The Klipschorn Woofer Polarity Challenge

[John Warren]

10 hours ago, Don Richard said:

Since the Khorn woofer is about 4 feet out of phase (greater than one wavelength) with the mid at crossover, along with the aforementioned crossover phase shifts which push the woofer even further out of phase with the mid horn, it's no wonder changing the woofer's electrical polarity yields little audible difference. Phase shifts greater than 1/4 wavelength do not allow for coherent summation of the woofer and mid horn outputs. The arrival times from each driver within the speaker need to be the same before polarity differences between the drivers can be consistently heard.

 

It's also why the steep slope, passive net doesn't get it right.  The fix is DSP.

[BeFuddledinMn]

It looks like we're getting all the pieces out on the table here thanks to the many great contributions, but I have to interject for a moment with a bit of a laugh......

 

In looking for Paul Klipsch's thoughts on the topic, I came across this piece from 1961 in reference to polarity and phase:

 

 

Too bad I couldn't locate the referenced report, but I had to chuckle a bit here because it would appear that if PWK were still here, and were to visit our forum, he might not stop talking for two weeks, lol.

 

- BeFuddledinMn

 

 

[Khornukopia]

My good sounding K-33's wires are soldered at both ends, so I decided I will leave well enough alone for now, and just read about other people having fun.

 

[Khornukopia]

Listening to some music and thinking about this topic, I remembered that my electronic crossover allows me to select the woofer, mid or high frequency driver channel and invert the polarity. Toggling between normal and inverted polarity does not seem to sound much different with the steep slopes and the music that is playing now, but this touch screen option will make things easier for when I can set aside a good amount of time to stand up a microphone and run some tests. 

 

[Wirrunna]

On 17/04/2017 at 8:57 AM, John Warren said:

 

It's also why the steep slope, passive net doesn't get it right.  The fix is DSP.

Well, an ES network gets it fairly right.

Measurements taken 1m on squaker axis using a Mitey Mike into a Liberty Instruements Mic / Probe Preamp then into REW.

I swapped polarity of the Top Hat connection rather than the woofer and nothing appeared to change.

 

[John Warren]

To eliminate the differences due to the path lengths must be DSP.  No passive or analog active can do it.  

[garyrc]

On 4/16/2017 at 3:30 PM, wvu80 said:

...

I have never understood how simply reading a graph can be translated to "how good is the sound?"  I believe the theoretical "perfect" graph would be a straight line, but if it's not, then what should it be?  If you took the best sounding speaker in the world (whatever that would be) then what does it's graph look like?

 

I know that is an elementary level, but that is my level, and I am willing to learn.

 

Go ahead with your discussions, I'll try to keep up. 

As I'm sure you know, "the best sounding speaker in the world" would still sound bad in some rooms, with some recordings.  According to PWK, the best speaker in the world would be one with very low distortion, including modulation distortion.   That would probably require horn loading throughout the range.  High efficiency would be a welcome side effect.  The "perfect graph," as measured in an anechoic chamber would not be a straight line in our listening rooms, as long as the rooms we put the speakers in are imperfect.    According to Harman inc, and other researchers, the best sounding sound system and room combination would, from the main listening position, have a frequency response curve that starts rather elevated in the bass, and smoothly descends as the frequency gets higher, until it reaches 9 or 10 dB lower at 20KHz than it was at 20 Hz.  That would be a proposed ideal, and I don't know anyone who has achieved it in a home or Home Theater.  I have managed that general shape in my Klipschorn system (31.5 Hz to 15KHz), and it usually sounds very good.  There are plenty of odd recordings that call for individual EQ, though.  Rumor has it that sometimes recordings are made very un-flat and compressed because the record companies think they will appeal more to the average user that way, and also help them win the "Loudness Wars."  Given all of the above, a straight line may be the last thing we want.  See J. Gordon Holt's article, "Down with Flat," in the archives of Stereophile, findable through Google (for those who don't know, Holt started Stereophile, and edited it for years).  Although he was not a great fan of Klipschorns, he hypothesized that the reason musicians liked them so much was that they triggered their "musical Gestalts."  I would add that in those days, musicians often had 15 i.p.s. 1/2 track reel to reel tapes of their own performances that hadn't been monkeyed around with.  I'm hoping (and betting) you are getting your musical Gestalt triggered by your Klipschorns, regardless of how old they may be..

 

 

[wvu80]

31 minutes ago, garyrc said:

I'm hoping (and betting) you are getting your musical Gestalt triggered by your Klipschorns, regardless of how old they may be..

To be honest, I'm mixed on the Khorns, currently in the living room hooked to an AVR and used for TV and occasional movies.  I have a Crites A-4500 XO and a much more robust tweeter but still can't get the dynamic sound @mustang guy gets with his 3.x La Scala setup.  He has a ton of power using an Integra solid state amp and pre/pro while I am using my pedestrian Onkyo 717 with a meager 110 wpc.

