drewb

I am sitting here listening to my 1983 Speakerlab khorn's. They sound as good as any khorn I have heard. I realize Speakerlab made many mistakes with their poor man's khorn. But by 1983 the bass bin and midrange were identical to the Klipsch. They offered the same Atlas midrange driver (non-solder version) and both the t35 and t350 EV tweeters. The weakness I had were: I purchased their version of the tweeter which was an EV with a "constant directivity" horn. It had a horrible downward slope in effeciency as the frequency went up and was optimized for the lower frequencies. I fixed this with an ebay purchase of the t35 horn, using my magnets and diaphrams. They never got close to a decent crossover design. I am using homebuilt ALK's. Al's crossovers have made them detailed and coherent, like any good khorn. Despite Edgar's blasting them I find the woofer is fairly close to the Klipsch offering. I have verified this by listening and doing a "Hornresp" speaker model of each. Both show similar response to horn loading. They are a better match than many of the JBL, etc. speakers many have made the mistake of using. If I were building today I would purchase the Klipsch woofer and 400 mid horn (only $49.00 per this forum). The Atlas mid driver can be found, as the EV t35 can be on Ebay. I would build Al's excellent crossovers of course. My point is that these can be made into decent horns and can still be built by the DIY'r. A recent thread in this forum concluded that there never was a legal problem between Klipsch and Speakerlab. Nice myth but I am sure PWK would have concluded it was better to let them go as a "wanaa be" rather than give them some credibilty by harrassing them.

I have finally started building the ALK crossovers for my Speakerlab clones. They have an 8 ohm version of the woofer. As far I can tell it is pretty close to the klipsch except for the voice coil. Using SpeakerWorks analysis software I found that the loaded impedance is about 9 ohms. I am thinking of using a 2.7mh coil (which is what I used before and seemed about right). Does this match your calculations for the woofer coil? The litz coils only seem to be available in Canada. Rather than import I was looking at the Jantzen copper foil coils. Do you think that these are an acceptable substitution? I would welcome a discussion of the various coil types. Thanks, Drew

Here is a picture of one that went bad in my Fisher 500c. The system was saved by the 10 ohm resistor (fuse) that I had added from cathode to ground. The first Ii knew of the problem was when the channel went quiet. It took me some time to notice the white getter and neatly cracked tube. Note the date code 01-00. I understand that this is a bad batch with a bad internal weld.

I noticed that your pcb layout style is to maximize the trace size by making a negative trace pattern. This leaves large traces under the coils! Al found that the nail in the AA crossover caused problems. I can only imagine that having traces under the coil would cause an antenna/reciever problem. At this late date in your work I would suggest you build a coil mounting sub-board and jumper over to it. I would be very interested if there is a difference. By the way, I do agree with the layout method, I just wanted to point out this potential gotcha.

Found this in my old wire bin. It is first generation "Monster Cable". It is not from a Klipsch but it is the type they used in the 1980's I am told. I offer as a reference to the uninitiated who are looking at their wire's condition. If your wire looks like this, replace it. This is copper oxide corrosion. It happens because they did not use oxygen free copper and put the insulation on in an inert atmosphere. Modern cable is done this way to prevent the problem shown here. Does it sound bad? In a word, yes. Very, very bad. Muddy, no highs or lows, like a cheap system.

I finally have identified my old crossover caps. I plan to use them in new crossovers if possible. I got them from Madisound back in 1985. They are SCR(Solen), mvp, 250v, +/-10%. They are marked PC2500(25uf), PC300(3uf) and PC200(2uf). I also have some PE125(1.25uf), 400v, no mvp mark, +/-5%. They are aluminum cans with epoxy potting on the bottom with two 22ga. tinned copper wires (pvc insulation) coming out. They are different than the current versions, axial instead of radial leads, metal can. Are they the same internally? Were the old ones as good or better than the current? Mine are so early that I am afraid they may be industrial or even prototypes. My fear is that they part of the "learning curve" and are not the quality of the current design. They have been in constant use since 1985. They still sound good. Is there an expected lifetime? They have never been overloaded or even close. They are probably still "green". Thanks in advance, Drew

Sorry my fault Al, I wasn't clear on my question. I was asking for "how to" not "where".

