Al Klappenberger

Derek, Yes, you are quite right. The woffer / squawker crossover is made of 6 dB / Octave filters. It's actual crossover frequency is very hard to pin down. Even a slight change in load impedance of the woffer will change it significaltly. The natural crossover is more a function of the horn cutoffs than of the crossover network! The Q doesn't mean much as 400 Hz either. All that really counts is the DC resistance. This is where the Alpha Core spiral inductors might be best used since they seem to be low DCR. Al K.

The General Radio 1608-A will measure R,L or C. It's internal resistance is only about .002 ohm. It will resolve to .0001 Ohms. Accuracy is specked at +-0.1%, +-.005% of full scale. In short, It's pretty d___ close! The thing is sort of old, 1970s vintage, but had a priced tag of well over $1000 when new. It's a laboratory quality instrument. Al K.

Sorry Randy, I wasn't trying to "show" anybody! "Q", or quiality factor, is the most important thing. It should be the highest number you can get. It is the ratio of inductive effect to total AC losses. DCR is simply losses (resistance) at DC (zero frequency). It is a portion of the total AC losses. The number shold be as low as possible. L is inductance in mHy. It should be exactly what is required for the application. If you order .2 mHy from the manufacturer you should get .2 mHy within some tollerance. In the case of Solen, it's within +-1% of .2 mHy. Al K.

============== Here is the results: =============== Solen .2 mHy: L=.1986, DCR=.128, Q=43.8 Home-made PVC .2 mHy: L=.2048, DCR=.143, Q=25.8 Alpha Core .2 mHy: L=.1879 DCR=.098, Q=29.4 North Creek .18 mHy: L=.1686, DCR=.058, Q=11.4 North Creek .3 mHy: L=.304, DCR=.080, Q=10.4 Solen .3 mHy: L=.293, DCR=.158, Q=49.8 The .245 inductor from the Klipsch AA network (not shown in the photograph): Klipsch .245 mHy: L=.2628, DCR=.37, Q=21 CONCLUSION: The clear winners are the coils from Solen wound of Litz wire. The worst are the coils from North creek music. While good, the Alpha Core spiral inductor only manages to beat out the home made coil by about 4 points. If you are considering using these, use the Solen coils instead! At a Q of 21, the coils used by Klipsch are better than I expected and better then the heavy "upgrades" from North Creek Music. As you can see from the DCR on the Klipsch inductor it is would of rather thin wire. This proves that heavy wire is NOT the answer to good Q at 6000 Hz, "Litz" wire however IS the answer. I might point out here that the use of Litz wire for the inductors used in the woffer channel would be of no value. At 400 Hz, only the DCR is important and solid wire is just as good and my be slightly better for the woffer inductor. Inductance accuracy is also an important factor. My networks are built in matched sets. All the capacitors are measured and manually matched to about +-1% pairs. The inductors from Solen are wound to 1% tolerance to begin with which means I do not have to measure and match them. The Alpha Core inductor came in at about 6% low. This is fine for a less demanding network but not good enough for use in networks featuring matched sets.

The picture shows the six inductors tested. In the back row, from left to right are two coils from North Creek Music. These are wound of heavy #12 soild wire. They are .3 mHy and .18 mHy. The .3 mHy coil has had several turns added to bring it up to .3 mHy from a lower value. The other was intended to be .18 mHy In the right real is a home-made coil wound of #14 soild wire, two layers on a piece of PVC plastic plumbing pipe. It was desinged to be .2 mHy. In the front row to the left is the .3 mHy inductor from Solen I am using in squawker channel of my network. It is wound of #14 "Litz" wire. Next right is the .2 mHy spiral inductor from Alpha Core. In the right front is the .2 mHy inductor from Solen. It is also wound of #14 "Litz" wire. It is the tweeter filter inductor I am using in my network.

Hi guys, There has been so much talk about inductor upgrades for speaker crossover networks that I have decided to do a head - to - head comparison of all the inductors I have collected while developing my AA upgrade. I also purchased a .2 mHy Alpha Core spiral inductor specifically for the test since these seem to have such a wide following. The measurements have been restricted to the exact value of inductance of each coil, its DC resistance (DCR) and quality factor ("Q") at the 6000 Hz squawker / tweeter crossover frequency. The Q of the inductor is to be considered the most important factor. The higher the better. Measurements were made with a General Radio 1608-A impedance (in the picture). This particular one had to be repaired and could not be calibrated to it specification of +-.1%. I think that it can be considered accurate to +-.5% however.

