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I am back in the East Coast again. I will be here till Feb 3rd. The Tweeters are still available if anyone is interested.

Lee: What OS are you running? While it works like a charm on XP, I cannot get it to work on W7 (and yes I followed all the procedures religiously).

It is also interesting that the K77F is labelled as a 8 Ohm nominal Imp tweeter. From the plot the average Imp is only around 6 Ohms.

This is K77F as measured by WT3. I am wondering what effect there maybe from what I see around 3.5KHz.

Here is what WT3 says about K53/K701 combo. The impedence peaks in the midrange ain't so pretty! Also interesting is Le is repordted as 2.2mH higher than a Woofer???

Al: The plot I have posted so far are for BEC's CS1526 Woofers (in my Cornscala cabinet) which are as per Bob close to specs as early K33's. I will be posting the K53 measurement next.

Bob: Have you done Le measurements on the CS1526 at various frequencies with something like a B&K precision meter?

Here is the measurement of CS1526C (mounted in cabinet) by WT3. I did more than 10 runs at different times and the results were quite consistent without much variation. Re is right on (my Fluke Meter measures 3.8). The WT3 impedence curve pretty much matches with my crude method above with a few minor exceptions at a few frequencies. Also, the min impedence between the double peaks is at 40Hz suggesting tuning to 40Hz. Interesting things are as follows: 1. Le is reported as 1.7mH (do not know at which frequency) 2. Qts, Qes and Qms are substanially different from free air specs (cabinet loading cause??) which are Qts = 0.2, Qes = 0.27, Qms = 9.93.

After getting the WT3 tester under Windows XP (it does not work under W7), I measured the impedence and T/S parameters of Crites CS1526C Woofer mounted in a Cornscala Bass Cabinet. My Cornscala Bass bin has almost same volume of Cornwall but with different shape. It is rectangular the first 9 inches of depth and then tapers like a trapezoid towards the rear. The port shelf is same dimension and postion as of cornwall. First I will post the impedence I measured earlier with my crude simple method using a known series resistor ans measuring voltage. Here it is.

Ok. It WORKS NOW!!!! Turns out the WT3 contradictory to claim of Windows 7 Support, is not working under Windows 7. I borrowed an Old XP Laptop and when I tried it on that it seems to work well!!! It caliberated well including test leads and I did some sanity tests with known resistors and inductors and it measures pretty close with good consistency across many sets of runs. I will be making a separate post with measurements on my drivers.

I have had such bad luck with the WT3 Woofer tester. My first one was defective and parts Xpress sent me a replacement. Again the replacement does not work properly. When I short the leads and do Test Lead Caliberation it says resistance is greater than 1 Ohm!!! just like the first unit did. When I measure a known 8 Ohm resistor it comes up with Re=40 Ohms!!! On Bob Crites Woofer it measures Re as 1 Ohm (BEC Woofer Re is around 3.6 Ohms). I am so disappointed with the WT3 and I do not know even if I get another replacement I will trust it. Lee - Have any of you used it with Windows 7? Or anyone used WT3 with W7 with good results? Thanks

Al: Just realized that that AP12 woofer section is an even (second) order one. I guess had it been an odd order one you could have subtracted the Le from the last inductor if its value were >= Le, but cannot in this case even order case.

Al: Subsequent to your finding of the actual complex K33 woofer impedence to be about 6+1j, you have mentioned that you actually subtract the 1mH Le from the required inductor value for the woofer section (instead of using a zobel) and thus you also now recommend 1.3mH for the universals instead of 2.3mH. However, when I downloaded your AP12 desing form your website, the inductor values shown for various Xover frequencies do not seem to have subtracted out the woofer Le. Could you please clarify this? Thanks

I am considering experimenting with the JBL 2426 Driver for my cornscala (I find the Atlas PD-5VH/K400 Combo very dull sounding and closed in with dominating midrange and as though the upper midrange were muted out). Looking at the published plot of JBL 2426 on a 2370 Horn that is attached here, it looks like I can even use it as 2-way without tweeter. While it extends nicely to 18KHz, the response between 5.5KHz - 18KHz is shelved down by about 3dB. This means the range between 900Hz-5Khz needs to be equalized down for flat response. Any ideas on how to implement this in a passive crossver? Also, is this difference in output between the feq bands change with a different horn? Al, have you run curves on your JBL 2426 on your trachorn? Thanks JBL_2426.pdf JBL_2426.pdf

Djk - Thanks. Now this is interesting - 1W SPL = 96.78 dB; 2.83V SPL = 100.5. The only value of R being nominal impedence for which 2.83V would yield an increase of 3.72dB compared to 1Watt is R=3.4 Ohms, which is actually same as the Re. However, ALK has actually measured the K33's nominal impedence to be around 6 Ohms. If we use 6 Ohms, then @ 2.83 V the SPL will be higher by 1.25 dB compared with 1 Watt. Now, I am confused.

