Beyond the Ariel

[BudP]

For large format wide range drivers, in 15 inch land, you might want to audition a pair of Audio Nirvana full range devices. The whizzer is actually a small relatively fast flare horn, connected to the end of the voice coil. Tremendously transparent driver.

Of course, if you would all just get busy learning how to EnABL, many of these crossover woes would fall to insignificance.....

Bud

[soongsc]

Originally Posted by Lynn Olson

I tried for many years to get Tannoy drivers on an OEM basis and the answer was always no. It's not easy getting them for replacement purposes; you have to prove to the factory you already have a dead Tannoy before they will cut loose a replacement driver. They are dead set against an OEM market developing as far as I could tell. Which is unfortunate, because the Tannoy really is a unique coaxial driver with a very good integral horn assembly.

I listened to a lot of small-format horns before I gave up on them. I suspect they don't work very well below 2~2.5 kHz - they might measure OK, but they sound strained and harsh below that frequency, even more than ordinary 1" soft-dome tweeters. Large-format drivers can be coaxed to much lower frequencies, but still demand low-diffraction horns - or the unobtanium multicells. Sectoral, MantaRay, and Bi-Radial horns with a diffraction "pinch" in the throat are all hopeless - once diffraction happens, no amount of EQ magic can undo it, and the horn-throat is the worst possible location for diffraction.

The Tannoy concept seem good at first sight. but if you consider the outer cone moving in relation to the horn lip, it is not difficult to figure out there is going to be something sounding funny.

I have been playing around with small format horns/wave guides, and I agree they sound somewhat stressed. But I still hesitate to conclude whether it's the horn or whether it's revealing a problem somewhere else in the system.

[tomtom]

Thanks Lynn and everybody for thoughts and comments.

Actualy i never listened my system without top woofer - and i certainly will after your comments.

My STW is crossed very sharply at ca 10k and there is only zing zang cang - no music at all. Even then efect of supertweeters polar responses to spatial presentation was very unsubtle and very very hard to choose which one is correct. Even presentation without STW at all has its magic. Ultimately its up to program material and subjective impression.

[Lynn Olson]

Originally Posted by tomtom

My STW is crossed very sharply at ca 10k and there is only zing zang cang - no music at all. Even then efect of supertweeters polar responses to spatial presentation was very unsubtle and very very hard to choose which one is correct. Even presentation without STW at all has its magic. Ultimately its up to program material and subjective impression.

Have you time-aligned the supertweeter? To a first approximation, put the supertweeter diaphragm about an inch/25mm behind the diaphragm of the compression driver, which is close to the back of the compression-driver assembly. Make sure the path to the listener is unobstructed and reasonably free of nearby reflecting surfaces (damp the surfaces with F13-grade wool felt if necessary).

More accurately, the acoustic center of the compression driver is about 1/4 to 1/2 wavelength (at the upper crossover frequency) behind the physical diaphragm. What moves it back further in space (away from the listener) is the combined lowpass of the horn+driver and the electrical lowpass of the horn crossover - the group delay of the horn+driver and lowpass filter are additive.

Although some people like to line up the horn mouth and front face of the supertweeter, this grossly misaligns the supertweeter - by several wavelengths - which is not good at all. The misalignment is perceived as incoherent and "spiky" sounding - in other words, the supertweeter draws attention to itself, and not in a good way.

[limono]

I decided to struggle with original arrangement before trying to change to Tannoy and supporting woofers. I'm not sure how 100dB woofer section will align itself(Bi-amping) with 92 dB Tannoy 10" , time will tell. The problem is handling of the speaker where weight of one is probably more than 300 lBs.

[tomtom]

Originally Posted by Lynn Olson

Have you time-aligned the supertweeter? To a first approximation, put the supertweeter diaphragm about an inch/25mm behind the diaphragm of the compression driver, which is close to the back of the compression-driver assembly. Make sure the path to the listener is unobstructed and reasonably free of nearby reflecting surfaces (damp the surfaces with F13-grade wool felt if necessary).

