Atlas Sound/ Klipsch equal?

[mungkiman]

I have a pair of Atlas Sound PD-4V drivers. They were purchased with thin plastic/fiberglass horns, the same dimensions as K400/401. The drivers are rated for 30 watts and 16 Ohms. Are these equivalent to anything produced by or for Klipsch for a midrange horn? Thanks for your help.

Chris

[djk]

The now discontinued PD4 is quite a bit different than the PD5 varient that Klipsch used. In many ways I like it better. It does require a completely different crossover network.

[mungkiman]

djk,

I am ignorant in the ways of crossover networks, and many things Klipsch.

If I can find the right network (Al K?), is there a specific application for the Atlas drivers? I would like to build a set of cabinets, and would entertain suggestions. I also own K-77 tweeters, and Tru-Sonic 15" 103-LX woofers stamped 16 Ohms.

This message has been edited by mungkiman on 06-10-2002 at 07:19 PM

[mungkiman]

<EDIT>

This message has been edited by mungkiman on 06-10-2002 at 07:22 PM

[djk]

A good crossover can make or break a speaker. What you need is a book that doesn't exist. Jon Risch (of Peavey) has been threatening to write one, but doesn't (seem to) have the time. Any book on speakers will have some filter theory in it. I hear the one by Alden at Radio Shack is OK. Weems is another popular author. While anyone can follow a cookbook formula and build a crossover that works, ie makes noise, even experienced designers can come up short if you are looking for good sound and adequate power handling. It seems to be as much of an art as it is a science. You can have state of the art test equipment and a PHD EE and still make a bad sounding speaker that blows up at the blink of an eye.

But I would still encourage you to try your hand at it. Sometimes an amateur will come up with something that an experienced hand will 'know' is impossible.

The PD4 will require a notch filter at 2.5Khz, even with that you will be lucky to get it flat enough to be 6dB down at 3.5Khz .I crossed the tweeter over with an 18dB/oct Butterworth crossover with a 5.5Khz notch filter. I won't recommend this for older K77/T35 except for low power use. The newer tweeters had the flat BeCu lead out wire and will not have problems. The EV/Tru-Sonic/Stevens woofers that Klipsch used in the Klipschorn were 3R5, I assume you are trying to build a Klipschorn since you mentioned the K400 horn and the K77 tweeter. You could make it all work, but there will be a lot of 'sweat equity' by the time you get it right.

This message has been edited by djk on 06-10-2002 at 02:50 AM

[mungkiman]

I thought about building Klipschorns, but the degree of difficulty is daunting. From the recent projects I've read about on this forum, I would really like to build some University Classics. The cabinetry will still be exacting, but with less labor than the Klipschorns.

These PD4V's came out of old Speakerlab Khorns, which is why I asked about the drivers. I also have University SA-HF drivers mounted to K1000 horns. I don't see an Ohm rating on the drivers, also rated for 30 watts. The K-77's are the older type ('59?).

Can the impedance on the woofer be changed? These are the hammer-tone blue basket 15" Tru-Sonic 103-LX. The rear "can" is stamped at 16 Ohms, as well as "tested and approved by Klipsch & Assoc. Dec 14th 1958". I thought the woofers would be drop-in components for a Klipsch/University project at first, but it doesn't sound likely.

As far as trying my hand at a crossover project, I find that daunting as well since I don't have the knowledge yet to understand how they work. I was hoping to have all/most of the components for an exceptional, proven speaker. With the right components, I would be happy to buy the correct crossovers.

Anyone want to share a copy of the University Classic plans? Thanks again,

Chris

[edwardre]

Mung....interesting about your Stephens woofers. The 103LX's were to my knowledge identical to the 103LX2's except that the LX2's were made by Stephens specifically for Klipsch horn loaded bass bins. They were 8ohms (3.6ohms DC resistance) as opposed to the 16ohm impedence of the LX's. Visually, they looked identical...striking blue. Very curious that yours would have the 'tested and approved by' labels.

Measure the DC resistance. If it is anywhere's close to 3.6 ohms, I would suspect that they are 'drop in' ready. If not...say they are about twice that, I would suggest a Cornwall-type 'ported' setup.

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Ed

This message has been edited by edwardre on 06-11-2002 at 03:36 PM

[mungkiman]

Thanks Ed. Now, how do I measure DC resistance? Do the woofers need to be disconnected from their present crossover terminals to do so? I have a Radio Shack in the neighborhood, and would be happy to invest in a meter of some sort.

