augerpro said:
Rising 2nd order distortion is intrinsic in all compression drivers. Basically the diaphram reacting to the phasing plug and compression undergoes asymmetrical/torsional stress. (..same basic thing happens with ribbons by the way). Titanium is marginally stiffer and as a result is slightly less susceptible to this.
Additionally, most horns increasingly unload the driver at higher freq.s , further compounding the problem.
Note that the larger the diaphragm (i.e. 2 inch exit drivers vs. 1 inch exit drivers), the worse the problem (..because of course the diaphragm's stiffness is also strongly predicated on its form, and larger domes in the 2 inch exit drivers are "weaker" than smaller domes in 1 inch exit drivers.)
The higher non-linearity present in the graphs is at output levels well beyond most tweeters failure point (..depending on the tweeters excursion limitation via crossover points/slopes).
For hifi I find the 2" exit with 3" diaphragm sound better than the 4" diaphragms. If you want to use the driver without a tweeter you have to accept the fact the top end is going into breakup, and it will never be as good as a good separate tweeter. I also feel a 4th order electronic crossover (a good one, these drivers are sensitive and revealing) helps control the beasts.
In the graphs above if you were to run a typical high end dome or ribbon at the same levels and frequency range you'd probably have massive distortion, a small puff of smoke, then on open coil in that order.
In the graphs above if you were to run a typical high end dome or ribbon at the same levels and frequency range you'd probably have massive distortion, a small puff of smoke, then on open coil in that order.
Member
Joined 2003
Davies,
These graphs are all at 1W...so about 110db at 1M. Distortion would be much lower in a 85-90db home listening environment, but I'd only be guessing a number.
Scott,
I fully agree reducing excursion down low via steep slopes and/or higher XO appears to be extremely beneficial. However, if loading the driver reduces excursion, I doubt unloading the driver would help the situation. In that case, we'd have a high excursion driver generating high harmonic output; while the fundamental would be suppressed, the harmonics would likely fall within the passband of the horn.
My take on the distortion down low is the suspension...mylar may be more "fluid" while the titanium suspension may be doing something like "oil canning". A titanium nitride diaphragm with plastic suspension might be interesting.
Until I learn more, my "formula" is aluminum/mylar, large waveguide, steep XO.
Paul
These graphs are all at 1W...so about 110db at 1M. Distortion would be much lower in a 85-90db home listening environment, but I'd only be guessing a number.
Scott,
I fully agree reducing excursion down low via steep slopes and/or higher XO appears to be extremely beneficial. However, if loading the driver reduces excursion, I doubt unloading the driver would help the situation. In that case, we'd have a high excursion driver generating high harmonic output; while the fundamental would be suppressed, the harmonics would likely fall within the passband of the horn.
My take on the distortion down low is the suspension...mylar may be more "fluid" while the titanium suspension may be doing something like "oil canning". A titanium nitride diaphragm with plastic suspension might be interesting.
Until I learn more, my "formula" is aluminum/mylar, large waveguide, steep XO.
Paul
Paul W said:
Though a compression driver's non-linear distortion is expressly "non-linear", near its lower end response it will have distortion levels practically unrelated to excursion - i.e. increase the fundamental's amplitude and you will increase the amplitude of the non-linear distortion even without any increase in excursion. (..of course the *percentage* will be less, but we aren't concerned with that.)
Still, its mostly a matter of steep electrical filters.
You are probably right about the suspension. Makes me think 18 sound's little one inch titanium nitride *with* the poly suspension could be a better than your average extended compression tweeter. Perhaps useful enough in say a DDS 1-110 COM to extend from 1.4 - to 16 kHz WITH the better subjective qualities of a 2 inch exits midrange? Ah, speculation..
Sorry for posting to old topic but I have seeked for new 2-way project and 8"+horn tweeter is one option. Speaker is going to be used in bass gaining room around 18 sq meters with openings (quite bad acoustics I think ).
Are these "edgy" horns as good as smoothly extending horns? I can't see they could be...
