All horn 2-ways need PEQ

[ClaudeJ1]

All of the curves I have done on bass and treble horns seem to have a "hump in the middle" type of response. This necessitates some form of EQ at the end (or a broad push down in the middle).

Since the efficiency is from 10-100 times greater than direct radiators that merely attempt to "push" air instead of shooting it. This is easy to do.

So I think the most coherent example of all modern horn design is the custom Jubilee and Tom Danley's Synergy horns.

But you still need sub-woofer below 40-60 hz. to get you flat to 20.

[djk]

Danley has a smaller Synergy horn that would work well with my PPSL designs.

A LaScala sized PPSL and Synergy combo would be 100.5dB in 2Pi (without room gain) and -3dB at 27hz.

I shouldn't mention this, but my prototype dual 15 PPSL made the Klipschorn sound distorted in the bass and anemic.

If you're willing to biamp then any F3 is possible on the low end, the above mentioned combo could be all passively crossed.

[ClaudeJ1]

Danley has a smaller Synergy horn that would work well with my PPSL designs.

A LaScala sized PPSL and Synergy combo would be 100.5dB in 2Pi (without room gain) and -3dB at 27hz.

I shouldn't mention this, but my prototype dual 15 PPSL made the Klipschorn sound distorted in the bass and anemic.

If you're willing to biamp then any F3 is possible on the low end, the above mentioned combo could be all passively crossed.

You appear to be a fan of PPSL. Do you have measurements? I seem to recall you also used EV 6040 horns........have 3 of those in the garage.

[DrWho]

I shouldn't mention this, but my prototype dual 15 PPSL made the Klipschorn sound distorted in the bass and anemic.

Distorted? Then something was wrong with your KHorns. No way a dual fifteen is lower distortion.

And don't get me wrong - I prefer my single fifteen, but it's not lower distortion and certainly doesn't have the same dynamic capability...

[Deang]

He didn't say it was more distorted, he said it sounded more distorted.

[DrWho]

Then he's deaf

[djk]

"Then he's deaf"

Is your IQ above room temperature?

Do you even know what a PPSL is?

The Klipschorns were brand new, we were at one point in time the largest single dealer that Klipsch had.

Art Welter measured a PP pair of Lab 12 woofers as having a 30dB reduction in distortion at full power, I usually only claim 20dB.

My PPSL make bass horns sound distorted, period.

Wayne Parham makes some PP bass horns, a derivitave of the LAB 12. His measurements show much less distortion vs non PP. He and Danley would get into it at some live sound forums about the PP thing. Danley now has four models with PP mounted woofers. A friend on mine converted his LaScala to PP and was stunned at how much better they sounded. He wants to produce them commecially and take them to the RMAF.

You know how the Klipschorn sounds so much cleaner than the Cornwall in the bass? The PPSL is an order or magnitude cleaner compared with the Klipschorn.

The stacked pair of PPSL are a 4Ω load, and use a custom-made varient of the Klipsch K43 (I have an OEM account with Eminence). With 2.83V they are about 107dB at 1M in 2Pi, and are -3dB at 31hz. They are crossed at 150hz to the mid horns, which in turn cross aound 1.2Khz to the HF horns.

My proposal above would be smaller (for WAF), go deeper, and and be 100.5dB/2.83V/1M for a cut-off of 27hz.

For the man-cave/shop I would build a half-stack of units similar to the photo.

Edited December 17, 2013 by djk

[DrWho]

Are you talking THD or IMD? I'm a big fan of PP but it doesn't fix the Doppler effects. You will see a larger reduction in distortion for drivers with extreme asymmetry in motion and diaphragm flex. For more linear drivers, the benefits start to reduce and then you're left with canceling mechanical motion to make it easier to brace the box - that's the biggest advantage in my mind for modern designs. I've not seen a Klippel on the K43, but I doubt it's a very symmetric or linear driver. Audibly the K48 seems more authoritative to me, but it's not the best available either.

Btw, I was kidding about being deaf, and was more trying to emphasize the importance of accurate correlation of perception to measurement. Saying it "sounds lower distortion" when it's not is applying a double meaning to the definition of distortion. Things like distortion have very strict definitions in the engineering world - why not reuse those definitions? Claiming it's not audiophile is missing the point entirely. And if you didn't catch it, I'm saying I too would prefer a PP over the khorn. The only thing I'd do differently is design a phase plug and run at a higher passband so I can use way better woofage on the bottom, and a different tweeter up top. Maybe even put a lens on the PP to help the polars line up with the tweeter better....

[djk]

"Are you talking THD or IMD?"

Both really, but mainly THD. About 4dB~10dB reduction in IMD (depends on the mix of frequencies).

"I'm a big fan of PP but it doesn't fix the Doppler effects."

The right-angle exit reduces it quite a bit as the cones are not moving towards and away from you.

"You will see a larger reduction in distortion for drivers with extreme asymmetry in motion and diaphragm flex."

True, it make inexpensive drivers useful.

