How to choose a horn/waveguide for home audio?

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#21
Like EarlK, I highly recommend the PRV clone of the QSC PL-000446GP waveguide. I have the QSC 152i used in a 3-way. I also switched from a smaller waveguide, that sounded beamy, to the 152i waveguides, which are not beamy at all. In fact, they have an excellent polar response and would be hard to beat: https://sites.google.com/site/drivervault/driver-measurements/horns-and-waveguides/qsc-pl-000446-gp

I also switched out the D220Ti for a BMS 4540ND. It sounded better and had an extended fr than the D220Ti, but also costs considerably more...

What are your XO points?
 
#22
Cask05 said:
The other VFM-sourced (an FS Audio horn from China) horn I mentioned from Australia looks like it would also be extremely good, and at 1/10th the price, but the issue is buying them outside of Oz. Perhaps they're available from FS Audio or through another non-Oz source.
Click to expand...

There is an ebay seller 'zxpc' who has some good stock, which seems pretty stable (I bought some horns in January, that are still in stock now).

This horn is within a few mm of being the same horn as the VFM:
2" Throat Horn Bolt-On 18"x10"For Assorted Bolt On 2"Exit Drivers 90°x 40°

2" Throat Horn Bolt-On 18"x10"For Assorted Bolt On 2"Exit Drivers 90°x 40°(398) | eBay

They also have a listing which looks exactly like a Faital horn 🙂
 
#23
Thanks! I bought another horn that is similar, but with an exponential mouth flare from the same seller about three months ago, but didn't see this horn. That other horn isn't a bad horn from my testing but a little too large for my needs, particularly its depth which I attribute to the exponential mouth roll-out instead of tractrix.

I'll let you know how it measures with a 2" throat compression driver when this newer tractrix-mouth horn you identified comes in.

Chris
 
#24
juliopr said:
What I meant by long or short throw is the fact that the Pyle has a depth of 9-5/8", while the others that You, EarlK, has recommended are only 5.5" deep. So basically I believe You just answered that part of my question about that. and I thank You as well as the others who have contributed with their opinion/ advice so far..
Click to expand...

Hi Julio,

Yes, in a nut-shell shallower wave-guides ( horns ) will have less LF response.

I suppose, robbing the compression driver of acoustic support in it's bottom octave ( which is in the hi-mid area ) is a valid approach to making that driver sound more like a tweeter ( sort of like leaving the clutch pedal "half-in" when driving a standard ).

EQ, ( either electronic or passive ) should accomplish similar goals ( though my experience is that I prefer the sound of passive EQ when the woofer is not horn-loaded ).

Mitchba participated in this thread at LHF that is worth the read ( as well as reading all the linked-to papers ).

What you are hearing ( Hi-Mid aggression ) may mitigated some by implementing a proper ( personal-preference ) House-Curve ( something Mitch is very well versed in ).

OTOH, that Selenium driver may need more drastic measures to make it palatable for extended listening in the home ( don't really know since I don't own any ) such as a touch of carefully applied ( Dynamic EQ ).

🙂
 
#25
Cask05 said:
Clearly it depends on your further (unstated) requirements:

1) If the requirement includes widest frequency band, then horns with a 2-inch throat compression drivers are best, IME. Two inch compression drivers using more exotic diaphragm materials than aluminum or titanium, which ring badly (i.e., beryllium or some type of polymer sound much better, but cost a lot more).

2) If you're trying to use 1-inch throat compression drivers, things get much more complicated. You'll likely wind up with a 3-way design (tweeter, midrange, bass drivers) to achieve full-range. I actually don't recommend this approach.

3) If uniform coverage is desired and you're using 2-inch throat compression drivers, the best horns in terms of their sound in-room and coverage are controlled directivity horns. These horns all require equalization with their compression drivers.

The best 2-inch throat horn that I've heard or dealt with by far is the Klipsch K-402 horn. It's expensive: $1K[US] with attached driver and stand. It holds its polars down to 170 Hz in a 90x60 degree pattern, which IMO sounds best in-room (narrower horn patterns suffer from less satisfying sound in-room, IMO) and permits either a two-way full-range design with attached direct radiating woofer(s) or multiple-entry coaxial configurations.

Its little brother, the K-510 horn, is good down to 550 Hz before losing is 90x60 degree pattern control, and is quite a small horn for what it does. It really can't be used effectively as the basis for a multiple entry design. It's also expensive.

There are other 2-inch throat horns that are almost as good, notably the VFM audio 2-inch throat horn (if you can buy it outside of Australia--good luck with that).

4) For 1-inch throat horns, the ones that Bill Waslo identified above would be my starting choices, however I've also stated that I wouldn't go this direction due to the complexities of getting the crossovers filters implemented (assuming that you're trying to use passive crossovers--which I don't recommend), getting the polar coverage of the crossing drivers/horns to match at the crossover interference band(s), physical mounting of apertures on the loudspeaker box/baffle to minimize lobing, and lowest distortion.

