Low qts, high Bl, 6.5" / 7" drivers

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Low qts, high Bl, 6.5" / 7" drivers

Hello folks,

Im looking for good 6.5 / 7" mid/bas drivers to go in a ML TL box.

What I really want is a 6.5 / 7" polyprop driver (or some sort of soft coated paper cone) with a qts = ~0.33 - 0.22, fs = 32 Hz (or less) and a Bl around 8 N/a. If someone know of anything remotely close to this please let me know.

This is going in to an old project that have ben constantly modified for about a year now. (Pic is hear: http://home.swipnet.se/Karlssons/speeker/frontside.jpg)

(Today it uses 6.5" HDS (plug'ed) driver's that Im just not getting happy with, not that it sound bad at all, in fact it's fantastic to acoustic music as well as trans and modern club music, but no mater what thins like Black Sabbath and good old Iron Maiden sound a bit "boring" and flat, and Im blaming that on the HDS sky high Fs and Qts)

I have looked at SS 7" kevlar diver, and in many ways it's just what I want, except what its a kevlar unit... And I am a bit skeptical about using kevlar in a 2 way. (I really do not want any "hard" or "cold" sounding mid range, or shouldn't I worry about that? Im very capable of dealing with it's nasty brake up from a XO point of)

Best Leif
 
exactly the ss 8546 was in my mind when starting reading your post. I ve experience in a two way with 8546 and the mids are great (as long as the phases of both drivers are matched of course). No funny cone break ups or anything. Very easy to filter and roll off. Bass is also great.
 
Monacor SPH-170c seems as a good value, for about 75 euro you get BL of 9.44, Qts of 0.26 and Fs of 38Hz. It is carbon cone, but it has no breakups,well at least if is to believe manufacturer's specs.
SPH-165 kep is even cheaper, has a Fs of 30Hz, Qts of 0.31 and BL of 7.6 . Drawback for you could be that it is kevlar cone.
Monacor also has one interesting speaker with polypropylen cone SPH-176, BL of 7.7, but Fs is higher than you wanted (39Hz) as Qts is, too (0.37)
Well, either they have different cone material from one you wanted,or their specs don't match to ones you aked for.
Well maybe if you want to pass cheaper than Scanspeak and can live with kevlar cone, SPH-165kep could be a good value for money. I haven't used it, but ones who did, say only good things about it.
I hope I was of some help
 
Leffemannen said:
Jomor, MBK:

SS8543 should be just about it, Im asking around for a price (no one here in sweden seams to have it in stock). Can't believe I missed that one on SS home page.

Tomac: Monacor drivers are interesting, but a bit hard to get around here, we'll see.

Thanks,

Leif


Note (by checking the off-axis responses) that there is a small hidden cone break up at 3Khz and a larger one at 5Khz at the 8543. Besides the large spl bump at the midband may require an extra notch filter. Apart from that it seems quite promising!

At 8546 the first hidden cone breakup appears higher, at 4.5Khz, and the spl bump at the mids is smaller.

Please let us know how the 8543 sounds when you finish your project. I havent any feedback about this driver so i m quite curious.


Btw the prices in europe are almost the same (as far as i can see from www.riviera-acoustics.com )

good luck
 
Hi.

here some thoughts about the 8543. I haven't heard it yet, since mine are also back ordered from Madisound, promised to arrive in ca. 3 weeks.

There is not much material on the web on it, but there is an old long discussion I found over Google groups, where Lynn Olson speaks highly of it ("one of the best midranges period"). Find it here:

news archive

The original is from the mid 90's, which shows it's not a brand new design - then again it shares the motor with the usual suspects of Scanspeak.

Apparently, as well, it has been used in ProAc Response models in the past (I believe later replaced by SS85310.

And finally, the best real data, in an extensive comparison, here:

Mark K's tests

As you can see, extraordinarily low nonlinear distortion in the midrange, and comparable energy storage with the other high end woofers. In this test, the currently popular test-champions are the Seas Excel 18W and 22W. If you look closely, though, they stand out in just a few frequency ranges in the linear distortion department (energy storage). I have heard the Seas 22W in an Orion and yes, it is remarkable transparent - but I still can't quite figure out whether I liked this "hyper transparent" effect (my wife shared my opinion).

