x-over A in a year 2k Khorn?

[esker]

Thanks for the measurement, Al K.

8% increase in the first volt seems like a significant trend. With a Klipschorn, SPL is in the mid 90s with this signal.

So the inductive reactance increases at the same time the driver resistance would also increase due to voice coil heating. I think that means the crossover frequency would shift less than you'd expect from the inductance increase alone. How much the effects offset each other would make an interesting study.

[WMcD]

Getting focused on the orginal subject.

Al is measuring the effective inductance of the inductor in the woofer circuit.

We see some variations at 100 Hz. But not too much.

The real issue is what it might be doing at 400 Hz which is the nominal cross over point.

I really wouldn't be too worried in any event. The overall system response up at 400 Hz is not going to rise or fall because of the inductor. Rather, I think, the driver and the horn are dominant.

My concern is that someone reads that the inductor shifts values and then goes off on a snipe hunt to find a perfect inductor and call it a silver bullet.

PWK had suggested we can remove the inductor and get a better response.

I say, So why worry?

Gil

[Al Klappenberger]

Gil,

Yes, I think this is a small point. One thing that my be a concern about it is that I believe the inductance is actually changing dynamically with instantanious voltage. That is, the inductance is different at the peak of each cycle than it is at the zero crossing and at every instant in between. After all, the magnet field has to be changing with the current through it. I believe this will translate to a certain, though small, degree of distortion. Once thing is certain though, an air-core inductance will not suffer for this problem becasue there IS NO core.

Al K.

[esker]

Al K.

Sounds like the distortion you're talking about could be related to the distortions in driver magnet circuits that JBL, Scan-Speak and others try to clean up with shorting rings, etc (though with drivers it's aggravated by motion). Fortunately, this distortion is much reduced with efficient speakers and short diaphragm excursion. No reason not to try to reduce it further, though, if you can hear the improvement.

Aren't you glag you're using horns?

[rune]

Thanks to everyone for all the input!!

The most of it goes way over my head,but I'm trying to pick up some,and learn along the way....

I don't wanna close the case,so please continue discussions.....

Only one thing:The AK-3 has an 4mH inductor in the woofer,while the A has only 2,5mH.....will this result in the woofer playing higher in frequencie?Or does it start rolling of at 400Hz as the AK-3?

Take care!

Rune

[Al Klappenberger]

Rune,

The inductor is larger in the AK network becaue it is second order (12 dB / octave). The AA network uses first order (6 dB / octave). You could say the additional capacitor in the AK un-does some of the inductance requring a higher value. That's a HUGE oversimplification though.

Al K.

[JohnA]

Gil,

Being the pragmatic engineer we know him to be, why was the inductor put in the crossover if it was not needed or if response was better without it? Would it be something related to providing a uniform impedance for the amplifier?

I've read about this before, but never was tempted to try it until now.

John

[esker]

Put a jumper across the inductor and you'll hear why it's in the circuit. The music sounds like it's coming down a tunnel.

By the way, PWK had no interest in uniform impedance, so long as the load didn't trouble the amplifier. Heritage impedances run all over the place, over 100 ohms, I think, in the case of the Heresy.

[Al Klappenberger]

Esker,

You can't just short out the inductor on netwroks with the 12 dB / octave woofer filter. If you do that you will be connecting a huge cap directly acroos your amp. That's why it sound like that when you short it out. You can only try doing that on the AA network.

The Belle Klipsch went through that experiment. The AA network had one inductor. The AB network had NONE and ran the woofer full range. The crossover was raised way up. I think it was somewhere between 700 and 900 Hz or so. Then came the AB-2 network which went to an inductor and a cap for 12 dB / octave slope.

Al K.

[WMcD]

I recall the comment by PWK came from the SpeakerBuilder interview by Dr. Edgar.

It is a good question why, if there is better response (at some place in the range) why put it in there to begin with.

I don't know.

It is probably correct to say the K-Horn woofer has some low level output up to 1000 Hz or so. Perhaps the thought was it was advisable to cut those off to some extent with the inductor, rather than have the sound interfer with the midrange.

Also, the inductor will start increasing the impedance of the woofer system above cut off and thus decrease the load on the amp. One of the last Dope from Hope-s showed that increased impedance will decrease some forms of distortion from an amp when it is driven hard.

One additional matter is that the LaScala used the same cross over. Is that correct? Its bass bin probably has a lot of output above 400 Hz and thus a rolloff is needed. So perhaps a universal circuit was thought beneficial.

Gil

[JohnA]

Gil,

Yes, my La Scalas have Type AA networks. I do hope they have good output above 400 Hz. I'm going to experiment with an Altec driber and a pair of 511Bs I have when I find a deal on the drivers. I need to arrange to go over to a coworker's house and have my bass horns tested to see how high they do go. I seem to always be too busy to remember to do it. 800 or 900 Hz would be great!

