Lowther speakers and elements
Full range speakers
In almost all ordinary box type speakers several speaker elements are used to reproduce all frequencies, either two or three elements are normally used. These elements are connected to the amplifier trough a "cross over" network consisting of coils and capacitors. By using several elements the element for low frequencies can be optimised to reproduce these low frequencies and the element for the high frequencies can be optimised to reproduce these. That sounds like a good idea but it has some problems also.
One problem with using several speaker elements is that the sound will come from different places for different frequencies, the difference is not much and for lower frequencies it can be ignored but for higher frequencies it has some significance. This is most annoying if the crossover frequencies are chosen to be inside the frequency range of human voices, on some speakers you can here the voice "move" if the singer uses a wide range when singing.
Another problem is that in order to get the best possible stereo effect all sound should ideally come from one point. If the sound that reaches the listener is indirect it is impossible to get the effect that the singer and orchestra is standing in the room. If the speakers are good and set up correctly it is possible to get a 3D effect where the sound seem to be coming from different places in the room, it can even be quite scary when you hear some one scraping a chair on the floor behind you!
There exists some speakers that uses reflection and indirect sound giving a very nice listening experience but they never give that live effect you can get with real point source type speakers.
In my mind an ideal speaker should:
It is difficult to make a speaker element that can reproduce both low and high frequencies with low distorsion and high efficiency, the main problem is "Doppler IM distorsion". Doppler IM distorsion is caused by the speaker element movement when fed by low frequencies, if high frequencies are also reproduced these will be modulated by the slow moving speaker membrane, the result is IM distorsion.
- Use one speaker element
- Give only direct sound, i.e. it should be directed towards the listener
If however the speaker element is placed in a horn the movement will be very much less and the distorsion will be lower even than an ordinary speaker using several speaker elements.
Lowther have been making full range speaker element since the early twenties and they also design and produce many different horn enclosures. Lowther speakers are real full range speakers that are ideal to use in horn enclosures.
Lowther PM6A element
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Created on ... december 12, 2000