Arkytype's Extreme Horn Makeover

[Q-Man]

Sorry for that drawing.

I ment to post a few pictures of my modified Klipschorn. I thought that drawing was one.

The drawing is a crude design for a new room that I'm working on.

I'll try to find the pictures later and post a couple.

[Al Klappenberger]

Q_man,

I'm glad you goofed! That drawing is very interesting.

Al K.

[Deang]

"The drawing is a crude design for a new room that I'm working on..."

That's a crude drawing? That's what mine look like when I'm getting serious, lol.

Shawn -- thanks for the time you took to do that well written explanation. I've read similiar things elsewhere, and even how they relate to some other speakers. If I'm remembering things right, isn't there some debate regarding the audibility of what you're talking about? Maybe some people pick up on it, and other's don't. Interesting stuff. Did PK ever address the issue in writing?

[Al Klappenberger]

Dean,

Try downloading the paper I wrote called "A case for extreme slope networks" from my web site. I think it deals with some of the points Shawn made.

Al K.

[sfogg]

Dean,

"isn't there some debate regarding the audibility of what you're talking about?"

There is debate regarding absolute phase audibility overall in a speaker (seems to basically be inaudible on music but can be audible on specific test tones) but very little debate about phase at the crossover points since it will alter FR at crossover points.

As far as interaction between drivers that is easily audible if you know how to listen for it or what to listen for.

BTW, the info I posted I didn't get from Al. I got it from papers and information written by people like Dr. Floyd Toole and Kevin Voecks who have done lots of research (and double blind tests) on things like audibility of phase, off axis response and so on.

Shawn

[John Warren]

A registration requirement with this BB is that manufacturers reps identify themselves. Given the information posted by Lee here AND his setup is posted concurrently on ALK website, the impression is given that Lee is an ALK rep. He is not. If he was, it would require that a statement be made to that effect.

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My questions were completely justified and clarification was in order. Also, for those of you that post on other BBs and moderated Usenet sites manufacturers are banned from posting entirely.

Some of you know that I have pitched the JBL 2404H tweeter as an upgrade. I have a page devoted to it on my website. Many, many of the members on this board have asked me questions about it. If I was receiving compensation of some type from JBL for posting the 2404H upgrade on my website, how would that sit? Especially after you purchased a pair based, without hearing them, on my recommendations. I suspect that a few of you would be pissed-off especially after plunking down $600 for a pair of the tweeters alone. For the record, I am not affiliated with JBL and if I was, I would state it.

I have no axe to grind with ALK on this. I consider him a manufacturer and, as such, hold him to a different standard than an individual contributor.

[Al Klappenberger]

John,

Your objections are noted. That makes ONE OF US!

....................

Oh, BTW: Here's a little quote from somebodies web site:

***Please note that manufacturing rights are the property of The Audio Engineering League.

Sounds like an equipment manufacturer to me.

Al K.

[Al Klappenberger]

Guys,

The subject of phase error audiblilty has been a subject I have been

quite interested in investigating. After a lot of experimenting I have

convinced myself that the type of phase errors created by time delay between

drivers (time alignment errors) and crossover network filters is totally

inaudible. Here is an experiment that I did a week or so ago to finalize my

thinking on the subject:

First a little background.. Consider what a square wave is composed of with

respect to its harmonic spectrum. It is a fundamental frequency (a sine wave)

combined with all its odd order harmonics (also sine waves) with amplitude

equal to 1 / n times the fundamental voltage level. Each harmonic starts at

zero time from zero voltage and rises in the same polarity for the first half

cycle. That is what makes the fast rise. All are going up or down together.

Each harmonic is therefore said to be "phase-locked" to all the others. This

condition repeats continuously.

Now.. Suppose we consider only the fundamental frequency, the 3rd and 5th

harmonic of the fundamental at 1 Khz. Phase distortion shifts the phase of

each of these harmonics by a different fixed amount for each harmonic. This

distorts the waveform. The question becomes, can you hear this distortion?

Suppose we generate this spectrum using THREE SEPARATE INDEPENDENT SINE WAVE

GENERATORS, one at 1 KHz, one set at 3 Khz and the last set at 5 Khz. We will

mix them together in the correct proportions to make a crude square wave.

That could be 1V, .33V and .2V respectively. There will be no way to phase-

lock each of these generators to one another making the phase relationships

totally random and continuously changing because of the slight frequency

errors between them. Each generator will be adjusted a closely to the proper

frequency as possible using a frequency counter to begin the experiment.

Connect the mixed signals to an oscilloscope and to an amp driving a set of

headphones. You will see the waveform on the oscilloscope slowly crawl and

squirm through every possible waveform that these three sine waves can

produce. You can refine the frequency of each generator by adjusting each to

get the most stable waveform you can get. For an instant, every once in a

while, you will be able to get it to resemble a crude square wave. While

watching the scope for visual clues, listen to the sound in the headphones to

see of anything in the sound corresponds to the change in the waveform on the

scope. I submit that you will not be able to hear any change at all! I

couldn't! Only when one of the generators was off-tuned enough to create a

beat note (a wa-wa-wa sound) could I hear any change. Note that the phase

distortion generated by a loudspeaker can not cause the phase of harmonics to

rotate as in this experiment, but only to be shifted by some fixed amount

from where it should be. That is, the waveform will be wrong, but totally

stable.