Does lower degree figures in horn coverage give more directivity and more pressure gain? (more like horn, less waveguide?) Could less directivity be better for normal domestic use for about 2,5 m distance?
).Are these "edgy" horns as good as smoothly extending horns? I can't see they could be...
Does lower degree figures in horn coverage give more directivity and more pressure gain? (more like horn, less waveguide?) Could less directivity be better for normal domestic use for about 2,5 m distance?
Composite Titanium (w\o nitride) PEN diaphragm assembly:
nd1460t ND1460T - HF Neodymium Driver
ferrite hd2080t HD2080T - HF Compression Driverhttp://www.eighteensound.com/index.aspx?mainMenu=view_product&pid=303
and hd1480t http://www.eighteensound.com/index.aspx?mainMenu=view_product&pid=303
Member
Joined 2003
I would like to get some opinion about b&c 3" drivers, about mylar vs titanium suspension in particular..
search on the forum gave a lot of results about de250..
and did anibody used dcm50 midrange driver B&C SPEAKERS ?
search on the forum gave a lot of results about de250..
and did anibody used dcm50 midrange driver B&C SPEAKERS ?
+1. The soft suspension / hard dome combo works very well with my Radians.
Has anyone had any experience with the 18 Sound NSD1095N?
Buy a pair of used JBL compression drivers and replace the diaphragms with beryllium units made by Materion. See[1] for details. For source of used drivers see [2]. For those that have done this see [3].
Regards,
WHG
[1] http://www.speakerrepair.com/EQF3023_PrecisionBerylliumDiaphragm.pdf
[2] Jammin Jersey: Speakers Horns Drivers Crossovers Tweeters
[3] Truextent diaphragms measurements
I would be wary of Jammin Jersey. I ordered some JBL CDs from them and one them was distorting severely. When I asked them what's wrong, they didn't really offer to help. Instead, they asked me to send it back at my expense and they would 'look' at it and fix it if something was wrong, again, at my expense. I finally took it to a local repair guy and he said there were large chunks of iron stuck near the diaphragm, probably from when the diaphragm was replaced. I ended up spending about $100 over what I initially paid for them.
All in all, not a very good experience.
All in all, not a very good experience.
ra7, good to know. I've been looking at some e145 jbl 15's for a long while now. They just lost my sale (jersey). Treat your customers badly and your business should suffer.
I just hopped in on the last page, but my money would be on a community m200 compression driver (2" driver but a low <2:1 compression ratio), but you'd need a tweet or supertweet crossed at 4khz.
Norman
I just hopped in on the last page, but my money would be on a community m200 compression driver (2" driver but a low <2:1 compression ratio), but you'd need a tweet or supertweet crossed at 4khz.
Norman
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Thanks for the heads-up on JJ. The purpose for the reference is to give a price point for shopping. All that is needed here are driver carcasses (sans diaphragms), in otherwise good condition. Expect cost to be at least half that of working units. As a result, you will end up with a pair of JBL drivers superior in performance to new ones. Expect performance to approach that of TAD units, at a cost well below the $2,000 budget proposed. Caveats: Beryllium is a poisonous metal. The workspace must be free of ferrous metal dust and fragments.
Regards,
WHG
Thanks for the heads-up on JJ. The purpose for the reference is to give a price point for shopping. All that is needed here are driver carcasses (sans diaphragms), in otherwise good condition. Expect cost to be at least half that of working units. As a result, you will end up with a pair of JBL drivers superior in performance to new ones. Expect performance to approach that of TAD units, at a cost well below the $2,000 budget proposed. Caveats: Beryllium is a poisonous metal. The workspace must be free of ferrous metal dust and fragments.
Regards,
WHG
i've been running the the Be dias in 2440s on 350 Hz Edgar Saladbowls for a little while now, and can not agree with member whgeiger more...
the dias are expensive, but worth the outlay IMHO...
The 802 is somewhere between a 2410 and a 2420.
The Alnico magnet drivers are no longer available of course, and may suffer from varying degrees of demagnitization, and different type and era diaphragms, so finding a pair of "equivalent" drivers can be a challenge.
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