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Message: <blockquote data-quote="Peter Morris" data-source="post: 137426" data-attributes="member: 652">Re: New DIY Mid HighNo, no, no … if the efficiencies are the same at a given frequency, the smaller diaphragm will move further (yes) but with the same input it will produce the same output. Provided there are no Xmax issues, there is no problem doing this.Output = efficiency x power irrespective of the size of the diaphragm.Efficiency (very simple explanation) is determined by the mass of the diaphragm and the strength of the motor pushing it. There is a point of maximum efficiency in the mid band of the driver’s operation. In general this relates to the resonant frequency the driver. If you raise the resonate frequency you raise the frequency of where the maximum efficiency occurs.The compression ratio of the driver also comes in to play. As with any electrical or mechanical system maximum efficiency occurs when the load impedance matches the impedance of the driving force.  (i.e. the theoretical maximum efficiency is 50% ignoring some practical losses that occur.)  In this case this occurs when the voice coils impedance matches the acoustic impedance presented to the diaphragm. Without going in to detail this is where the compression ratio can play a part … and one of the reasons why I mentioned the DH3A – its uses a particularly high compression ratio to increase the efficiency a little. Personally I agree with you, I prefer the sound of drivers with a lower compression ratio, it was just what EV did at that time.  It was optimised as a super tweeter and as such EV used a high compression ratio and resonate frequency. To obtain maximum VHF output what you need to do it find the best compromise between cone & VC mass, Xmax, BL, resonant frequency, initial throat area and cone area. The resultant compromise will depend on  the frequency range you want to cover.  All of this is in Keele’s paper that I posted above - in detail.This is what I said regarding distortion – “I won't go into detail but we tend not to hear 2nd harmonics that much because they are often masked, higher orders can be an issue as is IMD. The type and frequency of the distortion is important. This paper may be of interest - <a href="http://gedlee.com/downloads/Distortion_AES_I.pdf”" target="_blank">http://gedlee.com/downloads/Distortion_AES_I.pdf”</a>As we all know MP3 uses data compression, and the compression is not lossless.  The trick is to remove the bits / data we don’t need. If there is loud tone, we do not hear the softer frequencies either side, they are masked by the loud signal, the further the softer tone is away from the original, the softer it needs to be, to be masked by the loud tone.  The masking is not symmetrical. Frequencies higher than the loud tone are masked more than those below the tone. This is one of the things they do to compress audio files (there are other tricks), remove quite a bit of the information we don't notice because of masking.  It is also significant with regards to distortion. Second harmonics will be masked more than third harmonics of the same level. If the second harmonic is loud (e.g. an electric guitar) then of course you will hear it, and as you said second harmonics tend not to be that objectionable. <img src="https://cdn.jsdelivr.net/joypixels/assets/8.0/png/unicode/64/1f642.png" class="smilie smilie--emoji" loading="lazy" width="64" height="64" alt=":)" title="Smile    :)"  data-smilie="1"data-shortname=":)" />~<img src="https://cdn.jsdelivr.net/joypixels/assets/8.0/png/unicode/64/1f642.png" class="smilie smilie--emoji" loading="lazy" width="64" height="64" alt=":-)" title="Smile    :-)"  data-smilie="1"data-shortname=":-)" />~:smile:</blockquote>

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