I recommend instead using something like a miniDSP (with power conditioning to minimize noise) or an even better quality digital crossover to EQ everything flat.

5) If the requirement is least cost, then there are a lot of choices available, but typically much lower performance.

What's your cup of tea? Your specific price constraint is a good place to start.

Chris
Click to expand...

Are you suggesting modifying the K-402 to be a synergy horn or loading it with a single 2" compression driver?
 
#27
Cask05 said:
Thanks! I bought another horn that is similar, but with an exponential mouth flare
Click to expand...

That's the one I got in January.

Cask05 said:
a little too large for my needs, particularly its depth
Click to expand...

Different strokes: the depth is exactly why I got it 🙂

I wanted to get a horn that vaguely matched the throat angle of my drivers. I'd picked up an old pair of JBL 2445J. These have a ~5 degree throat angle, so they ideally need a <200Hz, slow expanding horn, like the Sato or the Inlow horns (about a metre long).

It seems slightly odd to me that manufacturers don't state the throat angles of their drivers. No-one would bolt a 1" driver to a 2" throat horn, but mis-matching throat angles seems to be pretty common practice.

This is my ABS horn, stock & extended (bigger, but not big enough):

http://www.diyaudio.com/forums/atta...mounting-midrange-horn-kicker-boots-small.jpg

http://www.diyaudio.com/forums/atta...r-coaxial-mounting-midrange-horn-imag1373.jpg
 
#28
funny, noone mentions the obvious consequenses of a 2inch horn, it will beam exactly twice as fast as a 1inch regardless of shape.
1" = 13.5khz
2" = 6.75khz

2" simply cannot work in a 2-way. all modern horn speakers are either 1.5" at worst (9k) or 3-way. from what i hear the Jubilee was a failure and quickly made into a 3-way?
how some fanboys hype up clearly obsolete tech never ceases to amaze me though. JBL has moved on miles since then, while Klipsch have not done ****. apparantly the owners dont want heritage changed out of respect for P.W (!)
 
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#29
multitask said:
funny, noone mentions the obvious consequenses of a 2inch horn, it will beam exactly twice as fast as a 1inch regardless of shape.
1" = 13.5khz
2" = 6.75khz
Click to expand...

I think I understand your reasoning, but I suspect it is more complicated than that.

Here are polar plots I did with an old 2" driver on a new horn.
http://www.diyaudio.com/forums/atta...ange-compression-drivers-budget-jbl-polar.jpg

These aren't pretty - they were rough ground plane measurements. I took these measurements simply to get pattern control info, hence no eq or gating or other care was taken to get the baseline flat.

As you can see, the HF lines are parallel - so equalisation to flatten the on-axis response would also flatten the off-axis response. That is:

on axis, 10kHz was ~9dB down relative to 5kHz.
off axis, 10kHz was ~9dB down relative to 5kHz.

I think the HF spikes (>10kHz) of a titanium diaphragm 2" driver are more of a problem than beaming is.

multitask said:
2" simply cannot work in a 2-way.
Click to expand...

There was a guy who forcing me to do this at gunpoint. I'm so glad the space ninjas locked him up. He and the Fireclown were really starting to freak me out.

multitask said:
how some fanboys hype up clearly obsolete tech never ceases to amaze me though. JBL has moved on miles since then, while Klipsch have not done ****. apparantly the owners dont want heritage changed out of respect for P.W (!)
Click to expand...

I'm not a genius or a fanboy, but I think that comment may be rather out of date. Quoting from the "Corner Horn Imaging FAQ"-

The Klipschorn was originally a 2-way speaker, but after the recording companies in the 1950s expanded their advertised upper-frequency limit from 12 KHz to include the very limit of human hearing: ~20 KHz (measured with young adults), Klipsch had to add a tweeter to the design since then-current compression drivers were not capable of extending their FR to that limit.​
 
#30
A ground plane measurement for HF? Doesn't the small distance of the mic from the ground mess that up in the HF? Though I don't think it would be likely to change if the speaker is getting directed (not the mic), and away from the ground, for the off-axis curves. It would be interesting to compare the result with some gating applied, and/or in free-field.
 
#31
#32
bwaslo said:
A ground plane measurement for HF? Doesn't the small distance of the mic from the ground mess that up in the HF?
Click to expand...

All kinds of things make the measurements a mess, but I don't think that the mess mattered for my purposes - all I needed was for it to show me where the horn had good control (where the lines are ~parallel) and where it didn't.

It appears that, from 900Hz and up, if I were to get the on-axis response flat, the off axis also be within a few dB of flat.

bwaslo said:
Though I don't think it would be likely to change if the speaker is getting directed (not the mic), and away from the ground, for the off-axis curves. It would be interesting to compare the result with some gating applied, and/or in free-field.
Click to expand...

The speaker and mic were on the carpet throughout. I shifted the mic in an arc in (if I recall correctly) 10 degree increments, from 0 to 40 degrees.

