DrewBolce

Not a bad idea, however, I want to preserve the constant impedance of the Universal. I have fine tuned my measurements and have come up with 1.4mH, 10 ohms at 406hz. It took me awhile to get the setup and finesse your method. Now that I have it down I like it, it is solid and repeatable. I guess my next question is how to calculate the 2nd order values correctly. My calculations for the woofer filter is 28uFand 4.23mH. I assume the cap ( 48uf ) to the upper section would remain, but would the value be changed?

Yes it is, but I have the 8 ohm version. They did offer a 4 ohm version which I suspect is a very close clone. I have read your "universal" thread and agree that it is quite adaptive. I am in the process of swapping my 39 + 1uf caps with a 25 + 25uf (as close to the 48uf as I have on hand) with 1.36mH coils (handwound 12 ga. and measured on a Sencore LC102) and was interested in the "optimum" values for my 8 ohm speaker. The main reason is I have other caps and coils at my disposal so matching optimum values is possible.

Oops, bad setup on the R measurement (I was leaving the speaker in circuit for the 10 ohm calibration). I am now getting 12 ohms. This is more like I expected. Now I know something will need to be changed since this a 2:1 error.

Thanks AL. It just got weirder on the ohm measurement. My speaker required a 121uf cap at 397hz. This calculated out to 1.326mH, very consistent with the manufactures spec of 1.3mH. But the ohms measurement is getting really weird, now I am getting 5 ohms. I am using a 200 ohm series resistor, I assume it's value isn't that critical in this setup. I am using a 1% 10 ohm resistor for the calibration. Am I on the right track? Can I use Xover to calculate the new values? If so, are they 52.75uf cap and 1.33mH coil?

Oops, sorry I forgot to post a link to Al's measurement method. http://www.alkeng.com/le/le.html I am not confusing the two, it's just that I would expect the measurement (which is supposed to be the sum of the AC and DC components) to be larger than the DCR. Yes, I am looking to match my woofer with his crossover design. I just read his paper a little more thoroughly and realized I need to change the cap value until I get a frequency close to the 400hz crossover point. I'll try that and post the results. Thanks, your questions got me to wondering about the 902hz and its relationship to my measurements.

I am finally getting around to updating my ALK universal crossovers to Al's new(er) woofer filter so I thought I would once and for all get some good measurements on my woofers. The Speakerlab woofers are 8 ohm nominal so I expected to have to tweek Al's numbers. To my surprise they measured 1.15mH and 6 ohms! Al's design is based on 1.00mH and 6 ohms. This is a little suspect since the DCR of these is 6.8 ohms. I would have expected them to measure 10+ ohms in the khorn enclosure. My measuments were done using my 10mhz Tek scope, ST1000B for a signal generator and Recal-dana frecuency counter. My cap was a 27.1uf Solen. I used a 1/2 watt 220 ohm 1% resistor, my channel 2 trace was prettier than Al's noisy Carbon comp. I nulled at 902hz. Using the formula I came up with 1.15mh. Inserting a 10 ohm 1% resistor and calibrating to 5 divisions I was surprised to see 3 divisions when I reinserted the cap. The only caviot is that I was only able to generate about 1.5vrms, maybe that is too little for this measurement? Unless I did something wrong this is a surprising result and indicates that the woofer is a much closer clone to the K33E than I thought.

Absolutely, I ended up running a frequency sweep from 1khz to 20 khz ( even though my hearing is gone at 14khz ). Sure enough, the 1khz dies as you tighten the screws. The higher tones however, get stronger. Just your normal resonance changes I am sure. I was able to perfect the alignment by doing this. There was a difference that can be tweeked by tightening the screws and twisting the assembly slightly. I removed my other tweeter and adjusted both for best operation and equality by ear. I am hoping this is a gross enough procedure so that it is ok to do by ear and will not require a set up with a microphone to do some real measuring.

I am finally replacing one of my K-77 tweeter diagphram ( 5 years overdue). I have read where a 1khz signal while assembling will help insure proper alignment of the components. When I do this I get a strong tone but as I tighten the screws it diminishes to almost nothing. I am using a 1 Vrms signal generated by my soundcard. This may be normal since the tone is well below the capability of the speaker. Has anyone done this? It seems to me that a 4khz tone would be more useful for a tweeter that is intended to be used above 3.5khz. It seems like a good idea but I would like to impliment it correctely.

