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New member Username: JimbogJersey United Kingdom Post Number: 1 Registered: Feb-09 | Hi, Please could someone look over what I am trying to achive here and give me the thumbs up or down, thank you. I am purchasing a Denon AVR-2809 to replace my old Kenwood Series 21 C-V750 that died yesterday. (It fed a matching Power Amp the M-A300) As part of the Kenwood 21 Series (about 10 years old) I have: 2 Front Speakers (Floorstanders) at 6 Ohm 100 Watt each Centre Speaker at 6 Ohm 100 Watt Two Floorstander Surround Speakers at 6 Ohm 100 Watts each OK - Each of the Front speakers ALSO have a single 15 inch 6 Ohm 100 Watt Subwoofer as well. The way I had to wire the speakers before was that the Kenwood Amp powered all speakers directly using separate terminals, with the subs being powered by a single terminal into the left speaker - which then has a "Subwoofer to Subwoofer" set of terminals designed to allow the subs to be directly connected but fed from the front left speaker. (Just to clarify the left speaker has three sets of terminals - Front "Three-way", "Sub In" and Sub to Sub" shall we say - wheras the right speaker has two sets of terminals - Front "Three-way" and "Sub In") This was a complete system when I bought it (many years ago) and was wired exactly as designed. I am confirming this for you so as to remove any confusion, this is as intended. My new Denon AVR-2809 allows for 6-16 Ohm at 150 Watts per channel. The problem is that the Denon does not have explicit speaker terminals for powering a passive subwoofer. It does allow for wiring up to a second "Zone" on a second set of Front speakers but this will then reduce the Impedence to 8-16 Ohms at 115 Watts per channel. So I thought about this for a while and did some research (including this forum) to see if there were any alternatives. Now I am reasonably intelligent but a complete novice to bi-wiring, bi-amping, series and parallel wiring. I'd like to avoid using "Zone B" just to run a "second set of fronts" for the subs, especially when the old amp was clearly running two 100 Watt subs off a single 100 Watt terminal. Not running the subs is also not an option as there is no low end in the sound space otherwise. Here's my idea: So, if I stick to the single "Zone A" ie 150 Watts per channel at 6-16 Ohm is it feasible to wire the two fronts and separate subwoofers from each speaker in series from their own respective terminal on the amp? ie. Series wire two 100 Watt 6 Ohm speakers (One "Three Way" and one "Sub") back to one Speaker terminal on the Amp which is capable of 150 Watt per channel at a maximum of 16 Ohm. Based on my research tonight my extremely limited understanding on how this works compared to Parallel wiring is that this will double my impedence rating per channel to 12 Ohm from 6 - still within my 16 Ohm limit. And 150 Watts of Power output *should* be enought to run 200 Watts of Speaker? Does this seem like it makes sense / is safe / won't kill my brand new amp? Thanks guys for any thoughts you have on this. With kind regards James Gillies |
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New member Username: JimbogJersey United Kingdom Post Number: 2 Registered: Feb-09 | Hi guys, I've just done some calculations based on a cool web page I found to see what power per channel I would expect to get using the method described above: http://www.termpro.com/articles/spkrz.html These are my calculations based on series wiring for my amp power rating, it's own impedence rating and the combined speaker impedences when wired in series. Po = 150 x (6 / 12) Po = 150 x 0.5 Po = 75 watts Pa = 75 x (6 / 12) Pa = 75 x 0.5 Pa = 37.5 watts If I've got this right I am expecting to get 37.5 Watts per channel for two 100 Watt speakers.... will this be enough? Any takers? Thanks again. Kind regards James Gillies |
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New member Username: JimbogJersey United Kingdom Post Number: 3 Registered: Feb-09 | Hi guys, Final post - I've done one more bit of research and found a "Amplifier Power Calculator" here: http://www.infinitesightandsound.com/Calculator_-_Amplifier_Power.php By entering in the following: Select "Dance" Music - (Will also watch DVDs) System has clipping built in = Yes Distance to relevant speaker = 10 Feet Sensitivity = 89dB (I've guessed this as I cannot find the specs for my speakers anywhere for the life of me Kenwood S-F700) Continuous Power Rating = 100 Watts Amplifier Power Required Per Channel = 37 Watts Max Allowed for Speakers = 200 Watts Well... looks a little bit coincidental!!! Is it possible that I could be THAT lucky?? Kind regards James Gillies |
