daoki Posted December 5, 2018 Share Posted December 5, 2018 Hey guys my setup is pair of Polk audio rti a7 speakers powered by a Yamaha PC2002M 240 watts per channel and a Yamaha cx2 preamplifier. My dad gave me some Bose Acoustimass 5 series 3 cube speakers not including the subwoofer. 4 cubes in total. So what I decided to do was run some speaker cables from behind the Polk A7s because behind them they have 2 sets of red and white terminals, 1 set is already been used from the speaker to the power amplifier, leaving the other set free to biwire speakers, but I am not biwiring them I think? What I have done is used the other set of remaining terminals on the A7s and plugged in speaker cable and ran them behind my couch where I have floor stands on each side essentially rear left and rear right and I have 2 Bose cubes on each side. My question is if my A7s are 300 watts into 8ohms and the Bose cubes are 135 watts. But the way I have set them up does it mean my polks are losing power because the Bose cubes are taking the power from them theM? Because the way the Bose cubes are connected behind the A7s? Does that make my A7s lose power going down to only 165 watts?What do you guys think of my setup is it worth doing ? Any issues ? Or does it mean if the Bose cubes are using 135 watts from the polks the Polk will just grab more power from the power amplifier to replace power used from polks? So essentially still staying at 300 watts and the Bose cubes 135 watts no power loss in any speaker ? Cheers Tony Link to comment Share on other sites More sharing options...
Guest Muon N' Posted December 5, 2018 Share Posted December 5, 2018 You are doing things wrong! Tony. Those terminals on the rear of the Polk's are not intended for that use. The wattage rating of passive speakers are not important, It's impedance that will be the thing that is a factor in what you are doing. If you want a multi channel set up get a multi channel amp. Link to comment Share on other sites More sharing options...
daoki Posted December 5, 2018 Author Share Posted December 5, 2018 What will happen if I set them up like that ? Link to comment Share on other sites More sharing options...
Guest Muon N' Posted December 5, 2018 Share Posted December 5, 2018 (edited) Tony, I just re-read your original post, and will say don't do it! You are as I read it wanting to run 2x Bose speakers off the back of each Polk? I'm back to suggesting that you do not use the Bose speakers in that set up. Edited December 5, 2018 by Muon N' Link to comment Share on other sites More sharing options...
Zaphod Beeblebrox Posted December 5, 2018 Share Posted December 5, 2018 8 hours ago, daoki said: Hey guys my setup is pair of Polk audio rti a7 speakers powered by a Yamaha PC2002M 240 watts per channel and a Yamaha cx2 preamplifier. My dad gave me some Bose Acoustimass 5 series 3 cube speakers not including the subwoofer. 4 cubes in total. So what I decided to do was run some speaker cables from behind the Polk A7s because behind them they have 2 sets of red and white terminals, 1 set is already been used from the speaker to the power amplifier, leaving the other set free to biwire speakers, but I am not biwiring them I think? What you are doing (if I understand it correctly) is very, VERY stupid. Don't do it. The Bose cubes are designed, SPECIFICALLY, to operate via the subwoofer. The subwoofer rolls off the low bass so the cubes will not be destroyed. 8 hours ago, daoki said: What I have done is used the other set of remaining terminals on the A7s and plugged in speaker cable and ran them behind my couch where I have floor stands on each side essentially rear left and rear right and I have 2 Bose cubes on each side. My question is if my A7s are 300 watts into 8ohms and the Bose cubes are 135 watts. But the way I have set them up does it mean my polks are losing power because the Bose cubes are taking the power from them theM? No. You'll just destroy the Bose cubes. It may take awhile, or it may take a few seconds. Ultimately, however, they will be destroyed. The Bose cubes are not designed to deal with frequencies much lower than 300Hz. 8 hours ago, daoki said: Because the way the Bose cubes are connected behind the A7s? Does that make my A7s lose power going down to only 165 watts? No. The Bose cubes will be destroyed and all the power will then be routed to the Polks. All good. 8 hours ago, daoki said: What do you guys think of my setup is it worth doing ? No. It's stupid. 8 hours ago, daoki said: Any issues ? Apart from sounding horrible and that you will needlessly destroy the Bose cubes, nope. 8 hours ago, daoki said: Or does it mean if the Bose cubes are using 135 watts from the polks the Polk will just grab more power from the power amplifier to replace power used from polks? Speakers do not 'grab more power'. 8 hours ago, daoki said: So essentially still staying at 300 watts and the Bose cubes 135 watts no power loss in any speaker ? Cheers Tony Just don't do it. It's a really dumb idea and you'll just destroy the Bose cubes. BTW: I want you to think on this for a bit. Have you ever felt how hot a 100 Watt incandescent light globe gets? Do it sometime. Even a 60 Watt, or 40 Watt one. Maybe a 50 Watt downlight. Do so, then you'll have an idea of just how much power 135 Watts is. Do you REALLY think those dinky little Bose cubes can handle 135 Watts, without melting into a blob, or catching fire? Those little Bose cubes can REALLY handle about 10 Watts, NOT 135 Watts. I know this may surprise you, but manufacturers often tell fibs about the ratings of their products. Shocking, I know. 1 Link to comment Share on other sites More sharing options...
