats happening...

I wonder if the crossover experts actually do this or is it all pure theory??

Again this is NOT meant to indicate subpar components in any speakers, but how much does this stuff really matter?

This topic may be as interesting as watching grass grow to some....
(at my age drinking beer and watching grass grow is somewhat enjoyable at times!!)

Alex

[R Swerdlow]

In designing a crossover, I would think that to accurately build a crossover that 'crosses' over at a design frequency the parts tolerance needs to be up to spec to allow the crossover to work as designed...

What I don't know and am not an expert is how much variance means 'anything' or should we care? Is a filter circuit that has components off the center of their values really mean anything to us at all?

If a circuit designed to allow frequencies above 60HZ (example) how far off does a component have to be that would change this frequency???

I guess you would have to hook up some resistor and cap decade boxes, a signal generator and a Oscope to actually see whats happening...

I wonder if the crossover experts actually do this or is it all pure theory??

Again this is NOT meant to indicate subpar components in any speakers, but how much does this stuff really matter?

This topic may be as interesting as watching grass grow to some....
(at my age drinking beer and watching grass grow is somewhat enjoyable at times!!)

From my limited experience in DIY speaker building, I can repeat the "conventional wisdom" I've picked up from others concerning capacitors.

Many caps are sold at a rated value ±10%.  For example, a cap rated at 10 µF, it might actually be anywhere from 9 to 11 µF.  For most crossovers dealing with audio frequencies, this is fine.  The individual woofers and tweeters sold by most manufacturers often vary more than this, and ±10% variations among drivers can sometimes make a much larger difference than ±10% in caps.  It is comforting to know that the drivers that Jim uses from SEAS, Hiquophon, Aurum Cantus, etc. are among the best in the industry with regard to quality control and individual variation.

The cheapest non-polar electrolytic (NPE) caps available do work for crossovers.  The rap against them has been that NPE caps dry out over time and their capacitance drifts out of spec.  Exactly how long this takes is estimated at 15-30 years, and may not matter depending on your age and how long you keep the speakers.  I'll probably be out of spec long before some NPE caps  .  A bigger problem with NPE caps is that many never are within 10% of their rated value.  Depending on who you buy them from, you might have to buy a carton full and measure each one to find several dozen that are the value you want.

For slightly more cost, you can buy metalized polypropylene (MPP) caps that seem to be made with much better tolerances and seem to keep their values indefinitely.  For someone working on a small scale, it just makes more sense to use reasonably priced MPP caps instead of the cheaper but questionable NPE caps.

There are plenty of high-priced MPP caps available, but they do not seem to have better tolerances, say ±1% instead of ±10%.  And finally, there are a variety of even more expensive caps made with different materials or construction.  For example, there are film & foil caps some of which have silver conductor and oil or teflon insulation layers.  Although there are those who swear by their superior "sound", it not at all clear just what is better or different about them, other than price.  The debate on that continues.

[adydula]

R Swerdlow,

What a nice reply and its very informative as well.

I agree on the driver components that Jim uses in his speakers, they are just wonderful from what I have read and based
on all the glowing reviews and reports.

This is what makes this 'past time' so intriguing there are so many angles to the 'end' result.

The music itself, the recording, the wires and interconnects, seperates vs receiver, small power vs lots of power, component types ....its endless....comparisions vs comparisons.

I laughed about you being out of spec before the components !!!

All the best
Alex

(speakers are in Kentucky!!)