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original Khorn AA Crossover values?


Tony T

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Finally reached a point where I'm going to order new AA crossovers for my 4 Khorns and wondering, what's the range of value of the original AA's? ALK will provide new crossovers (Super AA's) with the exchange of the old AA boards for $99.00 plus shipping. Anyway, it seems there must be some value to the old AA's if ALK wants them right? I'm wondering if there's actually a sales market for the old ones.

 

Thanks, Tony

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I should also add, the old AA's seem to be working fine. I don't have any idea on how to test them but, to my ears they sound just fine. No cap leaks, bulges, etc.

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Guest wdecho

If you are happy with the sound why change? If it ain't broke why fix it. I had a friend that was the manager of a motorcycle store that sold Harleys and Japenese motorcycles. When they sold a Japanese motorcycle they hardly ever saw the buyer again. When a Harley was sold most likely the buyer would be back spending money on aftermarket parts the next week. Go figure. Capacitors last much longer than most want to admit especially in a crossover network when the voltages are almost nothing. Most film capacitors are made to operate at 300 to 400V or more. The voltage seen in a crossover circuit is 1V continuous in our speakers. I have a technician friend who recently bought a 30 year old pair of LaScala's and tested the capacitors for leakage and ESR and found them to be in spec. Sellers of crossover networks will tell you different, of course. Capacitors for crossover networks do sound different and whether you like the sound of new caps or crossovers will depend on your preference. There are many on this forum that regret buying new crossovers complaining about being too bright. Some will say being too bright sounding is a good thing but not to my ears. 

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Guest wdecho

Just last week I built a pair of Type AA crossovers using these caps, 

https://www.ebay.com/itm/AC-450V-13uF-Cylindrical-Motor-Capacitor-CBB65-W7G9/253489139858?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2060353.m2749.l2649

https://www.parts-express.com/jantzen-audio-22uf-400v-crosscap-capacitor--027-916

 

I was surprised on how good they sound using my LaScala stock driver and horns. I am not going to get into a debate of caps which is how threads of this nature tend to do. All I can say is that they excellent to my old ears in my room. One is not going to beat the price for the caps. Not bright or harsh at all. Just lovely sounding. I original installed some L-pads to tame the mids if too bright but found them not necessary and removed the L-pads as being not needed. 

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 There is a Type AA schematic available in this forum.  I will.second the "ain't broke" sentiment.  However, if your Khorns are over 30 years old AND sound polite and recessed/reserved, you likely need new caps.  I will add a caution, the Type AA network has a deliberately inefficient tweeter section that tames a 105 dB hump in the K-77 tweeter.  Al's crossovers have not previously included that ~1 dB loss.  The result is a brighter speaker that bothers me.  It looks like his Super AA drops the squawker and tweeter 3 dB, leaving that 1 dB imbalance.  Though quite small, that 1 dB is very noticeable in my room.  YMMV.  

 

Replacing just the caps in kind is not a difficult project. 

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On ‎7‎/‎1‎/‎2018 at 12:19 PM, JohnA said:

However, if your Khorns are over 30 years old AND sound polite and recessed/reserved, you likely need new caps.

 

On ‎7‎/‎1‎/‎2018 at 12:19 PM, JohnA said:

Al's crossovers have not previously included that ~1 dB loss.  The result is a brighter speaker that bothers me.

 

A contradiction? :-)

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On ‎7‎/‎1‎/‎2018 at 8:09 AM, wdecho said:

Most film capacitors are made to operate at 300 to 400V or more. The voltage seen in a crossover circuit is 1V continuous in our speakers.

The rating is in Vdc. Crossovers pass AC. I never did get around to trying to figure out how that works exactly!

 

 

On ‎7‎/‎1‎/‎2018 at 8:09 AM, wdecho said:

The voltage seen in a crossover circuit is 1V continuous in our speakers.

Maybe with your speakers!