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Platinum Member Username: Jan_b_vigneDallas, TX Post Number: 13370 Registered: May-04 | . If you are certain you understand how to make the series connection between the sub and the speaker, then you should do so. The rest of your calculations are pretty much irrelevant. . |
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New member Username: JimbogJersey United Kingdom Post Number: 4 Registered: Feb-09 | Hi Jan, Thanks for your reply - but it makes no sense to me. Yes I do understand how to wire the speakers together in series, that's no problem. But I've just spent the best part of £1000 on a new amp and I want to make sure that I am not going to damage it or my speakers which are fine. Could I ask you please to elaborate on your post to give more detail on what you mean? 1.) Will this work? 2.) What is the risk? 3.) Will I get enough power to my speakers without damaging them? 4.) Will I get enough "oomph" without driving my amp too much? 5.) Is there a better way of doing it? 6.) Should I go for the "Zone B" approach? (115W down to 8 Ohm from 150W 6 Ohm) Sorry to be a bit pushy but I spent three to fours researching this and I need a better response than "The rest of your calculations are pretty much irrelevant." Sorry. Kind regards James Gillies |
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Platinum Member Username: NuckPost Number: 11651 Registered: Dec-04 | JG, if you have run this setup previously and it worked... If you have invested years of research into the setup... If you bought a new amp with this very setup in mind... It seems an odd time to ask for more info now? At some point you have to trust and just go forward. Any reasonable amp will protect itself against shorts, and if the load you have selected is too much for the amp, it will heat up or shut down very quickly. |
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Platinum Member Username: Jan_b_vigneDallas, TX Post Number: 13371 Registered: May-04 | . "Could I ask you please to elaborate on your post to give more detail on what you mean? 1.) Will this work? 2.) What is the risk? 3.) Will I get enough power to my speakers without damaging them? 4.) Will I get enough "oomph" without driving my amp too much? 5.) Is there a better way of doing it? 6.) Should I go for the "Zone B" approach? (115W down to 8 Ohm from 150W 6 Ohm) The "A/B" speaker outputs on your old amplifier were internally wired in parallel. You were running from the same amplifier despite having the separate connectors. By eliminating the second connector you are would still be making a parallel connection at the amplifier. What happens between the speakers and the sub is then what determines just what load the amplifier will be faced with. If you can make the appropriate series connection, that is the load the amplifier will see. The "6-16 Ohm" reference on your receiver is a guideline to start with as all speakers will swing their impedance up and down throughout the frequency range. No multiway speaker system is just one impedance load at all times. If the overall impedance dips below 6 Ohms and the electrical phase angle is not difficult the amplifier will deal with the momentary situation it encounters when playing dynamic music material. If you demand too much of the receiver's power supply, then it will react poorly and its protection devices will alert you to the problem. There's no way for me to tell you whether you will have enough "oomph" for your listening conditions. It would be unusual for the Denon to not satsify your needs but some people like to have blood pour from their ears, eys and nose when they listen to music. If this is your desire and the Denon doesn't manage this trick, it's the speakers which are at fault and not the amplifier. If you do not create a shorted circuit or an open circuit, there should be no real danger to any component. As Nuck suggests, a reasonable amount of care and common sense will preclude any damage. The average amount of wattage used in a home audio system is under 10 watts. I suspect your new amplifier will manage that succesfully. All of your calculations are without real meaning because they are paper numbers that do not reflect the reality of the world. Speakers are not producing "100 watts" and do not require "100 watts" to operate. Those numbers mean nothing in reality so you can ignore them and just listen to your music. Numbers are provided because people like to have something tangible in front of them when they have no real, clear concept of how something operates. The numbers mean nothing however even when you don't understand them. If the system works to your satisfaction, by producing on average 10 watts of program material, then you're OK. The numbers that matter to the amplifier are predominantly related to the load it must face. If you do a proper series connection, there's every reason to believe your new amplifier will live happily as will you. The better