MikeGinIllinois Posted March 9, 2008 Share Posted March 9, 2008 I have a Harman Kardon RV-4200 I bought from a guy on Ebay. I originally had it set up with two Cornwalls as fronts, no center, and two Radio Shack 4 ohm speakers as rears. I had a lot of trouble with this amp since day #1 and sent it to Rex Service in Worth, Illinois, twice. The short story is it's back now and seems to be working. Is it a bad idea to have 8 ohm Cornwalls as fronts with 4 ohm speakers as surrounds? Does mismatching ohms cause problems? Just to be on the safe side I am no longer running my old Shackers (and I do love the way they sound because they bleed less signal from the Cornwalls and leave those membrany bass and mids intact) but am using, instead, a couple of Synergys for surrounds that I got at Best Buy. I'm not as happy with the Synergys as I was with the Shackers but I don't want to blow out this RV-4200, if that is what I was doing. Thanks for any help! Mike Gallery Quote Link to comment Share on other sites More sharing options...
jacksonbart Posted March 9, 2008 Share Posted March 9, 2008 What where your problems specifically? I can't imagine that combo of speakers sounding "connected/complete" yet I can't that combination from stopoing your receiver from working. What did Rex tell you the issue was? Quote Link to comment Share on other sites More sharing options...
Daddy Dee Posted March 10, 2008 Share Posted March 10, 2008 I'd suggest to check the owners guide on what the amp will handle. Some will not handle loads lower than 4 ohms. Now, I'm a complete non tech type person, but if I am remembering correctly, two pair of 8ohm speakers wired in parallel would place a 4 ohm load on the amp. If someone who knows the properties of wiring up such a system chimes in that would be helpful. But to my thinking, what you describe would be a load lower than 4 ohms. Quote Link to comment Share on other sites More sharing options...
oldbuckster Posted March 10, 2008 Share Posted March 10, 2008 Do you have to set the impedence on the front speakers ? Maybe that's why it was on Ebay ......... or ... are you cranking the receiver into a clipping mode, and the automatic shut-off is working the way it should ........ many things it could be, but you should be able to run that combination !!!! Quote Link to comment Share on other sites More sharing options...
MikeGinIllinois Posted March 10, 2008 Author Share Posted March 10, 2008 Thanks for the discussion, guys. I had lots of problems with this amp. When I got it in the first time I turned it on it went on/off/on/off/on/off apparently on its own. I wrote that off to a glitch. I hooked it up and it was a sweet sounding amp. I played it for a few days, sometimes loud, and then it started turning itself off at various volume levels. Pretty soon when I tried to turn it on it would immediately turn itself off. With this HK AVR-7200 you turn on the power and then there is one 'click' followed a few seconds later by another 'click'. I never got to the second click. I'd turn it on and boom it turned itself off. I'd have to try turning it on for maybe 15 times before it would stay on and then, in the middle of a movie, it would turn itself off. It sits on top of a Cornwall so ventilation is not the problem. Well, I sent it off to Rex Service in Worth. They couldn't duplicate the problem except one time it turned itself off. Just once. What was different about their environment from mine? I dunno. They didn't have my speaker configuration was all I could guess. So, they "rebiased" the "transistors"?? and sent it back. It was ok for one day and then the same pattern began to emerge. I sent it back *again* and waited a month. Rex is not too much in a hurry on stuff but I was patient. I finally called HK support in New York and talked to a nice guy who had their senior tech call Rex. This time they resoldered some connections. I've had it back here for a week and no problems. It's only turned itself off once during hours of play and the 'can't turn it on' problem is gone - so it seems. In one of my calls to HK a tech asked me what the impedance of my speakers was. I didn't know. But now I do. The cheapier Shackers (surrounds) are 4 ohms and the Cornwalls are 8. Just to be safe I put new Synergies on the surrounds and so far so good knock on wood. This has been a real tough adventure in electronics. No one seems to really have the capacity to diagnose these kinds of difficulties. I *almost* bought a replacement 7200 or a 7300. I paid $500.00 for this and the guy who sold it to me gave me $150.00 as a partial refund which just about covered the repair costs. At one point I even went and bought a $2,000 Rotel amp. My buddy, whose setup duplicates mine (I copied off of him) and I listened to the Rotel for 20 minutes and concluded it was way too harsh with this speaker setup. I returned the Rotel. Well, to end this, the HK is the amp for me. That's why I stuck with it. I wish HK did factory repairs and diagnostics. I'm guessing that my cheapie 4 ohm shackers were the cause (or not) or maybe the resoldering fixed this unit. If there is no rule about mixing ohms on speakers then maybe that wasn't the cause but I'm being very cautious now about what I hook up to this amp. Thank you! Mike Gallery Quote Link to comment Share on other sites More sharing options...
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