" For more linear drivers, the benefits start to reduce and then you're left with canceling mechanical motion to make it easier to brace the box - that's the biggest advantage in my mind for modern designs. "

True, but you can still hear big improvements in PP with good drivers. Shorting rings don't really work in the bottom octave. The PPSL does a great job at canceling mechanical forces in the cabinets, they don't 'walk' at all, and they don't 'talk' much either (good but simple bracing scheme).

"I've not seen a Klippel on the K43, but I doubt it's a very symmetric or linear driver. Audibly the K48 seems more authoritative to me, but it's not the best available either."

I haven't seen Klippel data either, but don't really care one way or another. Klippel data on some inexpensive 8's run in PP vs normal show the PP ameliorating the really asymmetrical Bl vs position seen in the single driver data, and an increase in useable displacement of almost 3dB more than what you would expect from just doubling the drivers.

"Btw, I was kidding about being deaf, "

As I was in asking the question about your IQ.

"and was more trying to emphasize the importance of accurate correlation of perception to measurement. Saying it "sounds lower distortion" when it's not is applying a double meaning to the definition of distortion. Things like distortion have very strict definitions in the engineering world - why not reuse those definitions? Claiming it's not audiophile is missing the point entirely. And if you didn't catch it, I'm saying I too would prefer a PP over the khorn. The only thing I'd do differently is design a phase plug and run at a higher passband so I can use way better woofage on the bottom, and a different tweeter up top. Maybe even put a lens on the PP to help the polars line up with the tweeter better...."

The stack (which dates back to 1988) shown in my photo is mechanically time aligned, and pattern matched at mid and HF, so an inexpensive analog crossover may be used. The inexpensive digital crossovers leave something to be desired. I'm not overly worried about the measurements, the very strict definitons have little correlation with how things sound. Pehaps I should have said 'it has much less coloration when reproducing music'? A bass horn does not need a phase plug, and neither does a 1Khz mid horn.

A possible future project might be a vented PP Belle/LaScala with dual 15's, the vented LaScala my friend converted to PP uses quad 8's and he has a set of four of the K43 clones (which I have used 6th order to 28hz with great success). The 'throat' would have reduced area and dimensional spacing similar to a phase plug by virtue of the PPSL mounting. It will be worth exploring to see how much the HF can be extended with this method.

Edited December 18, 2013 by djk

[djk]

http://www.cowanaudio.com/images/unity28.jpg

This is William Cowan's clone of a Danley piece that is useable from 100hz to the limit of the HF driver you choose. It uses a pair of $232 B&C 8" drivers to handle a ton of power at 100hz. I would make the same sized horn (about 24" wide), and use a pair of 6's or a quad of smaller drivers (like the original Unity horn). The driver summation is even beter than the BMS co-ax drivers because the mids are ahead of the HF driver by a 1/4W at the crossover frequency, thus compensating for the inherent delay in the network (the tweeter in the BMS actually needs some delay for the best performance).

Renkus Heinz also has a similar setup with a pair of 6's and a 1" compression driver "In our original CoEntrant designs, the output of multiple mid and high frequency transducers were integrated into a single acoustic source, with inherent alignment in both space and time."

http://www.soundimage.dk/images/Renkus-coenmh.jpg

A Yorkville Unity model designed by Danley and Woods using three very inexpensive 5's for the mids.

http://www.dynamicmusic.com.au/ProductImages/YU0005.JPG

Edited December 18, 2013 by djk

[ClaudeJ1]

My Danley DTS-10's use a push pull configuration. I believe the argument between Wayne Parham and Tom Danley had to do with Danley saying that a pair of LABhorns in a home environment could be EQ'd flat to 20 hz. with about a 10 db boost, which it can afford, excursion-wise, with two 12's per cabinet, fully horn loaded (not tapped). Parham claimed the horn was too short (about 10.5 feet) to go that low. I agree with Danley, since, like the THT, it relies on cabin gain andn corner loading to pick up the low end substantially beyond the horn's Fc.

Edited December 18, 2013 by ClaudeJ1

[ClaudeJ1]

djk,

Are your mid horns 640's? Which drivers, the EV DH1A's? had a bunch of those. Great drivers, but that horn didn't satisfy my ears in my old MWM stack in the basement. Maybe I was crossing it too low.

Edited December 18, 2013 by ClaudeJ1

[DrWho]

Both really, but mainly THD. About 4dB~10dB reduction in IMD (depends on the mix of frequencies).

IMD should be a straight up 6dB reduction due to doubling of surface area. Anything greater should be a result of DI which should be ruled out for comparisons of this nature (not to completely ignore the final system response though).

The right-angle exit reduces it quite a bit as the cones are not moving towards and away from you.

If that were true, then IMD would be reduced when listening off-axis of a standard speaker, which is unfortunately not what we experience. The instantaneous particle velocity in front of the driver is the same regardless of where the listener is....and it's that particle velocity of the HF motion tracking along the LF motion that causes the doppler effect to happen right in front of the driver. The resultant wave starts with the distortion product and the rest of the acoustical behavior is straight up wave propagation which always preserves the original frequency content of the source.

The only reduction in IMD is back to the first point of reducing the overall excursion requirements by doubling up the surface area.

Shorting rings don't really work in the bottom octave.

