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loudspeaker materials

P

philiphifi

pfm Member
Would be most grateful if a knowledgeable person let me have his view on this topic.

It seems odd to me that modern loudspeakers tend to use very hard materials (metal, kevlar). It is natural to me that in order to replicate instrumental sounds, one should at least choose as close as possible to the original materials. That is, string/wood, reeds, natural fibre (for voice) etc.

No instrument is made of kevlar so why use it? I sort of understand the technicalities regarding unwanted vibrations in the cabinet etc, but to me that is almost secondary.

You don't buy a violin and glue the wood solidly to reduce internal vibration. You allow it to vibrate as much as possible with all the harmonics; yet for speakers the opposite is required. May be it is something to do with sound reproduction versus production.
 
< locking on, tinkly sound >

Beamed to audio.

Joe
 
Depends on how the speakers are designed, Peter Snell deliberately made the speaker walls thin and flexible so they contributed to the sound.
 
philiphifi said:
Would be most grateful if a knowledgeable person let me have his view on this topic.

It seems odd to me that modern loudspeakers tend to use very hard materials (metal, kevlar). It is natural to me that in order to replicate instrumental sounds, one should at least choose as close as possible to the original materials. That is, string/wood, reeds, natural fibre (for voice) etc.

No instrument is made of kevlar so why use it? I sort of understand the technicalities regarding unwanted vibrations in the cabinet etc, but to me that is almost secondary.

You don't buy a violin and glue the wood solidly to reduce internal vibration. You allow it to vibrate as much as possible with all the harmonics; yet for speakers the opposite is required. May be it is something to do with sound reproduction versus production.
Click to expand...
Because an instrument creates music and a loudspeaker reproduces it.
Keith
 
I can’t imagine a loudspeaker made from every material that a musical instrument could possibly be made from, including a human voice box!
 
philiphifi said:
It is natural to me that in order to replicate instrumental sounds, one should at least choose as close as possible to the original materials. That is, string/wood, reeds, natural fibre (for voice) etc.

No instrument is made of kevlar so why use it? I sort of understand the technicalities regarding unwanted vibrations in the cabinet etc, but to me that is almost secondary.

You don't buy a violin and glue the wood solidly to reduce internal vibration. You allow it to vibrate as much as possible with all the harmonics; yet for speakers the opposite is required. May be it is something to do with sound reproduction versus production.
Click to expand...

You want the speaker to reproduce the sound of a vibrating instrument - not be an instrument in itself. I’m sorry, but your hypothesis that the speaker needs to be made from similar materials to an instrument is entirely flawed. However, your last sentence does summarise the whole issue. You want the speaker to add as little of its own to the recording.
 
philiphifi said:
You don't buy a violin and glue the wood solidly to reduce internal vibration. You allow it to vibrate as much as possible with all the harmonics; yet for speakers the opposite is required. May be it is something to do with sound reproduction versus production.
Click to expand...
If you make speaker parts from stiff and light materials then they will only resonate at high frequencies. If these parts are used to reproduce only the low frequencies then they will add no resonances of their own to what has been recorded. The smaller the part the higher in frequency resonances start and so by using large woofers for the low frequencies and small tweeters for the high frequencies it is possible to keep most resonances above the passband of the drivers.

It is complicated and difficult to keep resonances out of the frequency passband of all speaker parts and so a different approach is needed when they are unavoidably present. This is to introduce damping which will reduce the magnitude of the resonance although it will still be present. The designer will seek to reduce the level of the unwanted resonances below audibility when in the presence of the wanted level from the cones of the drivers.

Perhaps it should be mentioned that various home audio speakers have audible levels of resonances as part of their characteristic sound. For audiophiles seeking sound that is attractive rather than technically accurate this can be a positive attribute of a speaker rather than a negative one. Making resonances inaudible is not always the objective for all designers of speakers.
 
I never wondered why my Tannoy 12" Silvers made brass instruments sound so good, they have a brass horn as the fist part of the tweeter.

My LS3'6 sound very good on double basses, I reckon that the cabinet has a resonance that suits this.
 
I don't think my trombone would be all that good as a high-fidelity loudspeaker (unless you want everything unreasonably strident or else like Charlie Brown's schoolteacher) even though it is quite light and made of a fairly hard material, but it does make very realistic tromboney sounds.
 
According to me, the most difficult instrument to reproduce is the human voice. I tried many different cone materials but always preferred paper or a mix including paper for this part of the bandwidth . Might not be the most accurate of all materials but IMHO the sweetest and less fatiguing for long listening sessions.

For the cabinets, the most rigid as possible is the way to go for me specially with fast paced music with double bass drum for instance.
 
A sound system does not produce music, it reproduces it. You seem to have delusions of grandeur that would require your own concert hall and musicians in your castle.

Think ersatz, best quality ersatz, and you will feel all better without these vegany notions dancing in your head.
 
As transducers, the job of loudspeaker is to translate electrical energy to acoustical energy with maximum accuracy, lowest distortion and, I would say, with the maximum efficiency that allows these to be achieved.

Flexure of the radiating surface means a loss of accuracy. Increasing weight of the radiating surface means a loss of efficiency.

So, stiff and light would appear to be desirable.
Hence carbon fibre, titanium, beryllium, Leaks sandwich, etc, etc. Paper's stiffness to weight ratio is actually very good.

To return to musical instruments, graphs of a violins sound output will show a frequency response with no place in hi fi. A violin as an amplifier has sacrificed accuracy for efficiency. But it doesnt matter, because we all have an expectation of this unequal output, and indeed like it's sound.

Bossendorfer, the piano makers, made high end speakers for a while which incorporated a resonating sound board. All reviews criticised their departure from accuracy, and were generally unfavorable.
 
I well remember the Bossendorfer speakers - the resonating panel was an awful idea - fatally flawed from the outset.
 
I must admit I am not keen on metal tweeters but it would be impossible to produce speakers which replicated all musical instruments. Better left to the manufacturers to choose their own design & you as a listener to choose the speakers with a sound you like.
 
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