Impedence Question

[Mark of Cenla]

I e-mailed a question to Sony Style, and I do not agree with thier answer. So I want some of you tech guys to help me out. I have Boston Acoustic T1000 tower speakers that I am very happy with. They are rated at 4 ohms due to the two 8" woofers. I asked about using them with Sony's current stereo (non-home-theater) receiver. They recommend 8 ohm to 16 ohm speakers. The receiver is capable of playing two pairs of speakers at the same time.

To the best of my knowledge, when an amp is driving two pairs of 8ohm speakers in parallel, the impedence drops to 4 ohms. So if it can work with that 4 ohm situation, it should work with my 4 ohm situation as long as I never connect another pair of speakers.

Sony recommends 8 ohms to 16 ohms so that the impedence will not drop too low in the event that two pairs of speakers are playing at the same time.

Am I wrong?

 

[mtrycrafts]

I e-mailed a question to Sony Style, and I do not agree with thier answer. So I want some of you tech guys to help me out. I have Boston Acoustic T1000 tower speakers that I am very happy with. They are rated at 4 ohms due to the two 8" woofers. I asked about using them with Sony's current stereo (non-home-theater) receiver. They recommend 8 ohm to 16 ohm speakers. The receiver is capable of playing two pairs of speakers at the same time.

To the best of my knowledge, when an amp is driving two pairs of 8ohm speakers in parallel, the impedence drops to 4 ohms. So if it can work with that 4 ohm situation, it should work with my 4 ohm situation as long as I never connect another pair of speakers.

Sony recommends 8 ohms to 16 ohms so that the impedence will not drop too low in the event that two pairs of speakers are playing at the same time.

Am I wrong?

Well, just beacuse the Sony can play two pairs doesn't mean that internally the speakers are wired in parallel. It could be series to comply with the ratings. But we don't know until looking at how it is wired or the manual explains it how it is wired.

However, the Sony may be able to drive the 4 ohms if you don't demand loud playing.

 

[Mark of Cenla]

If they are wired in series, you could not play only one pair of speakers because there would not be a complete circuit.

 

[Mark of Cenla]

I just looked at the owner's manual online. Speaker A and speaker B are indeed wired up in parallel.

Is there anyone out there who can tell me one way or the other if I am right or wrong?

 

[Unregistered]

You should have no problems operating the unit with 4 Ohm speakers. The unit will have to supply more current to produce the same power levels, so you need to make sure you provide plenty of ventilation.

I have an old Sony ES receiver which has always worked fine with my 4 Ohm speakers. It had it's A+B speakers wired in series.

 

[mtrycrafts]

It had it's A+B speakers wired in series.

Some are in series, others in parallel
That is what I tried to pass on

 

[av_phile]

I e-mailed a question to Sony Style, and I do not agree with thier answer. So I want some of you tech guys to help me out. I have Boston Acoustic T1000 tower speakers that I am very happy with. They are rated at 4 ohms due to the two 8" woofers. I asked about using them with Sony's current stereo (non-home-theater) receiver. They recommend 8 ohm to 16 ohm speakers. The receiver is capable of playing two pairs of speakers at the same time.

To the best of my knowledge, when an amp is driving two pairs of 8ohm speakers in parallel, the impedence drops to 4 ohms. So if it can work with that 4 ohm situation, it should work with my 4 ohm situation as long as I never connect another pair of speakers.

Sony recommends 8 ohms to 16 ohms so that the impedence will not drop too low in the event that two pairs of speakers are playing at the same time.

Am I wrong?

If your amp has A, B and A+B selection, meaning it can handle two pairs of speakers rated at 8 ohms each, then I think your amp can handle a single set of 4-ohm loads. But only a single set. Some amps I know only have A OR B selection, not both. Some have A+B but can only be in series or have internal voltage dividing networks or current limiting networks to maintain the 8ohm load as seen by the amp. Many separate power amps whose user manuals explicitly indicate power ratings into 2, 4 and 8 ohms would have little problem driving very low loads.

 

[annunaki]

If you intend to run 4 ohm speakers on the Sony make sure it is very well ventilated. The receiver will generate much more heat and it needs to be dissipated.

For instance, I had a customer with a Sony surround receiver (895-885-875??), running 6 ohm polk speakers on the front 3 channels, and 8 ohm MTX in-ceiling speakers on the rears. With the receiver in a cabinet (no doors, 6 inches of space on top, 4 inches on the sides), it would go into thermal protection after only 10 minutes at a moderate volume (not even close to reference level). The receiver also had it's 4/8 ohm switch in the 4 ohm position, for loads between 4 and 8 ohms, as stated in the manual. All connections and hook ups were verified to be in proper order. The house had a full HVAC system, and the ambient temperature was regulated at 70 degrees. The system needed a fan to keep the receiver from going into protection.