SpeakerLab Khorn Plans??

[heronrod]

I recent;y picked up a pair of what I think are SpeakerLab k's. I was hoping to find a copy of SpeakerLab k plans to compare against what I just purchased. Aside from assuring me that they sounded very nice, here is what the owner told me about them:

"The tweeters are Electro-Voice and I believe the woofers are Eminence (which are the drivers Speakerlab used in there clones). The midrange horns have Atlas (Model PD-4V) drivers which Speakerlab did not use. They are standard throat size horns so it would be easy to remove the Atlas drivers and replace them with more authentic drivers."

The cabinets are a little rough and I really got these as a project to see what it would actually be involved in getting these restored into premo condition. They currently are stored in nice controlled environment waiting until we can start working on them. Only had time to get one speaker hooked up and was very impressed with the sound.

[Southern]

The speakerlab K had two small level controls next to the midrange horn (at least in their late 70's version). Speakerlab also made a SK in the early to mid 80's that looked much different and used a 7" cone midrange. A picture of the speaker and crossover may help us decide what you have.

[WMcD]

There was a version of the crossover which used two L-Pads. There was another version with two three-position toggle switches.

Wm McD

SpeakerLab SK Manual.pdf

[heronrod]

I've got some photos but I haven't figured out how to post 'em on the forum yet.

[WMcD]

BTW, welcome to the forum.

I'll try this with a guinea pig photo on my end to walk you thought. I hope I get this right.

First. Please as a courtesy, reduce the file size to something about VGA. You can open your photo with MS Paint. Go to Image and stretch and skew. Typically set horizontial and vertical to 30 percent. Then save to desktop or your favorite location. The forum will take a large picture size and reduce to size, it but it is just good manners to keep file size down. You want a jpeg format natch.

On the forum go to Reply. Wait a sec for things to get set up.

Look for Options. and click.

See file attachment and add - update.and browse.

Use browse to select your file from your desktop. and Open.

The upload process will not take long if it is a small file.

Notice we're back at Upload file field. IMPORTANT Notice there is a slider bar at the bottom. It shows you're viewing only the left side of the field. So use the slider to move to the right, and you'll see SAVE. Click it.

Notice the "compose" tab. Click it and you're back to where you can put in more text, if you haven't done so before.

Then click on Post.

You can only put in one file in a reply frame.

Wm McD

[WMcD]

I suspect from the description that it is an SK rather than what SpeakerLab did later. The later model had a back loaded horn.

A quick run down on the SK from looking at those owned by others and comments on the forum.

Some used fir ply for the bass horn. Some used MDF.

Some used a fiberglass mid horn but later ones ? used a cast aluminum.

There were a number of tweeter options. One was an EV-35 which are like the Klipsch T-77 but Klipsch cherry picked the best of the T-35 types. EV had several models of the T-35 and some were sold without the EV trademark on the open market. Other option was a cheapo plastic tweeter which doesn't look anything like the T-35. It may be that SpeakerLab would sell the bigger and better T-3500.

I don't know about woofers. One that I saw had IIRC a horseshoe type magnet structure. Bruce Edgar thought that at least one of the SpeakerLab woofers needed to be broken up with a sledge hammer as the only cure. Whether the SpeakerLab woofer you have is one of those, whether it is from Eminence, or anything else, we can't know. These could be a weak point.

Re the mid driver: The one I've seen is very most probably an Atlas and I suspect it is similar to the K-55 which has push button type terminals and a one piece phase-plug; alnico magnet. Klipsch later used a variation of the Atlas with a two piece phase plug -- it is identified by solder-on terminals. Still later Klipsch went to an EV unit with a ferrite magnet, the K-55-M. You probably don't have that.

I can't say much about crossover topology (components and their set-up) except what is shown as part of what I posted. That crossover section in the pdf was not part of that manual, as is indicated by the pagination. It is safe to say that some SK's had L-Pads with those contols mounted in the front of the top-hat. But, another I've seen used three-position toggle switches for the mid and tweeter. These switches were mounted on a nice looking metal plate on the back of the crossover board.

Most SK's were sold as kits, to my understanding. You could buy a factory (SpeakerLab factory) version.