I built mine with a skill saw, ripping fence and blade set protractor. What an immense pain. However, the final cuts were better than you can get on a cheap table saw. This really is the territory for cabinet makers only. Fortunately I was able to get very high grade RTV from a local manufacturing company. Now that they are over 20 years old this decision is paying off.

So the Dayton Film and Foil are cheap how? The Auricaps mentioned are metalized, not film and foil. They are superior how? The biggest myth in Audio today is that insanely more expensive is better. You can put your money into the sound or the bragging rights, your choice. This is addressing the comments made before, not Don's quote. Essentially he is right. Materials, construction, quality control make better products not final sale price.

My midrange came with PD5VH's, but they are the early version with no phase plug. I did improve them somewhat by polishing, aka like porting an intake manifold. They did indeed have the 8khz "bump". As advertised the ALK universals took care of that issue. The fiberglass is too thin. Someday I will take the time to glass on a new layer, in the meantime I found that a good layer of rope caulk took care of the ringing problem. Yes, ringing. They had a resonance right in the midrange. Taping produced a ring that I guess was about 1500hz, not the thud (50hz or lower) that thick glass would have produced. To be fair I have not put the WA4000 ("wave aperture") horns back on and tried them with the ALK crossovers. Someday when I have time (not likely) I will try them and post the results. The cost of the tweeter is probably justified. The horn is a structural plastic casting, not really all that cheap. Before I thought it had poor imaging and a rolloff even lower than the 77's, but that may have been the crossover. I am still kicking myself for not spending the extra $26.00 and getting the 350's which as we all know are worth much more today. Note that the crossover does not have an autoformer. Substituting L-pads was no solution. To me it seemed like the L-pads killed the midrange clarity. From what I can tell the woofer is a reasonable copy of the Klipsch. I think Edgar was looking at a particularily bad one or some bad specs. The specs I have for the woofer vary dramatically. It seems like SpeakerLab had several versions. They might have been changed in response to Edgar's article. Anyway the "hole" at the midrange crossover point doesn't seem to exist on my system. Some other thoughts on the early rolloff may be, 8 ohm instead or 4 ohm impedance, coil mismatch (ALK has done some work on this, it is a problem), poor cabinet construction (even minor air leaks), or poor corner sealing. I have had all of them and have found them to be extremely important for good woofer performance. mungkiman - SpeakerLab suggested a woofer mounting board with the throat slot. This would then by attached to the motorboard inside the cabinet onto studs with thumbscrews. I would hate to try to put the woofer in with screws only. Sorry to hear your builder cut corners.

And finally the midranges. Even though they show the metal version of the HM350 the B means fiberglass.

Here are the tweeters:

Here are some old and poor quality copies of SpeakerLab catalog pages. Wish I had bought the HT3500's (350's). Instead I got suckered into the WA4000 junk. Fortunately it was a K-77 with a cheap plastic horn. I was able to get real metal horns off of Ebay. The mids were fiberglass with the early Atlas driver. At least the horn was a K-400 clone. SpeakerLab's main weakness was their crossover, IMHO. When I put an ALK universal in them they came to life.

Not really, I used 0.22 and 0.47uf values. Try to get them about 10% of the big cap value and have them add up to the spec value. Paralled them with the big cap and set them up so you can change them. I would suggest auditioning them. Get the same values in the brand of big cap (example, Solen) so you are not listening to the value change. Al has done some rethinking on the universals, I would suggest looking at his website and/or contacting him to get his latest insights.

Ah, yes. Thou shall not touch the cap with the soldering iron. Cost me a fotune when I was putting my first computer together (1974 - yes, before the beginning). I would not use Polystyrene in any place where voltage is a concern. I have been been using the Illinois polypropylene for some time now (yellow axial from Antique electonics). 630v, priced well with size and sound similar to most vintage caps.These caps have the same problem, one touch with the iron and poof, no cap. If you are saying that you need 160v or better caps for speaker crossovers I would like to hear your reasoning. I have always felt that 100v and above caps were good, 50v could be used with wisdom.

