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Old 26th July 2013, 08:51 AM   #11
Kev06 is offline Kev06  England
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Most interesting, many thanks!! The morel was on my short list mostly because it seemed to have an unusually good off-axis response, but IIRC it does seem to start becoming rather less flat than the others almost immediately after my 3kHz cutoff.. I'll have to look at the F5, but from these comments (and the doubts expressed by vacuphile) I suspect it may not be the one for me; I'm looking for something reasonably safe and uncomplicated.

Thanks again,
Kev
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Old 26th July 2013, 10:47 AM   #12
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You can find cut out drawings of the Morel magnet assembly on the web and it is obvious how assymetrical it is. Typically, a ferrite is glued on top of the pole to improve this, but I have never seen one that was glued on straight (I crashed one myself and saw other pictures on the web).
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Old 26th July 2013, 11:44 AM   #13
Kev06 is offline Kev06  England
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That doesn't sound good! Right, so I've now discounted the morel driver, leaving me with the seas (for which there seem to be mixed feelings) and the Audax - which is a little larger than optimum but probably still viable.

I had a SPL meter arrive today, so I can measure my existing system tonight for comparison; it may be that I'd be happy with less powerful/sensitive drivers and then my choices are wider.

(I investigated the 10F - it looks very nice so thanks for the recommendations. Though when I loaded the parameters into WinISD it doesn't achieve the kind of SPL that the others I was considering do. I'll have to decide if its going to be loud enough for me or not.)

Many thanks
Kev
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Old 26th July 2013, 12:33 PM   #14
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Lower effeciency was one of the issues I had with my design (not finished yet). I'm not using any of these drivers (cost), but will say that 87 can be a bit of a pinch. Going to an MTM this would rise to 90 but doubling the cost todo.

What listening level are you looking for @ what distance? From this we should get a better match to your needs. Small high effeciency drivers are hard to find with enough Xmax, perhaps a Faital Pro 4FE32. Odd I find it harder to find something today than what seemed to be more available 20 years ago. The industry must love backtracking for the more common flavor of the week variety. Must be a trending thing, marketing hype and all that poo.
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Old 26th July 2013, 01:27 PM   #15
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Whenever morel is mentioned zaph's distortion measurements always seem to come up, I think that they are probably responsible for a lot of people not using morel drivers. If I'd read those comments before I purchased my units I probably wouldn't have either.

I'd love to see some correlations between thpose measurements and subjective listening impressions of speakers using the same drivers (tested against other drivers in a double blind environment). It would be very interesting to see the results

Perhaps the distortion is a tradeoff required for something else the drivers do well... just a thought. I have nothing other than my own subjective experience to base this on, but I certainly don't find myself thinking oh my I really can't stand that 5th harmonic

Attached is an in room measurement of my MTM's no gating showing 2nd through 5th harmonic. As it is in room and not gated (1/12 octave smoothed) it should probably be taken with a big grain of salt, a gated measurement would probably be better. The room is pretty bad acoustically the biggest issue around the 50 - 150 Hz mark. I have no idea if this is bad, good or indifferent from a distortion pov, but apart from some reflection problems I think that they sound quite fine crossover point is at 2.8K

Tony.
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Old 26th July 2013, 01:36 PM   #16
Kev06 is offline Kev06  England
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Thanks Tony, nice to have it put into perspective. In a previous life I was involved in the human sciences and came to appreciate the differences between measurement and perception, so I can quite believe there are many things one wouldn't hear. And also many real-world environmental aspects which one would! Though I don't have the confidence/experience to necessarily know what yet, so I'm probably going to play it safe on this occasion.

Cheers
Kev
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Old 26th July 2013, 01:55 PM   #17
tinitus is offline tinitus  Europe
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not sure I would use the Seas ROY woofer

isn't it more a subwoofer with that big surround
I guess its best crossed much lower, and active

SB have a new 12" with low inductance...looks good

not sure about the size of midrange
I would think it depends more on construction
and IMO...I would try not to loose too much sensitivity
I like the small drivers, but power handling and sensitivity might be too low
distortion could be become a problem above moderate SPL
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Old 26th July 2013, 02:01 PM   #18
Kev06 is offline Kev06  England
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Thanks also Greebster. I had initially been looking for 85dB +20dB headroom = 105dB (though only at 1m, rather than at my listening position).

But looking at what the smaller mid drivers typically produce, and the alternative suggestions in this thread, I strongly suspect that I don't 'need' as much SPL as I think. So I bought a SPL meter and tonight will do some measurements to work out what I actually want - if its several dB less then my choices would be wider..

Cheers
Kev
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Old 26th July 2013, 02:08 PM   #19
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That all encompassing distortion peak @600Hz is something I'd be looking into, otherwise nothing else glaring at me. Well would like to see less 3rd between 1-2k, but doubt it would be detrimental to the listening experience.

-----

We need to see multimode distortion plots to sus out the qualitative aspects of drivers. Also minimal breakup out of band is important and is a quality I look for when choosing a driver. Most metal cone drivers epically fail at this. Sad too because what they do in band is so nice and often why they are choosen.
People think I'm wrong on this, but being true to my nature see it this way. If a drivers breakup even if subdued with a notch or filtered with a higher order crossover, the problem persists, tho doesn't show it's ugly face during tests. My take is that whenever a signals' amplitude rises at the rate in time that is equal to the frequency of the breakup it will cause distortion in the lower bands that are passed on to the listener. Only a very few metal cone drivers can pull this off well enough for my tastes. Good example of this would be a Tang Band W4-1337. Sadly another rule I have discounts it's use and that is a flat response beyond the natural roll off of a given diameter. Anything say more than an octave or so is a waste, unless you want to use it as a full range. In this case we're not tossing on a crossover or adding a tweeter, so everything is fine as long as you the listener is willing to accept beaming at the top.
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Old 26th July 2013, 02:23 PM   #20
Kev06 is offline Kev06  England
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Tinitus, thanks for the thoughts. I've not yet fully settled on the L26ROY, though I'm using it as a possible reference because people recomended it to me in some other threads as having unusually good response and little cone break-up until really quite high (for what it is); I gather theres no problem to 300hz. But I may easily choose something else still, it partly depends on what the mid is as well.

Yeah distortion at my listening volume isn't something I want at all, its one reason that I'm upgrading. I would sacrifice some of the off-axis performance if necessary to get enough SPL without nastiness, but I guess I'm starting out for an ideal and we'll see what comprimises I have to make. I suspect I could solve all my requirements with a pair of 200 illuminators, but price is also a compromise I'll have to need to make before I choose to.

Chers
kev
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