“New” Speakerlab K’s. Need to id crossover

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So after almost a year working with the seller, i have some nice Speakerlab K(“-horn”)s in my listening room. They’re completely original except for some failing veneer.

They have the wa4000 tweeter, cast “350” squawkers with k55 drivers and the 8 ohm speakerlab woofer.

Does anyone recognise this crossover? It has an extra choke? Unlike any I’ve been able to google.

I will sketch out the schematic next but the thing is glued into the tophat so need to figure out how to work on it without damaging anything. For now hoping someone has a schematic so i can maybe manage surgery without removing it.
 

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not much help - which choke looks like it was "added"? (square bobbin ?) are any of the chokes parallel to the horn drivers? I had Speakerlab K's 40 years ago with regular T35 and IIRC, PD4 Atlas drivers run from fresh at the time, Dyna MKIII and mod - PAS preamp - also stiffer walls than what now with my Khorns :(

be sure to ask at Audiokarma. btw, my WA version of the T35 seemed a lot less sensitive than regular (half blown ?)

assuming its all factory, replacement of the electrolytic caps would be in order. The L-pad resistors should be ok. My (Speakerlab K's IIRC had adjustable pads)
 
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yes. The iron core choke seems to not always be present in pictures of the crossover, and I've never found an actual schematic that shows it.

Mine also has the WA4000 tweeter, and i have 2 other speakers that use the T35 and I have to say the WA4000 is less "spitty" and slightly better behaved. But I think that sound seems to come across as "less" tweeter. I still haven't made up my mind if its quieter so sounds less harsh or sounds less harsh because its quieter or sounds quieter because its less harsh. I've only had the speakers for 2 days so I have lots of listening to do.

On the Crossover rebuild topic - I plan to go slowly and first find out what new caps will improve. Eventually I'd like to get an autoformer in there instead of a bunch of resistors. The Klipsh AA xo seems to only use it on the Squawker. I have the autoformer out of a cornwall, which drives the same K55 (at a 700 cutoff tho).

After that I'll decide if I want to do more. However I doubt I'd go with the univeral ALK xo that so many folks rave about - before I do something like that I'll get a digital active xo and bi amp.
 
since its over 40 years ago, my memory is fuzzy but my set didn't have a transformer core inductor. Is it in parallel with the large air core choke? That air-core unit on the woofer would raise qes somewhat. The midhorn copy (which I have with a 3rd Khorn) is heavier I think than a real K400. Speakerlab's basshorn IIRC (??) looked like it was glued together with silicone RTV (probably just used as a sealant -?) and was a good copy of a Khorn. Autoformers are good and Crites' 3636 handy with 1dB steps. A real KSN1016 piezo run from a 25 volt matching transformer in step-up mode would be ~103dB. Somewhere in my mess are a pair of the wide angle tweeters - didn't measure as loud as my K-tube Karlson stuff. One SpeakerlabK version had a cone midrange.

you will have a cool speaker once the crossover is sorted and rebuilt/refreshed. One of the first lps I played on mine was one of bagpipes and drums.
 
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BB, with the extra iron and WA4000, looks like have yourself a set of factory built 1979 Speakerlab K's. I have a set of 1980 factory K's, owned them for 20 years but never used. I lusted after the K's for years, back in the 70's I built a set of .1's, 1's, 6WA's, and finally the 7WA's, they're all still in the family and working perfectly. From experience with them I know you need to replace all the electrolytic caps & sticky magnetic fluid in the horn gaps. Refreshed they are like having brand new speakers.

My new house in Kona has a 27 foot wide room with 10-16 pitching ceiling, perfect for corner horns. I finally got my big K's up and working yesterday. Surprised how good they sounded right out the gate, the bass started to pump after just 4 hours. I had to work the L-Pads for 5 minutes each to get rid of the scratchy sound. Tweeters are way down in volume, no doubt gummed up with ferrofluid, you can purchase new fluid from Parts Express. Sounds stupid but I use a small Post-it sticky notepad, just push the sticking side down into the cap and pull out the old fluid. Like a monkey pulling termites with a stick, that's were I got the idea ... LOL.

