overlord311

I was not really sure which forum to put this question in, but I figure that I'll try here. Currently, I am in my second year in the Electrical Engineering School at Cornell University. I am looking to get some information on the backgrounds of some of the people at Klipsch and similar companies. There are, of course, obvious questions like schools and degree plans, but I think I am looking for more personal opinions and advice. Although the working of a speaker has always intrigued me, I am currently interested in amplifier design. My friends all call me somewhat of a geek because I have circuits on breadboards lying all over my room. I just finished my second solid state amp (I have an enclosure left to build) using dual IC's, LM3886t, from NSC. I also adapted it to drive guitar level input, and included 3 types of distortion. My question to those in the audio engineering field is this: what type of background would you recommend for someone looking to get in this field? Heavy EE, or Mech. E? I would imagine that this would vary depending on the project to which you are assigned (ie. crossovers, enclosures, etc.). I would imagine that fluid mechanics is very important, along with waves from phyiscs. Can anyone provide me with information and/or opinions on all of this? Is there any demand for engineers of this sort in the market today? in 4-5 years? I have always grown up with a philosophy on work (largely influenced by my dad) that says that you should do something that you truly enjoy and love. I can say, at this point at least, that this field is something that I love, but I am looking for insight to what it is like to actually be a part of it. I really appreciate all of your help and responses. Brandon Richter bcr5@cornell.edu; brandon_richter@hotmail.com

Why would grounding to the negative terminal of a battery cause noise? Why would a ground loop be created if both the amp and the head unit were grounded at a common location at the terminal, assuming that resistance in the wires is approximately equal? Thanks again. brandon

I forgot to mention something critical from my first post. When I have the amp powered up in the back of the car (from the battery), with the car on, I can unplug the rca inputs, and the noise disappears. stormin, I have not grounded the head unit...that didn't even occur to me. The logic seems to be right, though. Currently, it is using the same ground that the stock radio had, a fairly small wire that comes out of the saddle. Of course, I have no idea where it goes. I'll give a try in a couple of weeks when I make it home from school. If I were to use a shorter, thinner wire for the ground on the headunit and a longer, thinker one for the amp (in the back), I wouldn't need any kind of rca level isolator device, would I? I appreciate all the help.

I know this forum is not necessarily about car audio, but I wanted to post a question here in hopes that some of the knowledgeable people could give me some advice. Im an electrical engineer at Cornell University, and have installed the audio system in my car. I am using a pioneer head unit which drives boston acoustic 5 inch-ers in the front, and pioneer 6 by 9s in the back. My head unit has 3 sets of preouts, a front, a rear, and a sub output (200hz, I believe). I am using the head unit to feed a signal to a full range Rockford fosgate 100x2 (into 4 ohm) amp. The RF amp drives a pioneer 12 sub in a sealed oak enclosure that I made for it. My problem is that I am picking up a whine (alternator, I think) in the signal line from the head unit to the amp in the rear of the car (Isuzu Rodeo). Heres the list of scenarios that I have worked through to try to fix the problem: $$ First off, everything works pristinely when the car is not on, and is just in accessory mode. No alternator running to make noise. $$ The whine varies with engine speed. I think this narrows the whine to alternator, not ignition noise or anything like that. $$ For a power wire, I am using unshielded 6 gauge braided copper. I run the wire the length of the car, from the battery, through the fire wall, to the back to the amp. I know this is one of the causes of the problem, as the long straight wire essentially acts like a giant antenna, picking up electromagnetic signals from various components in the car (ie. the alternator) $$ For the line level rca cable, I have used both shielded and unshielded cable. More is outlined on this below $$ First thing I did was hook the amp up to a 10amp car battery charger from the wall to try to isolate the faulty component. There is, of course, inherent fault in this practice, as the relative ground of the car (which is not really a true ground) and that of the wall socket are different. Thus, the ground of rca cable is at a different ground than that of the amp, and a ground loop is created in the rca cable. Accordingly, when I hooked it all up like this, the whine was still there. $$ I tried shortening the power wire by moving the amp and speaker to the front of the car and using the same gauge for the wires, connected it with a piece 3 or 4 feet long. The rca cable ran basically out the car through the passenger door to the amp. The whine persists. $$ I moved the amp back to the back of the car, and used a larger wire for the ground wire. Of course, resistance is inversely proportional to cross sectional area. I did this to lower the resistance of the ground between the amp and the battery to make the level closer. It helps a little, but not enough. $$ I unbolted one of the bolts in the back of car, which gave me access to the undercarriage of the car from the inside. I crawled under there, and found a piece of metal that was attached to the frame, what looked like ran the length of the car. I ground it clean with a dremel tool, and ran the ground through the chassis underneath the car. After it was done, I had shortened the ground wire to 18 inches in length. It was better than before, but still a lot of whine. $$ Finally, in a last ditch effort, I went to Radio Shack and picked up a 10 amp noise filter. This did absolutely nothing. $$ I decided to move to the rca line, since I seemed to get as far as I could with the power line. There was absolutely no difference in shielded and unshielded cable. $$ Like I did with the power line, I rearranged the routing of the wire, to no avail. I tried all the preouts on the head unit, all with the same results. The only thing that I found to help was to attach the outside (ground) of the rca cable to the same ground attached to the amp. Thats the best that I could get it. So that covers the things I have tried. Obviously, there is a ground loop in the system somewhere, and I cannot work it out. I know that there are a handful of companies that make rca level noise suppressors, but I am skeptical of them. I love the sound of the system with just accessories on. If anyone has any idea on what I could do to work out the whine, let me know. I might have already tried it, because I know I am forgetting something here, but I could really use any help I can get. I am really stumped. Thanks for your time! Brandon Richter

I used to have sort of the same problem, since I live in a dorm too. The guy in the next room over and my desks are facing the same wall, and I can always tell when he uses his pencil sharpener from the magnetic interference that comes through the wall and flickers my monitor Anyway, my room is self contained on its own breaker. Originally when I got in the room, there was a 10 amp breaker in my closet. Running my comp, monitor, speakers (moderate level), and florescent light, it would do fine. When the fridge kicked in, the breaker would blow. So, I went to the hardware store, got a 15 amp breaker, put it in, and my power problems were gone. I do hear a slight clicking in my speakers when the fridge comes on, but a way to reduce this is to run the speakers through a power strip (a decent one) rather than through the wall sockets. Hope some of this helps a little. ------------------ The distance between insanity and genius is measured only by success.