m00n Posted March 17, 2005 Share Posted March 17, 2005 this is a crossover schematic for the cornwall. I'm trying to understand how crossovers work. I got the jist. I realize that certian frequencies are filtered out for each piece of equipment. But... HOW. How does the crossover actually do it? What is the circuit doing for the woofer? What is the circuit doing for the midrange? What is the circuit doing for the tweeter? Why are the circuits different? Why don't they look the same but with different valued analog components? Is there any importance to the fact that the person who drew this up put the tweeter furthest away from the source, midrange in the middle, woofer closest to the source? Also, are there any good websites that can put analog electrons into laymans terms for the unknowledged such as myself? Thanks all Rick Quote Link to comment Share on other sites More sharing options...
minn_male42 Posted March 17, 2005 Share Posted March 17, 2005 i could explain it to you but then i would have to kill you.... Quote Link to comment Share on other sites More sharing options...
m00n Posted March 17, 2005 Author Share Posted March 17, 2005 What a tease! Here I thought I was about to learn something only to see your poo poo post. Quote Link to comment Share on other sites More sharing options...
colterphoto1 Posted March 17, 2005 Share Posted March 17, 2005 Okay Moon, I'll bite, I barely know any electronics so this will be about as layman as it gets. I'll leave it up those double engineers to get detailed and get yer head spinning. First, terms- remember that low-pass means that it filters the high notes so that low notes pass through to woofer. hi-pass is the opposite in that low notes are filtered, so highs pass through to tweeter. a band-pass usually (note!) has both networks so extreme highs and lows are filtered, leaving the midrange (we'll get back to this one) Parts, you got only so much to build these out of. Chokes are the wires wrapped around an iron rod or air core (looks like a big bobbin) they cause the high notes to get lost because they can't make all the turns. (ok, it's basic). Capacitors are little electronic do-dads (Klipsch uses plastic black boxes to contain them) that filter the low notes out somehow, so they are in the network for the tweeter. (look inside a car coax speaker, there is a little capacitor that filters the sound going to the tweeter). THere might also be resisitors, the little boxy things that look like small bricks. They soak up power, which is usually necessary to bring the output of the mid and tweeter down to the level of the woofer. Now you stack all this stuff together and it makes the network. There are complicated schemes like using a small choke with a capacitor to make a steeper 'slope' on the crossover frequency of the tweeter, so it rolls off at 12 db/octave instead of the simpler 6 db/octave (this wouldn't offer much protection against power spikes if ya got 100 watts into a teensy tweeter) One oddity with the Cornwall is that the squawker does not have a low-pass network element, ie something filtering the highs from it. It was just allowed to keep on pumping out highs until it petered out. Then the tweeter takes over at about 6000 Hz. Do you understand how the HZ system works? 20-40 being one octave, then it's a logarhythmic scale so the top octave is 10,000-20,000 Hz. THis is just meant as a beginning primer course. I apologize for any generalizations or inaccuracies. Please correct and elucidate as necessary. EDIT this squiggly thingies are the chokes, the parallel lines are the capacitors. As stated, the diagram doesn't necessarily predict that parts layout on the board o cedar. Michael Quote Link to comment Share on other sites More sharing options...
Champagne taste beer budget Posted March 17, 2005 Share Posted March 17, 2005 It's a wiring diagram. The locations of the components on the diagram have nothng to do with where they are actually located, the distance from any connections, or how the location on the image effects any sound. I'll leave it to someone with more experience than myself to explain how the actual components in the crossover work. And probably learn a good deal by doing so. Good question. Thanks for bringing up something that everyone discusses, but I am sure a lot of people don't really understand. Quote Link to comment Share on other sites More sharing options...
Champagne taste beer budget Posted March 17, 2005 Share Posted March 17, 2005 See, Michael did the techno stuff, I did the basic diagram stuff, ask and ye shall receive. Nice description, Michael, sounded like I thought it should, I just wasn't confident enough in my theory of how it all worked to want to put it on paper for the world to see if I was wrong. Quote Link to comment Share on other sites More sharing options...
minn_male42 Posted March 17, 2005 Share Posted March 17, 2005 hey moon! sorry - but i couldn't pass up an easy one like that!!! Quote Link to comment Share on other sites More sharing options...
boom3 Posted March 17, 2005 Share Posted March 17, 2005 The schematic is from the Belgian review of the Cornwall II. The question mark refers to their not being able to deduce if there is a choke (or is it an autotransfomer, I am not sure either) in the circuit. I believe, based on the photos, this is an autotransformer, as is true of the other Heritage products, to knock down the sensitivity of the midrange horn. In brief, a capacitor resists instantaneous changes in current, and a coil (inductor, choke) resists instantaneous changes in voltage. For crossovers, these properties mean a cap will pass alternating current above a certain frequency, but not below it, and will block DC altogether. A coil will pass frequencies below a certain frequency, but not above it, and will pass DC. Thus a simple tweeter crossover features a cap in series. A simple woofer crossover features a coil in series. The two may be combined to achieve sharper cutoffs at a given crossover point. "Basic Electronics" by Bernard Grob (especially the late 50s editions before all that digital doo-doo came in are very good at explaining filters. Quote Link to comment Share on other sites More sharing options...
