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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.
dodgealum

Showing 4 responses by suits_me

suits_me
121 posts
 
I haven't read this entire thread, but it's not clear that a particular speaker which is or claims to be time and phase coherent will have a simple crossover network with few parts, although that seems to be the case with Meadowlark and Green Mountain.

Vandersteen and Thiel have involved crossover assemblies, for example.

I think the only real problem associated with first order crossovers, meaning the one problem which can't be mitigated by engineering or setup quality, is the off axis lobing. This lobing will exist, but may or may not be bothersome to a particular person in a particular situation....

As for whether the recorded music itself has any time or phase coherence by the time it winds its way through the rest of the recording and playback chain...who knows? I just think Vandersteen 2Ce Sigs are still a great bargain.
suits_me
121 posts
 
>The lobing is actually due to having 2 spaced sources of the same signal at the same frequency. It isn't really caused by the crossover, but by the drivers. (Just being pedantic here.)

This is news to me, as stated. Of course, any two or more driver units will have interference effects, some configurations less than others. (It's even controversial whether a line array of dynamic drivers is truly a line array, for example.)

But in addition to these driver interference effects, the crossover topology certainly does influence off axis lobing. And you could demonstrate this by using the same pair of drivers and swapping a first order crossover and an "infinite slope" crossover in turn.
suits_me
121 posts
 
It seems Roy is correct, as usual.

But I do want to chime in on one point: There are companies which design and advertise phase coherent speakers without making claims of time alignment, such as VMPS or Fried. There is nothing wrong with doing this, although it's understood that Roy Johnson would not pursue or endorse this design decision.

Then there are companies whose ads specifically claim time coherence, when their multi driver speakers do not have first order crossovers and the baffles are not stepped back in any way. These ads are lying consciously, or someone in the engineering or marketing department is confused. Dali is the most recent and eggregious example of this phenomenon, which unlike VMPS or Fried, amounts to snake oil.
suits_me
121 posts
 
>But anyway, what I understand as phase coherent means that the entire output is in phase ideally independent of listening position. The only speakers capable of this are full-range, single driver designs.

Since that last sentence is not true in all cases, nor in the majority of cases if we want to talk about phase and time alignment, which we do want to in this thread, primarily. There are other threads to talk just about phase coherent speakers which are not time coherent.

Note that I am agnostic on whether first order crossovers and stepped baffles are always the best selection of tradeoffs or not. I've mentioned near field listening situations as one situation to consider.
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