OK yes horn loading increases the efficiency, and so on. But generally we end up with horns whose sensitivity, especially as they are much more directional, is WAY above even pro woofers.* Thus (the relatively small percentage or so I believe of active crossovers aside) we wastefully end up padding down with resistors.
--> why don't the manufacturers make the horn drivers 16Ω or even higher more often?
Yes, some horns are drooping at higher frequencies, but even so are pretty hot.
???
*this thread was kicked off after reading this review in particular
https://audioxpress.com/article/voi...tal-pro-s-10hx230-coaxial-10-pro-sound-driver
but the "ailment" is a common one.
--> why don't the manufacturers make the horn drivers 16Ω or even higher more often?
Yes, some horns are drooping at higher frequencies, but even so are pretty hot.
???
*this thread was kicked off after reading this review in particular
https://audioxpress.com/article/voi...tal-pro-s-10hx230-coaxial-10-pro-sound-driver
but the "ailment" is a common one.
Legacy issue partially, JBL did dual 16s in the D2 driver for the M2 system, wired in series partially for these same reasons, but along with higher impedance also comes thinner wire, or fewer windings of the same thick stuff and lower inductance. You could use a less efficient conductor... if you want more heat. There's a natural balance for moving coil designs, given the real-world design constraints (weight v conductivity v thermal properties in conductors).
You CAN use cone/dome drivers on horns instead of CDs, which also can help you match sensitivity better. Most serious pro systems are all active nowadays, so matching efficiency is nearly irrelevant, where pro woofers and horns are concerned.
You CAN use cone/dome drivers on horns instead of CDs, which also can help you match sensitivity better. Most serious pro systems are all active nowadays, so matching efficiency is nearly irrelevant, where pro woofers and horns are concerned.
A constant directivity horn will drop off 6db/oct.
A horn that does not drop in the top octave/s will beam and create a very narrow directivity up top.
The compression drivers efficiency is rising until it's mass break point, and that is the part you usually have to pad down.
A a large format compression driver it's not uncommon the top end is down to 90-95 db.
They are also made predominantly made and marketes for Pro audio, meaning controlled directivity, arrays, and horn/waveguide loaded midranges and woofers. Something like a JBL 2250/2168/9 on they're WG's or the Seos 24 gets you 100db + of sensitivity.
Can't expect large pro audio companies to make products exclusively for a tiny % of they're market.
The pro woofers will keep up to some degree, as long as you have enough of them🙃 Hoffmans iron law still applies.
But yes when you try matching a cd/horn with a 85db "hifi" midwoofer, compensating for bsc. Therr is a lot to pad down.
On the positive side, the padding and a cap helps protect the compression drivers in "harsh" use.
And all the padding leaves room for response corrections in the filter, for the driver/horn anomalies.
A horn that does not drop in the top octave/s will beam and create a very narrow directivity up top.
The compression drivers efficiency is rising until it's mass break point, and that is the part you usually have to pad down.
A a large format compression driver it's not uncommon the top end is down to 90-95 db.
They are also made predominantly made and marketes for Pro audio, meaning controlled directivity, arrays, and horn/waveguide loaded midranges and woofers. Something like a JBL 2250/2168/9 on they're WG's or the Seos 24 gets you 100db + of sensitivity.
Can't expect large pro audio companies to make products exclusively for a tiny % of they're market.
The pro woofers will keep up to some degree, as long as you have enough of them🙃 Hoffmans iron law still applies.
But yes when you try matching a cd/horn with a 85db "hifi" midwoofer, compensating for bsc. Therr is a lot to pad down.
On the positive side, the padding and a cap helps protect the compression drivers in "harsh" use.
And all the padding leaves room for response corrections in the filter, for the driver/horn anomalies.
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One can also use a higher resistance conductor ("less efficient"), that has much lower thermal coefficient, improving linearity and power compression.
Look at JBL's low TCR voice coils for example.
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You can presumably horn-load your mid-bass too. The ANIMA by Tune Audio runs a 3 way horn loaded system with a passive x-over.
Padding down of horn tweeters and squakers to match up with non-horn loaded bass is perhaps.... a compromise when people want to use horn speakers in small spaces where a full horn system is too large. Then one can ask whether any horn loading is needed at all. So it's kind of a kludge for us DIY folk who want horns but not horns all the way down.
And I thought low impedance was something we don't mind now that we have high quality solid state power amplifiers.
Padding down of horn tweeters and squakers to match up with non-horn loaded bass is perhaps.... a compromise when people want to use horn speakers in small spaces where a full horn system is too large. Then one can ask whether any horn loading is needed at all. So it's kind of a kludge for us DIY folk who want horns but not horns all the way down.
And I thought low impedance was something we don't mind now that we have high quality solid state power amplifiers.
I am actually thankful for the increased efficiency. Back when I was regularly designing speakers, especially for monitoring. It actually gave me some room to smooth out the frequency and impedance response of certain horns, which had numerous peaks and dips. It was also an opportunity to place a resistor in series with that reactive network that normally sets the frequency response of your horn. That is, until someone burns up the VC of the horn. Then your amp becomes very unhappy running into the weird reactance produced by an unterminated crossover, especially if it is an L-C network. Usually magic smoke time, unless you speaker is fused! LOL
The pink noise curve means a CD is using only a seventh or less of the watts of a PA speaker. Example Peavey SP2(2004) where CD is rated 70 watts and combination rating is 500 watts AES. So the power loss in the resistors to the CD is no big deal. Resistor gives some room for transient plus square wave protection with series incandescent bulb. Eminence just discontinued some 16 ohm CD's, presumably because nobody bought them.
One big reason for HF "overkill" is loss of high frequencies with distance in pro applications. When setting up speakers for large venues, the HF fall far more rapidly than the low frequencies. That is one reason why many pros prefer Titanium diaphragms as distorted HF is preferable to lower HF.
In home hifi without compromise it's best to use horns on the lower end too. Pr0sound reinforcement people don't like to carry horns so they stack woofers. to "try to keep up" lol
TLHP lists 213 CD's 16 ohm nominal.
And 10 coax CD's 16 + 16.
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One thing I noticed about many horns, is the high frequency roll off due to the horn dimensions. Many of the popular horns from the 70's and 80's had a tough time above 10khz. One way around this was to pad the crossover, then run a small capacitor to the horn unpadded. Granted, this did cut into the power handling of the horn. But it also solved a lot of problems at distance. Unfortunately, most of my curves from those days are in Apple 2+ format. I still have that machine in storage. Problem is that it takes about 15 minutes to do a waterfall plot! Ah, those were the days....
Yeah I wondered about that. I never did design work needing something like that under high continuous power, and was wondering if thinner wire is less robust when wound on a former and pumped full of current.
There was an amusing AES paper purporting to show that stacks of ported boxes were more efficient than bass horns. A perusal of a large data chart in the paper in fact showed the opposite! 😆 I guess maybe true subwoofer horns are just inconveniently large per-each to truck around to shows?
The problem is not with the horn but with the use of it: you are using it not in the combination it is intended for. You need to pad them because the rest of the speakers you are using them with have too low efficiency. You need to pair them with other horns or loads of speakers. But ok, bass horns do get big so we do not want them or cannot place them and as a consequence we pad the mid/high horns instead of using more appropriate mid/tweeters.