So here you have it - apparently a good bet, the rest boils down to personal tastes.

Let's see how we'll like it in reality :cannotbe: :hot: :cool:
 
argofanatic said:
I've been looking at the Extremis 6.8

Looks like a perfect match for the parameters you're looking for.

The T/s para. sure looks good. Very good. Re of 7.02 is real nice then running them in parallel like I do too.

But I've heard some bad things about them also (and some good too, that's true), and if you look at the frec. response it ripple's about 7 - 8 db from 200 to 1500 Hz and still it looks like it's very smoothed.

And no brake up = very soft cone? I don't know if this is good or bad.

The SS 8543 ripple's less but have a defined brake up, I think I like that better, but only just.

I would really like to see some of axis SPL measurement of the extremis. That should tell allot.

/Leif
 
MBK thanks for the links. I am on midbass hunting myself. I m planning a TMM, probably with SS midbasses. Tweeter will be ss9700.
The midbasses will be either 8546 or 8531, or perhaps seas excel W18s. ( i kind of prefer the ss since they re quite more flexible at crossover design).
I ve just finished a TM for a friend with ss70005 ring radiator tweeter and 8531 midbass. The mids and highs where fantastic. Bass was also great, but not enough to cover a large room (as expected). Weird thing was that my cousin's wife who is a pianist, found the bass region of piano reproduction quite awful...(which i think is more a driver issue). Anyway i was expecting the mids to be tricky instead, since i ve read much on the net
about the 8531 not being good at the mids, but they proved very good. Great contribution to this was the tweeter's quality and the perfect phase matching at the cross frequency. I ve also heard a TMM with 9700 and 8546 designed by a well respected designer here, wich had very good bass and highs, but the mids where "a click" lower quality than the 8531's. Cant be compared directly of course since the tweeter is not the same but this was my impression.

I m a bit confused on which driver to choose. I would go for the 8531 but the pianist's review, and the low wattage of the driver gave me second thoughts about it.
 
Update:

Finally. my SS8543 arrived from Madisound, in January 06... The delivery was delayed several times, Madisound was very courteous in keeping me updated, but I preferred to wait for it anyway.

I have since then put it in my 3-way dipoles and started to update the crossover. The work is not done yet, especially for the lower midbass since I only took indoors measurements so far and those are not reliable of course.

My crossover is at 100 Hz and 1590 Hz with (presumed) LR4 acoustic, which I obtain (for now through half guesswork) by tweaking the Q of my adjustable MOX active X-O. Additional lowpass at ca 1300 Hz to get rid of the rising response >1kHz and notch -4 dB around 300 Hz for cabinet resonance.

The previous driver in this cabinet was a Diatone 610 Fullrange driver. I liked it very much for its naturalness, but it had the drawback of low Xmax, forcing a higher X-O point at the low end.

Sound: I initially stuck the 8543 in the cabinet w/o changes to the Diatone X-O, and even this already sounded good. After adjustments described above, this driver now has the same qualities as the Diatone, much to my surprise actually, but with higher output (read: you can play much louder without distortion), and better separation in the midrange. The added detail comes in an unspectacular fashion, you can hear more but without any graininess/exagerrated "contrast"/tizz so often heard from high end speakers. It's really strange how the overall balance has remained very similar to the Diatone's, except that now at higher volumes and with complicated material (orchestra, chorus), I can now better distinguish locations and individual voices. Of course now differences between CD's also stand out more, read, some CD's now stand out more for *not* sounding good.

Eventually I will check the 100 Hz X-O adjustment by outdoor measurements and may try a notch for the 1-2 kHz bump in response instead of the crude LP. But really, I find this driver very satisfying.
 
MBK,

Thanks for the revue on the 8543.

(Nice to see my old thread pop up again. BTW)

As for me, I never got around to try out the 8543 (dune to temporary lack of funds. And that it's hard to get). Still struggling with the HDS 164, it turns out that some of the things that I dint like about them was related to phase tracking problems in the XO (Lesson learnt: -NEVER trust someone else measurements, barley trust your own.).

Still, the 8543 vill probably find it's way in to my speaker some day.