I have had good luck with these on vintage amps. They are banana jack only posts. Just remove the screw and replace it with these (most are 6-32 threads). The banana jacks provide a good safety, since I am always tripping on the wires. Better to pull the wires out than drag and drop an amp. http://www.kvmtools.com/servlet/the-2290/Adapter,Termnal,Strip,-Pomona,-6720-dsh-0/Detail http://www.kvmtools.com/servlet/the-2291/Adapter%2CTermnal%2CStrip%2C-Pomona%2C-6720-dsh-2/Detail

I just used Dayton Film and Foil on my ALK Universals. I have been pleased with the results.

Beyond important. Some of my early computer measurements showed a significant change in db and frequency response. The water pipe insulation comes in two versions for 1/2" and 3/4" pipe, get both it is cheap. One of them should work. If you are not familiar this stuff can be cut with scissors in order to clear floor and chair rail moldings. The key here is to get an airtight, gap free joint. I am told the top is not as important as the sides but I did both.

I found that the light stuffing smoothed a ~100hz hump out (Speakerlab woofer). It is possible the hump is making you think you have lower bass loss since all is relative. I use pretty accurate computer based analysis, all calibrated, etc. However for subjective tests I like the Bach Fugue organ piece. I can't recall the exact name right now but it boasts notes down to 17hz. I went to Home Depot and got some large flat head furniture screws that are driven by a square bit. Using my cordless drill I can get the panels off very fast without stripping the holes ( they are about 3 inches long with a 3/8 thread). I use a closed cell flat foam gasket for the seal, again from the hardware section of the big orange box. I use water pipe insulation to seal between the wall and the tailboard. If you have not done this you will not get any reliable or repeatable bass results, in my experience.

Since this thread never seems to die, I will chime back in. I have experimented with rear chamber stuffing. What I settled on was plastic window screening stapled over the back of the woofers with as little as possible, highly fluffed Dacron pillow stuffing in the rear chamber. I cannot emphasize enough to use the least amount of stuffing possible. Over stuffing will kill the lower bass. Now for some complete heresy. The biggest effect I got was when I rounded off the sharp comer on the motorboard throat slot outside edge with a router rounding bit. This removed the "diffraction edge" like a modern bass port. The effect was to smooth the bass response noticeably. This may help with the "wood" sound several posters have complained about. I believe the Speakerlab plans called for a motorboard while the Klipsch mounts directly to the cabinet, so this may not be doable on most true Khorns. I should add that my cabinet has a 6' x 13" slot in the cabinet since I experimented with the larger throat slot in the early days. My findings where that the 3" x 13" slot worked the best with the Speakerlab woofer. I use the ALK universal crossover with a 1mh coil for the Speakerlab 8 ohm woofer.

I have replace the phenolic diaphragms on my khorns, both the mid and tweets. Both were worn out. As a disclaimer they have lead a hard life. I have abused them with many different amps in various stages of disrepair. They were about 25 years old. The sound improvement was dramatic. There was some whiting at the accordion edges, along with some phenolic dust. I believe the Koss KG75 (much appreciated $20.00 ear clips) headphones are Titanium. They have excellent bass. I wonder if Ti can be made to work for a low power application like a headphone but is no good for a compression driver.

You are quite right. I got Googled. I didn't catch that it gave me a link to a similar number. Here is the correct plot. It is a much better match to the khorn enclosure. I use the model to do "what ifs". It is not intended to match the anachoic chamber measurements. I used it as we did here to see if a particular woofer works in the enclosure before buying it. Here are the parameters I used:

Just to be clear the model I made was with the chamber stuffed with poly or the like. In my own khorns I have a similar configuration to Fig. 4-30. Mine have plastic window screening stapled to the back of the speaker with a thin layer of poly (wally world pillow stuffing) over it. I stuffed it at first, then kept removing material until I liked the sound again. What remained was just a thin layer . I confirmed my listening with the model. Heavy stuffing alters the response. I do not think the model is mathmatically sophisticated enough to show any refections or the like, if they exist.

Dylani, Waves, what waves? If a tree falls in the forest does it make a sound? You do not hear the back chamber. The stuffing changes the characteristics of the backchamber thereby changing the operating characteristics of the woofer, thereby changing what you hear from the horn. Stuffing will change different woofers/speakers differently. My AR speakers need it, my khorns do not.