Why do you need a speaker crossover - discuss

[nat8808]

Maybe you could try to describe the characteristics of the sound you've aimed for, prefer and we can try to come up with the opposite that still seems credible as a speaker/sound description and then discuss whether those properties can be achieved without a crossover.

[Dr Bunsen Honeydew]

Not a conventional OTL though, in this instance the anodes of the GM70's are directly coupled to the electrostatics. Nick built a breadboard prototype using 813's which sounded amazing, in many ways the best sound I've ever heard. The proper version will be much better.

So you have got a couple of thousand volts on your speaker cables Do you have any children or pets?

Actually always thought this was an interesting idea. Seemed daft to me to electrically to step down just for a set of cables and then step up again. But I would have built the amps in the speaker chassis because that is one hell of a voltage to be flying around the room on cables.

[Dr Bunsen Honeydew]

I don't need one

In so far as I am concerned, the only function of a crossover is to protect the tweeter in designs where a tweeter is necessary (as already noted).

I can think of one multi-way design that has no crossover whatsoever though. It comes from PHY-HP in France. The tweeter is a piezo unit with a small paper cone and requires no protection capacitor.

There are now quite a few driver manufacturers making full-range drive units that are also sensitive and so capable of satisfying in full the two most important criteria for any loudspeaker design, those being absolute coherence and realistic dynamics.

None of them have a flat frequency response but this is not important as it only matters to people who are obsessed with measuring everything. It is not required for realistic music reproduction (the music is already coloured in any case by the venue in which it is performed). The brains of normal people are not in the least bit bothered by a little frequency colouration and would never notice it unless it is pointed out to them.

Perhaps surprisingly, a flat frequency response is not required for movie reproduction either. The two most important criteria for that 'being there' feeling are as stated above - coherence and dynamics.

Of course there are limits to how far the frequency response can drift from the ideal. Nobody likes the Lowther quack of old (current Lowther drivers are very good) or a honking horn. Equally offensive are dome tweeters that are not correctly damped and make female vocals and electric guitars sound like nails down a blackboard.

Given the above, my choice of loudspeaker will come as no surprise. The Zu Druid uses a wide-band driver and a supertweeter with only a single capacitor and a high quality resistor to set the tweeter level. It is coherent. It is sensitive. It is dynamic. It starts and stops when it should both at high levels and at low levels. It sounds more real than any other speaker I have heard anywhere near its price and a long way above.

I used to think that I would never be able to afford the quality of sound that I have now. I take my hat off to Zu Audio. They didn't start out to create a speaker with high WAF or small size or a flat frequency response. They set out to create a speaker that would play music and make it sound real and do it at a real world price. They succeeded.

*dons flame suit*

No flames from me, from what I know of them Zu is one of the companies trying to do it right.

[Dr Bunsen Honeydew]

Many crossovers are more than that: they exist to prevent the driver from reproducing frequency regions where their distortion and/or phase characteristics are undesirable. Effectively, the crossover keeps them in the region where they work predictably.

So why can't you do that mechanically.

[Dr Bunsen Honeydew]

Maybe you could try to describe the characteristics of the sound you've aimed for, prefer and we can try to come up with the opposite that still seems credible as a speaker/sound description and then discuss whether those properties can be achieved without a crossover.

Nope.

It is then only words. It is about music, so you have to experience it.

[Dr Bunsen Honeydew]

Could it be Richard that you are tuning by ear a speaker with no cross-over that satisfies your own preferences and you are happy with the results..

.. but should you have had other preferences you would be finding it very difficult to come up with something satisfactory?

Are you saying that you think you can create ANY flavour of speaker by adjusting the mechanical properties of the drivers?

You could say *exactly* the same thing about designing crossovers.

[Marco]

No flames from me, from what I know of them Zu is one of the companies trying to do it right.

Indeed. I've heard a few Zu speakers, and they produce 'my' kind of sound, by simply sounding wide-open and detailed (not 'hi-fi') and capturing the 'soul' of music.

Therefore, I think there's something in what you're saying regarding loudspeaker design. For me, in many areas of audio, the K.I.S.S principle pays significant dividends!

Marco.

[technobear]

Many crossovers are more than that: they exist to prevent the driver from reproducing frequency regions where their distortion and/or phase characteristics are undesirable. Effectively, the crossover keeps them in the region where they work predictably.

This is another way of saying that the crossover is a sticking plaster to try and hide the fact that inadequate drivers have been used.

Many driver manufacturers have now learned (or should that be re-learned) the mechanical techniques necessary to avoid the need for complex crossovers.

[Beobloke]

I can't help thinking there are some sweeping generalisations going on here. A loudspeaker system is a whole that is equalled (or hopefully exceeded!) by the sum of its parts and if a designer has carefully specified and tweaked the drive units appropriately, then a complex crossover is not needed - to add one would be self defeating. On the other hand, if the drive units have been designed to achieve specific goals in specific areas, this may mean they exhibit some sort of resulting behaviour elsewhere in the frequency or time domain (been there, done that!) that is less than welcome. This means they will clearly need some sort of careful filtering, and a minimalist crossover is never going to work.

As an example, two of the finest loudspeakers I heard at this year's Munich Show perfectly demonstrated the polar opposites. One was a four way design using off-the-shelf drivers that had been very heavily modified and fitted to an incredibly complex cabinet that was machined from solid blocks of wood. The result was that they used two components in the whole system - an inductor on the subwoofer and a capacitor on the tweeter; both middle drivers were run full range. They sounded superb.

The second pair were from a company where the designer is known for his use of very steep crossovers. These were another four way design with crossover slopes of over 50dB/octave. They also sounded superb.

The conclusion I therefore drew from this is that simple crossovers are better, except when they're not!

[hifi_dave]

I can't help thinking there are some sweeping generalisations going on here. A loudspeaker system is a whole that is equalled (or hopefully exceeded!) by the sum of its parts and if a designer has carefully specified and tweaked the drive units appropriately, then a complex crossover is not needed - to add one would be self defeating. On the other hand, if the drive units have been designed to achieve specific goals in specific areas, this may mean they exhibit some sort of resulting behaviour elsewhere in the frequency or time domain (been there, done that!) that is less than welcome. This means they will clearly need some sort of careful filtering, and a minimalist crossover is never going to work.

As an example, two of the finest loudspeakers I heard at this year's Munich Show perfectly demonstrated the polar opposites. One was a four way design using off-the-shelf drivers that had been very heavily modified and fitted to an incredibly complex cabinet that was machined from solid blocks of wood. The result was that they used two components in the whole system - an inductor on the subwoofer and a capacitor on the tweeter; both middle drivers were run full range. They sounded superb.

The second pair were from a company where the designer is known for his use of very steep crossovers. These were another four way design with crossover slopes of over 50dB/octave. They also sounded superb.

The conclusion I therefore drew from this is that simple crossovers are better, except when they're not!

Exactly.

I have heard good and awful speakers using both simple/none and complex crossovers. It all depends on the drivers and the way they are used.