Best,

Leif
 
Hi Leif,

you're welcome. Actually I hope I can still improve on the current setup.
-NEVER trust someone else measurements, barley trust your own.
So true. I find meaningful measurements very difficult. I can easily get professional looking curves, but everything comes with mountains of caveats. I spent many sessions trying to hunt down an expected resonance of the dipole at the first peak, only to realize eventually why I got good looking but inconsistent results: I was measuring the floor reflection. Of course in the lower 100's of Hz windowing is not an option. And I still don't know how to get good data sub-100 Hz. Even my outdoors at 2 in the moring has enormous background hum from the city, air conditioners, far away airports. I simply can't get the SPL to drown out the low level crud.

As for your phase measurements, I don't even try (especially at the woofer to mid X-O). I barely trust the FR curve. With the various soundcard delays, trigger uncertainties etc, I can't imagine I get reality. FOr this I suppose one has to buy a really good, complete set including hardware, such as Clio or Praxis. And I don't have the money for that right now.

Soooo... how do you find the HDS164 now that you presumably fixed the X-O? With the long wait for the 8543 I briefly considered it, but after comparing data from Mark K's tests, plus the data sheet's FR graphs I realized that these coated cones (Peerless Nomex or the equivalent from Seas) have the *exact* same resonance peaks as metal drivers!! ... just with a lower Q. Once you resize the FR of the HDS 164 to say, the Seas W18's graph, they are virtually identical. So I thought, no, I stick with something different, both for design philosophy and just for the fun of it...

All the Best,
 
Hi MBK,

As for phase measurements I do trust them, but only above ~800 Hz, and that's measured at a relatively short distance. 40 cm in my case. As for mid / bas I don't care that mush as this currently is a 2.5 way layout.

Im just speculating but: For mid / bas phase measurements, maybe you could get something meaningful if measuring at a very short distance (not exactly nearfeald but maybe 5 cm from the baffle, or less)?

MBK said:


Soooo... how do you find the HDS164 now that you presumably fixed the X-O? With the long wait for the 8543 I briefly considered it, but after comparing data from Mark K's tests, plus the data sheet's FR graphs I realized that these coated cones (Peerless Nomex or the equivalent from Seas) have the *exact* same resonance peaks as metal drivers!! ... just with a lower Q. Once you resize the FR of the HDS 164 to say, the Seas W18's graph, they are virtually identical. So I thought, no, I stick with something different, both for design philosophy and just for the fun of it...

The XO is here: http://home.swipnet.se/Karlssons/speeker/2.5 rev 13.gif

Next rev vill have a lower OR higher bas / mid ox point as I get a small ~100 hz bump right now. If I ever get around to it...

Remember that Im using the old coated paper version. The nomex ones are probably different but:

Im cutting them at about 2.5 khz, and they are beaming. Not like crazy, but they do. Bas is good, maybe even very good if you take in to account it's hi fs. The mid's are clear, accurate and... some what boring. Im missing some "paper feeling" if that's makes any seance to you. Some transparency, but noting stunning.

I hear things on "Pink Floyd, The division bell" I've never heard before (a CD that I have played MANY times).

The main resonance peak is higher up in frq. then what DST's graph's suggest, but it's easy fixed with a nothfilter. The DST's of axis graph's are very close to real life.

If the 8" HDS drivers are anything like the 6.5" ones (but with it's lover Fs) I think it would be a really good bas driver in a old style 3 way.

Best,

Leif
 
Hi Leif,

thanks for the comments on the Peerless drivers. Seems to be many questions around these forums but few ppl actually using them, in spite of good paper data and very good price.

As for my measurements, my problem is to measure the entire speaker with dipole and diffraction effects. These are large dipoles, and to get a good picture of the performance, one would really have to back up 1.5 m, ideally 3 or 4 m before it can reasonably be considered "far field". But recently I got some quite ok results in the bass by simply measuring close to the ground (20-30 cm) and completely including the floor reflection which is part of the design anyway. My problem was that when I measured at say x=1.5 or 2 m dist. and y=1.1 m height (my mid's mounting height) then the bump of the floor reflection came in exactly in the lower mids, say 280-400 Hz. WHen I measure close to the floor now the reflection bump is pushed high enough to clear the area of interest...
 
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