Volunteer sir sanders zingmore Posted December 5, 2018 Volunteer Share Posted December 5, 2018 7 minutes ago, Zaphod Beeblebrox said: Do you REALLY think those dinky little Bose cubes can handle 135 Watts, I know the OP’s idea is risky, but why would the Bose cubes be getting 135 W? For the vast majority of the time the amp is almost certainly putting out far less than its full rated output Link to comment Share on other sites More sharing options...
Zaphod Beeblebrox Posted December 5, 2018 Share Posted December 5, 2018 Just now, Sir Sanders Zingmore said: I know the OP’s idea is risky, but why would the Bose cubes be getting 135 W? For the vast majority of the time the amp is almost certainly putting out far less than its full rated output Of course, but I was trying to make a point about the absurdity of relying on ONE number in isolation. The reality is that the Bose cubes are designed to deal with NOTHING below 300Hz. When serious bass is applied to the Bose cubes, both their excursion limits and power handling limits (which is around 10 Watts) will be exceeded and the cubes will be destroyed. Link to comment Share on other sites More sharing options...
Batty Posted December 5, 2018 Share Posted December 5, 2018 Plus, I am guessing the Bose will be in parallel with the polks and that will change the impedance that the amp is seeing. 1 Link to comment Share on other sites More sharing options...
Guest Muon N' Posted December 5, 2018 Share Posted December 5, 2018 (edited) Yeah, the impedance would possibly be below 2ohms, maybe well below with 2x Bose hanging off each Polk. I looked for those specs for the Bose without any result. The rest is covered by ZB, and nicely. Edited December 5, 2018 by Muon N' typo Link to comment Share on other sites More sharing options...
Zaphod Beeblebrox Posted December 5, 2018 Share Posted December 5, 2018 4 minutes ago, Batty said: Plus, I am guessing the Bose will be in parallel with the polks and that will change the impedance that the amp is seeing. Correct, but, as I already stated, only for a short time, until the Bose cubes are turned into smoking hulks. I'd give it 2 ~ 3 minutes. Tops. 2 Link to comment Share on other sites More sharing options...
Zaphod Beeblebrox Posted December 5, 2018 Share Posted December 5, 2018 9 minutes ago, Muon N' said: Yeah, the impedance would possibly be below 2ohms, maybe well below with 2x Bose hanging off each Polk. I looked for those specs for the Bose without any result. The rest is covered by ZB, and nicely. Here is the frequency response of the satellite filters fitted to the Bose system. Cut-off is a little higher than 200Hz, not 300Hz as I previously stated. Link to comment Share on other sites More sharing options...
Guest Muon N' Posted December 5, 2018 Share Posted December 5, 2018 I gave that a like, Trevor, even though I am a bit lost with the graphs But I agree, they would be toast! Link to comment Share on other sites More sharing options...
Guest Muon N' Posted December 5, 2018 Share Posted December 5, 2018 @daoki Time to look at some other way to improve the listening experience, and caulk this up as a learning experience. Link to comment Share on other sites More sharing options...
Sub Sonic Posted December 5, 2018 Share Posted December 5, 2018 2 hours ago, Zaphod Beeblebrox said: No. The Bose cubes will be destroyed and all the power will then be routed to the Polks. All good. 1 Link to comment Share on other sites More sharing options...
daoki Posted December 6, 2018 Author Share Posted December 6, 2018 Hey guys. If I was to get rid of the cubes and invest in some decent bookshelfs do you think it could be possible to hook up the A7s into speaker A of the power amp and the bookshelfs into speaker B of the power amp and then obviously switch on a+b from the front to produce sound out of all speakers. Is this a safer way of doing things you think? Surely it must be a more protective way if I was to set up 2 sets of speakers without a receiver and straight to amplifier ? I’m assuming my power amplifier would be able to handle this ? Other wise the power amplifier itself wouldn’t have the switch set if outputs speaker A and Speaker B? Link to comment Share on other sites More sharing options...