Now T H A T ' S what I call a home theater! Just wait until he gets my prototype crossover networks installed! Al K.'

Tony, ooowh, that's pretty! I notice the corner on the right Khorn isn't quite as good as the corner on the left. It looks like it's part window and a column of some sort is keeping it from sitting flush. Do you notice any difference in low frequency performance on the right one? Al K.

I will give anyone interested in ordering a set of networks details about payment via email. I don't figrue I should be detailing that sort of thing here. I am not so sure listing the price here was in such good taste either, but I did it anyhow! Thanks, AL K.

The replacement transformers are made by the same company that makes the transformers for Klipsch. The new design is bifilar wound for a tighter coupling and uses heavier wire for lower DC resistance. It also has a larger core area than the T2A. An additional tap was added to provide a little more flexibility for adjusting the squawker level. My tests showed that it has a very slightly higher top end frequency response, but in the squawker channel, that doesn't mean a lot. Both the new design and the T2A were capable of transferring 50W of power to a load with no measurable distortion. My prototype networks are now promised to someone. I will be building myself a new set later. I will be ordering parts for the next production run Monday June 19. Anybody who wants a set should let me know before then. I am asking $___ for a matched set with $___ deposit to cover parts cost. Thanks again to all! Al K.

Hi Guys, I have been asked several times about substituting the Jensen paper-in- oil capacitors for the Hovland and Solen capacitors in my crossover network. The short answer to this is NO! Here's why: I have done computer analysis to determine the acceptable tolerance of each part in the network. The 2.2 uF caps used in the squawker / tweeter crossover need to be within +-5%. The Jensen caps are -10% +20% tolerance, which is not good enough. The squawker / Tweeter crossover will very too much messing up the stereo image and the impedance match to the amplifier. I am also matching the caps within about 1% of each other between left and right. That means I need to order them in quantity or pay a premium to get them in matched sets. Matching parts with a 20% tolerance to 1% is kind of silly! To make matters worse yet, I need two 40 uF caps for the woffer / squawker crossover. Jensen doesn't make this value which means I would need to parallel 4 of the 10uF caps to get to 40 uF. With two networks, at $65 each, the price would be $520 for just this component alone! I might also add that the paper-in-oil capacitor was the best of YESTERDAYS technology and I think their excellent and well deserved reputation is left over form that era. The polyproplyne caps, like I am using, are extremely low loss. The Hovland MusicCaps that I use have less loss then several feet of AWG #10 wire! At 6000 Hz, their "Q" factor is so high it is actually off the scale of my impedance bridge, beyond 2000! Remember, oil and paper caps are what Klipsch uses in their stock networks. It is what was in my old "AA"s. I have measured their loss and it is NOT very good in comparison! I suspect it is the main reason for the "veil" people speak of. This is not to say that the Jensen oil capacitors are NOT good. Even though I have not actually measured one of them, I am sure they are MUCH better then the ones used by Klipsch! I believe those are actually motor- start capacitors. Manufacturers must pay close attention to the ratio of cost to performance. Klipsch must do this too. The capacitors they are using are very likely the most "bang for the buck" around! Al K.

Hi guys, This is just a note to remind you that a list is forming for networks. If you want me to build you a set, now's the time to contact me. I have already started to cut the boards! Many thinks to everybody for all the nice comments! Al K.

Steve, Well... If you got 60 feet of it, even up swap for my prototype networks! Deal! Al K.

Gosh Mark, With a pea like that, I might just have to cover the parts cost for the last two of the four sets myself just to get your dad's done! Anybody wanna buy my prototype networks, cheap? Al K.

Hi guys.. The long awaited plots of my network prototype in a Khorn done by Trey Cannon in the Klipsch anechoic chamber are ready. They are to large to display here but they can be downloaded from my web site: The URL is http://www.web-span.com/alk/klipsch.html Thanks, Al K. NOTE: These curves are no longer available.

GaryC An upgrade transformer to replace the T2a is available from Universal Transformer. It is their part number 3619. Talk to Mark Cooper. Tell him it's the ALK Engineering upgrade. (972) 442-2233. Al K.

Hi guys, I just discovered this discussion. I don't know if you are aware of it, but Paul published a paper on the redesing of the k5 to the K400 horn. It even includes performance curves on both horns. I have it and if anybody wants a copy, I could scan it. E-mail me and I will pass it along. NOTE: I have put the article on my web page. Look at the bottom of http://www.web-span.com/alk It's to big to e-mail at 1.4 Meg.