Large midrange for OB??? Scott G ?

[Paul W]

Scott,
The Ciare's choppy impedance curve is scary...I'm thinking floppy cone which isn't for me. On the other hand, the 10NDA520 looks better than the 10M600. I was wondering why I saw no mention of shorting rings in the 10M600...now I know where Eighteensound puts their technology! I'll check out the others you mention. What would you do if you were to break my bank?

Tech,
Do you have a link (other than Eighteensound) for comparisons of AI and shorting rings? Why do you regret buying the AI driver? Only price or is there something else I didn't catch?

MBK,
If you are doing more measurements, a full 360 degrees would be quite interesting.

[ScottG]

Originally posted by Paul W
Scott,
The Ciare's choppy impedance curve is scary...I'm thinking floppy cone which isn't for me. On the other hand, the 10NDA520 looks better than the 10M600. I was wondering why I saw no mention of shorting rings in the 10M600...now I know where Eighteensound puts their technology! I'll check out the others you mention. What would you do if you were to break my bank?

I noticed that to with the ciare - but it doesn't seem to manifest itself in the freq. response curve. Now it *might* with linear decay.. but here I'd be more concerned with getting the inital decay clean (say within 9+db down less than a milisecond). It would NOT be a floppy cone - in fact this cone should be incredibly stiff considering both the mass and material/shape, as well as the motor's field strength. If there is a mechanical problem, that would likely be at the transition between cone edge and surround (..i.e. stored energy). Again, this would prob. mean that the linear decay would be "messy" around 1.5 kHz, but it might not be a problem with a 4th order filter at 1kHz. Conversly I'd expect the driver to be otherwordly "clean" between 250 Hz and 800 Hz. Its "give and take" - no perfect driver and all that. Note however that stored energy IS something that can be significantly improved by a DIY'er with fairly modest modifications.

The more I think about the 18sound active impeadance drivers - the more I begin to suspect that the 12 inch driver's inductance value is a misprint by 10 times the value. (i.e. it should be .09 instead of .9) I'd check this out, and if it is in fact true, then I'd prob. select this driver even with a price premium. Effectivly there is nothing to suggest any sort of problem with this driver from what I'm seeing until at least 1.8 kHz. (..and the build quality is extraordinary for this series.) It could however be 50 to 100 US more than you were willing to pay however.

Breaking the bank..

I'd personally go in another direction here..

I purchase the Supravox 165 GMF and front horn load it (wave-guide) all the way down to 200 Hz to obtain the exact dispersion patteren I wanted. (..prob. 40 degrees vertical and 90 degrees horizontal.) Note that I would still operate the driver as an open baffle (..soley to keep the driver from non-linear compression and reflections).. and again, I would still crossover around 250 Hz LR 4th order. The driver's impulse response is absurdly clean for initial decay - and this translates into EXTREME subjective detail.

http://www.supravox.fr/anglais/haut_...rs/165_GMF.htm

The problem here is that I don't know of a good wave-guide for a 6.5" driver. So you would have not only the extra expense of the drivers as well as the shipping, but also the time and material of building and experimenting with waveguides. NOT and easy course to "plow" (..on the other hand I would say that with respect to making your own line-source true ribbon driver )

EDIT: Apparently DDS also does custom horns.. then it may only be a "small" matter of cash.

http://www.ddshorns.com/catalog.php?page=products

[tech.knockout]

Originally posted by Paul W
Tech,
Do you have a link (other than Eighteensound) for comparisons of AI and shorting rings? Why do you regret buying the AI driver? Only price or is there something else I didn't catch?

Theres a thread here: Faraday rings

Although there really very few material on this as no other drivers have this technology.


I regret buying it after reading about studies concluding that non-linear distortion plays a small role in our perception of sound (obvious exception is when abusing the driver).

If nonlinear distortion is such a small factor, I should have bought a cheaper alternative.

[ScottG]

Originally posted by tech.knockout
Theres a thread here: Faraday rings

Although there really very few material on this as no other drivers have this technology.


I regret buying it after reading about studies concluding that non-linear distortion plays a small role in our perception of sound (obvious exception is when abusing the driver).

If nonlinear distortion is such a small factor, I should have bought a cheaper alternative.

I'd prob. be the first on this forum to say that THD as non-linear distortion doesn't matter much unless very high order products are elevated in level.

However..

You are only getting part of the information..

IMD is a form of non-linear distortion. It is also VERY audible at even fairly low levels. In particular - it frequently occurs at the upper freq. limit of fairly large diameter loudspeakers. Moreover inductance is prob. THE contributor to IM distortion at higher freq.s..

So cheer-up.. You purchased a *REALLY* good driver and its technical prowess will almost certainly improve the subjective quality sound if you operate it anywhere near its upper freq. limit.. So its likely you shouldn't have purchased a cheaper driver IF you wanted such a large eff. driver as a midrange. (..note though it also depends on how significant the operating passband is.)

