Arkytype's Extreme Horn Makeover

[Arkytype]

There have been several requests for images of my horn mods. Since I can't finger out how to (or if you can) post more than one image at a time, I'll start with this one.

My primary goal from the start was to improve the sound of my 1979 Klipshorns (purchased new) while leaving a stock exterior. Al K. and I had been corresponding a little over a year when I learned he needed a Klipschorn owner to measure the top section to see how (or if) the Extreme Slope network boards would fit.

After some trial fitting, he settled on a very workable design size-wise.

About this time, I got interested in the Altec Lansing 511B horn. The next thing I remember, doc, was there were two 511Bs being delivered from an eBay seller! With driver throat adaptors from Parts Express, I was set to have a showdown between the K-400 and 511B.

On axis, the K-55V/K-400 measures a little smoother than the K-55V/511B. Well, I thought, that was a waste of money! As an aside, with audio gear, I usually take something apart or measure it before actually listen to it.

I set the 511Bs and the K-77s atop the horn and began listening in earnest. The first thing I noticed was the naturalness of vocalists emanating from the 511B. Compared to the K-400, there was almost no trace of the "horn sound".

The next thing I remember, doc, I had a pair of Beyma C25 tweeters sitting on top of the 511Bs in place of the K-77s. OK, now the horns are beginning to sound like a live performance. By this time, Al had finished my second ES network and soon the AA networks were sitting on the floor looking very low-tech by comparison.

Soapbox: Despite the grumblings I've read on the Forum about the various Klipsch networks, I would suggest a reading of PWK's crossover network patents and especially the other patents cited to get an inkling of the process involved in designing, testing and then producing a crossover network. Sure, PWK could have used more expensive components in the networks or designed higher order filters, but remember, he was first and foremost an engineer who, by training, sought the cheapest, most efficient solution to a problem.

Having had the privilege of spending time with him in his lab in the mid '70s, I found PWK's approach to his work to be in the tradition of his predecessors and contemporaries in the field. He was certainly no mad scientist who delighted in frightening small children as was widely reported!

He embraced new measurement technology cautiously. One day, I (foolishly) ask him why he didn't have the latest measuring equipment from Bruel & Kjaer or General Radio. He gruffly replied that some salesman had demonstrated a piece of measurement gear that would spit out twenty feet of undecipherable BS printout at the end of a measurement run. His old Hewlett Packard X-Y recorder, home-made Logarator (logarithmic compressor) and the Bruel & Kjaer 4133 1/2" measurement microphone were all he needed to confirm the many hours of design and listening that went into each network.

OK, where was I? Bottom line? Al has taken an RF engineer's approach to network design for audio use. It is an elegant solution to a long-standing problem with the various Klipshorn networks.

So, how does the 511b/Beyma C25/ES network combination sound??

The one word I found that best describes the improvements is FOCUS.

As an avid photographer, I've learned that there is focus and then there is focus. If you stop your camera lens down to minimum aperture, you have maximum depth of field and everything from a certain distance in front of the camera to infinity is in focus. If, however, you choose to open the lens wide open, your depth of field will be reduced and only object in a relatively narrow window will be in focus.

Using that analogy, the Extreme makeover combination opens up the soundfield and everything is in focus. One really interesting benefit is that the soundstage width on well-recorded source material is wider than the spacing of the horns! Finger that one out.

In a nutshell, here are the improvements my ears hear with the makeover: The 511B/C25 upgrade is certainly worth the effort. For about $300.00 or so, you can make an audible, worthwhile improvement in your horns.

If you stick with the stock crossover networks, you're gonna hear bass that needs a steeper cutoff and more importantly, the phase rumdiddlies at the mid to high transition is going to sound even more unnatural. Having run many curves (amplitude and phase) at the crossover points, it's easy for me to see why the acoustic output is "scrambled" at the mid-to-high transition with the AA network.

When Colin and I were listening to my setup the Friday before The Gathering, he kept asking if the center Belle was on--the imaging is that good.

Here's the Reader's Digest version of how to add the 511B and the Beyma to your horns.