The University SA-HF driver units are rated at 16 Ohms and 30 watts. Is this a better match than the Atlas PD-4V driver, or not?

Chris

This message has been edited by mungkiman on 06-11-2002 at 08:02 PM

[mungkiman]

I think I've answered some of my own questions. I brought home an 18-Range Analog Multitester from Radio Shack. I set the function selector to RX1 in Ohms, touched the probes to each other, and used the Ohms Adjust to bring the pointer to "0" on the scale. I disconnected both speaker wires from the push/pull Tru-sonic terminals, and attached the probes. The reading in Ohms was close to 11. At this point I've only tested one, and expect a similiar result from the other.

[edwardre]

I'm not certain that an analog meter is accurate to that small of DC resistence. You procedure for measurement was indeed correct. However, unless the push/pull terminals were connected to something exterior to the speaker itself, you should been able to simply measure across the two terminals for a reading.

WRT the SAHF vs Atlas, I cannot comment since I've never encountered a PD4. I can say that to me, I prefer - in the right setting (ie xover & horn) - the SAHF over the K55V sound. To me, the SAHF is more musical when ran through a sectoral-type horn that it was intended to mate to and an older K500-5000 or even an old oil-filled-cap AA net.

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Ed

[djk]

The SAHF is a much better driver than the PD4. The midrange is smoother and it goes much higher. The main benefit for the PD4 is also its big problem, it has no phase plug.

[mungkiman]

Ed and djk, thanks for your help and advice. I am glad to hear from both of you that the SA-HF drivers are good ones. I will continue looking for horns, as the K1000's are only 6" long with an opening of only 1 1/8" x 7 1/2".

I think I understand exponential horns, but I'm not sure about sectoral ones. Can anyone explain the differences (unless they are the same), and steer me towards a model(s) that the SA-HF's were designed to mount to?

I do have older ('59) K-1000-5000-W networks, as well as a pair of '73 AA's. Could the K-1000-5000-W's be modified for my project? Are the University N-3 crossovers like the Klipsch auto-transformers, or another animal altogether?

Thanks in advance,

Chris

[WMcD]

If you want a copy, I'll send you Don Keele's paper describing his invention of the constant directivity horn. It shows sketches of the sectorial horn.

I'll try to give some info here without drawings.

It seems that you have the Speakerlab near copy of a K-400 horn, which is classical exponential and has a cut off of about 270 Hz. You'll also notice its mouth width is about three times it height. Just FYI.

A problem, or benefit, with horns in general is that they tend to "beam". This can be very benficial to direct sound where you want it. And maybe keep it away from where you don't. This is most pronounced at high frequencies. The ability to get this to work depends on the geometry of the horn and the shape / size of the mouth.

Sectoral horns were a way to deal with beaming. You'll see there is, typically, a matrix of 2 x 5 openings over an arc(s) of the mouth. In fact, there are 10 small exponential horns feeding those individual squares.

An analogy is the following:

Suppose you wanted to illuminate an area of solid space with light. You want it to be about 100 degrees wide and 40 degrees tall. (This is like a listening area where one moves from side to side quite a bit from one seat to another, but not much up and down, only standing and sitting.)

There are a lot of light sources you can work with. None does a predictable job at illuminating that sort of "solid space" with even coverage. On the other hand, you do have a design of a flashlight which beams a 20 degree by 20 degree arc. You've got ten on hand.

You would do the obvious. Arrange the butt end of the flashlights so they are at a common location, and fan out the placement of the business end into a 2 by 5 matrix in a vertical and horizontal arc.

So the sectoral horn is a bunch of small mouthed exponential horns.

There are a lot of other issues in horn design. These involve how much you can trade off between frequency response, size, and directivity. Quite an art.

Gil

[djk]

http://www.peavey.com/media/pdf/aa/qwp1.pdf

[edwardre]

Your best bet would be to mount the SAHF's to Altec 511b sectoral horns. You'll be able to get a pair of these for about $100 on e-bay if you're in a hurry, probably a bit less if you wait it out and buy a couple of singles. Put a fair amount of dampening putty both thick throughout the throat area as well as along the outward mounting flange, as the 511b's will ring with just the right catalyst. Properly dampened, they are glorious. Every bit as equal in sound characteristics as the Klipsch fiberglass/wood sectoral of the 50's that the SAHF was originally mated to, but (a thousand pardons for saying so) IMVHO, more solid and authoritative. You will also need a flange to threaded adapter to mount the horn. These can be made or purchased from Atlas. P/N in the online Atlas catalog is DA-FH.

