I am buying parts to build a new pair of two way speakers. The woofer is a AE TD15H and the top is a trac trix horn which loads down to 400Hz. It has a 1,4 inch throat and I am planning to cross over at 800Hz. I need to find a really good compression driver and some options I have looked at are Faital Pro, 18 Sound, BMS coax. Unfortunately I cannot find distortion plots for most compression drivers. BMS 4594ND shows fairly high non linearities at high frequencies which does not convince me. Do you have any thoughts or proposals on low distortion drivers that work from 800Hz to 20kHz?
Ernie is right. Have you considered building your own horn? Take a good look at John Inlow's site which is inlowsound dot com. this way you can insure a perfect match. ''''''also at home levels you can cross much lower so long as your horn is large enough. With an EV DH1A you can cross as low as 350 Hz with simple crossovers so long as you are not looking to play at high levels, with the extender nose cup of the DH1A removed the exit is 1.4" dia. a horn mouth for these frequencies would start around 70 - 80cm. In a rectangular horn the Klipsch K402 would work well. The age old 12db/octave crossover point for large two way speakers is 500Hz. There are members on the Klipsch forum who have done this why not go search the archives there and chat with some of them?
I would also suggest that you take a look at the Karlson K-Tube in a double cutaway these are so simple to make it is stupid and they cost next to nothing. I like them better than horns. Don't discount them simply because they are simple and inexpensive to make.
I would also suggest that you take a look at the Karlson K-Tube in a double cutaway these are so simple to make it is stupid and they cost next to nothing. I like them better than horns. Don't discount them simply because they are simple and inexpensive to make.
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You are right, the exact crossover point will be selected once I have measured the off axis response of the woofer and horn. They have been bought already though, but not the compression driver. So again, which is the best compression driver around for this? BMS are expensive but are they good?
Faital Pro has their own Trac Trix horn LTH142 which exits at 60 and 50 degrees. As with my own horn it has a fairly long section in the start which is close to zero degrees. Is the driver exit angle only a limitation if the start of the horn has is larger than zero? I mean, if it starts at more than 29 degrees it would immediately loose its loading?
Well, there's been plenty written over the decades and a few of us on the forums have been periodically reminding folks of basic horn design that has been taken for granted since the earliest days of PA, cinema sound system design began in earnest circa 1915, but explanations as such, I've only seen in pipe/duct, muffler, transmission line and aeronautical design patents, technical journal papers and a few textbooks.
Regardless, anytime there's an abrupt transition in a pipe/duct there's an acoustical impedance mismatch at whatever frequencies it will support eigenmodes to form, i.e. reflections back to the throat or the previous bend of a horn for instance, among other types of reflections such as Dr. Geddes's HOMs; IOW a bad match makes a two segment diffraction horn, so no matter how dimensionally 'perfect' the rest of the horn is, if the driver is a poor match, then it just became an excellent narrow BW horn in a SOTA system if left undamped.
Even when there's no angular difference there can be significant reflections, diffraction anyway if the joint isn't seamless as I found out long ago by align bore matching a pair of Altec 802 drivers to Altec 511 horns with the same flare to 'see' if it made an audible difference and the improved HF response was not subtle, so if you don't match everything just so, then a foam insert is a good plan.
WRT driver selection, no 1.4" exit single system driver will work well out to > ~12 kHz 'flat' on axis and ideally only to about 9 kHz with some only good to half that at high SQ, so you're limited to one of the two way drivers or adding a 1" adapter for a 1" exit driver, though either may not go low enough unless your horn is quite large.
GM
You basically want the transistion from the inside of the compression driver to the horn to be seamless to prevent diffraction in the throat. Any sharp angles will create secondary sound sources and "smear" the sound. In practice it might not be a huge issue, especially if you never listen at louder output levels.
BMS
18 Sound 1460,1480
Radian Neo 745
Faital HF140,146
Seen these drivers documented in builds and tested well. Top of the line drivers from B&C, RCF, Ciare, Celestion, EV, JBL, etc...will all perform very well.
Progress, Richard at Radian helped me with the exit angle figures so now I know which one to use. I measured the Trac Trix horn to have 2,4 degrees in the entry so it will fit the 745 and 835 with ferrites. I do not exactly what the differences between these are except for the magnet force. Will I hear a difference in my living room? And, will the extra 800USD for Beryllium make me happier?
No personal experience, but quite awhile back when the late Jean-Michel Le Cléac'h diyAudio - View Profile: Jmmlc was still using Altec 511/802 horns recently converted to a TAD Beryllium, he told me that it only added a bit more extreme HF, though in retrospect it probably improves clarity at least a little that would have been 'lost' on a cast alum. 511 unless it was really well damped, which from dim memory, his wasn't.
For me and my hearing it would be a waste of $$, but would buy them anyway if budget permitted just in case there was someone around that might enjoy the difference, though not if female as they tend to prefer a rolled off top end IME.
GM
For me and my hearing it would be a waste of $$, but would buy them anyway if budget permitted just in case there was someone around that might enjoy the difference, though not if female as they tend to prefer a rolled off top end IME.
GM
The radian neo 745 is good up to 12k or so in a Le Cléac'h. There are measurements in the Beyond the Ariel thread.
The 18 Sound nitride coated drivers might be a better value for extended top octave performance but don't have the mylar surround which helps with lower crossover points. May not make a huge difference in the home though.
Keep in mind I have no direct experience with these drivers. Just observations of others over the years.
The 18 Sound nitride coated drivers might be a better value for extended top octave performance but don't have the mylar surround which helps with lower crossover points. May not make a huge difference in the home though.
Keep in mind I have no direct experience with these drivers. Just observations of others over the years.
Aluminium will be better for longer listening session. It gives an open and fatigue-free sound.
Try to hear both if possible before ordering. Leaving the cost part apart Aluminium is better choice for home use. Problem with Aluminium lies in power handling in PA use. That is the reason in PA mostly Titanium is chosen.
Regards,
Gautam
It is not that simple!
Issues of discontinuity are not limited to the first derivative (tangent angle) of the horn equation used, but also to the second (its curvature). For best results in terms of directivity control and minimization of HOM's, the horn and driver should be designed as a single functional unit. At the point of connection(s) both these parameters should match. How critical the departures are, of course will be dependent on the specifics of components used and the design mission to be filled.
Regards,
WHG
Issues of discontinuity are not limited to the first derivative (tangent angle) of the horn equation used, but also to the second (its curvature). For best results in terms of directivity control and minimization of HOM's, the horn and driver should be designed as a single functional unit. At the point of connection(s) both these parameters should match. How critical the departures are, of course will be dependent on the specifics of components used and the design mission to be filled.
Regards,
WHG
You'll need eq on the top octave to make the most out Be, other wise it'll roll off earlier than the aluminum version.
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