More accurately, the acoustic center of the compression driver is about 1/4 to 1/2 wavelength (at the upper crossover frequency) behind the physical diaphragm. What moves it back further in space (away from the listener) is the combined lowpass of the horn+driver and the electrical lowpass of the horn crossover - the group delay of the horn+driver and lowpass filter are additive.

Although some people like to line up the horn mouth and front face of the supertweeter, this grossly misaligns the supertweeter - by several wavelengths - which is not good at all. The misalignment is perceived as incoherent and "spiky" sounding - in other words, the supertweeter draws attention to itself, and not in a good way.

yes i have it time aligned. I use DSP /no kosher, i know/ so i can delay. In my setup everything is flush so no diffraction problem. I'm talking about different polar characteristic of different tweeters. Even if you setup them that each is ruler flat - each sound very different. 3/4 dome can sound like rear ambient tweeter on some speakers, ribbon sound different etc... In this context it is hard to speak about which is better it is just different. This is why i was interested in your implementation.

BTW, I was so interested about your Appolito note, that i make switch on wire that i can switch upper woofer off/on from listening position. Off course there was 3db difference in level but no other negative effect of WTW pattern. But i have woofers as close as possible. From 80cm and up it sound like single source. It is important to lowpass woofer very steep /48db/oct in my case/ otherwise lobing from out of band is problem. So not very doable passive and probably not your cup of tea.

many thanks and sorry for non-native English

Tomas

[Robh3606]

Hello tomtom

Have you tried matching the polar paterns at the crossover point or have it as close as you can?? Any abrupt change will be more audible as you move off axis.

Rob

[tomtom]

Yes i tried and i know it should be matched. But when you limit dispersion of tweeter so it has /at xo/ directivity of horn with 1,4 inch throat /no diffraction slot/ - there is almost no audible contribution of such tweeter over horn alone. Im talking about crossing at 10k and up. So STW to be actualy audible, it has to have wider dispersion over "extended mid" horn. How much wider is THE question. And i think this debate is very old - i read somewhere that even Greg Timber like Everest /do not know which one/ without STW more... Off course you need compression driver capable of UHF.

Basically im talking about solution to UHF for system with large diagram CD.
/Im assuming it is capable of UHF/

U can use STW - means problem with lobing and choosing right polar for STW

U can use diffraction slot - means HOM

Or and this is way that investigating right now. - Mimic the perceived inroom timbre of system with STW - without it by EQ. I do it by ear on pink noise with instant switching STW vs just CD + eq. This off course lead to non flat on axis response - but actual perceived timbre can be very very similar.

Actually i cannot be capable to tune CD UHF right without listening to STW to same time.

I hope that this post is not very misleading and hard to read. And sorry for my English.

Tomas

CD - compression driver
UHF - ultrahigh frequency
STW - supertweeter

[Zene Gillette]

Lynn ... can you give me an estimate for a conical window in front of a supertweeter so I can space horns either above or below and be relatively assured of a clear pathway? I thought an included angle of 30 degrees would be sufficient but even that makes for a large spread between adjacent horns. Crossover would be => than 8kHz.
Thanks, Zene

[Robh3606]

Hello Tomas

I run mine both ways with a TW/STW and with out. I have two systems that have tweeters integrated that sound good one an old large format monitor JBL4344 and the now generation 1400 Arrays with Be drivers. I also have an HT set-up with 2435's on PTH1010 waveguides with no TW/STW.

No matter how you do it it's compromise. Both of my systems are not time aligned and frankly I don't see the point. Time aligned is a 1 point in space solution.

The Arrays match the Horizontal dispersion at crossover as does the 4344. The Array more so than the 4344. Both seem to work pretty well.

U can use diffraction slot - means HOM

I am not buying that until there is a definitive measurement for comparison. The 9800, 9900 6600 Everest 2 and the Arrays all use a " diffraction" type horn. I don't hear to many people complaining about how harsh they sound. I don't think it's as simple as just using a diffraction slot it's more how it's done that determines how audible any issues are from the "slots"

Rob