 

I am aware that the Khorns like tube power but I really don't want to go down the rabbit hole of tube gear.  I want an AVR for ease of use that will have the dynamics I crave.  The love the Onk with all its sound codecs and listening modes but the fact is there is better stuff out there.  All it takes is money.

 

My highly modded CF-4's with a sealed 15" sub is what gets me going.  Even with an dated Pio AVR it sounds better than anything else I have heard.

+++

 

Thanks for the explanation of the charts and graphs curve.  I know some of you guys can read those things like a book but I still need the Cliff's Notes edition.

[oldtimer]

Dave.  Dave, Dave Dave...Try a little tenderness

 

But it's all so easy
All you got to do is try, try a little, tenderness yeah
All you've gotta do is, man
Hold her where you want her
Squeeze her, don't tease her
Never leave her, get to her
Just try, try a little tenderness, y-y-yeah
You got to love and kiss her, man
Got to, got to, got to, don't lose her, no, no
You got to love her, tease her, don't you leave her
Got to try, now, now, now
Try, try a little tenderness
Yeah, watch the groove now, you gotta know what to do, man

 

[CECAA850]

Dave, doesn't Mustang guy have his Lascalas in a huge garage area?  The difference between that room and your living room is enough to void all speaker comparisons. 

 

Receivers aren't the last word in sound quality or amplifier sections either.

[oldtimer]

You know I'm right Carl.  Rather, Otis Redding is right.

[CECAA850]

9 minutes ago, oldtimer said:

You know I'm right Carl.  Rather, Otis Redding is right.

You're both right.

[garyrc]

19 minutes ago, wvu80 said:

To be honest, I'm mixed on the Khorns, currently in the living room hooked to an AVR and used for TV and occasional movies.  I have a Crites A-4500 XO and a much more robust tweeter but still can't get the dynamic sound @mustang guy gets with his 3.x La Scala setup.  He has a ton of power using an Integra solid state amp and pre/pro while I am using my pedestrian Onkyo 717 with a meager 110 wpc.

I doubt if the problem is that your Onko has a "meager 110 wpc."  AVRs tend to produce about 80% of their rated power when all channels are operating, about 88 wpc for an AVR rated at 110 wpc, but 88 watts is plenty for a Khorn, unless you have a huge room.  Some electronic components do sound more dynamic than others, but the reasons are mysterious (at least to me).  This might be another one of those instances in which the measurements and specs don't tell the whole story.  I assume you have the Khorns pressed into the corners, with some gasket material (pipe insulation or the like) and no obstructions 4 feet out from both corners.  With my Marantz pre/pro, NAD 150 wpc power amp, the Khorns are dynamic as all get-out.  If you have tone controls, have you tried boosting the bass a little?

[Wirrunna]

wvu80, here are some Cliff's notes on my earlier graphs.
First, the purpose of the graphs was to show that an Al Klappenberger (ALK) Extreme Slope (ES) network all but eliminates the interaction between the woofer and squaker and therefore the polarity of the woofer becomes irrelevant.

If you look at BeFuddledinMn's first post, the second and third graph show the output of the woofer (second graph) and midrange (third graph). Of note here is the amount of sound that these drivers put out after the nominated crossover point of 400hz. The midrange (third graph, green trace) has output down to 250hz. The result of this is that any music that has a note between 250hz and 400hz is output by both the woofer and the midrange and due to the woofer horn length the midrange's output arrives at the listener before the woofer's output.

Some people have described this as "smear" and there are lots of opinions of how audible this is.

 

My graphs, especially the third graph, show that an ES network cuts the output of the drivers severely at the crossover frequency of 400hz - look at the blood red and brown traces - virtually eliminating the interaction between the drivers and so making the question of woofer polarity irrelevant.

 

Now, the big debate is "does this sound better ?".

My 2 cents worth is a resounding yes, but there are a lot of folks that say no.   

[wvu80]

1 minute ago, garyrc said:

I assume you have the Khorns pressed into the corners, with some gasket material (pipe insulation or the like) and no obstructions 4 feet out from both corners.  With my Marantz pre/pro, NAD 150 wpc power amp, the Khorns are dynamic as all get-out.  If you have tone controls, have you tried boosting the bass a little?

I do have them in corners, but they are poor corners and I do have obstructions, a couch on one side, and the left Khorn is tucked up against some window curtains.  I also don't have them sealed as you say.  What would you suggest for me?

 

As far as tone controls I go back and forth on that.  I have used the AVR to boost the 250 and 400 range from 1-3 db and I have also tried lowering the mid 1-3 db, all with unsatisfactory results.  What I perceive I am missing is authority in the range of a tuba.  I can hear the sound, but I don't feel it like I think I should.

[wvu80]

14 minutes ago, Wirrunna said:

wvu80, here are some Cliff's notes on my earlier graphs.

Thanks!

