What type of amp for 16ohm ATC SM75-150


2013-05-10 4:11 pm
Darwin is right. Any transistor, and any tube amp should be able to handle that. The only exceptions would be if the speaker had an unusually high impedance peak (50 Ohms or more) which could cause a tube amp some heart burn which would be very unusual in a loudspeaker.


Thanks for the replies Darwin, Erik.
ATC rates their mid as 75 watts "normal power rating" so I will be looking for a 150watt into 8 ohm amp.
I think I have read that D class amps have better figures (distortion) into 4 rather than 8 ohms, so I assume that the figures get worse for a 16 ohm load.
I see D class amps used for low frequency use, subwoofers, but not for 16 ohm duties.
I like the D class amps because of their thermal/efficiency, but should I be concerned that they are not a good match for the ATC?
Anyone have figures of D class amps under this load?
ClassD would be a great choice for driving 16ohms but perhaps the output filter would need modification to suit the higher impedance. Its likely to be under-damped otherwise and hence ring, though the ringing is going to be well beyond the passband of your mid.

I'd be surprised if classD's distortion was worse into higher impedances - all the amps I've ever seen do better into high than low impedances.
An IRS2092 with 200w should drive this cleanly - perhaps a slight mod to the output inductor might help but I have driven 16ohm speakers with my nominal 8ohm class D amp and did not hear or measure anything offensive distortion wise.

This for example is 0.007%THD at 60w for 4ohm. This amp is probably good for 100w at 16ohm.

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