The 511B is about 3/4" taller than the interior of the horn top. There's plenty of room left-to-right to mount the 511B and Beyma CP25 tweeter. After CAREFULLY measuring, I routed two 3/8-inch deep grooves in the top housing so the 511B top and bottom flanges would be sandwiched. Since I didn't know if tweeters-out or tweeters-in would sound the best, I made the grooves wide enough (left-to-right) to build a mirror-image pair.

I replaced a few of the mounting strips to make a neater installation. The ES network fits nicely. One section of the 400 Hz board mounts on the woofer access door while the other two network boards fit inside the top housing. The ALK "A" network should fit entirely insidethe top housing.

The last item on the makeover list is one that will cause many of you to think, "OK, Arkytype has gone one step too far in this project."

Over the years, I've approached passive and active graphic equalizers (for home use) with some suspicion. For large arenas and other public nenues, an equalizer is usually a necessity to increase gain before feedback.

If one measures the "frequency response" of a home stereo, you quickly learn there are hundreds of different response curves that can be generated depending on the locatrion of the measuring microphone. The loudspeaker/room environment intreraction almost guarantees a response curve that doesn't match the advertising copy (or hype).

While my listening room is a work in progress, (I'm using RPG Flatffusor panels (www.rpginc.com/products/flatffusor/index.htm) as well as some inexpensive one-inch thick fiberglass lay in ceiling panels), it is "sounding" pretty good. I prefer a rather dry listening environment with the first-order reflections highly trapped or absorbed.

OK, back to the equalizer. I'm using a Behringer Ultracurve Pro DEQ 2496 which is an electronic Swiss Army knife in a box. Check out their website for the full specs. For $300.00 the DEQ 2496 will add the final touch to your horn makeover.

You can get Behringer's measuring mike for about $40.00 and with the built-in pink noise generator, get your system response within a 4 to 5 dB window from 32 Hz to 16 KHz without trying too hard. The unit also has an AUTOMATIC EQ mode for the truly lazy audiophile! It's like Ron Popiel says, "You set it, and you forget it!"

I EQ using a two-step process. First, position the mike at squawker level about one meter centered in front of the horn. Starting with the tweeter spectrum, adjust the filters to smooth out any peaks in the response (the Beymas are very smooth without EQ). Next concentrate on the 400 Hz to 5800 Hz range. Tame the peaks but don't try to fill the steep "holes" you might see.

Using a tip from Al K, make sure the left and right EQ settings for the mid frequencies (about 1 kHz and up) are the same. Otherwise, your imaging will suffer. Next, smooth any bass peaks but don't get too serious about getting the bass "flat"--that comes in step two.

Now, position the mike at the listening position. Unless your listening room is an ideal acoustic space (good distribution of room modes and a linear reverb time spectrum), you'll probably notice the bass probably has exaggerated peaks in the response that weren't there one meter away. Notice also that the high frequencies have a decided rolloff. Don't touch the EQ settings above 400 Hz. Instead, work to tame the bass peaks. At this point, you can energize both speakers and see the bass energy addition. If there is still a peak at say 100 Hz after individual equalizing, reduce both left and right EQ an equal amount.

It's a good idea to at check the response (of each corner horn) left to right at the listening distance just to make sure your "sweetspot" doesn't need moving forward or backward. BTW, I prefer to have my ears about four feet away from where the horn centerlines cross. It's a subjective thing, but you should experiment to hear the difference in the center image. At this point (listening to pink noise) you should hear a smoooooth souce of noise without peaks. Try an extreme setting of one of the EQ settings to hear the difference between "flat" and "noticeable".

With the Behringer, you can save your EQ settings so feel free to try different setups.

This post is way too long but, hey, I'm done!! Thanks for reading.

Feel free to contact my e-mail address for additional construction images or steps. lclinton@aetn.org

Lee

[D-MAN]

Thanks, Dude!

Me likey.

DM

[Arkytype]

Here are a few more images of my horn mods.

Lee

[Arkytype]

Here are a few more images of my horn mods.

Lee

[Arkytype]

Sorry, had a brain fart and sent the same image twice. Here's another.

Lee

[Arkytype]

And another.

[Arkytype]

Here's half of the 400 Hz extreme slope board.