Wm McD

[heronrod]

Thanks Wm McD! Hopefully this has a photo attached.

[heronrod]

Here's another of the horn.

[heronrod]

This is the last one so far. I haven't had a chance to get into the lower section. Once I get into it I'll post some pics. Not sure exactly what I'll end up doing with these aside from probably reskinning the veneer. To my ears they do sound very nice as is. Any help with identification would be appreciated.

[ab0ez]

Ive got a set of the Speakelab Khorn plans....somewhere. And just to ease your mind about the PD-4V driver, one of my two pairs of Speakerlab K's came with the PD-4V drivers. I'm right in the middle of modifiying my top cabs to take the Altec 515B horn, but I can tell you that driver sounds very good with the Altec.

[heronrod]

ab0ez,

If you stumbel across those plans that would be sweet but don't knock yourself out. Once I get the fabric pulled and can get a looksee at the lower section I'm sure you guys can tell if these were based on a SpeakerLab set of plans. Thanks for the info.

[djk]

The Klipsch driver used is usually the PD4, the PD4 has very different response.

I would suggest a trap on the PD4, and an 18dB crossover around 4.5Khz for the tweeter (same frequency used in the current Klipschorn).

3.3µ + 0.25mH + 10µF

14µF~15µF with 0.29mH~0.3mH in parallel with each other, this to be in series with the PD4. In this network I would short out the 0.6mH and place the trap in parallel with the 8R resistor that is in series with the L-pad.

[heronrod]

DJK: What is the major difference between the PD4 and PD4V? I'm totally new to this.

[djk]

"What is the major difference between the PD4 and PD4V?"

I'm being lazy, they are the same part.

On the newer PD5 the letters mean something(ceramic or alnico, with/without transformer), on the PD4 they don't.

[consistent]

Thanks for the plans Gil...how did the bottom end of these stack up against the khorn bottom end...let's say using the same woofer. Would there be a major difference in sound to what Klipsch produce today?

Cheers

[WMcD]

It is reported that the SK plans for the bass horn are pretty close to the official Klipsch units. So with the same driver there is no reason to think there is any difference. Of course the official Klipsch units today use a closed back and a more sophisticated crossover (which Klipsch has not made public).

Please know that PWK, IIRC, threatened suit over the use of the K. So we have to be a little careful what we call them. But here let's use SK for the sake of identification knowing that they didn't come from Hope.

PWK had criticism of the SK units and this appears in a Dope From Hope. I'll look for that.

I have a grudging respect for what Speakerlab made. We have a "close copy" situation. Much of what is good about horn loading shows up in reviews of horn units of all stripes -- and many of them are not close copies of Klipsch units. But in the SK we have similar midrange horn, similar midrange drivers, similar bass bin, similar tweeters. People have opinions about the best crossover but that doesn't tarnish the overall physics.

PWK was very proud of his quality control and he is entitled to that. I agree that the SK's always look a bit home made. I believe that someone who is careful can make the good seals which are necessary. It wrankles a bit when Speakerlab says that there is no mistake so big that it can't be solved with RTV. None the less, a lot of constructors have essentially duplicated the functional attributes needed.

So why would anyone have built an SK kit? There are many people who just want to do it themselves and investigate the mysteries of the design. Guys love to tinker.

Wm McD

[WMcD]

Here is the DfH.

Wm McD

DfH More About Imitations.pdf

[consistent]

thanks Gil, much appreciated

[Tom Mobley]

Gil,

Are you the guy who converted Khorn plans to use 3/4" plywood instead of the 1/2" Klipsch used?

I'm back to thinking about building a set and selling my '60s. What concerns me is the pieces that have both beveled edges and are tapered lengthwise.

I think you sent me, many years ago, a CD of plans and dimensions of building Khorns. Maybe I should dig it out.

[Guest " "]

"What is the major difference between the PD4 and PD4V?"

I'm being lazy, they are the same part.

On the newer PD5 the letters mean something(ceramic or alnico, with/without transformer), on the PD4 they don't.

actually....the pd-4v is 30 watts, 128db driver and the pd-5v is 40 watt , 131db driver, the pd-5t is a 40 watt , 131db driver with a transformer.