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Ed

[mungkiman]

Gil - Thanks for explaining sectoral horns in a simple concise manner. I understand the horns and theories better, and am intrigued.

djk - I was not able to view the file from the link you provided. I have a Mac rather than a PC, and it doesn't recognize pdf files. Thanks just the same.

Ed - Thanks for the horn suggestion. Would an 811B also be a good choice, or is the 511B superior?

Does anybody know if the K-1000-5000-W networks can be modified to K-500-5000, or if I would be better off using stock AA's? I am looking for different woofers, so the 16 Ohm Tru-Sonics are not a factor for my project. Thanks,

Chris

[edwardre]

I wouldn't say either is 'superior' to the other. They are simply for different applications. The 511 goes down to 500 cycles, the 811 down to 800 cycles. They are both fine horns. I know Al K has utilyzed a 811 in his Belle. You might 'ping' him to get additional info. I use a 511 in my Belle with an AA network to very excellent results.

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Ed

[djk]

"djk - I was not able to view the file from the link you provided. I have a Mac rather than a PC, and it doesn't recognize pdf files. Thanks just the same." You need to download this free program: http://www.adobe.com/products/acrobat/readstep2.html

They have seven different Mac platforms. I think you would really enjoy the Peavey reference I linked to, it is a very complete overview on different high frequency horn types. The SpeakerLab fiberglass K400 clone is a good copy. If you put some of that rigid expanding foam on the back side it will get even better. You might consider buying a pair of E2 networks from Klipsch, they are #116014 and only $28 each. With these and a pair of either 4µF or 13µF caps you can build your choice of A, AA, B, and E type networks.

[mungkiman]

djk - thanks for the follow up. I downloaded acrobat reader, and greatly enjoyed the Peavey link. I learned a great deal about several horn types, both in theory and practice.

Would you, or anyone, be willing to help me with construction "know-how" for a AA network project? I am fascinated with the idea, but don't know where to start other than a pair of E2's. Thanks again, I really appreciate the help and knowledge you (all) have shared.

Ed - thanks for the additional info. Clarification helps me understand the specifics. I will ask Al K to share his Altec experience if he is willing.

[WMcD]

Thanks for the kind comments about my explanation. After sending it off, I thought it might be too condesending. You never know how simple and pedantic to make a tutorial. It can be educational to some and annoying to others.

The Peavy paper is very nice indeed. The paper by Keele I was referring to is cited there. I'm going to order the author's paper.

The Peavy paper mentions something illustrated by Don Keele. It is that the small clustered horns of the sectoral design do themselves beam a bit at high frequencies, leading to "fingers" in the pattern of the response.

The Peavy paper fails to mention the tractrix horn design originated by Voight (sp) in 1930s and championed by Bruce Edgar. The attention to waveform shape was Voight's intuitive idea as young lad. It addresses the same problem as the Peavy design.

There is a nice article in Audio by Kerry Geist and Roy Delgato about the adoption by the Klipsch organization of the tractrix design, based on Edgar's articles in SpeakerBuilder. The first application for Klipsch (to my knowledge) was the Forte II, Chorus II and Quartet. A prime issue was controlled directivity.

That article doesn't speak of the wavefront issue. But it does describe how much the tratrix curve for the wall generates something like a hyperbolic cross section near the throat, a cone during much of its mid length, and a rapid flare at the mouth. They don't mention how close this mimics Keele's design, but obviously it does.

It must be pretty obvious what whould happen in an IP fight. Klipsch as a defendant can legitimately claim they're just using Voight's design, which has patents long lapsed. And if Peavy gets into an IP fight, the defendant might claim the same.

The K-5 horn by PWK is also missing from the Peavy article. In reading the patent document on the K-5 it seems to me that PWK was designing for straight side walls (like the conical) while keeping an exponential expansion by use of a specific geomety near the throat and fins inside the bell of the horn. (The fins seem to have been dropped in later implementations.) So I conclude that PWK was on to the issues from the start.

There is a common problem with "new" technology. Often, recently discovered old documents describe new technology. This leads to the accusation, "The ancients have stolen my invention!"

Gil