John

[esker]

Yes, of course Al K's right, you don't want to jump the inductor in the 12 dB lowpass. Sorry!

My AA Klipschorns sound horrid without the lowpass in place. In 1976, one of the salesmen at Bill Bell's store told me he removed the inductor and he liked it that way. I tried it and couldn't stand it. On the other hand, if you like reverb...

Do others get the same results I did?

[johnnyp]

I agree, Esker, the inductor for the bass horn on the Model AA network should not be bypassed.

I have Khorn clones with Klipsch AA networks and drivers. I ran my Khorns for about 6 months w/o the bass inductors after conducting a simple listening test. But my test was flawed. During the test, I listened to a bass unit with and without the inductor while leaving the squawker and tweeter disconnected.

I preferred (and still prefer) the bass units without a series inductor if listening to the bass units only.

Al Klappenberger convinced me, in a private email conversation, that the bass inductors are needed to "balance" the network. He was correct. I reconnected the inductors and conducted a similar test this time keeping the squawker and tweeter connected. Al was right and I noticed an immediate improvement. The bass is tighter and the sound is more "coherent".

Now, I run my AA's with the tweeter diodes disconnected. Also, per a post by djk and Al I have increased the value of the second capacitor in the tweeter circuit. Both of these mods are improvements to my ears.

------------------

John Packard

[Guy Landau]

Hi,

I was thinking about building the type A crossovers as well.

I would like to order the inductors from Solen,but they do not have a 2.5 mH value.

Is it possible to use 2.4mh+0.1mH in series.

Thanks

[Al Klappenberger]

Guy,

Don't worry about the extra .1 mHy. It is not at all critcal. Just use the 2.4 mH.

Al K.

[djk]

"I recall the comment by PWK came from the SpeakerBuilder interview by Dr. Edgar." For a while the Klipschorns with AA networks in the Klipsch showroom had the inductor bypassed. This was suggested by PWK in response to questions about bi-amping. PWK was opposed to bi-amping. He thought the only benefit to bi-amping was the removal of the DCR of the woofer choke, and as such he suggested that it simply be jumped and the speaker would then sound the same as it did bi-amped. While I did not agree with PWK about bi-amping, and bypassing the woofer inductor in a AA network did not sound the same as bi-amping, for a long time I felt the same way PWK did about the DCR of woofer inductors. The speakers that had the most 'slam' were either bi-amped or had no woofer inductor (the time frame here was late 70s). By the early 80s I realized this was a red herring and that the transfer function was all. I think the Bakgaard patent

http://164.195.100.11/netacgi/nph-Parser?Sect2=PTO1&Sect2=HITOFF&p=1&u=%2Fnetahtml%2Fsearch-bool.html&r=1&f=G&l=50&d=PALL&RefSrch=yes&Query=PN%2F4031321

referenced by PWK in

http://164.195.100.11/netacgi/nph-Parser?Sect1=PTO1&Sect2=HITOFF&d=PALL&p=1&u=/netahtml/srchnum.htm&r=1&f=G&l=50&s1='4237340'.WKU.&OS=PN/4237340&RS=PN/4237340

when used with a LaScala produced the most coherent sound with more 'slam' than anything I have ever heard. The 24dB/oct Linkwitz Riley comes in a close second (but maybe first, as it needs no filler driver).

Linkwitz,Siegfried: Active Crossover Networks for Noncoincident Drivers, JAES, Vol. 24, No. 1, January/February 1976. Reprinted in Loudspeaker Anthology, Vol.1, AES 1978, Abstract: Active Crossover Networks for Noncoincident Drivers.

The spatial separation between drivers in a loudspeaker system affects the radiation pattern over the frequency range where more than one driver contributes to the total acoustic output. An analysis of conventional crossover networks shows that the main lobe of the radiation pattern shifts in direction and increases in amplitude. A new network transfer function, which can easily be realized with operational amplifiers, eliminates this problem.

[Guy Landau]

Thanks,

I will keep you posted.

[djk]

Klipsch has a limited number of E2 networks, Klipsch #116014, at $28 each. These have the stock Klipschorn woofer inductor, T2A autoformer, a 2µF oil cap for the tweeter and misc parts. By adding a 13µF cap for the midrange and changing the taps on the T2A you will have a type A Klipschorn network.

[Guy Landau]

Thanks djk,

I have allready ordered litz inductors from Solen and I am planning to use the transformer from my AA crossover.I have the ALK crossover and thought that it would be interesting to compare them to the type A.

If I won't like the type A's,I'll use the 10 awg litz inductors in my ALK's.

Regards

Guy

[Guy Landau]

Hello everyone,

I have built the type A crossover for use in my 82 khorns.I think that they are wonderfull sounding.You can read about it in "updating older speakers" if you'd like to have more details.

cheers