samuel r Posted December 4, 2001 Share Posted December 4, 2001 on my denon 4800 receiver, i have two sets of REAR speaker inputs (a+. i just want to know if using both sets at once will overwork the receiver or will it just lessen the power to each speaker? i currently have one set of rears hooked up in the "a" side. i have an extra pair of rears i would like to utilize for more effect and added spaciousness. the manual states that using both sets as A+B may lead to damage. could that be? it also states later in the manual that either a, b, or a+b can be used. should i use a higher gauge wire(thinner) if i'm to use both sets? or does wire matter in this situation? or should i not do it at all? Quote Link to comment Share on other sites More sharing options...
lynnm Posted December 4, 2001 Share Posted December 4, 2001 The manual for your receiver should specify the minimum nominal impedance rating of the speaker system(s) that may be connected. Do not connect speakers or combinations that are below that minimum! Speaker systems connected to both the A and B outputs will be connected in parallel and the nominal impedance will be reduced. I forget the exact formula....(R1*R2)/(R1+R2)<?>... but the practical result is that if 2 sets of speakers have a nominal impedance of 8 ohms and are connected in parallel then the result is that the amplifier will "see" an impedance of 4 ohms. Similarly if 2 pair of 4 ohm speakers are connected in that way the impedance drops to 2 ohms and so on. The important thing to observe is that if the impedance is too low then the amplifier can be presented with the equivalent of a short circuit and serious damage can result to the amplifier and possibly to the speakers. Typicallly the power output of an amplifier increases as the effective impedance load decreases. This is why you often see amplifiers with specifications like 100w./ch into 8 ohms - 200w./ch into 4 ohms. ------------------ It is meet to recall that the Great Green Heron rarely flies upside down in the moonlight - (Foo Ling ca. 1304 BCE) This message has been edited by lynnm on 12-04-2001 at 09:00 PM Quote Link to comment Share on other sites More sharing options...
samuel r Posted December 4, 2001 Author Share Posted December 4, 2001 ok, kinda understand. but i have two sets of inputs for the rears. input for rear speakers "a" and input for rear speakers "b". i am not running TWO pair of speakers off one input. ok, right now i have only one pair of surounds hooked into speaker input "a". i want to use the extra pair of rears i have and put them into the "b" input. after doing this, i will be able to select which set of rears i want to use. i can use either set "a" or i can use set "b". OR i can use both sets "a+b". will the use of both sets "a+b" bring the impedance down to 4 ohms since both pairs are 8 ohm speakers, or will they stay at 8 ohms and just overwork. is it safe to use both at the same time in the long run? Quote Link to comment Share on other sites More sharing options...
boa12 Posted December 4, 2001 Share Posted December 4, 2001 sam, from my denon research I remember some confusion from the manual that using A+B surrounds could be damaging. turned out that was just some confusing wording in the manual. verdict was A+B surround setting is fine but cuts the allocated power in half to each of the speakers. assume your speaks are 8 ohms so should be no problem there. hook 'em up & see how it works. if A+B was a problem why the H would they allow that setting for some or all modes. & don't worry 'bout the speaker cable guage shutting down your denon. i'd just use 16ga. or thicker myself. ------------------ My Home Systems Page Quote Link to comment Share on other sites More sharing options...
samuel r Posted December 4, 2001 Author Share Posted December 4, 2001 well thanks to both of you, lynnm and boa12. i kinda figured it had to be some mis-wording. when i was younger(early teens), i always experimented with my electronics. from taking apart, to litterally blowing up...not big explosions, but electrical blue light pops that made me realize i needed to unplug the receiver before operating under the cover. well, i also experimented with multiple speakers on stereo only receivers. those with a+b speaker settings. nothing ever happened. the reason i ask the question now is because those receivers never costed me $2000 and weren't digital. i'm older and wiser now and only repair what i know...simple circuitry trial and error 101.(just a joke) anyway, i did try the speakers all at once(a+ before i looked into the fine print on the denon4800 manual. i removed rear speaker "B" and never used them in conjunction again. just didn't want to ruin anything and i know i can't just go inside and start tinkering. but anyway, i will use them both again. i looked at the manual over and over and it states you can use them both. it just doesn't say anything about impedance. i would assume that denon is refering to 8 ohm speakers since that is the more common impedance on most home speakers. well thanks for your time guys. Quote Link to comment Share on other sites More sharing options...
dougdrake2 Posted December 5, 2001 Share Posted December 5, 2001 samuel - To answer your question, hooking a pair of speakers into A and another set into B appears to the Denon the same as hooking both pairs of speakers in parallel to the same set of outputs -- the effect is to present an impedance of about 1/2 the impedance of each speaker. So, your 8 ohm speakers appear to the Denon as 4 ohms when you have both A & B connected and functioning. The fact they are hooked to separate outputs merely gives you the ability to select either or both pairs. Doug ------------------ My System Quote Link to comment Share on other sites More sharing options...