The Speakerlab K's were in constant evolution, the crossover changed every year. For the 1980 model David Graebner did a final tweak to the cabinet design and the crossover. This was to once-&-for-all surpass the sound of the Klipsch Horn and also to get around the patent that Paul Klipsch recently updated in 1979. My friends Dad replaced his Klipsch Horns with the K's in Feb 1980. Many late night parties told the real story ... no contest ... the Speakerlab K's crushed them. The news spread like wildfire and from late 1979-81 Speakerlab sold a bunch of K's, mostly factory assembled which featured matched drivers and crossover components. Unfortunately Paul Klipsch got his lawyers involved which quickly stopped Speakerlab from selling fully assembled K's, and some say horn speakers in general. This short lived battle reinvigorated Paul, already well into his 70's, to acquire modern test equipment and upgrade his drivers, crossovers & cabinets. Ironically it was probably all this drama and newly focused energy that insured the survival of the Klipsch Company and at the same time forced a young David Graebner in a new direction where he ultimately designed some of the worlds finest planar magnetics. (But that's another story).

Attached is a wiring diagram of a 1978 K-Horn crossover and pictures of my 1980 K crossovers.
An externally hosted image should be here but it was not working when we last tested it.


In 1980 Graebner added an additional parallel set of 52uf caps (104uf total). This was to start rolling off the midrange before the throat cutoff of 400hz. In the 80's Paul went on to computer match his drivers, tweak the crossover components, and gasp ... raise the lower crossover point of the the midrange. Some fanboys on the Klipsch forum would disagree but IMO Paul's final designs never surpassed the 1980 K-Horns. That is by no means an insult to Pauls achievements as he was without question the pioneer in this horn loaded wilderness.

With that said & plenty water under the bridge I was recently introduced to the new Klipsch Horn III's. I spent many hours listening to these at CES and wow ... just wow! I don't care how seasoned and jaded an audiophile you are these new K-Horns have to be experienced. Totally unexpected, every preconcieved notion vanished and I was left choking on crow feathers having already swallowed the bird.

I'm going to make a serious effort to get my K's back on song, but I don't think my fondest memory's of the Speakerlab K's come close to what I heard in that tiny room at CES.
 
The choke

The choke Is part of a parallel notch filter to flatten out a frequency spike of the woofer at 163 Hz which causes the horn to produce a boomy noise it is combined with a 100 µF capacitor and 2 15 ohm resistors. I have a set of 1980 Speakerlab k’s And the exact crossovers you have in that picture I’ve already done the tracing out of the circuit diagram and measuring of all the caps and coils and I’m in the process of recapping it with modern capacitors. I built my k’s base bins when I was in high school in 1979 through 80. No matter what anybody says they are fantastic speakers I have owned mine for over 40 years. I just got through updating mine with the enclosed back like the new K 6 Klipschorn And building 2 inch riser pedestals for them they look awesome.
Depending on what woofer they use a 2.56mh coil for the 8 ohm woofer, and a 1.3mH coil for the 4 ohm woofer. A midrange band pass with a 24uF cap and a .60mH coil. Both the woofer and the midrange use a 6db 1st order alignment and the tweeter uses a 12db 2nd order alignment. The midrange is connected 90 degrees out of phase because of the tweeter second order alignment. For this reason the midrange is connected polarity reversed. The drivers for the midrange are Atlas PD-5VH's. They are the exact same drivers used in the Klipschorn the k55v, and the k55x. Atlas makes them for Klipsch. In fact the new Klipschorn K6's went back to the Atlas PD-5VH. You can look at the picts of them on Klipsch's website and you can buy them from Atlas still today.
The tweeter uses a 2uF cap and a .39mH coil with a .05uF cap across the leads to sweeten the tweeter up a bit. There are also 2 9.1 volt 1 watt zener diodes for tweeter protection. if these blow the tweeters will become very quiet. You need to check those to make sure there not blown. There are also various resistors for the midrange and the tweeter for the 2 and 4 db cuts that the switches control.
 
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as an edit to the above post with additions

