MudPuppy176 Posted February 1, 2007 Share Posted February 1, 2007 I just bought a pair of RF-83s. I fried a channel in my Yamaha M-2 amp in about 2 minutes at less than indicated rated wattage (240). I sez hmmm, in 27 years I've only blown speakers with this amp. Like a dummy, I hook up an M-4 (120 watts) and fry it as well. Hmmm, two amps with cooked TO3s. Not easy nor cheap to replace. The 83s are advertised as 8 ohm speakers, but it seems the only plausible cause for these failures is less than an 8 ohm load on my amps. I drove my old 8 ohm speakers regularly with the amps' overload lights on fairly solid with no amp problems (sacrificing some sound quality for more sound quantity), but did need to replace some drivers from time to time. I read on another forum that a resistance measurement will yield about 75% of the impedence of a speaker. Anyone know if this is true and/or fairly accurate? Has anyone else had problems with RF-83s like I have? Quote Link to comment Share on other sites More sharing options...
DrWho Posted February 1, 2007 Share Posted February 1, 2007 The nominal impedance of any speaker is a bit misleading. Measuring the DC resistance isn't going to tell you anything - it's not uncommon for "8" and "4" ohm drivers to measure exactly the same. That said, I believe the lowest impedance dip on the RF-83 is around 3 ohms. They're listed as 8ohms compatible because the average impedance over every frequency is much higher. This behavior and nominal rating style is not uncommon. How loud were you listening? and to what kind of music? Did the same channel blow on both amps? I wonder if you don't have a short in the speaker wire - either in the middle or a loose frayed end near the terminals of the amp/speaker. I would probably recommend swapping the mains to see if the other channel of the amp blows up, but that's probably a bit insane at this point [] The RF-83's will handle 1000W peaks (holy crap), so it's not unlikely for your amp to blow up before the speakers do. If you like it loud, then I might suggest investing in a nice pro amp - perhaps something like the Crown K2 - no fan, insane power, and one of the smoothest sounding amps ever made. Quote Link to comment Share on other sites More sharing options...
TNRabbit Posted February 1, 2007 Share Posted February 1, 2007 I agree with DrWho; it sounds suspiciously like a wire short. I can't believe no protection circuit blew before you fried the channel.... I have the RF-83s as well; you will be hard pressed to hurt them at any level below immediate deafness... Quote Link to comment Share on other sites More sharing options...
MudPuppy176 Posted February 1, 2007 Author Share Posted February 1, 2007 I should add I swapped back to my old speakers for a few days between blowing the amps. The M-4 was fine until I hooked up the RF-83s. I closely inspected the wire (about 10 feet long) and see no frays or nicks. It was the right channel in both instances, so I also suspected a wire problem. Mayhaps new wire would be a "sound" investment before my shiny new McIntosh MC-252 arrives next week. In any event, the Mac should prove a formidable ally to the RF-83s. Quote Link to comment Share on other sites More sharing options...
DrWho Posted February 1, 2007 Share Posted February 1, 2007 While things are outta commission, you might try inspecting the inside of your cabinet just to make sure there are no loose wires inside. It's a rare occurence, but I've seen it happen twice on the forum where the driver leads wiggle off during shipping...only one of those times did it trigger the protection circuitry on the receiver (the other time the driver just didn't play). Quote Link to comment Share on other sites More sharing options...
TNRabbit Posted February 2, 2007 Share Posted February 2, 2007 Also check for a single stray strand or two of copper touching at the speaker or receiver end of the connection. Were these new or used RF-83s? If used, they may have issues. I'd check the impedance as a precaution. Quote Link to comment Share on other sites More sharing options...
pauln Posted February 2, 2007 Share Posted February 2, 2007 PWK in the Dope from Hope papers stated that the range within with impedance was most important was from 250-500Hz as this was where the majority of the power was being transfered (this was probably based on measures of symphonic natural instruments so may not apply with "modern" music with more down low). But the point is that the impedence match is most important where the power resides. Although the big Heritage impedences varied with frequency, they where close to 8 ohms in the 250-500Hx range where it mattered - so he stated that they should be treated as 8 ohm speakers. Now, if what you where listening to was a CD with some real low "modern" style music sound the real impedance may have been somewhat lower enough to knock down the amp. What were you listening to (were you testing the spakers' limits?) and how loud? 240W sounds a little much... Quote Link to comment Share on other sites More sharing options...
Jay481985 Posted February 3, 2007 Share Posted February 3, 2007 dips down to 2.8 ohms..... same as the rf-7..... I use a harmon kardon hk3480, cheap 250 dollar reciever that is i believe 4 ohm stable but they put out 120 watts rms..... it works fine no blow out. I have heard people run on less and good results. Quote Link to comment Share on other sites More sharing options...
Deang Posted February 3, 2007 Share Posted February 3, 2007 The problem is being caused by a loose connection in the speaker, and it's shorting out -- in other words, I agree with Dr. Who and you should get in there and take a look. Next, considering your listening habits and that your amps have no protection circuitry -- you should fuse your speaker lines. Quote Link to comment Share on other sites More sharing options...