IndyKlipschFan Posted December 5, 2001 Share Posted December 5, 2001 I think if your Denon is anything like my 3802 Denon unit, you should have separate amps for each channel so your fine. I believe this is also true in the a and b channels. This info would be in your manual, and the reason Denon is more expensive but that warm great sound should sing in your ears too. Enjoy!!!! Quote Link to comment Share on other sites More sharing options...
Mighty Favog Posted December 5, 2001 Share Posted December 5, 2001 I don't mean to be a stick in the mud but wouldn't running four speakers rather than two lower the volume level in which the amp(s) would start to clip? ------------------ Tom KLF-20 Mahogany (Cornell Hotwired) McIntosh C33 Preamp McIntosh MVP-841 CD/DVD Rotel RB-1080 Amp Yamaha PF-800 Turntable/ Sure V15 Type V Cartridge Ortofon VMS-30 mkII Cartridge Stanton 999SS Cartridge Yamaha K-1020 Cassette dbx 1231 EQ H.H. Scott 830z Analyzer Monster Interlink 400mk II Monster Interlink 300mk II Monster Video 2 (DVD to TV) Monster Power HTS-5000 MIT Terminator 2 Bi-Wire Speaker cables (and I do mean CABLES) Studio Tech U-48RW Cabinet Vibrapods Enough empty boxes for a fire hazard! Quote Link to comment Share on other sites More sharing options...
samuel r Posted December 5, 2001 Author Share Posted December 5, 2001 i understand now, but my question is somewhat like tblasing's as well. i don't think they would clip though since i'm using small wall speakers...if that matters. i think a larger speaker setup would probably make it clip before a smaller, less power handling one would. i have them set to "small" already. okay, i'm really gonna make it even clearer. i want to buy a pair of rs-3's. my existing cambridge soundworks speakers will remain in the speaker "A" input with the selector on "A" only. when i buy the rs-3's, i will hook them into the "B" input. i will then select both rear speaker pairs to run at once by choosing "A+B" on the selector. i guess that means the two pair of 8 ohm rear speakers will become two pair of 4 ohm speakers. so then i guess i should be okay since the rears won't be as loud as the mains and center and the receiver is supposed to be "torture tested" at high volume-low impedances. well, i'm gonna just do it. thanks all. Quote Link to comment Share on other sites More sharing options...
lynnm Posted December 5, 2001 Share Posted December 5, 2001 Let us know how it turns out. ------------------ It is meet to recall that the Great Green Heron rarely flies upside down in the moonlight - (Foo Ling ca. 1304 BCE) Quote Link to comment Share on other sites More sharing options...
boa12 Posted December 5, 2001 Share Posted December 5, 2001 sam, assuming u want to use 2 sets of surrounds for mostly for HT, u could connect the rs-3 as surrounds, get a lil 2 channel add on amp, & connect/place those cambridge as rear surround/effects. just a thought. ------------------ My Home Systems Page Quote Link to comment Share on other sites More sharing options...
ShapeShifter Posted December 6, 2001 Share Posted December 6, 2001 While saving up for a 5 channel amp, I used the method boa suggested, it worked great. Bought a used NAD 2 channel amp, connected surround pre-outs to it which powered Cornwall rears. Then connected the RS-3's to receivers rear surround speaker terminals. Having added additional amps, the NAD amp is now used in bridged mode to power my SVS sub via receivers LFE out. So an inexpensive 2 channel amp could power the additional rears, which would lessen the load on the receiver. Can have future uses should you upgrade later. Wes ------------------ "KLIPSCH IS MUSIC"f> This message has been edited by ShapeShifter on 12-06-2001 at 06:40 AM Quote Link to comment Share on other sites More sharing options...
boa12 Posted December 6, 2001 Share Posted December 6, 2001 yea or u could also get 1 of them newer 7 channel amps that many of em seem to be releasing. outlaw has or soon will have one out i believe. as usual $ky's the limit ------------------ My Home Systems Page This message has been edited by boa12 on 12-06-2001 at 11:25 AM Quote Link to comment Share on other sites More sharing options...
toddvj Posted December 6, 2001 Share Posted December 6, 2001 I agree with boa12. You have a receiver with 7.1 capablility, why not use it. The A and B surrounds are made for different types of material (A for dipoles for HT, B for Direct Radiating Speakers for Music.) If you use both, all you're doing is doubling up. If you use the preamp outs you are getting more seperation. One cool thing with your receiver is that you can assign the amps, so if you get more than just a cheap 2 channel amp, you can use if for your fronts and let your receiver control the surround backs! Quote Link to comment Share on other sites More sharing options...
