MudPuppy176

Klipsch must be well aware of the improper rating of their reference series of speakers. They are now offering to repair my amps. RF-83s really don't qualify as 4 ohm speakers, let alone 8 ohm speakers. A horrrid dip to 2.8 ohms can never qualify as an 8 ohm load. Their willingness to repair my amps is a testament to good customer service, but honest marketing would've precluded the problem. Rf-83s are less than 4 ohm speakers, but may be considered 4 ohms within reason. If it all pans out, Klipsch will have redeemed themselves in my eyes, but others' amps may self-destruct with less than designed speaker loads. Just a word of caution: RF-83 are actually less than 4 ohms, certainly not 8 ohms. On the positive side, they have no reason to falsify their efficiency. They are quite impressive. Very nice speakers, just count on 4 (or even 2) ohm loads.

Headroom and power compression, interesting terms. As far as I know they're rated at 250RMS, 1000peak each. Anything more than 64 watts goes to heat, gamma rays and/or invisible light? Maybe I need a tin foil hat. Please advise ASAP.

Thanks for your concurrence DrWho. The whole impedence issue is grey at best as I know of no "standard" means of measurement. Its very complex as its frequency dependent as you noted. The amp and speaker manufacturers all have their own methods of rating their products it seems. There are people (I for one) that like it quite loud at times. A fried amp is never the goal however. To Fish who said get a real amp (or words to that effect) I tend to lean towards the belief that a McIntosh MC-252 more than qualifies as a real amp. (250W into the RF-83 is WAY fricken loud).

I know they're different speakers because I had both pair here at the same time. The dealer dropped off the new and picked up the old pair. I spoke with McIntosh tech support yesterday. He said the RF83s dip to 2.8 ohms at some frequencie(s) but didn't have access to an actual impedence plot. He seemed very surprised Klipsch would call them 8 ohm speakers. He mentioned B&W's high end speakers dip to 3.2 ohms which he also found too low to be classified an 8 ohm speaker. His opinion was that its basically a marketing ploy to raise the efficiency numbers. Consumers want to see 100dB/watt when they're paying high dollars for speakers.

I didn't hook them up to the 4 ohm posts because I wanted 250/channel, not 125/channel. I didn't hook them up to the 2 ohm posts because I didn't want 62.5/channel. If you hook up 8 ohm speakers to the 4 ohm posts, you get half the power. Halve it again with the 2 ohm posts. Unfortunately the opposite also holds true: Hook up RF83s to an 8 ohm post and you'll cook/overheat an amp because they're 4 ohm speakers and will draw twice the power. These are 4 ohm speakers advertised as 8 ohm speakers. It does wonders for that fabled Db/watt number, but doesn't do an amp much good. Don't get me wrong, they're awesome on the 4 ohm posts. Conversly, I have a couple of expensive large paperweights that were designed for an 8 ohm load they simply didn't get.

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.

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?

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??

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

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.

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?