[tech.knockout]

Originally posted by ScottG
I'd prob. be the first on this forum to say that THD as non-linear distortion doesn't matter much unless very high order products are elevated in level.

However..

You are only getting part of the information..

IMD is a form of non-linear distortion. It is also VERY audible at even fairly low levels. In particular - it frequently occurs at the upper freq. limit of fairly large diameter loudspeakers. Moreover inductance is prob. THE contributor to IM distortion at higher freq.s..

So cheer-up.. You purchased a *REALLY* good driver and its technical prowess will almost certainly improve the subjective quality sound if you operate it anywhere near its upper freq. limit.. So its likely you shouldn't have purchased a cheaper driver IF you wanted such a large eff. driver as a midrange.

I also got this impression as people talk about supravoxes, eminence beta 8s, paudio coaxes, very old 15" altecs, etc. These drivers from what I can tell use conventional motor structures. The common denominator seems to be low mass, high efficiency, and lack of cone breakup.
It seems these three matters; instead of buying a midrange driver that must have the bells and whistles in the motor which was my main priority at the time.

[ScottG]

Originally posted by tech.knockout


I also got this impression as people talk about supravoxes, eminence beta 8s, paudio coaxes, very old 15" altecs, etc. These drivers from what I can tell use conventional motor structures. The common denominator seems to be low mass, high efficiency, and lack of cone breakup.
It seems these three matters; instead of buying a midrange driver that must have the bells and whistles in the motor which was my main priority at the time.

To a large degree - however, it also limits very high output though. i.e. most of these motors can't take the heat from lots of current and won't work as well substantially beyond their reference sensetivity.

So while I advocated a supravox 165GMF as a driver - practically speaking it shouldn't be "seeing" much more than about 32 watts. On the otherhand at "lower" spl.s (i.e. +3-6 db above their reference) its a non-issue. (..also factor-in about 5 db of gain for the waveguide I've spec'ed - that would place the driver around 100 db eff. 1watt/1 meter) Doing the "math" indicates that 100 db + 4-5 times the gain puts the output max around 112-115 with a waveguide. Thats still extreme spl's in my "book".

(note.. I should have mentioned that while IM distortion is a significant factor at higher freq.s - its often the lower freq. inductance value, (..not the inductance at higher freq.s), coupled with even a low spl lower freq. "tone" and a higher freq. tone that generates the problem.)

[Paul W]

Scott,
I printed all of the AIC spec sheets today and was stumped by the 12"...doesn't seem to be any reason it would have high inductance. I'll write them and cross my fingers for an answer! BTW, why did you discount the other 10", lack of directivity, lower xmax?

Do you know the US distributors for 18 Sound? I had 3 choices for the 10M600, but none list the AIC drivers.

Supravox ah yes...seem to remember you recommended them to Shin! Actually I would like to try my hand at horns/waveguides, but I'll start small...like HF. Probably buy a pair of the DDS Eng 1-90 Pro for a reference standard so I can see if I'm on the right track...or if I'm just burning plastic

The ribbon thingies are actually easy by now. Didn't you recently say you were thinking of building some? Maybe I can return the favor with some tips...and fewer bruised fingers. Here's another pair I built last week.




Tech,
Great link! I read the thread and then bookmarked it!
Thanks,
Paul

[MBK]

The more I think about the 18sound active impeadance drivers - the more I begin to suspect that the 12 inch driver's inductance value is a misprint by 10 times the value. (i.e. it should be .09 instead of .9)

I entered the 12NDA520 data into SL's handy spreadsheets. If Le was 0.91 mH, we'd expect 7.3 OHms at 1kHz and 59 Ohms at 10kHz. At 0.091 mH we'd expect 5.2 and 7.8 Ohms for 1 and 10 kHz, which is much closer to the data sheet. In fact the data sheet's graph shows even lower reactance than that.

If you are doing more measurements, a full 360 degrees would be quite interesting.

I'd love to comply... but I have to find a cleaner setup to get truly trustworthy data. Indoors and without suspending the speaker, any measurement beyond 32" / 80 cm or so, becomes increasingly haggard due to room effects and especially, floor bounce. But 80 cm is too small to fully account for the baffle effects - at 80 cm front-to-mic distance the rear wave travels a full 80 cm farther than the front wave, which means it is 6 dB down.

[Paul W]

I've written Eighteen Sound about the Le spec, but no answer yet.

Haven't found them in the US but, curiously, the European sites have the 12" AIC priced considerably lower than the 10". Maybe the 10" also have shorting rings the 12" doesn't have? Interesting.

[MBK]

Just for info, what are the prices like? In Singapore there is one distributor but on the web they only list one model (the 10" AIC), and w/o prices or further info.