Speakerlab networks?

[DizRotus]

Curiosity alone prompts my search for schematic(s) for the Speakerlab SKhorn balancing network(s). In addition to the components, Im curious about the cross-over points. Was the SK mid crossed at 350 Hz? I have no intention of using them as a recipe. A search unearthed much about Speakerlab, but not the schematic(s).<?xml:namespace prefix = o ns = "urn:schemas-microsoft-com:office:office" />

As some of you already know, in the mid-70s I used 4 SKhorns in a mobile DJ business. They were factory built ½ plywood with aluminum SK-350 squawker horns, Atlas drivers and EV T35 tweeters. With false corners permanently attached, they were perfect for that use.

The Speakerlab networks seem to be universally criticized on this forum as inferior to Klipsch, which they probably were. While they appeared cheap, Its my recollection that they used air core inductors similar to those favored by the DIY tweekers of Klipsch. Is it possible that the cheap looking Speakerlab networks were actually precursors to the improvements to Klipsch networks being touted today?

[ajsons]

Here's one. Let me find the reverse side.

[ajsons]

This one is my schematic of the first one, the additional info based on a letter I received from a generous SK owner.

[tigerwoodKhorns]

I just went and looked at my networks. They have solid core inductors. The layout is somewhat sloppy too. That being said, the Speakerlabs (I have a factory built set) appear to be of high quality construction and use quality parts. The tweeters look much nicer than the K77's.

Chris

[DizRotus]

These days, memory is a tricky thing. While I rcall that my SKhorns had wax encrusted air core inductors (could be mistaken), I forgot about the L-pads instead of auto-transformers. Even if I'm correctly recalling air core inductors, the L-pads as attenuators suggest "cheap" when compared to Klipsch. I've got no specific recall of the source of any of the components, I don't even recall if they bore any markings to identify manufacturer and/or value.

Armando-

Thanks for the schematic.

[WMcD]

Here is the only schematic I have. Note the passband filter for the midrange.

This shows the use of L-pads. The one that I've seen in person has two three-position toggle switches with resistors. If anyone has a schematic showing the details of that, I'd like to have it.

I'll point out once again that PWK seemed to like the A type with the woofer inductor shorted out. That left the autotransformer, the 13 uF cap, and the 2 uF cap. So if you want to follow his ways, start removing parts.

Smile,

Gil

[ajsons]

The only other thing I have is the change to the instructions.

[Deang]

"I'll point out once again that PWK seemed to like the A type with the woofer inductor shorted out. That left the autotransformer, the 13 uF cap, and the 2 uF cap. So if you want to follow his ways, start removing parts."

"Less is more until less is just less." -- Mark Deneen

[tigerwoodKhorns]

Why is everyone so interested in Speakerlab stuff and accept them all of the sudden?

I guess that I need to thank everyone but here is what happened to me. About 9 months ago a set of factory built speakerlabs appeared in the paper for $1,000. I called and then posted here. I was told that I am crazy for even thinking about buying a set of speakerlabs when I already have the real thing. OK, $1,000 for an inferior speaker, no brainer, keep the K Horns and mod 'em like crazy.

The ad appears again about a month or two ago, but now for $500. Well, now I have to look into it. I post again and this time everyone tells me that these agre great speakers. I went to listen to them and they appear well built and put out bass when in the middle of the room. I bought them (for less than $500).

A similar thing is happening with solid state on the forum right now. I think it started with the digital amps.

Just an observation.

If anyone is interested, I will sell my speakerlab tweeters, mids and crossovers cheap. The tweeters appear to be much higher quality than K77's. The mid is a short throw bass reflex with a huge magnet. The crossovers are as described above.

Chris

[ajsons]

Chris,

This thread starts with "Curiosity.....", that's all on my part, and maybe the others, too. I like to learn as much as I can about crossovers, though. Some years ago, I converted Bullock's crossover formulas into a working program. Now I found out, all I need are good schematics and frequency scaling to handle my crossover needs. A little info here and there, helps, even if they're just historical in nature.

I don't need a Speakerlab crossover. But I'll keep a copy of the schematic.