This is what I got from your pictures also. Two plugs, one swaged inside the other. The sound has a shorter path around the inside cone which kills the 9k spike by being a mechanical bandpass filter. One last question. What do you have on diaphragm replacement? The fiber ring separated from the phenolic voice coil when I took it apart. I believe I need to glue them back together using the O.D. for alignment? Thanks for all of your help.

Al, I am not sure if your remeber this or if you could even tell. Is the phase plug two separate pieces? As you can see from my picture the one I removed is one solid piece. Your picture shows an inner ring, hinting that the plug is two separate pieces. Or, am I missing the difference? Thanks.

Thanks Al, I think I get it. The two pieces are a cone press-fitted into another cone. This creates a double taper plug, right? Attached is a picture of my phase plug for reference. I believe it is the single piece cone. Did Klipsch do this mod or was it Atlas?

Hey Al, I saw one of your archived posts in which it appears that you say that Klipsch replaced the push-pins on the Altas mid driver with the solder type and altered the phase plug. Do you have any info on this? Does anyone have any pictures or info on the phase plug differences? I understand that the performance of the solder type is better and I am excited about the possiblilty of doing a mod. I am already tracking down some solder type lugs. It just makes sense to incorporate this into my crossover upgrade.

Yes, the picture does help. I had visualized something completely different. Frzninvt, are these disc's the same as your 1988's? Thanks to all.

Very interesting, thanks. Perhaps it did get on PWK's scope in the high power 80's. Does anybody have any pictures of these disks? What are they? How big are they? Where are they? What is the gap? It would be most helpful. I have some industrial sound material that is a heavy rubber with foam bonded to it. Cuting this into disks would make more sense than squeezing a full size sheet between the two.

I noticed the post on the khorn top cabinet(khorn pictures) and saw that several of the forum users have a good knowledge of the construction in this area. I have read that it is a good idea to (vibration) isolate the top from the bottom. Any ideas on the best way to do this? From the pictures it seems that PWK either ignored this or did not consider it to be a problem.

I have a long explaination from a person in the AudioAsylum who ownes or has owned all of the versions of the t35 and t350. He indicated that EV changed some of the tolerances and design of the driver when they switched to the ceramic magnet. "The workmanship and material quality of the older alnico EV tweeters is very good, however the later ones have much tighter tolerences and refinements, though the materials are not as good with more use of cheap molded plastic." This is a much more plausible reason (IMHO) for the difference than the choice of magnet material.

I have a long explaination from a person in the AudioAsylum who ownes or has owned all of the versions of the t35 and t350. He indicated that EV changed some of the tolerances and design of the driver when they switched to the ceramic magnet. "The workmanship and material quality of the older alnico EV tweeters is very good, however the later ones have much tighter tolerences and refinements, though the materials are not as good with more use of cheap molded plastic." This is a much more plausible reason (IMHO) for the difference than the choice of magnet material.

I am doing a model of the khorn using David McBean's Horn response program to get a rough idea what the effects of various woofer changes, etc, would have. I have parameters for the k33e woofer and have created a model for it. I am not 100% sure how to handle the "rubber throat" but the results look pretty close to the other graphs I have seen produced by PWK and others. Any help in the geometry would be appreciated. I cannot find any parameters for the k55v(push-pin) squawker or the k77 tweeter. If anyone has any of the T-S parameters for these drivers it would be appreciated. Thanks, Drew

I am in the process of changing lenses from a cd type to the t35 in my khorns. Everything is going perfectly and then I notice that the phenolic is touching the plastic phase plug. I have attached a picture of the problem. Anyone who has changed their diaghram's or knows these tweeters, is this right? If not how can I fix them? They are working but have never been strong. Thanks, Drew

DJK uses the autoformer to boost the tweeter 6db. This is an interesting approach. However my research shows that constant directivity horns have a 6db slope downward. If this is true boosting the tweeter 6db will not solve the problem. As the frequency goes up the amount of boost required would increase. Is this the case? Any input here would be appreciated. Al, thanks for the schematic. You are the king of the extreme xover games. 70-120db slopes are definitely out there. I searched but could not find any conclusions on extreme slopes. Do they solve the Khorn crossover point timing issues? You were right that the crossover schematic was to busy to easily isolate the tweeter equalization. Could I trouble you for a simplified sketch (like a text book 12db rlc example)? The Beyma's look like the best I have seen so far for the khorns. Unfortunately I don't have the real estate or wallet for them. Thanks to all for some very helpful responses.

