If you're in an anechoic room then that will work fine, otherwise the off axis will still have an impact on the overall sound. That is unless you are running with the mic only a couple of centimetres away from the cone, but then again that wouldn't be a good idea now would it.
Well unless they request it before hand 😉
Although I agree with most or all of what you've said, I think we both may have jumped the gun. It sounds like he knows all these things we keep pointing out, and he's just doing these subjective tests up front as an experiment to see how close his subjective impressions compare with the hard core testing with mics and such that he will be doing soon.
I'd also like to say thanks to all contributors in this thread. It's been a very juicy thread. 🙂
It's not ideal, there will be a huge droop in the power response in the 1-5khz region. Using steep crossovers confines it to a smaller region around the crossover point but does nothing to reduce the severity of the null as you move vertically off axis.
EV VMR?
What do you guys think of the Electro Voice VMR mid? Huge magnet from a 10in driver frame.
I have heard good things about it - problem it's no longer in production.
What do you guys think of the Electro Voice VMR mid? Huge magnet from a 10in driver frame.
I have heard good things about it - problem it's no longer in production.
I can only briefly remember the vented midrange in EV's 1503 in a local store - also the heart of the Interface D which never got to see/hear - might pick up a rebuilt pair but perhaps more interested in hotter horns at this point - it used basically the same motor as EV15L and is rated for 125dB peak levels - if I get one - you know how I'll load it ;^) I have Altec 290/1 which need to be put into action sometime with either great white horns or 203B
16lb magnet structure, 2.5" aluminum edge wound coil
16lb magnet structure, 2.5" aluminum edge wound coil
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Zaphs tests show very little vertical directivity =<30deg from a ribbon of that size @ ~3KHz
Zaph|Audio
At 21cm CTC, the drivers are completely out of phase at 3KHz at only 17degrees off axis.
Personally i'd only cross an 8" driver at around 800Hz or below. Using it higher than that results in 'head in a vice' listening position or having to sit very far away which is problematic for small listening spaces like homes.
Agreed with all of this. Even closed back drivers will suffer a huge dip in performance under 1KHz due to edge diffraction. If the edge diffraction is equalised, it will push the drivers under test pretty hard <1KHz and reveal non-linear distortion.The reason why I keep coming back to this thread is because I am curious to see just how you are going about doing this test. This is mainly to see whether or not it has any actual merits to it.
So far you just keep doing more things wrong rather than right.
There is absolutely no way you can assess a loudspeakers performance by subjectively testing it outside of the role that it was intended to perform. The fact that you think you are doing something meaningful by trying drivers out, and in free air of all absurdities, is beyond laughable.
You do understand that the exposed rear wave, when drivers are run full range, interacts destructively with the front wave right? This effectively means that you have a 1st order acoustic high pass in effect that is dictated by the diameter of the driver. This roll off will be preceded by a peak in output just before the roll off occurs plus a plethora of other nasty diffraction related effects. With the drivers motor structure and how open the rear of the basket is having a degree of influence too. This will then be modified by the surrounding environment.
For a driver such as the 10F you are going to be listening to a tweeter. When run free air this is a close approximation of how its frequency response will be modified.
For something like the ATC mid dome, that already has its rear wave blocked, due to its construction, you're not going to get anything like this occurring. The two will sound completely different simply because of this one simple fact. Trying to judge any drivers capabilities under these kinds of testing conditions is completely pointless.
You may have been inspired by xrk's threads to start this thread, but his threads and tests have a decent amount of scientific merit too them and control in place, so that the driver comparisons are valid.
What you are doing so far has no more meaning than saying I prefer class A amplifiers because they get hot and can keep my coffee warm. That's great but it tells us nothing about how the amplifier actually performs when doing the job that it was designed to do.
I have absolutely no objection to you listening to drivers like this simply because it suits your fancy. What I have objection to is you actually deciding some drivers fate simply because of it.
This is my test baffle:
And this is the edge diffraction @ 30cm:
The larger the cone, the further back you need to place the mic to avoid path length differences across the cone and achieve accurate frequency response. The further back the mic is from the baffle, the worse the baffle edge diffraction becomes. My baffle is really only good enough for 3-4" drivers and >500Hz.
Zaph-Audio's baffle is even bigger and his performs even better.
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For reference, this is a closed back 2" dome (Dayton Audio DC50F-8), free air (black) vs baffle (red). As you can see, even with a closed back driver the edge diffraction off the faceplate of the driver is unacceptable
I was just thinking about this and the solution is obvious - you bandpass the mid under test and mix in a virtual ideal woofer and tweeter by high/lowpassing the original music track.
Nope, a harmonic obviously have a harmonic relationship wih the fundamental. Overtones by definition is any tone above the fundamental (or input stimuli if you will).
Exactly, and could also be described by "the first harmonic overtone" or the "first" harmonic distortion component".
Of course there is. Language is something we use to communicate and describe something. In a system with add harmonic distortion on a single component input, I can not see how anyone can complain about the input being the fundamental.
Yes and that was my point and this whole semantic thing feels a bit odd. 🙂
But in this thread the whole point is listening to the drivers, not recording them. So what do you use to play back that perfect woofer and tweeter material with?
Your suggestion would work recording the driver an mixing it in with the original track but then you'd need another playback listening devise, yet another parameter.
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Indeed it is a semantic thing and you are mixing two ways of naming the same thing.
Frequency Order Name 1 Name 2 Name 3
1 · f = 440 Hz n = 1 fundamental tone 1st harmonic 1st partial
2 · f = 880 Hz n = 2 1st overtone 2nd harmonic 2nd partial
3 · f = 1320 Hz n = 3 2nd overtone 3rd harmonic 3rd partial
4 · f = 1760 Hz n = 4 3rd overtone 4th harmonic 4th partial
(from wiki)
Sorry it got a bit squished pasting it and is resisting all my attempts to fix it but it should be possible to figure out what goes with what.
Either way the reason nobody talks about 1st harmonic distortion is because there is no such thing, the 1st harmonic is your input signal or 'fundamental'.
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Of course. I was more reffering to how the blind testing should be conducted over the internet to ensure that the focus is only on the midrange. At least by mixing the original bass/treble of the recording it ensures no more distortion of the bass and treble than the end users system introduces.
I am finding the 5MR450NDY to behave nicely as a broad band mid over in the B&O test bed thread.
