Reputator Posted March 4, 2011 Share Posted March 4, 2011 I'm looking into getting a pair of RB-51 IIs, but right now I've got an old reciever rated at 40W RMS per channel. Until I can replace the reciever, do I run the risk of blowing out the speakers? Thanks. Quote Link to comment Share on other sites More sharing options...
tube fanatic Posted March 4, 2011 Share Posted March 4, 2011 The risk to the speakers is from being driven by an amplifier that is clipping (i.e. being pushed to the point that it generates distortion products which can overheat the tweeters, in particular). So, it all depends on how loudly you intend to listen, how far from the speakers you will sit, whether the room is very heavily sound absorbent (carpets, rugs, book cases, drapes, and so on), and the type of music that you listen to. For most applications, however, 40 watts/channel should be plenty. Quote Link to comment Share on other sites More sharing options...
Reputator Posted March 4, 2011 Author Share Posted March 4, 2011 The RB-51 IIs certainly has very good sensitivity, which is encouraging. What would be the advantage of going with a more modern reciever closer to the 75W RMS rating of the speakers? Quote Link to comment Share on other sites More sharing options...
DizRotus Posted March 4, 2011 Share Posted March 4, 2011 I wouldn't worry about harming the speakers. Quote Link to comment Share on other sites More sharing options...
tromprof Posted March 5, 2011 Share Posted March 5, 2011 I have a 9 watt amp running my K-horns, and so far no explosions. That is the beauty of Klipsch speakers, when it comes to amps it is quality, not quantity. Quote Link to comment Share on other sites More sharing options...
tube fanatic Posted March 5, 2011 Share Posted March 5, 2011 The RB-51 IIs certainly has very good sensitivity, which is encouraging. What would be the advantage of going with a more modern reciever closer to the 75W RMS rating of the speakers? None whatsoever. For each doubling of power applied, you will only get a small increase in sound (typically around 3 db). The maximum power rating of the speaker really doesn't mean anything as you couldn't possibly stay in the room with them (or possibly in the same house!) if you applied that kind of power. Most listening, even at loud levels, isn't going to need more than a few watts/channel. The best thing is to buy the speakers and try them with your current receiver. If it plays loudly and cleanly enough, and you are pleased with the sound, save your money and just enjoy them. Quote Link to comment Share on other sites More sharing options...
Reputator Posted March 5, 2011 Author Share Posted March 5, 2011 Thanks guys. The speakers are on their way, can't wait! Quote Link to comment Share on other sites More sharing options...
Danzo Posted March 5, 2011 Share Posted March 5, 2011 Some, as you see, sniff at 'mere 3db increase with doubling of power' and go with 'small but good', others firmly believe that 'you need 400W per channel for proper headroom and slam'. Would be best if you could try different ones for yourself and see if it makes difference for you. Enjoy your new speakers! Quote Link to comment Share on other sites More sharing options...
Crown1 Posted March 7, 2011 Share Posted March 7, 2011 The advantages of using a modern receiver with more power, would be cleaner more dynamic sound. When matched with a good quality, high current receiver, the results will be far superior to that of under powering. Under powering causes the amp to work harder, producing a higher percentage of total harmonic distortion . This leads to imprecise bass, cloudy midrange and brittle treble. It can even lead to speaker failure. Power isn't just for playing loudly, its for better overall clarity. If your speakers are rated for 75 watts RMS , knowing Klipsch, the peak may be 3 times that. Optimally 100 watts per channel would be great. Yes, Klipsch speakers are efficient, however that does not mean you should starve them. :-) Quote Link to comment Share on other sites More sharing options...
sebrof Posted March 8, 2011 Share Posted March 8, 2011 As a guy who ran Klipschorns with 4 watts (very loud), 40 watts would have been about 10x what I needed. Not sure about the RB-51s, but if you have a good 40 watts (just because the receiver is old doesn't mean it ain't no good) then available power is not your problem. As others have said, no worries about blowing up your speakers. How does it sound to you? Quote Link to comment Share on other sites More sharing options...
Coytee Posted March 8, 2011 Share Posted March 8, 2011 As a guy who ran Klipschorns with 4 watts (very loud), I get a kick out of that. Then again, some think I'm a volume *****.... (can I say that about myself? [^o)]) If I'm watching a movie or heck...sometimes even a good concert DVD... I'll see peaks of 15/25 watts on my meters. Given how brief the transients are, I don't know if that is accurate or if in real life, I'm using more power. I sold an 8 watt SET amp because it simply ran out of gas. Mind you, its only responsiblity was to run my top horn so it had no job responsiblity from 500hz and below which gave it even more headroom. It did however, sound VERY nice for what it did and I must admit, would be nice for 75% of my listening. But for those times when you want to hit it just a little harder.... it's nice having some reserve. Quote Link to comment Share on other sites More sharing options...