The choke Is part of a parallel notch filter to flatten out a frequency spike of the woofer at 163 Hz which causes the horn to produce a boomy noise it is combined with a 9.52mH laminate iron core inductor, a 100 µF capacitor and 2 15 ohm resistors. I have a set of 1980 Speakerlab k’s And the exact crossovers you have in that picture. These are the second generation more advanced crossovers that speakerlab built for the k's before they went to the cone midrange version. The first generation had the L-pads. The were basically copies of the AA crossovers Klipsch used that were very flawed. Speakerlab fixed a whole host of issues that the L-pad versions had. Even the L-pad versions were still better than the Klipsch AA crossovers. For instance Klipsch AA's did not use a bandpass for the midrange. They just let the midrange voice coil peter out on the top end and allowed all of the high frequencies bleed into the midrange driver. Just to name one issue of many.
I’ve already done the tracing out of the circuit diagram and measuring of all the caps and coils and I’m in the process of recapping it with modern capacitors. I built my k’s base bins when I was in high school in 1979 through 80. No matter what anybody says they are fantastic speakers I have owned mine for just over 40 years. I just got through updating mine with the enclosed back like the new K 6 Klipschorn And building 2 inch riser pedestals for them they look and sound awesome.
Depending on what woofer they use a 2.56mh coil for the 8 ohm woofer, and a 1.3mH coil for the 4 ohm woofer. A midrange band pass with a 24uF cap and a .60mH coil. Both the woofer and the midrange use a 6db 1st order alignment and the tweeter uses a 12db 2nd order alignment. The midrange is connected 90 degrees out of phase because of the tweeter second order alignment. For this reason the midrange is connected polarity reversed. The drivers for the midrange are Atlas PD-5VH's. They are the exact same drivers used in the Klipschorn the k55v, and the k55x. Atlas makes them for Klipsch. In fact the new Klipschorn K6's went back to the Atlas PD-5VH. You can look at the picts of them on Klipsch's website and you can buy them from Atlas still today.
The tweeter uses a 2uF cap and a .39mH coil with a .05uF cap across the leads to sweeten the tweeter up a bit. There are also 2 9.1 volt 1 watt zener diodes for tweeter protection. if these blow the tweeters will become very quiet. You need to check those to make sure there not blown. There are also various resistors for the midrange and the tweeter for the 2 and 4 db cuts that the switches control.
 
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So a little over a year later...

So i put my plans to rebuild the speakerlab khorn xo’s on hold while i worked on building a linux based dsp crossover. Limited success, but mostly as life has limited the amout of time I’ve been able to devote.

So not sure why, but i never got notice when mech58 and bill answered. Very valuable info, wished I’d seen sooner.

So realizing fro the sake of protectign the drivers i realized I’ll still rebuld the xo even if i biamp, so I’m back to work on the xo. Mech - your detailed xo info is fantastic. did you ever draw a schematic? Any advise?
 
Also just for your information I’ve done some more research on mine and speaker labs PD5VH Mid range drivers are ferrofluid filled I just replaced the ferrofluid on mine and a WA 4000 Are ferrofluid filled as well. Incidentally the WA 4000 tweeters use the K 77 Klipsch diaphragm and the wide angle wave aperture horn for better dispersion Angles on the tweeters. You can buy a new diaphragms from simply speakers for both the atlas PD5VH drivers for the mid range And the WA4000 tweeters
 
FWIW my K-horn peak seemed to be around 131Hz - think normally its considered 160 as no different than the SpeakerLab clone.

I should still have some WA4000 - seems like it was not as loud as a T-35 ?

Tom Danley suggested a series notch filter - others said not to worry about it as it was not present at my standing listening position.

I tried a couple of filters but the main problem in my situation are flexy room walls which impart a nasty ringing "booommmmmmm". Even harpsichord excites the awful walls.


tomservo
Manufacturer
Posts: 6918
Joined: July 4, 2002
Hi Freddyi
Sorry for the delay.
What you want is a series tank or notch filter.

Using your magnitude and impedance and eye balling your peak at around 10dB over flat, what you should try is a 3mhy choke, in parallel with 500mfd np and also in parallel 6 ohms.

That is in series with your woofer.
This should flatten your response nicely.
Have fun, best
Tom


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Nothing like the wonderful clean room-filling sound of a corner horn. But they do need subwoofers, by today's standards. And some of us think the mid and tweeter horns would be better replaced with electrostatics because the bass horn is the only way (except for motional feedback) of having bass clean enough to pair with ESLs.

An iron-core choke... OK because power levels to horns are very low. Likewise, going DSP (as any forward thinking audiophile ought to) with horns means you only need maybe 20 watts per driver. Klipsch used to say all he needed was 5 clean watts.

With corner horns you are literally "painted" into a corner. But that should make a bunch of acoustic complications (like nearby wall reflections) moot.

B.
 
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IIRC, my Speakerlab K's purchsed new in the mid 1970's, lookled like the entire basshorn was glued together with silicone RTV (???) They were fun with music such as bagpipe and drums and at that time had fresh Dynaco KT88 MKIII driving them. Speakerlab's cast metal K400 copy (I have one) was good weight wise. Didn't one version of their K-horn ripoff have a 6.5" direct radiator midrange?
 
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Yep. Mine are completely glued together with silicon rtv. And yep, they later used a direct radiator in place of the tophat.

I thought it was funny someone said khorns need subs. I have an 18” jbl in a 8cf ported cab on a dsp also in the room, and it is an improvement as long as you realize you’ll be screwing down your drywall every once in awhile. Sand filled false corners are on the to-do list.
 
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