davewantsmoore Posted December 6, 2018 Share Posted December 6, 2018 (edited) On 05/12/2018 at 11:19 PM, daoki said: does it mean my polks are losing power because the Bose cubes are taking the power from them theM? No.... It means that your amplifier need to produce "more power" to feed them all. Quote Or does it mean if the Bose cubes are using 135 watts No... These numbers are the peak power that the speaker is designed to handle.... not how much the speaker typically draws. If you are playing loud, each speaker might be using 10, 20, 50 watts.... something like that. On 06/12/2018 at 3:22 AM, daoki said: What will happen if I set them up like that ? Your amplifier will work harder (almost definitely OK) Bass frequencies will go to the cubes (if you play don't keep the volume down low, they will sound bad at best, and be destroyed at worst) On 06/12/2018 at 9:05 AM, Zaphod Beeblebrox said: Correct, but, as I already stated, only for a short time, until the Bose cubes are turned into smoking hulks. I'd give it 2 ~ 3 minutes. Tops. The drivers will suffer from over excursion before excessive power .... so no smoke/toast. Although damaged/angry speakers, none the less 13 hours ago, daoki said: Hey guys. If I was to get rid of the cubes and invest in some decent bookshelfs do you think it could be possible to hook up the A7s into speaker A of the power amp and the bookshelfs into speaker B of the power amp and then obviously switch on a+b from the front to produce sound out of all speakers. Yes. Using the A+B function is better/safer ..... although there is nothing super wrong with how you have them hooked up now. The problem is that those cubes are not designed to be driven from anything other than their subwoofer --- because the subwoofer stops them from receiving bass frequencies. Too much bass will rip the cones in the cubes.... so watch out. Edited December 6, 2018 by davewantsmoore 1 Link to comment Share on other sites More sharing options...
daoki Posted December 6, 2018 Author Share Posted December 6, 2018 Here are pictures of behind my power amplifier is it possible to do and how ? https://www.canuckaudiomart.com/details/649315113-yamaha-pc2002m-2-channel-amplifier/images/1383908/ Link to comment Share on other sites More sharing options...
Guest DarkNark Posted December 6, 2018 Share Posted December 6, 2018 35 minutes ago, daoki said: Here are pictures of behind my power amplifier is it possible to do and how ? https://www.canuckaudiomart.com/details/649315113-yamaha-pc2002m-2-channel-amplifier/images/1383908/ No it's not possible, speaker A and B are referring to 2 channels, left/ right, stereo, however you want to describe it. It is not referring to 2 different sets of speakers. Big thumbs up to @davewantsmoore and others, for answering the questions from a beginner without using the words "stupid" "VERY stupid" and "dumb". Link to comment Share on other sites More sharing options...
Martykt Posted December 6, 2018 Share Posted December 6, 2018 20 minutes ago, DarkNark said: Big thumbs up to @davewantsmoore and others, for answering the questions from a beginner without using the words "stupid" "VERY stupid" and "dumb". Very well said, we were all beginners once !!! Link to comment Share on other sites More sharing options...
Sub Sonic Posted December 6, 2018 Share Posted December 6, 2018 5 hours ago, davewantsmoore said: The problem is that those cubes “are” designed to be driven from anything other than their subwoofer Might need to correct this Dave (my italics) SS Link to comment Share on other sites More sharing options...
Zaphod Beeblebrox Posted December 6, 2018 Share Posted December 6, 2018 7 hours ago, daoki said: Here are pictures of behind my power amplifier is it possible to do and how ? https://www.canuckaudiomart.com/details/649315113-yamaha-pc2002m-2-channel-amplifier/images/1383908/ Nope, it is not possible for two reasons: 1) Channel A and B refers to left and right. Since the amp is a pro model, left and right are not the usual conventions used, but it simply means Channel A = Right and Channel B = Left. 2) Your amplifier has a minimum rated impedance of 8 Ohms. If you try to connect two pairs of 8 Ohm speakers, then the connected impedance will be 8X8/(8+8) = 4 Ohms. Your amplifier could be damaged by a 4 Ohm load. 2 Link to comment Share on other sites More sharing options...
davewantsmoore Posted December 6, 2018 Share Posted December 6, 2018 (edited) 7 hours ago, Sub Sonic said: Might need to correct this Dave (my italics) Oh, right - I see my grammar error. EDIT: I had also misunderstood how they were hooked up - they're parallel (I had thought series). We also didn't know the amplifier was only designed to drive above 8 ohm loads..... so I think we need to walk this back a little bit, sorry. On 06/12/2018 at 3:22 AM, daoki said: What will happen if I set them up like that ? Ignore most of my previous advice. Don't hook them up like you have. You amplifier isn't rated for the extra load .... and even if it was, like I said before - these cubes are going to be swamped by the bass frequencies, and it will likely hurt their cones (no smoke fro the speaker, but torn cones and bad sound). Edited December 6, 2018 by davewantsmoore 2 Link to comment Share on other sites More sharing options...
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