LOADEDTUNES Posted November 16, 2003 Share Posted November 16, 2003 I've been following most of the cross over threads with great intrest, but i lack the circuit knowledge. Could someone be kind enough to try explain the circuit path and what the components functions are. I've got a few questions about the AK-2. 1) Whats the reason for changing the woofer caps to 100uf from the factory 140uf ? is this not a lower value ? 2)changing out the iron coil in the midrange circuit to an air coil of a higher value ( 4mh- 5mh ) ? 3) I've read one post where the 13uf in the squawker curcuit was updated but a bypass was used with 1 12uf and a 1 1uf . whats the reasoning here ? the reply from trey cannon to this post was speed of reaction and this curcuit is used in the pro-models ? Still don't understand. I would very much like to update my ak-2 networks but would like to know what physical changes are taking place in the cross- over and how it works, i'm thinking there are others here that don't understand but have yet to ask, so i'll ask for and explanation for all us less informed posters. Thank you. Quote Link to comment Share on other sites More sharing options...
Al Klappenberger Posted November 16, 2003 Share Posted November 16, 2003 Loadedtunes, There is really no way to know exactly why the cap and inductor changes were made to the AK-2 network without getting inside the head of the engineer who made the change, but.. Those changes ARE the difference between the AK-2 and the AK-3. I can speculate that it was done to compensate for some sort of anomoly in the transition crossing from the woofer to the squawker. These changes tend to casue a greater overlap between the two. The 5 mHy inductor change brings the squawker low while the change to 100 uF brings the woofer up. The 1 uF bypass allows a lower loss path around the 13 uF squawker cap for the extreme high end to the tweeter. Big value caps tend to work better at lower frequency. Small ones do better up high. Parallel a small one and a large one to equal a needed value and you have both worlds. Al K. Quote Link to comment Share on other sites More sharing options...
lorcoll Posted November 16, 2003 Share Posted November 16, 2003 Thanks Al for your explanation, but I would ask you another question about AK-2 (or AK-3): in case of passive biamp for this network how we must change the circuit (what resistor we have to insert and where). Thanks. Quote Link to comment Share on other sites More sharing options...
Al Klappenberger Posted November 16, 2003 Share Posted November 16, 2003 Lorenzo, You will finds 4 binding posts on the back of the woofer door. One set is marked input. The other set connects to a cable to the upper section of the crossover. Remove this cable and connect it to your high frequency amp. Connect you low frequency amp to the posts marked as input. This will do it but is not opimum. You should open the woofer door and bypass all the parts and connect the lower amp directly to the woofer driver. You should also have an active crossover ahead of both amps. This is still a compromise, but it's better than direct connections externally. No resistors are added. Al K. Quote Link to comment Share on other sites More sharing options...
WMcD Posted November 16, 2003 Share Posted November 16, 2003 Regarding function . . . Overall the function is to keep low frequencies from getting to the tweeter, and getting high frequencies to the tweeter. Similarly we must keep high frequencies from getting to the woofer, and getting low frequencies to the woofer. So, you're filtering out the highs and the lows accordingly. If you look at a schematic, you'll see the paths to the woofer and tweeter are just in parallel, with both connected to the input to the speaker, which, through the speaker feed wire, is the output of the amp. Each individual circuit is a type of filter. The effect is that, going up in frequency the woofer is connected and the tweeter is not. Then at some frequency, the woofer is not and the tweeter is. This "some frequency" is the "cross over frequency." The combination of the two filters is called "a crossover." How is this accomplished? Very simply, a capacitor conducts at high frequencies and not at low ones. An inductor conducts at low frequencies and not at high ones. (There is no brick wall though, it is gradual.) You have to look at various schematics. In a simple circuit, the caps and inductors are just in series with the feed to the tweeter and woofer. At the crossover frequency they are about half " turned on" I will not belabor the point. When things are designed properly, the filters roll off at 6 dB per octave. This means there is 1/4 power at a point where the roll off starts, or 3 dB from the crossover frequency, when you are at 2 times or 1/2 times the crossover point. Diagrams would help. input - - - cap - - - tweeter - - - ground input - - - inductor - - - woofer - - - ground The next step is if you want a sharper rolloff. It is more difficult to diagram and I'm not going to try it. But follow along. Above we turned off the connection to the tweeter or woofer to thereby not feed them power. Another way of depriving them of power is to create a short circuit across them. I.e. in parallel. So we want to put an inductor in parallel across the tweeter. Remember, it (any inductor) turns on to be a good conductor at low frequencies. So now the tweeter is being cheated out of power in two ways at low frequencies. The series feed capactor is turning off (to prevent power getting through) and the shorting inductor is robbing it of power by turning on and shorting it out. Same thing is accomplished by putting a cap across the woofer in addition to the feed inductor. At high freqencies the series inductor is not conducting power to the woofer and the parallel cap is shorting it to ground. This is a gross oversimplification but is a start. Gil Quote Link to comment Share on other sites More sharing options...