 

First, the purpose of the graphs was to show that an Al Klappenberger (ALK) Extreme Slope (ES) network all but eliminates the interaction between the woofer and squaker and therefore the polarity of the woofer becomes irrelevant.

If you look at BeFuddledinMn's first post, the second and third graph show the output of the woofer (second graph) and midrange (third graph). Of note here is the amount of sound that these drivers put out after the nominated crossover point of 400hz. The midrange (third graph, green trace) has output down to 250hz. The result of this is that any music that has a note between 250hz and 400hz is output by both the woofer and the midrange and due to the woofer horn length the midrange's output arrives at the listener before the woofer's output.

Without input from anybody else, this particular range has never been as solid as I think it should be.  My reference point is orchestral, and I've never heard tuba play with the authority those things put out, even with a sub.

Some people have described this as "smear" and there are lots of opinions of how audible this is.

I would describe that range as "anemic."  I have tried to compensate by boosting that 250-400 range, and sometimes lowering the midrange by 1-3 db, but I can't seem to get it right.  I don't blame the Khorns as my setup is not ideal.

 

My graphs, especially the third graph, show that an ES network cuts the output of the drivers severely at the crossover frequency of 400hz - look at the blood red and brown traces - virtually eliminating the interaction between the drivers and so making the question of woofer polarity irrelevant.

 

Now, the big debate is "does this sound better ?".

My 2 cents worth is a resounding yes, but there are a lot of folks that say no.   

I think my Crites A-4500 XO has a gentle slope.  I have heard others say they like the clarity of the steep slope but the trade-off seems to be the steep slope works better at higher SPL.  I prefer something that is comfortable in the low to middle SPL range.

 

Your thoughts?

[garyrc]

On 4/16/2017 at 7:59 PM, BeFuddledinMn said:

 

Too bad I couldn't locate the referenced report, but I had to chuckle a bit here because it would appear that if PWK were still here, and were to visit our forum, he might not stop talking for two weeks, lol.

Here is the abstract.  Bolding is mine.  I think the paper is in the Audio Papers that may still be available from Klipsch.

 

Abstract:

Following the teaching of the early Bell Telephone Laboratories' experiments in auditory perspective, wide speaker spacing is needed to realize accuracy of geometry. This results in substantially random phase, so that polarity is relatively unimportant. This is supported by Lissajous figures of two-channel stereo signals. It is still good practice, however, to observe polarities, if for no other reason than to permit monophonic reproduction over a stereophonic array. Where the stereo signals contain a strong monophonic component, correct system polarity is better than random polarity. In some stereo situations, bass is improved by correct polarities.

Published in: IRE Transactions on Audio ( Volume: 9, Issue: 1, January-February 1961 )

 

 

[garyrc]

1 hour ago, wvu80 said:

I do have them in corners, but they are poor corners and I do have obstructions, a couch on one side, and the left Khorn is tucked up against some window curtains.  I also don't have them sealed as you say.  What would you suggest for me?

The window behind the curtains doesn't provide enough firmness (unless, maybe, it is very thick plate glass, and not too large), and there isn't supposed to be a gap between the Khorn and the wall(s).

 

About all I can think of -- other than moving them to another room with good corners, which is probably best -- would be artificial corners, 3/4 inch plywood and studs, no floor, perhaps with hardwood veneer and a nice stain, minimum 48" out from the vertex.  Some of these can look good, but generally have a low WAF.  Someone else can discuss closing off the backs, BUT I suspect, in your case, this would be a compromise, because the side grills would be speaking out to that (probably flimsy) window glass.  If you get them into good corners don't be shy about trying up to 6 to 8 dB bass boost (a boost of only bass control + 2 on my old McIntosh).  Don't give up on the tuba -- do you play one?  The fundamentals may range from about 50 to 400 Hz, with overtones up to about 2K.

 

 

[wvu80]

2 hours ago, CECAA850 said:

Dave, doesn't Mustang guy have his Lascalas in a huge garage area?  The difference between that room and your living room is enough to void all speaker comparisons. 

 

Receivers aren't the last word in sound quality or amplifier sections either.

Yes, all true.  It's a big garage area but Craig has his sound dialed in.  You would think there would be an echo but there's not.

 

The heck of it is while I was there Craig put on some vinyl and immediately while standing within a couple of feet of his LS I could hear "the sound" I am missing.  I am hearing sound directly from the speakers, and they sound great as-is.

 

And yes, I know AVR's have inherent limitations, especially a low mid-tier AVR like my Onk.  @teaman got me hooked up with the highly regarded Sherbourn SR-120 AVR and the sound is phenomenal.  Unfortunately the SR-120 went belly up so I don't have access to it anymore to experiment with the Khorns.  I used it with my nearfield CF-4 setup and the results were spectacular.

[CECAA850]

A couple feet from his speakers you wouldn't have been hearing any boundary reflections.  It makes a big difference.