Inductance modulation only affects the top side of a driver's passband anyway.

The inexpensive digital crossovers leave something to be desired.

Totally agreed.

I'm not overly worried about the measurements, the very strict definitons have little correlation with how things sound.

To date, I have never experienced the lack of correlation between measurement and audible perception. When I hear people make these comments, the only logical conclusion is that they have not yet learned to understand the correlation. And I certainly don't say that in a demeaning way whatsoever as there are many things where my correlation continually gets refined. This hobby / profession is so interesting to me because you can't ever look at any one variable in complete isolation - there's always tradeoffs to be made.

My experience thus far has been that people (especially engineers) tend to way over-emphasize the importance of certain quantifiable attributes - especially attributes where the mechanism is felt to be understood extremely well. On the flip side, people (especially engineers) will under-emphasize attributes that aren't very well understood, or don't fit existing paradigms. I believe this to be the major source of discontinuity between the measurements and the audible perception - in fact, if you define the audible significance of a quantifiable parameter by its actual audible significance, then the measurement and perception will ALWAYS correlate....but humans don't naturally observe the world in that manner. For me it is often a conscious exercise.

In other words, it's called being open-minded and continually refining one's perspective of the quantifiable world.

All that to say, I have enough quantifiable data to rationalize my distaste for the khorn's sound - which I want to stress is my favorite bass horn of all time from an engineering perspective. The data I've seen correlates to acoustic impedance mismatch from an undersized horn and the corresponding ringing that results in drums sounding like they're being beat inside a bath tub. I don't want that tonality added to my bass guitar - I'd much rather have the fatness generated from extra IMD....especially considering the studio monitors were exhibiting that distortion at the bottom octaves too. Bass don't got no soul when it gets too clean....but it's gotta be the right kind of grunge or it gets annoying. And of course that changes with the type of music - and some of it don't want any kind of grunge and benefits from the ultra-clean....but I personally don't generally find that music or those recording styles to be that interesting. I would much rather just go experience the real event in person.

Edited December 18, 2013 by DrWho

[mark1101]

Agreed........mostly. But measurements can't totally dial in your sound. You may prefer the sound of a curve or waterfall plot that does not appear to be as technically correct as another. You can have 2 plots......one on top of another..........but they can sound different. Why? There are characteristics of sound reproduction that defy measurements. So what do you correlate then? All I am saying is that you will never be able to dial in your final sound without listening to it. I understand that you can use measurements to weed out anomalies, and can get good at that with practice.

Edited December 18, 2013 by mark1101

[djk]

"Agreed........mostly. But measurements can't totally dial in your sound. You may prefer the sound of a curve or waterfall plot that does not appear to be as technically correct as another. You can have 2 plots......one on top of another..........but they can sound different. Why? There are characteristics of sound reproduction that defy measurements. So what do you correlate then? All I am saying is that you will never be able to dial in your final sound without listening to it. I understand that you can use measurements to weed out anomalies, and can get good at that with practice."

+1

[ClaudeJ1]

vewy intwestink.

[ClaudeJ1]

We got a bit off track here, but I digress...........................................So do my expert engineer friends agree with the title of this thread?

[djk]

"Are your mid horns 640's? Which drivers, the EV DH1A's? had a bunch of those. Great drivers, but that horn didn't satisfy my ears in my old MWM stack in the basement. Maybe I was crossing it too low."

The HF horns are HP640 with DH1A with the thinner DH7 diaphragms. They are crossed above 1Khz (as required by the thinner DH7 diaphragms), with CD horn EQ. The horn has about 2" of rigid foam on the backside, that alone makes them sound better. The whole system measures very flat without using a graphic EQ (crossover has CD EQ for the HF and the 6th order filter for the PPSL cabinets).

I don't generally use an EQ to go after room modes (that are in the time domain), EQ is best used for amplitude response issues.

[ClaudeJ1]

"Are your mid horns 640's? Which drivers, the EV DH1A's? had a bunch of those. Great drivers, but that horn didn't satisfy my ears in my old MWM stack in the basement. Maybe I was crossing it too low."

The HF horns are HP640 with DH1A with the thinner DH7 diaphragms. They are crossed above 1Khz (as required by the thinner DH7 diaphragms), with CD horn EQ. The horn has about 2" of rigid foam on the backside, that alone makes them sound better. The whole system measures very flat without using a graphic EQ (crossover has CD EQ for the HF and the 6th order filter for the PPSL cabinets).

I don't generally use an EQ to go after room modes (that are in the time domain), EQ is best used for amplitude response issues.

Thanks for filling in the blanks. Time domain issues are handled by Audyssey Voodoo in my listening room. Takes a while to master the miking technique because it messes with the imaging quite a bit, but once it's done and all the receiver selections tweaked, it's nothing short of amazing. 2.1 or 7.1 for dummies, I call it. Sometimes I like to be a "dummy" and just enjoy the music without breaking out the all the measuring tools, which should be tweaked before applying Audyssey anyhow. Love them Blue Ray concerts, but most times, they sound better in 2.1 than DTS.

Edited December 20, 2013 by ClaudeJ1