way to do this would be to buy new speakers. The ones you are using were meant to pair with your old amplifier. There is a small chance their response was trimmed to mate with that amplifier and that amplifier alone. That subject aside, you have a new amplifier, treat yourself to the improvements in speakers that have occurred in the last dozen or so years. Zone Two would not easily be controlled by the volme control of your new receiver if you were also controlling the main speakers. You would not be able to simultaneously track both speakers and sub with one movement. Zone two is meant for an indenepdent area of operation such as a secondary room and as such has the discrete ability to set independent volume levels. . |
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New member Username: JimbogJersey United Kingdom Post Number: 5 Registered: Feb-09 | Hi Nuck, Thanks for your response. I think you have misunderstood me. I bought the Kenwood system about ten years ago. The amp died on Sunday meaning I was was in the market to replace it quite quickly and found the Denon. I haven't had to look at amps and so on since that time so I am a bit rusty. (Nor did I have to go into that much detail in the past to be perfectly honest.) In terms of research I had spent three to four hours - that's it. I had learned pretty much everything that I had talked about in that time before posting yesterday. On that basis I was looking for some opinions to help me a) understand what I'm doing b) avoid any catastrophes by going too quick. Based on what Jan has come back with in his (what appears to be extremely detailed) post I am looking forward to digesting what he has to say. I am happy to go forward with trust but I am a technical person and as such *need* to understand what I'm doing as best as possible. Thanks again for your response. Kind regards James Gillies |
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New member Username: JimbogJersey United Kingdom Post Number: 6 Registered: Feb-09 | Jan, Awesome. Thank you very much. I fully accept the paper numbers now.. I was merely attempting to get a grip on something that I have no real knowledge on. As per my first post I was pretty sure I would have enough power but wanted to double-check. I *think* I understand what you mean about the two subs currently being wired in Parallel... the first sub takes the feed in one terminal and then pipes it back out to the sub on the other speaker. I have since looked closer at the user manual online for the power amp itself, page 5: (S-F700 Speakers) http://manuals.kenwood.novenaweb.info/languages/EN/support/manuals/M-A300-100.pd f I totally agree that going forward I should and will buy new speakers... but I only bought the new TV two weeks ago! :o) I would prefer to use a powered sub and can see connections on the back of the Denon for that so no problems there. I am not 100% sure of what you mean when you say "By eliminating the second connector you are would still be making a parallel connection at the amplifier." Just clarify am I to wire the Left Front Three-way to the Left Front Sub in series off the single Zone A Front Left Terminal on the amp and the Right Front Three-way to the Right Front Sub in series off the single Zone A Front Right Terminal on the amp? If so, do you foresee any issues with the Front Left speaker not having it's "Sub Out" wired to anything? (I should have asked for clarification on that last night) - In other words do you think that the speakers are "expecting" to be wired together in this fashion to keep them both happy or will it be alright? I don't need to have it that loud - even in my old setup where "nothing" was 89db on the scale and 0db was the loudest I would very rarely take it past 25db for sustained periods of time. Thanks again for a great response, just what I was looking for. Kind regards James Gillies |
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Platinum Member Username: Jan_b_vigneDallas, TX Post Number: 13373 Registered: May-04 | . "Just clarify am I to wire the Left Front Three-way to the Left Front Sub in series off the single Zone A Front Left Terminal on the amp and the Right Front Three-way to the Right Front Sub in series off the single Zone A Front Right Terminal on the amp? If so, do you foresee any issues with the Front Left speaker not having it's "Sub Out" wired to anything? (I should have asked for clarification on that last night) - In other words do you think that the speakers are "expecting" to be wired together in this fashion to keep them both happy or will it be alright?" This should work fine until you can replace the speakers and sub. . |
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New member Username: JimbogJersey United Kingdom Post Number: 7 Registered: Feb-09 | Hi Jan, Nice one, thanks very much. James |