4 ohm speakers on 8 ohm receiver?

benmac12

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Feb 5, 2016
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newbie - I have a 200 watt 2 ch receiver that has a 8 ohm impedance. I wanted to use with 2 sets of speakers (2 different rooms). Concern is that one pair (A set KLH 970A) is listed as 4-6ohms/5-50 watts recommended power) . The 2nd set of speakers is ('B' set Architech AP-602). is listed at 8 ohms/50watt-140max. Concern is with the 4-6 ohm pair not matching up to the 8ohm receiver. Am I taking a chance of ruining the 'new' 200w 2 ch receiver by trying to use the 4-6ohm KLH speakers? On line searches have me suspecting I would be ahead of the game by replacing the KLH with a set of 8ohm speakers but would appreciate any advice - thanks in advance!!
 

kanewolf

Splendid
Moderator
You do run the risk of damaging the new amp with speakers that are too low in impedance. They will allow too much current to flow which can damage the amp.
How you wire these 4 speakers will also have an impact. What is your plan? You didn't list the amp so I can't see what it has for connections.
 

benmac12

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Feb 5, 2016
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So the 'old' amp I am replacing and the 'new' amp have A & B speaker inputs and up until right now, all 4 speakers have been traditionally wired ( + & - on each speaker to red & black on amp). I did stumble into possibly wiring the 'A' (4=6 ohm) set of speakers in a 'series'
(#1 of A set has negative going to #2 of A set positive ; #1 of A set positive direct to amp; #2 speaker negative direct to amp). - am I understanding tha correctly? It would increase the impedance on the 4-6 ohm to at least an 8ohm? Not quite sure I can reach those wires as going through some walls.

Fessing up, big reason I am replacing the 'old' amp is that after system played for a bit, both the A & B set of speakers would experience a 'blip' or disconnect anywhere from a few seconds to a few minutes, but would then return to normal. Seems as if the disconnect would only affect the 'left' speaker of each set.

Base on your response, I guess it is quite likely that I damaged the 'old' amp as speaker wiring was traditional.

Bottom line - do you think I should just avoid messing with the series wiring and just replace the 'A' (4-6 ohm) set of speakers? I don't want to run the risk of damaging the 'new' amp --

You don't know how much I appreciate your help in this -- floundering for last few days hesitant to hook up new amp.for fear of having same disconnect, now I am happy I waited.

 
If your amp is saying 8 ohms, and nothing on fine print is saying it can handle lower, then whatever you do, DO NOT make it see less than 8 ohms. 12 ohms is fine, 16 ohms is fine.

One of my amps says if using A+B, must make sure when both connected and enabled, the total ohms is 8, what that tells you is, they are connecting both A+B in parallel and if you use TWO 8 ohms that way, the total impedance is 4 ohms, which the manual says you DON'T.

BUT you can also connect them in SERIAL, that configuration gives you 16 ohms and acceptable but you get lower volume, that's the price you pay:

AMP(-)----------(-)SPEAKER1(+)----------(-)SPEAKER2(+)--------AMP(+).
 

benmac12

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Feb 5, 2016
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So the receiver (200 watt 2 Ch with connections for an A and a B set of speakers) booklet shows: Power Output: Stereo mode, 8 Ohms, THD 1%, 40Hz-20kHz; 2x100 W
Can I just serial wire the set of 4-6 Ohm speakers, connected to the A on receiver and leave the set of 8 Ohm speakers which is connected to the B ? Also assume if A wired serial and B wired paralleled, can I (at times) just play the A or just the B (ie just play music in 1 room) ? Truly appreciate your help!
 
On receivers that cannot handle a 4 ohm load the A+B position puts the speakers in series to prevent damage.
If the receiver can handle 4 ohms then it would put them in parallel to provide greater power.
You can add an outboard speaker selector with impedance matching to maintain an 8 ohm load to the receiver.
You can also use an impedance matching volume control for each pair. These allow you to set the impedance that the receiver sees as well as allowing control of the volume of each pair. Might be useful to do that when you run both pairs together.
 

benmac12

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Feb 5, 2016
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Insignia NS-STR514 - appreciate your patience.
 

benmac12

Estimable
Feb 5, 2016
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Americanaudiophile - Thanks so much for your help! I am just looking for reassurance tha tif I connect the A set of speakers (which are listed at 4-6 ohms) in series, I can terminate them to the A connection on the receiver while the B connection on the receiver will have a 2nd set of speakers that are traditionally wired (ie +speaker-+amp; - speaker to - amp on both left/right speakers). Will having one set (2 speakers) of speakers wired in 'serial' and the 2nd set of speakers wired 'traditional' cause any harm (or likely to cause) any harm to receiver? OR would I be much better off just replacing the set of speakers with the lower (4-6) ohm rating? Not really looking to maximize output. Sorry if I appear thick headed, I am sure my use of terminology may be confusing things.
 
You can't connect 2 speakers in series and get stereo. The diagram that jsmithepa posts is for a single channel not a pair.
You could hook both lefts in series and both rights in series then connect them to the same A speaker terminals. That would raise the impedance to 12-14 ohms which is safe for a receiver with an 8 ohm minimum.
Both pairs would have to play all the time. It would degrade the bass quality of both pairs.
Get an impedance matching speaker selector or get 8 ohm speakers to replace the 4-6 ohm pair.
 
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