[D-MAN]

Chis, I have not changed my opinion on Speakerlab, even though I felt that I was sometimes a lone voice crying in the wilderness.

Aside from the crossover, I have always felt them to be unfairly undervalued and certainly under-rated. The K-type top cabinet aesthetics are horrible, though, also my opinion. I do think that $1k per pair is probably a little too high, though, personally speaking.

They have always been a good source for quality drivers, and the bass bin is a ver batim Klipschorn knockoff with a couple of excellent mods in them right from the factory.

SL was also free to experiment and advance, which they did. They are still in business here, and still sell the plans, but alas, not the horns anymore.

DM

[drewb]

Great thread! I built Speakerlab Khorns over 20 years ago. After many missteps I installed ALK universal crossovers. I now have great sounding horns. Speakerlab never did get the crossovers right, IMO. In reference to the original post the problem is with the design, not the components. High quality components cannot makeup for bad design.

You could still build a set given the necessary cabinetry skills. I would use a Klipsch K33e woofer, ALK's trachorn midrange and a JBL tweeter.

Here is a pic of them:

[tigerwoodKhorns]

The pics did not post.

I am doing almost exactly what you suggest. I am going to use the Speakerlab Bass bin with the woofer that came with it. I have a Pair of JBL 2470 midrange drivers and Altec 511b horns for midrange and a pair of JBL 2404 tweeters. I have ALK Type A's that I built but they will be used on a set of Belles. I am currently using an active crossover that I will retain. I should be a great combo, but it will be a while before I get it complete.

Chris

[drewb]

The Speakerlab woofer is fine. Don't let Edgar fool you into thinking it is inferior, it is not. I have some suggestions (mods) if you are interested.

Evidently insert image does not work but file attachment does. This limits me to one picture per post, so here is the picture of my homebrew ALK's:

[ajsons]

Mine has an EVM-15L woofer with a 6 x 13 throat., EVM SM120 for the mid horn. The mid driver is always changing, although my favorite is EV's 1824, which should cross at 3500hz, the correct crossover is still under construction. T35 for the tweet.

[ajsons]

The Speakerlab woofer is fine. Don't let Edgar fool you into thinking it is inferior, it is not. I have some suggestions (mods) if you are interested.

Drew,

What kind of mods do you suggest?

[ajsons]

I didn't build the Speakerlab crossovers. I built a pair of 12db 3 way crossovers (back in the 80's) from Bullock's formulas. Unfortunately, I used el cheapo parts. I changed to ALK's and what a difference! I think the 12db circuit is good, I just used low quality parts. I might have to revisit that sometime. I am presently using the ALK's on the University Classic.

[tigerwoodKhorns]

I'm interested in the mods too.

Nice looking speakers ajsons!

Which size opening iws correct for teh Speaker;ab woofer? (the 3" or 6")?

Chris

[ajsons]

Thanks, Chris.

The SK's have 6 x 13 openings. According to D-man, 3" is too small for the EV that I used.

[drewb]

For the Speakerlab woofer use the 3 x 13" opening. I routed a 1/2" radius on the outside of the motorboard opening. This makes a flared opening like they are doing now on speaker ports. This smoothed the bass response noticeably. I stapled plastic screen over the back of the woofer and very loosely stuffed the back chamber with polyfill I got from Walmart. This seems to increased the bass. I put water pipe insulation from Home Depot on the corner sealing joints. A good seal is probably the most important factor (IMO) for good bass response. Currently I am using the woofer without the 2.6mh inductor, ALK may want to comment on whether this is a good idea or not. It may destroy the constant impedance that is a major feature of his design. I used a 2.4mh inductor but I am unsure what the correct value should be since the Speakerlab woofer I have is 8 ohm nominal.

I wrapped the midrange horn with several layers of rope caulk. This removed all of my midrange complaints.

I made a 3/4" spacer out of plywood in between the base and top sections. This made the appearance much more acceptable and "Klipsch" like.

Originally I had the "wave aperture" tweeters. This may be what was described earlier as "better" tweeters than the EV35. They are not. They are EV35 tweeters with Speakerlabs own (and inferior in design) horn. I was able to get a set of EV35 horns from Epay. This make my khorns into Klipsch clones.