 

 

On ‎7‎/‎1‎/‎2018 at 8:09 AM, wdecho said:

Sellers of crossover networks will tell you different, of course.

Yes, I recommend that capacitors be changed out at the end of each month!

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Guest wdecho
2 hours ago, Deang said:

The rating is in Vdc. Crossovers pass AC. I never did get around to trying to figure out how that works exactly!

 

 

Maybe with your speakers!

 

 

Yes, I recommend that capacitors be changed out at the end of each month!

"The rating is in Vdc. Crossovers pass AC. I never did get around to trying to figure out how that works exactly!"

 

Capacitors are rated at VDC for sure, because that is what they are supposed to do, block DC and pass AC.

 

"Maybe with your speakers!"   

 

Most of the time much less than 1V continuous with your LaScala's as well. If you take the time to measure the AC voltage at your speakers with normal music playing you will find around 1V to 3V peaks peaks. The continuous rating is much, much less. Speakers are usually rated at 2.8V, 1 meter and LaScala'a have a   103db rating with a continuous 2.8V. With peaks in music with 2.8V continuous  music playing you would destroy your hearing quickly. One can use their signal generator and send a 1000hz signal for 2.8V out continuous and see what it sounds like. A 2.8V AC continuous signal is far less than what a capacitor sees in say a power supply network with current thrown in the mix. Capacitors in a crossover netwrok should see hardly any DC if the amplifier is adjusted correctly. Most of my amplifiers have less than 50mv of DC at the output. Capacitors in a crossover network are not working hard at all and their life expectancy is for longer that use in a power supply section. Usually the only capacitors that need to be replaced in a 30 year old amplifier are the power supply ones that are taking a beating. The first capacitor in the power supply often has expanded because of working so hard.   

 

The last statement,

 😃

 

One with the proper equipment can test a capacitor for ESR and capacitance. One can use an oscilloscope to do some testing as well. Leakage is a problem with old capacitors that dry out with age. I am not talking about what one can see with their eyes but leakage of DC between the plates. ESR is a measurement of leakage. Optimally a capacitor should measure as an open circuit with no resistance but that is in a theoretical world. 

 

Dean those last crossover networks you built are eye candy for sure. I am sure they sound fantastic. I saw and admired them on another thread. Also we have discussed the advantage and disadvantage of autotransformers vs resistance for attenuation in the past and I have to say this last AA network using an autotransformer sound fantastic. Many ways to achieve the same result, great sound. 

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On 7/1/2018 at 8:20 AM, Schu said:

About a hundred bucks or so...

And then there's the other part of this equation, which is how much are they worth installed in their original speakers should one decide to sell the farm? Selling LSs with ALKs vs original AAs might limit one to certain buyers...or it may open the sale up to more. 

 

I'd say if storage fees don't kill ya, keep those AAs for down the road.

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Guest wdecho

Regarding gold parts, expensive caps and crossovers, I have nothing against anyone going for any gold parts. The only problem with expensive caps is if you do not particular like the sound you are out a lot of dough. Caps do sound different. I have changed out many different coupling caps in tube amplifiers changing the sound. Coupling caps along with crossover caps are film caps. The truth is that film caps in very old equipment will still test and work fine in the circuit. Electrolytic caps are the ones that age and deteriorate the most with age especially in power supply filtering use where they filter out the residential AC left from the rectification component used. If you are happy with the sound you now have I still say why change anything. If not go for a new network or caps but I would hang on to the old ones just in case. They are many on this forum totally satisfied with new X-overs or replacing the caps for new ones in the crossover they have. There are also those that complain of being too bright after spending money. I am a cheap diy'er. I look for the best bang for buck in good parts, not junk. In my AA builds I used the stock 2.5uf inductor along with the .245uf  inductor used by Klipsch. Good enough for me. Being that my old AL X-overs used a different autotransformer than the one used in the AA ones I had purchased a 3636 autotransformer from Bob Crites many years ago and used it. I just used 20 gauge wire for all connections. Nothing fancy or expensive and they sound outstanding, surprising even me on how good they sound with the stock horns and drivers. I have an Altec 511B horn and I am using a Selenium D250X driver with it along with a Selenium horn and driver for a tweeter on a wood sled along with my LaScala bass bin and another x-over network I designed that I can sit on top of my cab just for something different when I choose to. Also just last month I bought a full range speaker and have the same setup on a different sled with another crossover using my LaScala bass bin for the lows I can play with as well, just for fun. I like to play. 

