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Khorn type A crossover question


Painful Reality

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On 11/24/2004 4:18:23 PM Painful Reality wrote:

Shouldn't the squawker be wired in reverse polarity compared to the woofer and the tweeter despite the factory schematic showing it wired in phase?

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Actual driver locations in relation to each other and the listener can change which polarity to use on the individual drivers for the best acoustical blending. So in other words the networks ,driver physical locations and listener locations have to be taken into account when selecting the proper polarity for the individual drivers.

mike1.gif

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strange jeff you mention that, I had a really hard time re wiring my k-horns because I tended to want to wire my mids out of phase (electrically) due to listening tests but was worried because the schematics show differently, try it both ways and see which sounds best to you, tony

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Painful,

The insertion phase contributed by a network filter is 45 degrees per element at the crossover. A single cap will only shift it 45 degrees. A 2nd order crossover with 2 parts in each filter (4 total) yields a 180 degree shift (4 times 45 degrees). In that case you just invert one driver.

Your ears are totally deff to phase relationships between woofer and squawker. What you MIGHT hear is the ampitude variations casued by interaction between the two sound sources at different places in the room. It might cause a dip somewhere. It takes instruments to really determine the proper phasing. The time dealy between the sources is a big source of phase shift between driver too. With a single cap, like in the "A" netwrok, I would bet the path length difference is a biger factor then the network!

Al K.

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On 11/24/2004 5:46:53 PM Al Klappenberger wrote:

The insertion phase contributed by a network filter is 45 degrees per element at the crossover. A single cap will only shift it 45 degrees. A 2nd order crossover with 2 parts in each filter (4 total) yields a 180 degree shift (4 times 45 degrees). In that case you just invert one driver.

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OK...

I'm definitively not in my element with crossovers. Any good suggestions for reading about it?

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On 11/24/2004 7:05:01 PM ssh wrote:

Jeff,

What are you into here?

SSH

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At first modifying my type AA crossover for some type A.

I'm not to familiar with crossovers having being bitten by the full range driver bug for quite a long time. So I am trying to learn here as I'm not sure the type AA is for me.

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Jeff:

I did not care for the AA. They are what came with our Klipschorns, but they just did not work for me. I have a friend with La Scalas who liked them more than the A network I loaned him, but he also said that the AA is maybe a little on the dull side -- depending on what one's preferences may be.

If you are interested, I have a few books with good information on crossover design and application.

Erik

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Erik,

When making these comparisons, were they with stock boards? Did you by chance catch any of the threads a few months ago with discussion involving the much higher than normal ESR's in the older capacitors. Bob Crites measures the old cans he removes from the networks he rebuilds, and the numbers are consistantly very ugly. As compared to the Type A, the tweeter of the Type AA is 3db down from the squawker to begin with, and with the old cans, it's not uncommon to see the tweeter anywhere from 6db - 10db down total in relationship to the midrange.

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On 11/26/2004 9:15:16 AM DeanG wrote:

As compared to the Type A, the tweeter of the Type AA is 3db down from the squawker to begin with, and with the old cans, it's not uncommon to see the tweeter anywhere from 6db - 10db down total in relationship to the midrange.

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That would be confirmed by what I hear. The khorns are actually quite rolled off and my room is quite bright sounding at the start.

I'm waiting for some GE polyprop in oil as a first experiment. I'll make a type A at first.

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I switched from stock AA's to Bob Crites type A's in my Khorns a few months ago. I noticed that the sound was a bit sharper in the midrange, not in a good way. Of course, my system has been very midrange-forward since I started using the AES SET amp a couple of years ago, so any change in the midrange is very noticeable.

After listening to my Horus' for a while now, I'm noticeing that the tweeters sound a bit dull, or rolled off. Is this normal for 2A3's? Horus'?

I'll be interested to see what experiments you work on Jeff.

Greg

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When I replaced the stock Klipschorn tops with different drivers and horns I found that I had about a (+) 2 db in output at 400Hz everytime I reversed the polarity of the different midrange drivers that I tried. My final driver selection is now wired with the polarity reversed.

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On 11/26/2004 10:16:58 AM greg928s4 wrote:

I switched from stock AA's to Bob Crites type A's in my Khorns a few months ago. I noticed that the sound was a bit sharper in the midrange, not in a good way. Of course, my system has been very midrange-forward since I started using the AES SET amp a couple of years ago, so any change in the midrange is very noticeable.

After listening to my Horus' for a while now, I'm noticeing that the tweeters sound a bit dull, or rolled off. Is this normal for 2A3's? Horus'?

I'll be interested to see what experiments you work on Jeff.

Greg

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Greg,

If you have a set of my Type As, you can easily attenuate the midrange by another 3db using tap 3 on the autotransformer instead of tap 4. You should find it is already wired out and just involves unplugging the wire from tap 4 and plugging in the wire from tap 3. This will change the crossover point a bit for the midrange but not very much. Several have found that they like the sound better with the midrange attenuated another 3 db.

Bob

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Dean:

These comparisons were made just using the stock AA networks. The As I built use poly caps. I don't doubt that the age of the capacitors might possibly have caused some drifting from their original specifications.

We found a local source for brand new motor run capacitors, and my friend is in the process of making his own version of a combined AA/A network. When I say combined, I mean of course that on can easily be changed to the other.

He has never built a crossover before, but finds the process pretty easy and fun.

I'm using the AL network right now, and am not spending much time with it. It sounds good as it is. I'm waiting for those L-pads I mentioned to arrive, and then might play around with things some more. I also have some plans for a higher order network of my own design, but those tend to get costly. The type A could actually be very good, and with the addition of either simple series resistance, or a fixed or variable L-pad, one could also very easily adjust the tweeter output if it's too bright or out of balance with the midrange.

This other guy and I have both bought some of the GE motor run caps, and they are not too expensive. There is also no reason why combining different kinds or types of capacitors in a network might be beneficial -- for example, using oils in the tweeter circuit or plastic tubulars in the midrange branch..or vis-versa. Also, combining smaller values in parallel (which I have done for years and have no problem with)can have lower ESR figures than using a single capacitor of the desired value.

But back to your point: I bet you are right, and that the AA will sound different with new capacitors. I have read much of what both Al and Bob have shared with us on that topic.

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On 11/26/2004 11:34:22 AM greg928s4 wrote:

Thanks Bob, I had forgotten about that option. I'll give it a try.

Greg
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Once I changed the squawker tap I never went back. Thought I had a brand new pair of Khorns. Don't know if it was my musical preference or a better complement to the room... but the change was dramatic and delightful to my ears.

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