I still have the parts, so I might give this another crack (sometime after Christmas?) I'm still learning the various measurement tricks - I didn't know how to apply gating when I collected that info.

Next time, I'll also rotate the speaker, and not move the mic - I've realised that by moving the mic, I would have been capturing a different set of room reflections in each plot.
 

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#33
hollowboy said:
...Different strokes: the depth is exactly why I got it 🙂...I wanted to get a horn that vaguely matched the throat angle of my drivers...It seems slightly odd to me that manufacturers don't state the throat angles of their drivers. No-one would bolt a 1" driver to a 2" throat horn, but mis-matching throat angles seems to be pretty common practice.
Click to expand...
Are you familiar with the concept of a "rubber throat"?

Chris
 
#34
multitask said:
funny, noone mentions the obvious consequenses of a 2inch horn, it will beam exactly twice as fast as a 1inch regardless of shape.
1" = 13.5khz
2" = 6.75khz

2" simply cannot work in a 2-way. all modern horn speakers are either 1.5" at worst (9k) or 3-way. from what i hear the Jubilee was a failure and quickly made into a 3-way?
how some fanboys hype up clearly obsolete tech never ceases to amaze me though. JBL has moved on miles since then, while Klipsch have not done ****. apparantly the owners dont want heritage changed out of respect for P.W (!)
Click to expand...
Actually it depends on phase plug design.
 
#35
Yes....and the length of the throat of the compression driver before the final flare of the horn is encountered. The longer the "snout" after the phase plug, the more issues that you have with coverage angles at higher frequencies.

In general, the response that you see for at least 2" compression drivers above 8-9 kHz is said to be in the domain of the exact compression driver used.

I think you should first listen to a pair of Jubilees with 2" compression drivers (almost any reasonable brand/model). Then look at the measured polar plots vs. frequency. I think that your opinions (@multitask) would shift--fairly quickly.

If you're in the D/FW airport area, there's an invite to come listen.

Chris
 
#36
Cask05 said:
Are you familiar with the concept of a "rubber throat"?

Chris
Click to expand...

1) I think I've seen it without paying much attention. At a glance, it looks like an ugly compromise: an approximately conical horn, with lumps. I'd rather have a compromise that looks elegant 🙂

2) It looks like there's a typo in the page you linked to - "Now, we introduce an initial flare with, say, a 100 Hz. lower cutoff." 40Hz -100Hz doesn't make sense.

3) With old compression drivers, the mismatch is usually the other way around to what is shown on that page.

e.g. until they changed up about 10 years ago, a typical all-JBL system mounted a driver with a skinny (~160Hz) snout on a squat (~500Hz) horn:

JBL Technical Note, Volume 1, Number 21

By our calculations, the initial flare rate in the older
driver design was approximately 160 Hz, reflecting the
need to drive the very large horns that were used in
early motion picture systems. Today, we can double or
quadruple that flare rate, inasmuch as many horns are
now intended for nominal crossover at 800 Hz.​

I really like this quotation:

a) it's great of the company to admit that for a couple of generations, they were manufacturing drivers that were inconsistent with their applications and horns.

b) It makes me wonder what other design assumptions are currently being copied, just because 'that's how it's done'.
 
#37
hollowboy said:
1) I think I've seen it without paying much attention. At a glance, it looks like an ugly compromise: an approximately conical horn, with lumps. I'd rather have a compromise that looks elegant 🙂

2) It looks like there's a typo in the page you linked to - "Now, we introduce an initial flare with, say, a 100 Hz. lower cutoff." 40Hz -100Hz doesn't make sense.

3) With old compression drivers, the mismatch is usually the other way around to what is shown on that page.

e.g. until they changed up about 10 years ago, a typical all-JBL system mounted a driver with a skinny (~160Hz) snout on a squat (~500Hz) horn:

JBL Technical Note, Volume 1, Number 21
By our calculations, the initial flare rate in the older
driver design was approximately 160 Hz, reflecting the
need to drive the very large horns that were used in
early motion picture systems. Today, we can double or
quadruple that flare rate, inasmuch as many horns are
now intended for nominal crossover at 800 Hz.​
I really like this quotation:

a) it's great of the company to admit that for a couple of generations, they were manufacturing drivers that were inconsistent with their applications and horns.

b) It makes me wonder what other design assumptions are currently being copied, just because 'that's how it's done'.
Click to expand...


Rubber throat can be good for cones that peak at flare Frequency. never seen anyone try it with compression drivers.

The slow flare in the old drivers work with the big horns that sound good with the slow flare and mated with a bass horn. They can also be good with mid size 300 hz horns. The short fast flare drivers (radian, celestion, new JBL mid format, Faital ect) are for the fast flare new style horns that are mostly used much higher with success and mated with the compromised direct radiation low range. It has zero to do with fidelity IMO and has to do with size and weight compromises.
 
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