MudPuppy176 Posted February 3, 2007 Author Share Posted February 3, 2007 Firstly, thanks to you all for your help/suggestions/advice, its very much appreciated! Now for the replies: They're brand new RF-83's. There are no stray wires as I generously tinned both ends of the wire. 240 watts is not a bit much for speakers rated for 250-1000 watts apiece. I listen to mostly rock, some "harder" than others and like it loud and clear. I think America's Greatest Hits was being played during the smoking of the amp. Not the hardest of rock by any means, but "testing" the speakers at about 200/channel. The OL lights are calibrated at 420/channel (2% distortion) @8 ohms and were NOT even blinking. My old speakers could handle the OLs on fairly solidly for hours, with no amp nor speaker damage. As for protection circuitry, the relay actuates to protect the speakers if DC is detected at the speaker terminals (as in blown outputs?). Not really amp protection, but rather speaker protection. My dealer has an RA number and they are being sent back to Klipsch as replacements are on their way. This sadly does little to replace two very respectable vintage Yamaha amps. That's another bridge, I suppose. If my brandy new McIntosh MC252 gets smoked, Klipsch can expect a personal visit from a VERY unhappy camper. Your further thoughts and/or comments are welcome.d Quote Link to comment Share on other sites More sharing options...
DrWho Posted February 4, 2007 Share Posted February 4, 2007 why are you sending your speakers back? or did i read that wrong? Quote Link to comment Share on other sites More sharing options...
MudPuppy176 Posted February 4, 2007 Author Share Posted February 4, 2007 You read it right. Klipsch is also at a loss as to why my amps blew. I assume they're going to test them to ensure they're at factory specs?? Quote Link to comment Share on other sites More sharing options...
michael hurd Posted February 4, 2007 Share Posted February 4, 2007 If I had an amplifier channel go out when connected to the speakers, I would have checked the dc resistance on both loudspeakers. Chances are that there is a wire off or a damaged component. Stuff happens, I feel bad for your loss... hopefully they are not too expensive to have repaired. Quote Link to comment Share on other sites More sharing options...
MudPuppy176 Posted February 10, 2007 Author Share Posted February 10, 2007 Here's the latest: The speakers were replaced today with a new pair. I have since bought a McIntosh MC-252 amp (250/channel). I didn't hook up the other pair to it, but the new pair today. Listening at 25 watts(yes twenty five) per channel causes the amp to overheat and shut down connected to the 8 ohm outputs. I find it hard to believe I got two defective pairs of speakers. The techs are naturally off at McIntosh and Klipsch today so I can't ask them what's up. Any thoughts? Quote Link to comment Share on other sites More sharing options...
TNRabbit Posted February 10, 2007 Share Posted February 10, 2007 Well, the first thing that comes to mind is the only other link in your system; the WIRES! Have you checked them for resistance/continuity/etc.? Quote Link to comment Share on other sites More sharing options...
Fish Posted February 10, 2007 Share Posted February 10, 2007 I had the 83's hooked to a HK 635(75 watts per)chno issues at really loud levels.You have a wiring issue of some type,I would not hook those interconnects or speaker cables to my to my set again until I tried somethig different. Quote Link to comment Share on other sites More sharing options...
michael hurd Posted February 10, 2007 Share Posted February 10, 2007 Obviously there is a problem here.... Is there any chance that the amps may be picking up and amplifying UHF? What else is connected to these.... Cd player? Sat Box? Cable Tv? home theater receiver??? Try and find / borrow a cd player with output level controls and connect it directly to the input on the amp. Drive the speakers, using the output level control on the CD player, let us know what happens. Strange things can happen, and I agree that having 2 pairs of "problematic" speakers is very unlikely. JWCullison on the forum has run his Mcintosh with a 2 ohm stereo load ( 2 K-33 on each channel ) with no problems. I have dumped the full output of my QSC PLX II ( 550 w/ch, 20 - 20khz ) into my RF3II's, with nary a problem. ( lost one tweeter, found out that the treble was boosted + 4 db in the Marantz AVR, and I set it flat, dunno what happened there, maybe conflicting remote signals ) So I really can't complain, the tweeter died of abuse. Hopefully this problem will be fixed soon. Can you give us more info on the setup? Quote Link to comment Share on other sites More sharing options...
Jay481985 Posted February 10, 2007 Share Posted February 10, 2007 michael do you still hear..... how much juice did you give them! btw i have a cheapo harmon kardon hk3480 stereo reciever that works just fine Quote Link to comment Share on other sites More sharing options...
DrWho Posted February 11, 2007 Share Posted February 11, 2007 I too blaim the wires. Quote Link to comment Share on other sites More sharing options...
MudPuppy176 Posted February 11, 2007 Author Share Posted February 11, 2007 Let me recap: Old amp and speakers: no problems for 25+ years. Change to RF83s, amp fries a channel in minutes. Change amps and go back to old speakers, no problems. Hook up RF83s, amp fries a channel in about an hour. Closely inspect speaker wires, look fine. Buy new McIntosh amp, hook up to old speakers (with new speaker wires), no problems. Replacement RF83s arrive, hook up to new Mac. Mac overheats at 25 watts indicated (RF83s hooked up to 8 ohm binding posts). Hook up the RF83s to the 4 ohm binding posts, voila, works fine. Loud, nice to say the least. Simple conclusion: these are NOT 8 ohm speakers, I have two cooked amps and a new Mac that say so. Interconnects, speaker wires, etc are not to blame. The only variable was the RF83s. Could two pairs be assembled incorrectly? I suppose its possible, but highly unlikely. They are just not 8 ohm speakers. Quote Link to comment Share on other sites More sharing options...
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