Crown1 Posted March 8, 2011 Share Posted March 8, 2011 LOL. I never said anything was wrong with his receiver, I was purely referring to the need for more clean power. Bookshelf speakers are naturally less efficient due to the fact that they have smaller cabinets and smaller drivers than large speakers. Your Klipschorns are significantly larger and posses significantly more radiating surface with which to produce sound. Despite the efficiency ratings of the RB51 version II, it will benefit from the extra power of a well matched receiver which meets and or exceeds its power requirements. There is a reason for the continuous rating on the box, it is the point at which the speaker will sound its best provided that it is powered correctly, hence the recommendation of a newer high current receiver. Quote Link to comment Share on other sites More sharing options...
Reputator Posted March 9, 2011 Author Share Posted March 9, 2011 Good news, got the speakers in today, and they're working out great with the old reciever. No distortion whatsoever. I probably will upgrade the reciever, especially since I suddenly feel a pressing need for a better DAC (friggin cascade effect of audio), but for a while I think what I have should hold up fine. Again, thanks for the passionate discourse on my behalf. Quote Link to comment Share on other sites More sharing options...
tube fanatic Posted March 9, 2011 Share Posted March 9, 2011 There is a reason for the continuous rating on the box, it is the point at which the speaker will sound its best provided that it is powered correctly, hence the recommendation of a newer high current receiver. Absolutely incorrect!!! Who ever told you this??? Quote Link to comment Share on other sites More sharing options...
sebrof Posted March 9, 2011 Share Posted March 9, 2011 LOL. I never said anything was wrong with his receiver, I was purely referring to the need for more clean power. Bookshelf speakers are naturally less efficient due to the fact that they have smaller cabinets and smaller drivers than large speakers. Your Klipschorns are significantly larger and posses significantly more radiating surface with which to produce sound. Despite the efficiency ratings of the RB51 version II, it will benefit from the extra power of a well matched receiver which meets and or exceeds its power requirements. There is a reason for the continuous rating on the box, it is the point at which the speaker will sound its best provided that it is powered correctly, hence the recommendation of a newer high current receiver. Hello Crown - I assume you were referring to my post since you referenced KHorns. I said the 4 watts was enough for me, I didn't say it was enough for him. 4 watts isn't enough for many (most?) people even with KHorns. I do think 40 watts should be enough for him with his speakers, though. And I'm with Tube Fan, the realtionship between the max continuous power rating and the best sound does not exist. Quote Link to comment Share on other sites More sharing options...
Crown1 Posted March 9, 2011 Share Posted March 9, 2011 PyI have been a live sound tech and audiophile for many years, it is a known fact that speakers generally sound their best when properly powered. Why do you think sound companies use racks and racks of the same amp? One of the reasons is head room. It's okay. We will agree to disagree. Quote Link to comment Share on other sites More sharing options...
sebrof Posted March 9, 2011 Share Posted March 9, 2011 PyI have been a live sound tech and audiophile for many years, it is a known fact that speakers generally sound their best when properly powered. Why do you think sound companies use racks and racks of the same amp? One of the reasons is head room. It's okay. We will agree to disagree. In your previous post you said "There is a reason for the continuous rating on the box, it is the point at which the speaker will sound its best provided that it is powered correctly..." That's what a couple of us were questioning. I just don't know where that statement came from and I'm having a hard time making sense of it, that's all. Quote Link to comment Share on other sites More sharing options...
Quiet_Hollow Posted March 9, 2011 Share Posted March 9, 2011 I'm looking into getting a pair of RB-51 IIs, but right now I've got an old reciever rated at 40W RMS per channel. Until I can replace the reciever, do I run the risk of blowing out the speakers? Thanks. How much power is too little? Not enough to hear would suffice me. ;-) As far as blowing out your speakers..how loud is "loud enough" for you? Until you know that number in dB SPL, for certain, power figures will be meaningless, regardless of design or intent. Quote Link to comment Share on other sites More sharing options...
artto Posted March 10, 2011 Share Posted March 10, 2011 The RB-51 IIs certainly has very good sensitivity, which is encouraging. What would be the advantage of going with a more modern reciever closer to the 75W RMS rating of the speakers? Your existing amplifier/receiver is 40 watts. Doubling power output to the speaker increases the sound level by about 3 decibels. Ten decibels sounds twice as loud. So 75 watts is not going to make much difference. Quote Link to comment Share on other sites More sharing options...
Quiet_Hollow Posted March 10, 2011 Share Posted March 10, 2011 Doubling power output to the speaker increases the sound level by about 3 decibels Bingo.You'll be able to tick-off the neighbor good and plenty before that combination runs out of gas thanks to the RB's generous sensitivity. It won't get your clothes flapping, but it'll certainly be loud, even at 40W playing music with a 10 dB crest factor. Quote Link to comment Share on other sites More sharing options...
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