Citaat van: TurboMarco op mei 05, 2016, 00:09:23
Graag ,want daar ben ik erg benieuwd naar :yes:Los van smaak of kwaliteit ,zou je toch willen linken naar het voordeel van laag rendement systemen ?
Sure...als je dat graag wil weten hier wat techniek volgens ATC:
Why do ATC speakers have such low sensitivities (85dB for example on the SCM40) yet have such amazing dynamic abilities?
Sensitivities are 'low' for two reasons:
1. We aim for honesty and transparency in our specifications
2. If you want a good low frequency response from a smaller, sealed enclosure, sensitivity has to be sacrificed. For any given driver diameter, you have the choice of designing for efficiency or extended low frequency or, somewhere between. If the design demands both, a larger driver is needed or the use of multiple drive units in order to increase the radiating area. All our loudspeakers have good low frequency output for their size so, sensitivity has to be sacrificed. We could achieve a higher sensitivity by using a small vented enclosure but, we don't like the lower mid balance of this type of design. Plus, the excursion control the enclosure has (effectively an open cabinet below port tuning) is severely limited.
Our loudspeakers amazing dynamic abilities come from careful drive unit and system design. Loudspeakers that have high sensitivities have to be large, use low mass moving parts or employ horns. The low mass parts are often not suited to the forces and resonances generated when reproducing audio at high SPLs and the structures that behave well at low levels can become unstable.
We specify our moving parts to have excellent mechanical stability and high internal damping at all drive levels and many listening tests are conducted using 25V – 35V rms swept sine waves. These tests brutally expose problems in the drive units, many of which would not show up if only tested at 1W or 90dB SPL (two common reference levels).
A downside to ensuring stability at high drive levels is reduced sensitivity. On paper, the sensitivity would seem to be greatly beneficial but in practice it shouldn't become too narrow a focus.
When Billy Woodman founded the company in the early seventies, part of the philosophy was to try and find a better balance between the loudspeaker systems available at the time. The UK had a very wide range of loudspeaker manufacturers producing systems capable of very high fidelity but, limited dynamic range. In the US market were loudspeaker systems heavily influenced by cinema sound and capable of very high dynamic range (often using horns) but with high levels of coloration. Billy wanted to bring the best of the two philosophies together and engineer systems capable of the highest possible fidelity and a large dynamic range.
Going back to the moving mass issue, an area where mass can be shaved off is the voice coil. By reducing it's diameter, we can gain efficiency (and reduce cost) but, at the expense of power handling, power compression and passive crossover performance.
Loudspeakers are very inefficient devices and the majority of input power is dissipated as heat. We need to 'sink' this heat out of the voice coil as quickly as possible and smaller, lighter coils perform poorly in this area due to the reduced coil surface area. Dynamically, this leads to power compression due to the increase in coil resistance as input power increases and also (in passive designs) a modification of the crossovers frequency response due to the variable load resistance vs. drive level.
In summary, we think the key is designing the drive units and systems for use under high drive levels and not sticking rigidly to the known reference levels for testing. Drive unit parameters do vary with drive levels so try to design for the changes. Performance at 1W or 90dB SPL is relatively easy. What happens at 100W or 110dB SPL?
bron:
http://www.acousticfrontiers.com/atc-speakers-technology/Hoop dat je hier wat mee kan
