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WMcD

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  1. Be careful. I suspect the HIII has a second order crossover for the woofer. If so, when you remove the connection to the woofer the crossover will form a series LC circuit to ground (i.e. across the input terminal). This will create a short circuit at about the crossover frequency. Damage to the L and C is certainly possible. I think of this tip from a moderator here long ago. Independent of that, I read about a train wreck in a non-Klipsch unit pro unit where a bass driver was found blown, the cross over was found foblown, and the amp was found blown. I suspect what happened was that the woofer was driven to destruction and was an open circuit and this caused the LC short. Then it was a race between whether the crossover components burned out from taking all that currect, or the amp was blown from the effective short circuit. (I suppose the coil could overheat causing a fire though I'm not sure.) Maybe someone can give advice on electrically disconnecting the LC, I suppose you could replace the woofer connection with a dummy load resistor of appropriate rating. However, that could heat up and cause a fire in the box. "Let's be careful out there." per Sgt. Phil Esterhaus WMcD
  2. Yes. Any anomoly is potentially dangerous. Have a licensed electrician take a look at it. WMcD
  3. I believe there was a Cornwall which was meant to be situated landscape or portrate. Neither the mid nor the tweeter were at the midline. Also there is something with a K-1000 midrange. Eventually it was superceded with what was initially called a Cornwall II. This had the K-600 mid like you see, the woofer, mid and tweeter were at the midline and it was presented as a portrate orientation speaker. Woofer near the floor. Eventually the "II" got dropped. This is probably why you see II on the spec sheet. But then there was a switch to plastic tweeter and mid and that was called the Cornwall II. Woofer moved up. The above might have so errors but close. WMcD
  4. Go to HD or Lowes and see what you can find that is not made in China except maybe lumber and paint.
  5. I highly recommend a temperature contolled (not variable temperature) soldering station. About $100. I have a Weller but Hakko is also recommended by by others. Over the years I have used a half dozen lower priced irons and I consider them dangerous for projects because of the potential to over heating or under heating. When you buy a kit, ask the manufacturer whether I'm correct. WMcD
  6. I believe this thread has drifted off course. Let me use small chunks of information. Sorry if it simplistic. Ya gotta understand the basics though. Sorry if the following is too simple and complicated at the same time. It is very possible that the tweeter is burned out. This is to say the wire windings have melted in a small section. The wire in the coil is finer than a human hair. The tweeter is capable of absorbing only about 2 to 5 watts continuous power despite specs that the system as a whole will take 100 watts. The mid driver might take 40 and the woofer 100 watts. Know that you don't have to have done anything very naughty to blow a tweeter. The tweeter wire is wound around a tube which is mechanically connected to the diaphragm. This is perhaps why people say the diaphragem is damaged. Essentially this is true of all drivers. This is winding is called the "voice coil." Voice coils sit in a magnetic field caused b the permanet magnet of the speaker. Current through the voice coil makes a magnetic field which pushes and pulls with force to move the diaphragm. The moving diaphragm makes the audible music. It is a bit more complicate than grade school of winding wire around a nail and picking up paper clips but that is the general idea. We want to test whether the coil has melted in a section and thus causing an open circuit. If no complete circuit, no current flow, no magnetic force, no movement of the diapragm and no music. But there could be a loose electrical connecton. About which more later. We are though trying to determine what is going on deep within the tweeter at a microscopic level by using a multimeter (ohm meter) connected to feed wires. Testing or listening for acoustic output is well done with a listening tube. However. You should know that these tweeters as filtered by the crossover or not really sound tinny and that is because music above 3000 Hz sound like that. Testing electrically is the most classic and reliable when a burned out voice coil is suspected. Use an ohm meter. which is part of a multimeter. This is really sending a direct current or zero Hertz signal to whatever is connected to the ohm meter probes. This may seem strange. We are testing a speaker by feeding a 0 Hz signal to determine whether it works at 3000 Hz and above. Actually the ohm meter is just detecting whether there is an electical path free of gap(s) in the wire. We actually detect the d.c. (direct current (zero Hz) resistance of the coil. This is usually about 5 ohms, 8 or 10 ohms is good too. A burned out winding measures "infinite ohms" which is what is shown on the diplay when the probes are not touched together. Maybe OL on the digital display. Older and newer meters will show 'infinite in their own way. Actual electrical testing. You should go to the crossover screw down teminals. Turn the amp off of course. The two wires connected to the tweeter should be seen and please note which wire (red stipe and another not). goes where. Take a picture or make a drawing. Disconnet both (not technically necessary but lets keep things simple). It is a matter of backing off the screws about a half turn. Righty tighty, lefty loosy. The "spade lug" (U shaped) should come free from under the screw head. I see no reason to mess aound with the tweeter driver end and that end is usually soldered. Now, connect or hold the ohmmeter probes to those two wires / spade lugs. If the voice coil is good, you will see on the meter a reading of 5 to 10 ohms or like that. Also you will hear a mild scratching sound from the tweeter. This sound is because the meter, through the probes, is sending a little current into the tweeter. The tweeter is trying to make a bit of music. A good sign that is can make music. OTOH: You may well find that the meter is showing OL still and there is no scratching sound. That is just about proof positive thatthe voice coil is blown, ie melted. Note: Sometimes over age the screw down connection at the crossover has corroded or loosened. Just snugging up the screw will cure that. Do it for all the screws while you're in there. There is some traffic above which is showing the measurement of the overall speaker "impedance" at the input terminal to a driver or box by the constant current technique. While intersting it is certainly not necessary to determine whether you've got a blown tweeter. Sorry if I've said too much or too litle. WMcD How to test acoustically? Yes, the improvised stethoscope with a paper towel roller works.
  7. Yup: As fathers have passed down to their sons for centuries, Righty tighty lefty loosy. Liquid Wrench gets good reviews. I would put the assembly with the big end on a table and squirt some in there. Wait overnight. Are these the aluminum horns? Perhaps the aluminum corroded a bit.
  8. Please consult a professional. These are potentially lethal insects unless they are honey bees. You're being nice to think about relocating the hive but this is like relocating a nest of rattle snakes. I was stung just below my right eye by a yellowjacket when I was young. Maybe I had tried to brush it away but they are agressive. My face was like pumpkin. Had it gotten to my eye I'd probably have lost it. You can read plenty of stuff on the internet. There is already a chance a queen has established another hive near you. The reproductive rate is phenomenal. Listen to Jeff (thanks Jeff). These are killers. WMcD
  9. WMcD

