Suggestion for the best cone for 150-3000 Hz range.

[bombardon73]

Like Nemophyle allready said, the 102kep or the 135kep from monacor are true gems among the midrange (kevlar) units.

It's like a coincidence but today I just disassembled an old projekt of mine with a 102kep. Since I didn't have any measure equipment back then I was curious about how good this unit actually is. I measured it today and the frequency responce and decay diagram are impeccable! I think I'm going to use it in some highend projekt in the near future together with the Seas Noferro12 tweeter wich is to me his ideal partner.

[thalis]

There is no best cone, but there are goof cones for a specific work and price/value ratio. If you would like to proceed to a high sensitivity design, here is another candidate, if you are willing to pay a little more:

http://www.phlaudio.com/datasheets/17_pdf/1220_1230.pdf

Really crispy clean even in very high listening levels, able to reveal information that is lost in many insensitive drivers, exceptionally dynamic, relatively smooth response.
You would have to perform your measurements though, since the manufacturer doesn't provide any;-)
Regards,
Thalis

[thalis]

Not goof, but good, I meant ;-))

[Curmudgeon]

Thiel used the 13M8640 long ago, in their first three way; the speaker that made their reputation. I used the 8636 coated Kevlar to good effect in a commercial design that was on the market for ~ 5 years. By modern standards, both would be sweet and a bit veiled, the 8640 more so. But both are very musical drivers.

[filgor]

Originally posted by beppe61
I am a fan of soundstage reproduction (expecially in the depth direction)

I’m not a huge advocate of this concept. Either way, most of the claims I have seen regarding staging depth involved preference towards very directional speakers such as electrostatics and other dipoles in which delayed reflection from the rear wall also contributes to the sound.

Whether you are going for this ideal or not, some level of controlled directivity is actually a “good idea” as Owdi said before.

Originally posted by beppe61
I understand that the problem of directionality (is that correct?) starts from 80 Hz and go up with frequency.

Driver directivity does increase with frequency.

No not at 80Hz!!! I think it is most likely that you have heard this number referring to the frequency at which our ears can start to hear the direction from which bass is coming!? Don’t confuse that with the directivity of drivers!

For any given driver the point at which directivity starts is a frequency called “Fd” and is dependant on effective driver diaphram diameter
(Effective diameter can be roughly estimated by measuring the distance between the centre of the suspension on one side to the centre of the suspension on the other side)

Fd = 109500 / diaphram diameter in mm

Dome shaped drivers sometimes may have slightly better dispersion because the initial wavefront they create is a little more sperical.

Fd is around 1.3kHz for the 4 inch drivers I mentioned
Fd is around 860Hz for the Vifa XG18 I agree with Owdi & Zaph that tis is a great driver
Fd is around 3.9kHz for your average 1” tweeter!

Drivers become gradually (not suddenly) more directive above Fd which is why we happily use 1 inch tweeters.
For mid range drivers most sane people are happy to use a driver well above Fd. I don’t actually think about Fd when designing but as an observation my mids are most often used to within 2.4x - 3x their Fd.

Originally posted by beppe61
I understand that there is a summing effect at the crossover point but if I cross two drivers in order to get a flat response on axis what happens off axis ? could I have a dip in the response at the crossover points ?

If your mid driver is – 4.00dB at 60deg off axis at the crossover point then the net total is likely to be more like –1.77dB at 60deg off axis at this point.
Smaller than you might imagine?

Originally posted by beppe61
And this problem could be more severe with 6db/octave crossovers ? I mean which value of slope do you recommend between the mid cone and the tweeter and between the mid and the woofer ?

With 6dB cross overs any dip will be much wider. I would recommend 12dB/oct crossovers in most cases for a large number of other reasons. Between the mid and woofer a 6dB might be better.. depending on the final low frequency response and capability of the mid.

Originally posted by Zaph

It would be a mistake to think that paying more gets you a better driver. There is almost no link between price and performance.

Listen to Zaph.. He knows what he is talking about!

[DarkOne]

And what about Audax HM130Z12? It has great cone made of aerogel and it's rated very well in DIY speaker building comunity.

[Taco]

I would not use kevlar for the mids, use a good paper, poly, glassfiber cone instead. Less breakups and easier to filter. If you want pistonic operation consider Alu/ Magnesium cone, but these cone's need more work on the x-over.

So in short, look at Seas L15, W15, Scanspeak 15W, C-quenze 15H, Peerless HDS/ Exclusive, Vifa PL 14 and so on.

You can also consider a larger cone to reduce distortion, Vifa XT & XG 18 are great value. Or Dayton RS180/ Seas L18 for alu cone. Or my personal best 18H.

[Curmudgeon]

I generally agree with the Kevlar comments above; in the case of the 8636 a dampening "goop" tames the typical fierce Kevlar high end breakup.

The only Aerogel I ever evaluated, some 5 or 6 years ago also had a bad high end breakup. As a rule of thumb, based on limited experience, polypropylene is a more reliable choice than other cone materials.

Since this is a first project, I do strongly urge using drivers with a flat frequency response, without a strong peak at the high end.

[bombardon73]

taco wrote:

would not use kevlar for the mids, use a good paper, poly, glassfiber cone instead. Less breakups and easier to filter. If you want pistonic operation consider Alu/ Magnesium cone, but these cone's need more work on the x-over.

I surely don't agree with that. I have experience with several kevlar units from monacor and even the 200ke (8" unit) is very easy to filter.
What I don't understand is why you say that glassfiber cones are easier to filter and have less breackup. All the glassfiber cones I know of have a very large resonance peak somewhere in their freq. response.

[Nemophyle]

i agree on the comments above about polypropylene and paper, although the monacor drivers are very well behaved, and may not be hard to filter.

the vifa XG18 looks also like a very good solution.

bombardon i would be very glad if you could send me your measurements about the SPH-102KEP !