LOADEDTUNES Posted November 16, 2003 Author Share Posted November 16, 2003 Thanks guy's , you've been a great help. I understand alot better now. The 100uf basicly gives the woofer more power, i was thinking of a cap being a storage devise and not a filter, it makes perfect sense now. I'll keep reading past posts and decide on the best parts and there source before i try to modify my own networks. Anymore help would be great. Quote Link to comment Share on other sites More sharing options...
JohnA Posted November 17, 2003 Share Posted November 17, 2003 The big caps in the woofer circuit are apparently to cause a "ripple" of some sort in the response curve so that the overall response of the system is flatter, too. You asked about air and iron core inductors. Iron core inductors have less resistance for their inductance, but the iron core will "saturate" and the inductance will change if too much power is applied. Sometimes the saturation power can be surprisingly low. Air-core inductors don't saturate, but have more resistance, or are larger than an equal Iron-core inductor. Quote Link to comment Share on other sites More sharing options...
LOADEDTUNES Posted November 17, 2003 Author Share Posted November 17, 2003 Thanks john , you seem to appear on most of the cross over threads i've read so i'll trust your knowledge. Where is a good place to order the replacement parts ? some threads have mentioned parts express but i've had no dealings with any american suppliers as of yet. On another note, are the AL networks i've got in my lascalas worth any upgrading ? Plus should i be consider swapping out the monster cable clear jacket copper cable that currently resides in my k-horns? My lascalas have the older style zip cord. Quote Link to comment Share on other sites More sharing options...
formica Posted November 18, 2003 Share Posted November 18, 2003 If you want to avoid cross border hassles solen is actually Canadian: http://www.solen.ca as well as http://q-components.com/ , http://www.creativesound.ca/, and http://www.audiyo.com/product.htm ... I'm sure you could find others... but those are a couple which come to mind... Rob Quote Link to comment Share on other sites More sharing options...
djk Posted November 18, 2003 Share Posted November 18, 2003 "The big caps in the woofer circuit are apparently to cause a "ripple" of some sort in the response curve so that the overall response of the system is flatter, too." The woofer has trouble getting to 400hz. The larger 4mH woofer choke plus the 140µF (or 100µF) cap boost the midrange to the woofer. The choke on the midrange driver should match the cap in the woofer circuit, the low end response of the midrange driver is adjusted to match the output of the woofer. There is no such thing as a free lunch. Boosting the midrange to the woofer lowers the impedance seen by your amplifier. This may be one reason why Klipsch backed off on the amount of boost and went to the 100µF cap. Another reason is that the more the boost, the more the tendency of the crossover to 'ring'. Prior to 1982 the Klipschorn was spec'd at ±5dB with either the A or AA network. The AK and newer varients are spec'd at ±3dB. Quote Link to comment Share on other sites More sharing options...
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