Rockets Posted March 17, 2005 Share Posted March 17, 2005 Go here for a fairly simple introduction(s) This site will tell you more than you want to know in rather simple terms http://www.bcae1.com/ Click on "home page" and on the left side of the screen you should see a list of chapters...go to chapter 54 "passive crossover" Once you're done there go back to the beginning Chapter 1 for a good overview of electronics http://hyperphysics.phy-astr.gsu.edu/hbase/audio/cross.html#c3 http://www.passivecrossovers.com/ http://www.members.shaw.ca/loudspeakerpage/crossover.html http://www.audiocontrol.com/techpapers/techpaper102.pdf Quote Link to comment Share on other sites More sharing options...
LarryC Posted March 17, 2005 Share Posted March 17, 2005 I'll display a little excess ignorance here, and oversimplify crossover points and issues while I'm at it -- Moon, trace the "positive" or + side only, and note the coil on the way to the woofer. That passes the woofer's lows but resists the frequencies above and pushes them to the upper drivers, so that they're not wasted in the woofer, and used where they're supposed to be. That's one-half the job of determining the lower crossover point. I believe the capacitor across the woofer leads shunts away frequencies that are too low for it. Next, our traveling frequencies (minus most of the woofer's lows) head up to the other drivers. The cap in the squawker's hot lead does the other half of the lower crossover job and blocks woofer's lows from reaching (and potentially harming or distorting) the MR driver. Just so's the tweeter's highs don't waste themselves in the squawker, the coil that follows the cap (which is probably the autotr.) should block those and push them to the only place left to go -- the tweeter. Thus, that coil does one-half of the upper crossover's job, if I anything like understand it correctly, that is. This means that the squawker's frequency band is properly limited below by the lower crossover point (woofer coil) and above by the upper crossover point (squawker cap). Finally, the remaining, tweeter's highs head that direction, but not before a final pair of caps block the highs that are not high enough for it. These do the other half of the upper crossover's job. I believe the coils across the squawker's and tweeter's leads serve to sharpen the crossover slope, since the simple crossover-coil combo cuts off the drivers at only 6 db per octave. I hope this isn't all that far off, but I did have fun writing it! Larry Quote Link to comment Share on other sites More sharing options...
D-MAN Posted March 17, 2005 Share Posted March 17, 2005 That is an iron-core coil symbol on the mid. The woofer coil is an air-core. DM Quote Link to comment Share on other sites More sharing options...
yaffstone Posted March 17, 2005 Share Posted March 17, 2005 And the iron core raises the inductance a bunch with respect to air. That's becasue iron has a higher magnetic suceptability. Quote Link to comment Share on other sites More sharing options...
yaffstone Posted March 17, 2005 Share Posted March 17, 2005 D-Man, I just noticed your sign-off. I never knew that "economy" meant spending more than you make. Interesting... Quote Link to comment Share on other sites More sharing options...
m00n Posted March 17, 2005 Author Share Posted March 17, 2005 EVERYONE... THANK YOU SO MUCH FOR THE HELP! Greatly appreciated! This is really helping a lot. ---------------- On 3/17/2005 6:27:33 PM yaffstone wrote: D-Man, I just noticed your sign-off. I never knew that "economy" meant spending more than you make. Interesting... ---------------- CMon now, lets stay on topic Quote Link to comment Share on other sites More sharing options...
yaffstone Posted March 17, 2005 Share Posted March 17, 2005 Moon, Spending more than you make is part of the definition of an audiophile isn't it? Quote Link to comment Share on other sites More sharing options...
m00n Posted March 17, 2005 Author Share Posted March 17, 2005 What is impedance? I'm not finding a definition, or if it was there I missed it. yaffstone, boy, that aint no joke. Quote Link to comment Share on other sites More sharing options...
yaffstone Posted March 17, 2005 Share Posted March 17, 2005 Inductance is like electrical momentum. Once you get a current running through a coil it creates a magnetic field in the direction perpendicular to the current flow (through the center of the coil) If the material in the coil gets magnetized it takes energy to change the strength or direction of the field. This induces delays or phase shifts in the electrical signal. Impedance is similar to resistance but I've never been quite sure how. Quote Link to comment Share on other sites More sharing options...
mike stehr Posted March 17, 2005 Share Posted March 17, 2005 "What is impedance? " There's this place "Google", and it's called a "Search Engine". You type in what info you want to find, and it'll find it for you! It's really Amazing! Quote Link to comment Share on other sites More sharing options...
yaffstone Posted March 17, 2005 Share Posted March 17, 2005 Unless you happen to be impeaded by your inductance into the hall of flame. Quote Link to comment Share on other sites More sharing options...
m00n Posted March 17, 2005 Author Share Posted March 17, 2005 ---------------- On 3/17/2005 7:06:51 PM mike stehr wrote: "What is impedance? " There's this place "Google", and it's called a "Search Engine". You type in what info you want to find, and it'll find it for you! It's really Amazing! ---------------- Dood... Be nice. I have always for some reason found electronics to be a difficult subject to grasp. I can write software until the cows come home but electronics always cooks my mellon for some reason. Quote Link to comment Share on other sites More sharing options...
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