Lee

[Arkytype]

A shot of the network installation.

Lee

[Arkytype]

Here's some extreme damping putty purchased at the local Homeless Depot.

Lee

[Arkytype]

Here's a shot of the extreme damping putty in action.

The 511B only "rings" at the front bell, but it really rings! Behind the flange, it is well damped and I didn't bother with it.

Lee

[hwatkins]

Very, very nice and informative article. As a piddler and DIYer I, of coursr, read it twice.

[pierceb]

Thanks Arkytype, it was an excellent read and reminds me again why I come to this board.

Nice pics too. Boy, Al's ES crossovers sure look big. They must be an awesome sight in person.

Let us know which side you prefer the C25's on.

-PB

[Arkytype]

Hey, thanks for the kudos. Right now, I've got the Beymas positioned on the inside. This weekend I'll swap horns and try the outside position. Don't even go there!

I'm sure everyone has her or his favorite source material for loudspeaker evaluation. IMHO, the pianoforte and the human voice are the most difficult to accurately reproduce.

My "reference" vocalist is k.d. lang's "Wash me clean" from the "Ingenue" album. This album is simply produced and the vocals are stunning on a good system.

Most any of the James Taylor albums are a good source for male vocalist. "Gaia" from his "Hourglass" album has some awesome timpani that will impress your friends who think Bose hung the moon.

Lee

[Colin]

Wonderful story, great pics, thanks, Arkytypical guy, I got my 511Bs from ebay guy, who sold me two and closed his auction, he shipped immediately, they were wrapped kinda simply, with a few pads of foam, but the horns are in very good condition, a few nicks, but boy are they big and heavy! Much larger throat than my stock K-77-M horns.

The focus and soundstage was excellent, the Beymas seemed exceptional smooth and extended, I too like kd lang and put her at the top of the list for favorite female vocalists

I am surprised that you didn't bi-amp?

[Daddy Dee]

Lee,

Thanks for the post and the pics. Nice job.

[Erik Mandaville]

Beautiful work all around!

Erik

[ssh]

Thanks for posting the pics, Lee. Colin was very complimentary of your system when we were at Dee's. Now I see why.

SSH

[John Warren]

If I get this right, you recieved the hardware at cost from ALK.

You now have a predisposed bias so your review is critically flawed.

Also, the pics you post are also on the ALK website, so one would conclude you have a financial interest in promoting these designs.

I see a crossover craze on this board that goes well beyond reason but to each his own.

This post enters a grey area.

[Al Klappenberger]

John,

Your implication is that Lee is getting paid to promote my networks or he is getting a cut from me or something. NOT TRUE!

The photographs of his installation on my web site are there with his permission and were put there BEFORE this thread was begun. Where else would I get the pictures for my web site? That is the only set of ES-Khorn networks ever built at this time! They are the prototypes. I have an entire directory of pictures he sent me of mock-up boards that he made to simulate various configurations that didn't work out. Do you want see a few? I'll post some of them (if it's ok with Lee)!

I did the networks for him at my cost becasue I needed a Khorn to use as a test bed (I have Belles) and I needed somebody who knew how to do measurements and who I could trust to do them correctly! That describes Lee exactly.

If you will check back on the forum you will see that I made the same offer to Qman to build a 300 Hz extreme-slope network version for his project but was ignored. Did you have a hand in talking him out of that offer? Maybe becasue YOU built the conventional one for him? How much did you get paid to do that? I assumed it was also on a no-profit basis, or am I wrong? Maybe I should also assume the worst too!

Al K.

[Colin]

They both put a lot of work into this new ALK driver crossover.

We all have experiences which predispose us, so we all have bias that flaw our critical reviews

Arkytype has no financial interest in promoting these designs

I think the drivers of classic Klipsch corner Khorns merit a crossover upgrade craze

Front-end equipment with big ole horns is a gray area

I have a vested in new friends I made at preacherman DaddyDees Klipsch gathering in Little Rock, Arkansas (May, 2004), this colors my approach, but NOT my perceptions.

I heard Arkytypes system, I like the velvet smoothness of the mid and upper range, though it did NOT have the depth and punch of subs