Why do you need a speaker crossover - discuss

[Theo]

My techncal knowledge on speaker design is pretty minimal: I can read specs without knowing how relevant they are - ultimately I'm just a punter who buys what he likes the sound of. I understand where Richard is coming from simply because the speakers with the simplest crossovers seem to be the ones I like to listen to, past and present (Royd, Allison, early Snells, etc).

However, my other bug bear is the box itself: no matter how you damp it (or indeed, don't damp it, allowing it to become a musical instrument in itself), I'm aware of the "box" characteristics in so many designs. My own speakers are very good (Neat Ultimatum MF7s), but even with these you cannot escape the point source effect, no matter how good the dynamic impact. It's why I love the ESL 57s: they don't do all things well, but they can do fabulous imagery, soundstaging, and the sense that music is not coming from a fixed source, but all around you.

The only modern production version I've heard recently that give me that lack of boxiness is the Jamo R909 dipolar speaker. These are simply astonishing in the soundstage and dynamics they portray, with the bass impact so needed for rock/jazz music, and a total freedom of box effects. I absolutely love them, and when I next rob a bank, I'm going to buy some. I've no idea what the crossover is doing, but I don't really care - these speakers work - IMHO

http://www.jamo.com/eu-en/products/r-909-description/

[Dr Bunsen Honeydew]

My techncal knowledge on speaker design is pretty minimal: I can read specs without knowing how relevant they are - ultimately I'm just a punter who buys what he likes the sound of. I understand where Richard is coming from simply because the speakers with the simplest crossovers seem to be the ones I like to listen to, past and present (Royd, Allison, early Snells, etc).

However, my other bug bear is the box itself: no matter how you damp it (or indeed, don't damp it, allowing it to become a musical instrument in itself), I'm aware of the "box" characteristics in so many designs. My own speakers are very good (Neat Ultimatum MF7s), but even with these you cannot escape the point source effect, no matter how good the dynamic impact. It's why I love the ESL 57s: they don't do all things well, but they can do fabulous imagery, soundstaging, and the sense that music is not coming from a fixed source, but all around you.

The only modern production version I've heard recently that give me that lack of boxiness is the Jamo R909 dipolar speaker. These are simply astonishing in the soundstage and dynamics they portray, with the bass impact so needed for rock/jazz music, and a total freedom of box effects. I absolutely love them, and when I next rob a bank, I'm going to buy some. I've no idea what the crossover is doing, but I don't really care - these speakers work - IMHO

http://www.jamo.com/eu-en/products/r-909-description/

Blimey Jamo producing an acceptable hi-fi speaker if this goes on Bose will produce one next

Seriously Theo, I would never have looked at them as I remember what Jamo were like in the past, cheap boom boxes. So congrats on finding these.

[John]

Theo a lot of us have moved away from boxed speakers because of the issues of colouration that can be associated with this approach and whist I think the Jamo are good the drivers are not the most friendly to drive so consider other options as will give you a bit more freedom over amp choice in the future

[Theo]

Hi John

Yes, I'm aware they really need some muscle to get the best out of them - I think my four Exposure XVI monos can cope

The speakers in your avatar look, er, interesting. I assume they are dipolar - are they DIY?

[Dr Bunsen Honeydew]

Theo a lot of us have moved away from boxed speakers because of the issues of colouration that can be associated with this approach and whist I think the Jamo are good the drivers are not the most friendly to drive so consider other options as will give you a bit more freedom over amp choice in the future

It is possible to design a box that doesn't behave or sound like a box. Material and driver orientation has a lot to do with it.

[John]

Yes but will generally weigh a ton and cost a small fortune

Theo Yes Dipole DIY and not so hard to make either

[Dr Bunsen Honeydew]

Yes but will generally weigh a ton and cost a small fortune

OK I will give another of my opinions, but please remember it is my opinion and does not deny or destroy any other members opinion

To stop a box being a box. well number one use a material that doesn't *sound* original versions had HDF boxes and they had a sound. The current version uses 20mm black acrylic and it simply doesn't sound. Now lets look at acoustic influence. Well LF is omni directional where as HF beams from the transducer and in between them it slowly progresses from one to the other as the frequency increases. Convention says that drive unit should face you, but as you see with some sub woofers for LF the driver orientation is meaning less. So by putting the bass mid physically 90 degrees out of phase with the listener you have a acoustic filter removing HF from your perception from that driver unless you stand up and walk over to it. All the HF from the top does is provide omni directional in fill to the sound stage. Then all you have to do is gently roll off the tweeter at approx the same rate as the acoustic rolls off the bass / mid oppositely. The doping is purely to control nodes and in fill nulls.

The added advantage is that now the bass mid is in phase with its coupling to the environment (the speaker stand). So there is no potential for even minute rocking vibration that disturbs the HF phase characteristic of conventional loudspeakers. Also bass notes being coupled direct to the environment means that the bass goes down lower and into the feeling as well as heard band as it drives the floor in phase with the music. This gives superb bass definition compared with conventionally positioned drivers of similar size.

Disadvantages, well they need setting up in the acoustic and this is more fiddly than with normal speakers. Frequency balance is adjusted by the distance from the back wall. In large rooms back to six inches or less, in smaller rooms further away. Toe in acts as a camera lens adjusting the focus of the image. When set correctly you create a cinemascope sound effect with a very large out of box image both pasted across the back wall and in the third dimension (this adjusted by toe in).

Anyway that is the basis of the idea, and using the drivers conventionally did not show the lack of crossover potential that this configuration gives you.

[John]

Richard could you give a simpler explination of what you wrote, sorry a lot of this went over my head

[nat8808]

I do not accept you argument - full stop! but I respect you opinion,

I don't think Marco was arguing or making an argument.. at least not in the terms that I would call an argument. Just an observation that is out there for others to pick up on too - lots of people love BBC style speakers and even in LOVE with them!

Not a fact that can be ignored really - it all comes down to subjectivism and people simply enjoying what they hear rather than worrying about how they are constructed or their design specs..

Someone who doesn't like the "BBC sound" could say that those that do were deaf or idiots or have been brainwashed.. but that would smack of arrogance or fighting talk and really doesn't go down well at all in an open forum like this!

Better to realise instead that people have differing tastes and accept that calmly.

As someone who doesn't know that much about electronics I have to go on what I hear too and have become (and enjoy being) a box swapper and make my choices via my ears. I did study physics for many years and realise how complex interactions can become from a small number of variables and so, especially when it comes to human reactions to sound and music which we don't fully understand, it's all far too complex to have absolutes.

Even if I did know a lot about it I'd still rely on my ears at the end of the day.

I'm surprised really as I thought Richard was the ultimate advocator of subjectivism - it's all in the ears etc

[Dr Bunsen Honeydew]

Richard could you give a simpler explination of what you wrote, sorry a lot of this went over my head

That is why I originally argued that you had to listen, and tried not to describe it, it was this that got me into the spat yesterday.

I really cannot make it simpler than it is, I could make it more detailed and theoretical, but that would probably confuse you more.