    Parental Phrases

    I get it. When a child fails to act like a responsible adult, the solution is for the adult to act like an irresponsible child. WMcD
  10. 13500/(2.75 x 18.1) = 271. The K-400 paper by PWK says it doubles in area every 2.75 inches and that means the fc is 271 Hz. The cut-off wavelength is 18.1 times the length in which area doubles and 13500 in/sec is the speed of sound. That number might be for the protype and I'm not quite sure that goes for the production model. But is probably close.
  11. When I was doing this sort of thing many years ago: I had a bit of a form with a temporary central piece of 3/4 ply following the curve of the side but a tad smaller. For the side pieces I had three or four layers of what was sold to me as bending ply which was just very thin ply. Then slathered a thin layer of yellow glue into the many touching surfaces of the flat sandwich. Like mayo on a triple deck wish sandwich. Then starting at the throat I used drywall screws with washers under the head driven into the curved form to pull the sandwich into shape. Quite a bit of force necessary. The overall project required quite a bit of triming and patching the screw holes. It all held together when the glue cured. OTOH I still worried that sometime in the future the internal stresses would cause the horn to explode into a pile of toothpicks. WMcD
  12. Of course I agree with Preston Tom. If you don't have a multimeter, you need one. If you don't know how to use there is a lot of how-to s on YouTube. Generally, at the tweeter teminals you should get a reading of 10 ohms or so if it is good and you'll hear some scratching noise from the tweeter as you apply the probes. If it is "open" meaning burned out you'll get a reading of infinite ohms. (Maybe OL.) Whatever you get when the meter is set to ohms and the probes are not touching. In theory you don't even have to disconned the wires. One good move is to back off the screws on the cross over about one half turn and then snug them down. The tweeter is the driver of the three which is the most delicate and will take 2 to 5 watts continuous. Failures are common. Check if Bob C will replace the diaphragm for you by mail. WMcD
  13. In Goldfinger, Bond slips out of bed to get some freshly chilled wine out of the fridge. He quips generally that drinking the wine above a stated temperature 'just isn't done. It's like listening to The Beatles without earmuffs.' Then Oddjob gives him a neck chop. Ha. In a forward persupective, Sir Sean was there dumping on Sir Paul and got a neck chop. Who would have thought it. Best line by a mature Sean in a movie: "She talks in her sleep." WMcD
  14. Looks good. An issue is the condition of the cartridge and stylus. But even at the seller's price the budget should have funds left over for a replacement. OTOH it appears to have had TLC and those are not particulaly wear items. WMcD
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