First Order Crossovers: Pros and Cons


I wonder if some folks might share their expertise on the question of crossover design. I'm coming around to the view that this is perhaps the most significant element of speaker design yet I really know very little about it and don't really understand the basic principles. Several of the speakers I have heard in my quest for full range floorstanders are "first order" designs. I have really enjoyed their sound but do not know if this is attributable primarily to the crossover design or to a combination of other factors as well. In addition, I have heard that, for example, because of the use of this crossover configuration on the Vandersteen 5 one has to sit at least 10 feet away from the speakers in order for the drivers to properly mesh. Is this really true and if so why? Another brand also in contention is the Fried Studio 7 which also uses a first order design. Same issue? Could someone share in laymans terms the basic principles of crossover design and indicate the advantages and disadvantages of each. Also, what designers are making intelligent choices in trying to work around the problems associated with crossover design? Thanks for your input.
128x128dodgealum
I gave the source as an explanation of vector addition. Then since the thread is about 1st-order crossovers, I included a quote that shows the superiority of 1st-order crossovers. There can be no argument with that. "It yields a piece of wire."

You might argue that some drivers won't tolerate 1st-order crossovers. Ok, that's valid. You can then either look for "better" drivers, or you can compromise with a higher-order crossover.

Lobing? If you're looking for certain types of directivity or power response, then that could be a valid concern. I would certainly look with favor upon a high-order L-R crossover for sound reinforcement use, and this is one of the reasons.

There is much concern with flat frequency and power response. I'm a bit skeptical about their importance. (I feel there are other more important problems. Besides that, to paraphrase Pat McGinty, "Once you solve the transient response, power and frequency response fall right into line."

A number of people have suggested ways to test whether phase coherence is audible, and there are indeed studies with conflicting results.

Rane's suggestion of passing a signal through a 4th-order L-R crossover and then summing the output makes sense. (Linkwitz suggests a similar thing.)

But, in order for the test to be valid, we need to play the summed signal via a transducer with no phase distortions of its own.

A panel speaker would seem to be out, since it has widely spaced sources of the same frequency. In the near field, it smears transients.

Speakers with high-order crossovers are out because they're doing the very thing we're trying to test for and there would be no possibility of a control in the experiment.

Speakers approximating a point source, with 1st-order crossovers might be suitable, but I feel the best bet is headphones. It completely removes any phase distortion due to the room as well.

I do plan on performing this test at some point, but at present I can only say that I find the sound of speakers designed to be time and phase correct to be more realistic than those that are not correct.

Looking at this logically, we can say that a speaker that can pass a transient is better than one that can't. We expect the same from other components in the chain.

The compromises needed to build a speaker that will pass transients is where argument arises. That, or the compromise of building a speaker that won't pass transients. :-)

As for "Infinite Slope," I question whether it is beneficial. What is the phase and time behavior like? Don't sharp filters like these ring? Do most drivers actually need such steep slopes? What kind of load does it present to the amplifier?

The NHT Xd would seem to offer more of an "Infinite Slope" than JosephAudio does. :-)

If one is going to go with steep slopes, then the approach taken by DEQX seems attractive. It corrects some of the problems.

As for the intent of the Rane article, for their purposes the high-order L-R alignment is ideal. They sell such crossovers, so their intent was to sell more of them. However, they certainly cannot say "It yields a piece of wire" about their crossovers.

I did not quote out of context, because I did not change the meaning of what I quoted by quoting only it. As for the author's intent, I don't actually care a fig for his intent. The quote I made stands alone.

The rest of the article deals with: "Are 1st-order crossovers more accurate?" "Yes, but..." The author's intent lies within the "Yes, but..."

Would I choose Rane crossovers for sound reinforcement use? You betcha. I wish I had had them. They offer a superior product for that use.
Karl,Roy&Skrivis:SERIES v PARALLEL 1st Order XO, What are the pos&cons of each in a two way and three way system also in a three way what is more important the T&M or the M&W interface?Would a HEIL be suitable for a 1st order tweeter if OX at about 3k with the new PEERLESS 134 HDS NOMEX paper cone? And A BIG THANK YOU GUYS for a great thread.

Thanks,
Ben
There's some disagreement on the benefits of series vs. parallel. I feel series is superior, but I'm not the last word on things. :-)

You can find a fair bit of info on the net about series and parallel crossovers. Rod Elliott has some good info, for example. http://sound.westhost.com/parallel-series.htm

I don't see that you can say that either the W/M or M/T interface is more important. Both will affect the operation of the mid driver, and that's where your ears are most sensitive.

I don't know enough about the Heil to render an opinion, sorry.
As per Skrivis, my own (unsollicited) opinion would be slightly in favour of a series -- IF you can easily get the drivers' electrical parametres VERY close (or near identical). Again, I'm just a hobbyist -- not a professional.

As to the Heil, 3kHz seems quite high -- which model are you using? As I know nothing about the Peerless, I really can't offer an opinion as to that particular match.
However, the Heil is dipole, so are you considering a 3-way with an open baffle mid -- or are you going closed cab after the Heil? If so, getting your system radiation pattern acceptable 3kHz downward could be a bit tricky!

ASAIK, the guy who makes "Heil" speakers crosses his AMT's about two octaves lower onto an upward firing peerless (quite a big unit if I remember correctly...). Frankly speaking the result is excellent down to the peerless: then things get a bit messy BUT that's just my opinion.
Cheers
Cheers
Ooops, no "edit" function anymore. Well, the BIG Heil is dipole, of course, the other one has a back chamber...