Tweeter Diffraction

[Mr Pig]

I like treble diffraction myself. I have no idea why you would want to reduce it.

Having the treble beam cleanly at your head is fantastic for imaging but sod all use for anything else. And as imaging is a largely artificial effect rarely found in real life, why would you want to improve it?

Have you ever hit a cymbal in real life? It's not a very directional sound. Real instruments send sound cascading in all directions, reflecting off every surrounding surface to fill the room with vibrant noise. The more directional a speaker is, the less it sounds like real life.

[MartinT]

And as imaging is a largely artificial effect rarely found in real life, why would you want to improve it?

You must be listening to Linn speakers, then

[YNWaN]

The purpose isn't to cause the treble to 'beam directly at your head'; the treble drivers natural dispersion pattern isn't effected. The purpose is to stop the edges of the cabinet (and things like bolt heads) acting like secondary radiation points.

Imagery isn't 'largely artificial', it is entirely artificial and carefully constructed in the recording studio or/and when the microphones are placed.

[Mr Pig]

The purpose is to stop the edges of the cabinet (and things like bolt heads) acting like secondary radiation points.

I know. Unless you modify the actual tweeter you're obviously not going to alter the dispersal characteristics of the unit itself. But you are altering the treble dispersal characteristics of the loudspeaker? Which is effectively the same thing. And by reducing secondary reflections you are making the treble more directional.

Imagery isn't 'largely artificial', it is entirely artificial and carefully constructed in the recording studio or/and when the microphones are placed.

I wouldn't say it's 100% artificial, mostly though. Certainly massively exaggerated.

If you listen to live music, whether it is a band in a pub, stadium rock concert, orchestra or solo artist playing unplugged, you will find that the tight 'holographic' imaging effect that a Hi-Fi system can create relatively easily does not exist in real life. At the most you get a vague idea of where something is but that that's it.

The best imaging speakers are the most directional ones. Turning them to point straight at your head will improve the effect dramatically. Cutting down on secondary reflections will help too but don't think you're creating a more lifelike sound.

Real life is awash with secondary reflections! Think about how many bits of the drum kit the sound from your cymbal is going to reflect off. Not to mention the other things around the kit. It's a vibrant, room-filling cacophony. And you're worried about a couple of screws on the tweeters? ;0)

[MartinT]

If you listen to live music, whether it is a band in a pub, stadium rock concert, orchestra or solo artist playing unplugged, you will find that the tight 'holographic' imaging effect that a Hi-Fi system can create relatively easily does not exist in real life. At the most you get a vague idea of where something is but that that's it.

I listen to lots of live music, but only classical counts for this exercise (rock music is usually way too loud, in a poor acoustic venue and fired from all sorts of speaker stacks). I have closed my eyes in a centre stalls location in the Festival Hall and could pinpoint with pretty good accuracy where an instrument is located within the orchestra. It is this which I seek to reproduce although I do agree with you that modern music imaging is very hit and miss.

[Mr Pig]

I have closed my eyes in a centre stalls location in the Festival Hall and could pinpoint with pretty good accuracy where an instrument is located within the orchestra.

Is it mostly classical music that you listen to? I very rarely listen to it myself, I find the odd piece spellbinding but mostly too drawn out.

Even in the situation you describe though the imaging information present is not as good as a Hi-Fi can manage, I've been in similar situations.

I'm not saying that imaging is evil! Not at all. My system happens to image quite well, the key word being happens. From my experience, when you try to do things to deliberately enhance imaging the coherence and life of the music suffers.

[MartinT]

I'm not saying that imaging is evil! Not at all. My system happens to image quite well, the key word being happens. From my experience, when you try to do things to deliberately enhance imaging the coherence and life of the music suffers.

Ah, now we're on the same page. I certainly wouldn't want to sacrifice coherence for imaging. For me it's a matter of getting the speaker spacing and toe-in right and reducing reflections. I like a fairly dead room and have my TubeTraps set for maximum absorption. This seems naturally to enhance coherence and imaging, so twice the bang for buck.

P.S. I listen to a fairly eclectic mix of music, with about the same proportion of rock and classical.

[YNWaN]

It can do but is not always the case.

The foam grills fitted to Linn and Naim speakers effectively do the same job (except on them a small amount of foam still exists in front of the drivers) - hence both of these manufacturers recommend that the grills are left in place.

[Mr Pig]

The foam grills fitted to Linn and Naim speakers effectively do the same job

Interesting. I've always thought the opposite.

I've always thought that speaker grilles reduce treble output and increase dispersal. That's just based on my general experience with grilles on speakers.

How can the foam grilles on Linn speakers be dense enough to stop reflection when they are transparent enough to allow most of the energy through? The materials used to stop reflection are typically much thicker. I can see how that might be part of the story though as the foam would be effectively denser at a more oblique angle.

With the grilles on, speakers are less directional. There is less of a 'sweet spot' suggesting to me that the grilles spread and break up the treble. I have always preferred speakers with the grilles on and not toed in. My experience equates both of these traits with better treble dispersal, better coherence and poorer imaging.

Don't those tube traps work primarily at low frequencies?

I like a sort of 'medium' room, I like to keep a bit of reflection to add to the 'live' feel. A lot of that sort of thing is equipment dependant though, how bright your kit is.

[YNWaN]

I'm not sure you understand what secondary radiation of high frequencies consists of. Any sharp edge (usually the cabinet edge) will act as a point of secondary radiation - this is not a good feature and can only serve to colour the natural output of the drive unit - it does not improve the treble drivers dispersion (except in a delayed and chaotic manner). You can't increase a drivers dispersion by putting foam in front of it - you can alter the dispersion significantly by adding a horn loading element, but that is another issue entirely.

The Linn speakers have a few millimetres of open cell foam in front of them but there are quite a few inches before the edge of the cabinet is reached.