Three very different amps. Which to choose?

[terryforsythe]

I dont have room for a sub bigger that 12" on th left.

So, do I get one larger sub on the right 15-18" or two 12" subs?

Are you going to be listening from a single position or over a wide area? I got a fairly decent response with my single 26 year old 18" subwoofer at the listening position, but as others have said multiple subs probably are better over a wide area. In that regard, I have seen recommendations to use at least three subwoofers spaced around the room, and at different heights, to achieve the best results. Anyway, here is what I got with my single subwoofer at my listening position, tuned to the Harman Curve:

 

[YSDR]

View attachment 361793

The question is, can the F208 withstand 322W (or 350W according to the factory data) even in the short term?

The answer is:

According to the Unibox simulation (with passive filters, like the F208 have) of 2x SB23NBACS45-8, it's not. More precisely it depends on the frequency as we can see, but that just the mechanical part of the story. The red line is the mathematical linear excursion of the woofers, the mechanical excursion limit of a typical hifi woofer usually didn't extend to 2x of the xmax so there is a possibility that even with 120W input (the combined rated power handling of 2 pieces of SB23NBACS45-8) , the voice coils of the woofers would hit the pole piece or jump out of the gap. Unfortunately there is no data for the mechanical limits of this woofer, but if it's not a typical woofer, they may can survive 120 of low frequency input Watts at and above the vent tuning frequency in the F208.
In real world, there is another possible scenario, where the woofers don't want to move further (because of force factor loss or suspension stiffening caused by the large excursion), so the voice coil don't hit the pole piece and will survive (if didn't burnt down already), but that would lead to high distortion and several dB compression.

 

[Blumlein 88]

The question is, can the F208 withstand 322W (or 350W according to the factory data) even in the short term?

The answer is:
View attachment 361927View attachment 361928
According to the Unibox simulation (with passive filters, like the F208 have) of 2x SB23NBACS45-8, it's not. More precisely it depends on the frequency as we can see, but that just the mechanical part of the story. The red line is the mathematical linear excursion of the woofers, the mechanical excursion limit of a typical hifi woofer usually didn't extend to 2x of the xmax so there is a possibility that even with 120W input (the combined rated power handling of 2 pieces of SB23NBACS45-8) , the voice coils of the woofers would hit the pole piece or jump out of the gap. Unfortunately there is no data for the mechanical limits of this woofer, but if it's not a typical woofer, they may can survive 120 of low frequency input Watts at and above the vent tuning frequency in the F208.
In real world, there is another possible scenario, where the woofers don't want to move further (because of force factor loss or suspension stiffening caused by the large excursion), so the voice coil don't hit the pole piece and will survive (if didn't burnt down already), but that would lead to high distortion and several dB compression.

Well I have a 250 wpc @ 8 ohm amp on mine and at the lower impedance it would be over 500 wpc. Mine haven't blown the woofers out yet. So they get loud enough I've not turned it up enough to blow anything up.

 

[Chrispy]

The question is, can the F208 withstand 322W (or 350W according to the factory data) even in the short term?

The answer is:
View attachment 361927View attachment 361928
According to the Unibox simulation (with passive filters, like the F208 have) of 2x SB23NBACS45-8, it's not. More precisely it depends on the frequency as we can see, but that just the mechanical part of the story. The red line is the mathematical linear excursion of the woofers, the mechanical excursion limit of a typical hifi woofer usually didn't extend to 2x of the xmax so there is a possibility that even with 120W input (the combined rated power handling of 2 pieces of SB23NBACS45-8) , the voice coils of the woofers would hit the pole piece or jump out of the gap. Unfortunately there is no data for the mechanical limits of this woofer, but if it's not a typical woofer, they may can survive 120 of low frequency input Watts at and above the vent tuning frequency in the F208.
In real world, there is another possible scenario, where the woofers don't want to move further (because of force factor loss or suspension stiffening caused by the large excursion), so the voice coil don't hit the pole piece and will survive (if didn't burnt down already), but that would lead to high distortion and several dB compression.

Would you expect anyone to be putting that much continuous power into such speakers in the first place?

 

[YSDR]

Would you expect anyone to be putting that much continuous power into such speakers in the first place?

Not necessarily, but we can never know. Like a previous poster showed us the calculation result of 322 Watts for this speaker. Why?

 

[Worth Davis]

I dont have room for a sub bigger that 12" on th left.

So, do I get one larger sub on the right 15-18" or two 12" subs?

I prefer dual subs, 2 12s