How will a 2-way speaker switch affect impedance?

 

New member
Username: Tugunkid

Post Number: 3
Registered: Apr-07
I would like to add a second set of speakers to my NAD 3225PE amp. The amp has 4 & 8 ohm switchable impedance as do the current speakers. Impedance of second speakers is unknown but most likely 8 ohm.

The (Crest) speaker selector has impedance matching allowing any combination of speakers separately, or all four on together with the minimum impedence seen by the amp being 4ohm. (Based on using 8ohm speakers).

Does this mean impedance is 4 ohm when using both A & B speakers. It will be rare that I use A & B at same time. Am I risking the amp if keeping amp impedance at 8 ohms when using both A & B speakers?

Thanks
 

Platinum Member
Username: Jan_b_vigne

Dallas, TX

Post Number: 10155
Registered: May-04
.

How is "impedance matching" achieved with this switch box? Autoformers or a load resistor?
 

Platinum Member
Username: Jan_b_vigne

Dallas, TX

Post Number: 10156
Registered: May-04
.


https://www.ecoustics.com/electronics/forum/home-audio/342822.html
 

New member
Username: Tugunkid

Post Number: 5
Registered: Apr-07
Jan, as a new member my forum etiquette is poor. Have posted this message on the original string re: affect of sub on impedance also, as I wasn't sure if I would catch you on this one.

To answer your question I don't know how the matching is achieved and would have to ask the supplier.

Adam
 

Platinum Member
Username: Jan_b_vigne

Dallas, TX

Post Number: 10158
Registered: May-04
.

No, you won't be risking the amplifier, but if it runs very hot when both pair are connected, I would consider my options.
 

New member
Username: Tugunkid

Post Number: 6
Registered: Apr-07
Jan, the only technical info the the supplier could give was the wiring of the switch is such that the load presented to the amp will not fall below half the impedance of the speakers used, or 220 ohms with no speakers connected.

I am not really sure where this leaves me or whether I should choose 4 or 8 ohms on the amp considering I will mostly be presenting 8 ohms to the switch using one set of speakers.
 

Platinum Member
Username: Jan_b_vigne

Dallas, TX

Post Number: 10163
Registered: May-04
.

Use the eight Ohm setting and just make sure the amp doesn't begin to run hot. If you have the switch box, just open the lid. If it has autoformers inside, they will be clearly visible.
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