I am thinking about using the ALK crossover on my Speakerlab clones. The drivers are identical to the Klipsch except for the tweeter. I have the wa4000 tweeter. This is a "constant directivity" speaker. After much research I found out that they require a 6db upward pole zeroed at the crossover point. This matches my observations that they are weak in the extreme highs. I have been unable to find an example of this "equalization" in a passive crossover. I am aware that you must pay for an upward tilt by lowering the output. This matters little to me with the power of the khorns. How would you alter your crossover to accomplish this? Thanks, Drew

I started building these speakers in 1986. I hope to have them done soon. They now sound as good as any Klipsch's I have heard. Let me bore you with some of my hard gained "wisdom". Forget the Speakerlab crossovers with the L-pads. Use a design like the ALK or a klipsch version, get the auto-tranformer for the midrange. I got mine from a company in Texas (ALK has the address in his design notes). Dampen the midrange horn. Use Dynamat, rope-caulk, duct seal, bat guano or concrete, just do it. I can't speak for the cast aluminum version but it solved the "horny sound" problem for me. Tubes only please. If you have only heard khorns powered by solid state amps you have not heard khorns. I have tried a lot of amps on these speakers over the years. None of the solid state amps from the cheapest to top of the line McIntosh could hold a candle to my tube amps. This being said I have also found it important to beef up the caps in the power supplies for tight bass. (added qualifier: This only applies to poor people like me. I am comparing SS vs tube in my price range (cheap). As you can see I but old inexpensive good tube amps and rebuild/upgrade them.) I have the smaller horn version of the tweeter (WA4000). It does not have the detail I like. Snare drums, etc. just don't have that "snap". I added a high effeciency horn style ribbon tweeter on the other side of the midrange horn. I have tried it with a crossover at 12k as a super-tweeter. Currently I have it wired in parallel with the tweeter. I cannot tell the difference, so in the interest of minimum crossover components I have removed the additional crossover point. It also helped with the problematic Speakerlab location of the tweeter on the side of the midrange horn. I have my speakers very close together. I find it pulls the sound image back to the center of the speaker. The lack of detail may have been solved by the larger HT350 tweeter, but Speakerlab never did put it above the midrange like Klipsch. If I was to build new top cabinets I would waste the extra wood and do it like the Klipsch. I have other horror stories of building the cabinets and crossovers, but I will spare you. The bottom line is new Klipschorns in 1986 were $2000.00, my time and effort over the last 17 years, $20000000000...........??????? P.S. I started this thinking that speakers were the weak link in the sound chain. So if I had good speakers I wouldn't have to upgrade any of my other components. Needless to say the speakers are the only component that I haven't replaced.

Dale, My major reason for Bi-Amping is to get the higher power like your Mono blocks. How did you Bi-amp? Did you go to four Mark III's? The 35 watts from the Fisher is adequate but when I am listening at "concert levels" I find the volume control is set very close to the beginning of the distortion range. By Bi-amping I will go to 70 watts per channel. Your input is appreciated.

I have a pair of Speakerlab Khorns which I have used for the past few years with a restored Dynakit ST70 and a borrowed McIntosh tube reciever/preamp. Recently I have had to return the Mac and got a Fisher 500C to replace it. Now the Dyna is just sitting there. Let me start by saying that a sane person would sell the Dyna and be content with the Fisher. I am not that person. So now I plan to mod the Fisher to preamp out into a pair of Steve Bench's tube active crossovers (http://members.aol.com/sbench101/#Electronic). The low side will go into the Dynakit ST70 and the high side will go back into the Fisher 500C amp. I plan to add level equalizing before each amp to accomodate the differences between the two amps. I will use AA klipsch type crossover design for the mid and high passive crossovers. Please comment on the above scheme. Is this worth doing? Can I "phase delay" between the woofer and upper section? How do I adjust the passive crossover values, if at all? Thanks,

I have finally gone all tube and have noticed that something isn't quite right with my kluged crossovers. I built stock Speakerlab Khorns in 1985. They are all ferrite cooled Speakerlab speakers. I built my own crossovers from suggested values supplied with the speaker specs. I am interested in what the Speakerlab crossover design was. I know many of you are familar with this clone and have posted many other crossover schematics. Any input on this and possible mods would be appreciated.