1. Searching the forum for K33 sensitivity, I find a wide range from 92.5dB to 98.5dB being mentioned. What is the actual sensitivity spec of the K33 Woofer? 2. As per Klipsch Cornwall II brochure, the speaker's overall sensitivty is sepcified at 101dB @ 1w/m. How did the sensitivity increase to 101dB when the K33's sensitivity is only in the 90's? Does cabinet the loading increase it?

Al: In your zobel network recommendation you had mentioned to use non polarized electrolytic capacitor. Why does it have to be electrolytic and not say polypropelene? Similarly in woofer bypass caps or a N order T section filter to woofer, does it necessarily have to be electrolytic? Thanks

I do not have the equipment to do proper A/B compariosn. But in any case My listeing is not just the woofer, it is integrtaed as a whole. Anyway, the main point here is if adding 80dB or 60dB to 90dB results in mathematically to only 90dB, what is is the advantage of building complex higher order network from a freq response stand point?

The way the dB output of two drivers sum by math, does not seem to correlate with listening when using higher slope networks Vs lower order in terms of tonality. Of course, there are other advantages of higher order networks that consequent to reduced region of overlap lead to reduced combing effects and such. But for this thread I am confining the scope to ONLY SPL Vs Freq Response, since that primarily dictates perceived tonal balance. For example, Let us take the following hypothetical example for simplicity: - A woofer with a sensitivity of 90dB with a flat bandwidth of say 20-1000Hz. - A midrange driver with a sensitivity of 90dB with a flat bandwidth of say 300-5000Hz. - The midrange has a first order high pass circuit with a crossover (-3dB) freq of say 700Hz which is well within the drivers’ inherent passband. 1. Let us say we first implement some first order network for the woofer and let us say in doing so the output of the woofer is about 84dB (-6dB down) at say 1000Hz. 2. Let us take another case where we implement a higher order low pass such that the woofer’s output at 1000Hz is say 80dB (-10dB down). 3. Let us take another case where we implement a even higher order low pass such that the woofer’s output at 1000Hz is say 70dB (-20dB down). 4. Let us take another case of extreme slope, where we implement a higher order low pass such that the woofer’s output is say 40dB (-50dB down) Now let us sum the total spl in both cases: 1. In case 1, the total output is 84dB + 90dB = 90.97 2. In case 2, the total output is 80dB + 90dB = 90.41 3. In case 3, the total output is 70dB + 90dB = 90.04 4. In case 4, the total output is 40dB + 90dB = 90 According to the above, whether the woofer is at 10db, 40dB, or 70dB or 80dB the total spl is always 90dB, implying that a higher order network has no effect on ultimate spl due to overlapping driver output. But, clearly I hear difference between a third order and 1st order in such a situation. Of Course, we have less of combing effect and such at the overlap region with higher order that contributes to listening differences. But I am, as I said confining to tonality issues alone that is primarily determined by SP Vs Freq and I do hear difference in tonality. Can anyone explain this?

Robert: I agree with others that with a 1st order network moving from 500 to 600Hz is not worth it. Also, not to confuse you, but I spent a few hours at ALK's house last Sunday, and I was mightilyy impressed with the the JBL mid range driver + Al's trachorn, he uses in his modifed Belles. It had a certain palpability and naturanlness that was so good and that too I later realized that the source was FM Radio and not CD or Vinyl! I think he had the JBL 2426 but I do not exactly remember the model. You can check with Al on the JBL driver as well, since I am contemplating myself on replacing my K55/K400 combo (which I a personally do not find that great and actualy prefer the Herseys K53/K701 combo in comparison) with JBLs and Al's Trachorn myself. Just another flavor to think about. Whatever direction you go, good luck and have fun. Regards

drbtt: Are you still interested? Thanks

psg: Yes. I have Bob's Cornsxala Xover which does the same thing rollling off the highs of the squawker with a series inductor that suits the CT125 much better.

I am in New Jersey till Oct 8th. Thanks

I have a pair of CT125’s in excellent condition. I bought these for my Cornscala project but ended up with K77-F’s instead. This has been used very lightly at most 60-70Hrs. The only thing I would like to mention is that one of the tweeters, the terminals have a slight play (they can swing a bit if you push) due to my frequent connecting & disconnecting during evaluation. But the connection is secure and does not cause any issues whatsoever. I am asking $99 for the pair Plus Shipping. I will be in the US only between Sept 20 – Oct 8th and will be back in India. So if anyone is interested we need to conclude the sale before Sep 27th so that there will be enough time to ship and resolve issues if any before I leave (I do not foresee any, but just in case like bad UPS handling or such).