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On 6/24/2018 at 5:51 PM, Tony T said:

Finally reached a point where I'm going to order new AA crossovers for my 4 Khorns and wondering, what's the range of value of the original AA's? ALK will provide new crossovers (Super AA's) with the exchange of the old AA boards for $99.00 plus shipping. Anyway, it seems there must be some value to the old AA's if ALK wants them right? I'm wondering if there's actually a sales market for the old ones.

 

Thanks, Tony

 

Quite the opposite if you read ALK's website about the Super AA.  He details exactly what it is, what it does, and why.  You don't get new networks for $99.00.  You get someone else's trade ins that he rebuilt into Super AAs.

 

IMHO..........and you shouldn't believe everything you read on audio forums.............they are excellent in my lascalas.  Best networks I have ever used in them.  The Audyn caps ALK uses are very good sounding.  When I put those networks in my Khorns in the past..........I didn't like them as much.  But in Lascalas they are superb.

 

PS.  You can convert your AAs into Super AAs yourself for about $80 and have a little soldering fun too.  For me.............this was a very worthwhile upgrade.

 

.............Go ahead Dean.  It's coming guys.

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^xactly...

It may very well be, not in marks case, that a listener is not capable of hearing or discerning any difference... whether from a physical stand point or one where they perhaps can't experientially.

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On 7/2/2018 at 2:12 PM, Deang said:

 

 

A contradiction? 🙂

 

LOL!  Not really, but a deliberately over simple description. 

 

So the real deal it the Type AA tweeter filter is not a smooth Butterworth and creates a sag in the response from about 6k to 9k Hz.  That is what removes the response hump in the K-77-*.  I believe the design is called a Constant K filter.  It uses a simple calculation, but it not used much anymore.  PCs and modelling software have taken the work out of filter design.  

  post-43-0-09240000-1469647383_thumb.jpgpost-43-0-94920000-1469647842_thumb.jpg

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Thanks to wdecho for your advise. For a mere $100.00 resale per pair of AA's I think I'll hold on to them to use for future comparison. The thought never did enter my mind to retain for comparisons. Hmm, GREAT idea!

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22 hours ago, JohnA said:

I believe the design is called a Constant K filter

Yes, using the VERY old Image Parameter method.

 

I think knocking down that hump at 6kHz was just incidental, and not a deliberate design goal.

 

The AL-3 should sound better, but I didn't think so. I may revisit that one here in the near future.

 

 

Dope_710700_v11n2.pdf

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Maybe.  Mr. Paul writing "Response curves...... indicate a slight improvement in amplitude-frequency-response" and the notation of trying several filter types seems to indicate a desire to do more than a simple 18 db Butterworth.  Whether deliberate or a happy coincidence, it is the filter design I prefer.  I wish I been able to spend more time with the AL-4 or 5 to see if they were better.  They were immediately familiar years ago in Indy, but were not available 2 years ago in Hope at that Pilgrimage. 

 

My initial reaction to Al's Universals was "Wow!"  They are quite good, especially midrange detail, but eventually the tweeter's output wore me down.  I have attributed that to Al's low loss Butterworth filter vs the Type AA. 

 

And I admit to a large prejudice, having first heard K-horns and Belles wearing the Type AA crossovers (deduced after owning my La Scalas for a year or 2). 

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