I'll admit that not to many people (other than equipment manufacturers, that

is) will have three sine wave generators laying around as I did, but some of

you may have two. You might also be able to do it with only one by recording

the fundamental frequency on a cassette deck then playing it back into the

mixer while using the same generator to make the 3 rd harmonic. The 5th

harmonic is really not needed to prove the point.

I encourage everybody who has the equipment to try this experiment! I would

like very much to hear if others can hear a change as the phase changes.

Al K.

[John Warren]

----------------

On 6/7/2004 8:16:01 PM Al Klappenberger wrote:

John,

Your objections are noted. That makes ONE OF US!

>>you or me, I'm a bit confused? which one is the "one" and which one is the "us"?

....................

Oh, BTW: Here's a little quote from somebodies web site:

.

***Please note that manufacturing rights are the property of The Audio Engineering League.

Sounds like an equipment manufacturer to me.

>> I said "please" and what of it? I like that statement. It makes perfectly reasonable sense given that the contents of a few of the pages contain intellectual property (the 2404H and the dual 2123J Projects).

Al K.

>>Now it's your turn...

Here let me start it for you...

Blah, Blah, Blah...

----------------

[Al Klappenberger]

Guys,

Here's more evidence that phase errors don't matter.

The attached graphic is a plot of the "transfer function" of one of my

modified Belle Klipsch speakers with the mike at two different distances

represented by the two traces (black and yellow). The top plot is the phase

response. Each "tooth" of the sawblade represents a 360 degree change in

phase at each frequency. As you can see, phase changes so fast your ear /

brain combination can't possibly follow it. In addition it is drastically

different at every place in the room! Your brain has long since given up

trying to sort out something that is so random.

Another big scare factor people always talk about is "group delay". This is

defined as the "slope" of phase change with frequency change. On the plot, it

is the angle of each tooth with respect to the next. In an extreme case it

would show as a curve rather than a straight line on each "tooth". A

crossover network contributes its biggest group delay distortion right at the

crossover. That's at 7500 Hz in this speaker (the red marker). Can you see a

change in the slope of the "teeth" there compared to others? I can't. This is

an extreme-slope network too! It admitadly has the worst group dealy

distortion of any type network.

Al K.

P.S.

I just looked more carefully at the phase plot below the woofer / squawker crossover at 700 Hz. You can clearly see the spacing between the "teeth" is tighter down below 700 Hz. I believe this is due to the longer path length from the woofer. This makes more time dealy.

[Shock-Late]

Nice informative post.

Arkytype, did you remember if the k55v/511B/beyma CP25 sounded "too soft" when still using the AA network?

I'm using EV SM120 mid horns, would like to upgrade the tweeters... i find the T35 rather harsh and a bit too loud on some music now that i modded my AA x-over (1uF bypass x-over)

But that said, I like some "bite" in the treble and don't want my scalas to sound overly soft.

knowing that I wont upgrade my x-overs before a long time, should I still buy some CP25? What's your advice?

[Al Klappenberger]

Shock,

Before you buy a new set of tweeters, try putting an adjustable "L" pads in the tweeter cables first. I bet that will solve the problem and save you a bundle.

Al K.

[sunnysal]

al where I can I see more info on the extreme slope x-overs. have you designed them for k-horns yet? regards, tony

[Al Klappenberger]

Anthony,

There's some details on my web site about the new networks (alkeng.com). I have not release the design to the DIY group yet for the Khorn version becasue I am still tweaking some details. The 600 Hz version for the LaScala running 2-way is there for download though. I may not be able to release the 5800 Hz design at all becasue the layout is so critical. Time will tell though.

Al K.

[Colin]

Nobody within the fall-out radius of Arkytypes seminal home music reproduction system has an excuse NOT to email him and get his fat butt over to hear his system. It is NOT the end all and be all of dream systems, but the ALK ES crossovers, with Behringer EQ, larger JBL 511 lens and Beyma baby-cheek tweeters is a smooth combination with his vintage solid-state McIntosh receiver. It is as thoughtful and economical improvement to big ole horns as any I have heard.

Caveat emptor: I am only saying nice things so ALK will give be a discount on his ES crossovers.

(just kidding as usual; still debating bi and tri-amping, to get more bass power cheap)

[Al Klappenberger]

Colin,

CAREFULL! Somebody might say that you are on my payroll!

Al K.

[Colin]

Well, in the interest of full disclosure: I am blonde, blue-eyed, extra padding from living so large

[J.4knee]

OK informal poll here: How many of us needed a lift gate to pick our jaw off the floor when we saw Q-Man's "crude" drawing? I thought I could pee in the tall grass with the big dogs because my rig will have 3 La Scala's across the front 2 Heresy II front effects and 3 Heresy II surround and rear center speakers. Q-Man you have more La Scalas used for front effects and surrounds than I have my main array. Did you do the JBL/Altec/John W mod to all of your K-horns or just the front 3? I know your mains and center have it I saw that in your K-horn center thread. Not to mention but all 10 channels you have are all Mac powered correct? WWWWOW!

[Colin]

pee in the tall grass with the big dogs gee, can I steal that?

Q-mans drawing? How about ALKs explanation! Whoof!

[J.4knee]

Sure you can steal it. But if I had my prefernce you'd rent it.

Yeah Al's explantions are always impressive kind of like taking a filter design class with no homework required. I should not be so overly wowed by Q-Mans stuff by now as I followed his K-Horn center thread fairly closely but his stuff still just amazes me. The man is a true craftsman.