Mike Lindsey Posted December 6, 2001 Share Posted December 6, 2001 I have the 4800 and now wonder if I am doing something wrong. I have an Acurus A200X3 connected via the pre-outs (FL, C, FR) of my 4800. I then have my Chorus I's connected to the Surround A posts and then my RS-3's connected to the SB-L and SB-R posts. On the 4800, I have all my speakers (Surround B set to None) set to Small w/Subwoofer. I have the THX-EX feature set to ON (as opposed to Auto) and have the Power Amp Assignment set to Center/Surround/Surround Back. Is this correct? When I select DTS or THX from the 4800, is it recognizing the ES or EX input and turning on the surround back speakers? I don't have any movies with that format yet... Thanks in advance, Mike ------------------ My Music Systems Quote Link to comment Share on other sites More sharing options...
boa12 Posted December 6, 2001 Share Posted December 6, 2001 yea mike u want that Center/Surround/Surround Back setting. then u connect the surr back speaks to the fronts terminals. i think u have the acurus A200X3 so of course u connect those 3 speaks in front to that & run those respective preouts from 4800 to acurus (which u probably have done no? ) can't u set it up so that u get the surr backs to play w/ other HT, not just es & ex? ------------------ My Home Systems Page Quote Link to comment Share on other sites More sharing options...
Mike Lindsey Posted December 6, 2001 Share Posted December 6, 2001 Thanks for the reply, boa! The SB-L and SB-R speaker connections are the same posts as the FL and FR - to be used when you are using a separate amp to drive the mains. One thing I'm curious about is what is driving my center? I'm using the pre-out to the Acurus but on the amp assignment, I selected Center/Surround/Surround Back. Does it ignore the Center amplification from the Denon if I'm using the pre-out to the Acurus? As for hearing anything from these speakers (SBL/SBR), it's almost impossible since they are like 9 feet high up on my wall. When I put my hand to them, I can feel something, however. Within the next couple of weeks, I plan on moving them down the wall to about 5-6 high. I'll let you know what I come up with... Mike ------------------ My Music Systems Quote Link to comment Share on other sites More sharing options...
boa12 Posted December 6, 2001 Share Posted December 6, 2001 though the center is designated on that setting mike, u shouldn't get any real load on the denon amp from the center if u don't have anything connected to the denon ctr speak terminals. somebody else could answer how much that relieves the denon amp (or is it amps). i'm not hands on here. i just looked heavily at the denons a while back, especially that 4802 ------------------ My Home Systems Page Quote Link to comment Share on other sites More sharing options...
ShapeShifter Posted December 6, 2001 Share Posted December 6, 2001 Still with 5.1 receiver, so not familiar with any 6.1/7.1 receivers operation and output. But the most significant thing I noticed and felt with my receiver was a drop in operating temperature after adding the out board amps. The only load it presently has is the additional RS-3's in rear. Decreasing operating temperature at a minimum should add to life expectancy. Wes ------------------ "KLIPSCH IS MUSIC"f> Quote Link to comment Share on other sites More sharing options...
samuel r Posted December 6, 2001 Author Share Posted December 6, 2001 well thanks guys. i am planning on purchasing the poa5200 two channel amp from denon for the surround backs. just to relieve some confusion, the 4800 is only 5.1. a seperate amp(poa5200) must be added to it for the 6/7.1 channel es/ex. the guys who have the setup for center/surround/surround backs on the receiver are doing the right thing. i will be using that same setup. mike lindsey, since you have the three channel setup for front soundstage, and the ex set to "on", the receiver will automatically go to "ex" and the surround back speakers will go on. although you don't have the dvd's with that format, the surround backs will still kick in. the receiver will take some of the sound from the rears and "matrix" it to the surround backs and give it a fuller sound. when you get a rare dvd with ex/es encoded sound, you will really hear the surround backs kick in. check out www.dtsonline.com and you will find any dts-es movie available. they are also having a clearance sale on dvd's and dts encoded cd's that are dirt cheap. anyway, thanks again for all the helpful input. by the way, you could see my setup under the "odds and mods" section. just look for samuel r's denon/klipsch setup. there have been some mods since then. the power strip has been replaced with an hts1000 line conditioner that just makes a world of difference...especially for video. the speaker wires are all now monster cable mcx-is bi-wire, and the playstation2 has been replaced by the awesome(and i mean awesome) xbox. well, thanks again. Quote Link to comment Share on other sites More sharing options...
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