Poleelop Posted October 4, 2002 Share Posted October 4, 2002 Okay, I'm rearranging stereo's in my house to make way for my new system, and I'm thinking about putting two pairs of bookshelf speakers in one room to appease my wife. These bookshelves are rated "4 to 8" ohms which seems a little ambiguous to me. Is that normal? Regardless, I want to hook these speakers up in tandem and run two of them together each (pair) to one channel of an old amp I have. What is the best way to do this? Electrical-wise, I'm a dummy. I remember something about wiring in series or parallel, but I don't remember which is which and which does what. I'm sure this is a neophyte question, but throw me a bone here. Thanks in advance Quote Link to comment Share on other sites More sharing options...
Deang Posted October 4, 2002 Share Posted October 4, 2002 The impedance spec is wishy washy for sure. If you wire directly to the amp with both sets, you could end up overheating the amp if the speakers are both closer to 4 ohm. That would be "parallel" wiring. To wire "in series", hook one pair up the amp as you normally would, and then wire the other set to the terminals of the first set. Quote Link to comment Share on other sites More sharing options...
lynnm Posted October 4, 2002 Share Posted October 4, 2002 If two speakers are run in series: +Amp ->+Speaker1 -Speaker1 -> +Speaker2 -Speaker2 -> Amp the result will be that the impedance presented to the amp will be additive. In other words 2 8 ohm speakers in series will be seen by the amp as a 16 ohm load. In a parallel arrangement: +Amp ->+Speaker 1 and +Speaker2 -Amp -> -Speaker1 and - Speaker2 the effective impedance will be halved. In other words 2 8 ohm speakers in parallel will be seen by the amp as a 4 ohm load. The math: Series Resistance Rt = R1+R2 { 8+8 =16} Parallel Resistance Rt = (R1 X R2)/(R1 + R2) { 8 X 8} / {8 + 8} = 64/16 = 4 You have to bear in mind that the impedance for a speaker is a nominal value based on the impedance measured at some frequency,(1 Khz?), and will vary considerably depending on the frequency fed to the speaker. A potential gotcha is that an 8 ohm speaker may under some conditions get down as low as 2 ohms in which case the overall impedance could drop as low as 1 ohm which for many amplifiers would be seen as a direct short and cause protection circuits to kick in and in some case burn out transistors. A tube amp might be somewhat hardier in that case but the output transformers would not be real happy about being subjected to that condition for very long. My recommendation would be if you insist on going with 2 speakers per channel - wire them in series. Quote Link to comment Share on other sites More sharing options...
Clipped and Shorn Posted October 4, 2002 Share Posted October 4, 2002 I have a Rotel Speaker Selector RS-900 with one "Direct" switch and 5 other switches. This unit seems to allow hooking up a lot of combinations of speakers, sometimes I have them all on at the same time. Supposedly this alleviates the strain on the amp. Anyone know how and why these things work electronically? -c7s Quote Link to comment Share on other sites More sharing options...
dougdrake Posted October 4, 2002 Share Posted October 4, 2002 And because I love to overstate the obvious, I just wanted to point out that lynnm has included the + and - signs so that you connect them correctly. + from amp to + of speaker 1, then - of speaker 1 to + of speaker 2, then - of speaker 2 to - of amp. That will give you a series connection. DD Quote Link to comment Share on other sites More sharing options...
Deang Posted October 4, 2002 Share Posted October 4, 2002 You actually wire them out of phase in relationship to the first set? Uh...I never did it that way. Hmmm. Quote Link to comment Share on other sites More sharing options...
Poleelop Posted October 4, 2002 Author Share Posted October 4, 2002 If I'm understanding this then deang, you were wiring them in parallel when you thought you were wiring them in series. ....because really, wiring from the -amp to -speaker 1, and then from -speaker 1 to -speaker 2 is the same as taking two wires from -amp, one of them going to -speaker 1 and the other going to -speaker 2. I think I'll go with series if I'm gonna try this. Ultimately, I'd rather risk the speakers than the amp. I hooked it up to my forte's last night with my new Sony SCDC555ES, and really, it sounded pretty good. Quote Link to comment Share on other sites More sharing options...
dougdrake Posted October 4, 2002 Share Posted October 4, 2002 ---------------- On 10/4/2002 2:59:00 PM deang wrote: You actually wire them out of phase in relationship to the first set? Uh...I never did it that way. Hmmm. ---------------- I believe they would be in phase, because we are only dealing with one channel of the amp, and one signal. It follows one straight path all the way out to the last speaker (2 in this case), then makes a home run from the - terminal of the last speaker back to the amp. (I can't 'splain it very well...). Quote Link to comment Share on other sites More sharing options...
Deang Posted October 5, 2002 Share Posted October 5, 2002 No, I had it right - I just thought you wire the positive of the second set of speakers to the positive of the first set, and like-wise for the negative (negative to negative). I see you got the 555es. Ain't it sweet? Hardcore audiophiles love to split hairs -- but the ES Sony machines sound very good. Quote Link to comment Share on other sites More sharing options...
DizRotus Posted October 5, 2002 Share Posted October 5, 2002 deang No! Sorry to say that you got it wrong on both counts. The wiring arrangements you described are both parallel. The series arrangement that was described correctly by lynnm is in phase. By connecting the neg. terminal of speaker 1 to the pos. terminal of speaker 2, phase is preserved. Each speaker has its pos. terminal fed by the pos. output from the amp. Quote Link to comment Share on other sites More sharing options...
Deang Posted October 5, 2002 Share Posted October 5, 2002 Yes, you are correct. I'm pathetic. In "series" is the loop bit. I'd completely forgotten about that. Yep, both my ways are in "parallel". It does save on speaker cable though:) Quote Link to comment Share on other sites More sharing options...
DizRotus Posted October 5, 2002 Share Posted October 5, 2002 deang Don't feel bad. If I don't draw things out I can never get the VCR, TV, DVD, etc. re-connected properly. Something about a continuing series in a parallel universe. Quote Link to comment Share on other sites More sharing options...
JoeC Posted November 16, 2003 Share Posted November 16, 2003 If the second pair of speakers are wired in parallel but also have a volume control inserted between the speakers and the amp will that help reduce the chance of overload to the amp? I have an acurus 100 wall amp; the main speakers are 6 ohm nominal and the second set wall speakers are 8 ohm nominal. What else does wiring in series do to the sound? The apparent level? And would the volume control still work or does it also add resistance? Quote Link to comment Share on other sites More sharing options...
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