Rythmik F15HP B-stock for $1040

[Steve81]

This is a different animal - I think you have to figure the effect of the servo!

The servo will help to compensate for compression, but the original statement isn't altogether wrong: it's a matter of EQ and power to shape the curve. The servo just helps to maintain that curve up until you run out of juice.

I don't know how much better 15" with their high power option - 600Watts RMS with 4x63V/18000uF (Panasonic) caps - would be at greater SPL before compression.

If I were to take an offhand guess, I think the performance window for maximum output capability would be somewhere in the neighborhood of the PB13U in sealed mode, and it is unlikely to exceed the DD18+, especially down low. Worth noting, the PB12-NSD is at rough parity with the DD18+ at 20Hz per the CEA2010 test protocol, which really highlights the efficiency of a ported design. Obviously the DD18 dominates the PB12 everywhere else.

 

[slipperybidness]

Played around a little last night. Turned off the rumble filter, bumped up the volume a bit, WOW.

Definitely a beast. I have yet to play around with defeating the limiter or the PEQ, or messed with the damping settings etc. Taking a day off work maybe this week and next, so that will give me some time to mess with it without the GF complaining about shaking the walls

 

[KEW]

The servo will help to compensate for compression, but the original statement isn't altogether wrong: it's a matter of EQ and power to shape the curve. The servo just helps to maintain that curve up until you run out of juice.

Maybe, but I don't know of any other 12" sealed sub near the F12's $935 (shipped) price bracket that can legitimately claim 14Hz low extension. This sub is +/-4dB down to 11Hz!
If you are not so much worried about max SPL, what other sealed sub can mimic the F12's FR curve at 90-95dB (below where power compression becomes a factor).
I guess I see the Rythmiks as not playing by the normal rules; and thus, a different animal. There is really no knee in the curve until you hit power compression effects!

Here is SVS's own FR curve the $1600 SB13-Ultra which is a very well designed (but non-servo) sealed sub sporting 1000Watts RMS:

 

[Steve81]

FWIW, AFAIK, the SB13 doesn't utilize much , if any EQ to boost the low end to make it more suitable for use in smaller rooms where room gain will naturally boost the response anyway. I'd also guess this might be why you don't see many subs quite like the Rythmik: you're usually not utilizing such subs in very large rooms with minimal gain, so there isn't much reason to design them for flat response into the teens.

 

[KEW]

I am getting a pair of F12G's for music only. I will permanently engage the 20Hz rumble filter (unless I move them into HT use down the road).
Do you have any idea if this would free up power so the 100dB curve would avoid power compression down to 20Hz. It makes sense that the rumble filter will free up power (as when crossing to a sub from a bookshelf speaker).

 

[Steve81]

I am getting a pair of F12G's for music only. I will permanently engage the 20Hz rumble filter (unless I move them into HT use down the road).
Do you have any idea if this would free up power so the 100dB curve would avoid power compression down to 20Hz. It makes sense that the rumble filter will free up power (as when crossing to a sub from a bookshelf speaker).

If I understand what you're saying, I don't believe utilizing the rumble filter will allow it to deliver any more output in a sine sweep like what Ilkka did above the 20Hz mark. Think of it like playing a 1kHz sine tone through a speaker; it's not going to matter if its crossed at 80Hz or not, it will reach its output limit at the same point regardless. However, when you introduce real world content, with the filter engaged there won't be as much amplifier power and driver excursion wasted on content below 20Hz.

 

[Steve81]

PS: Just a general FYI, it's not so much an issue of power compression with Ilkka's curves, which the servo will try to fight through with additional amplifier power; the amplifier has simply hit its limit.

General Audio FAQ

What is "power compression"? Speaker voice coils are made of copper or aluminum. As these voice coils increase in temperature during normal operation, the DC resistance of the voice coil increases. Greater voice coil resistance means less power transfer from the amplifier. As a result, the speaker will not play as loud when it's "warmed up" as it did when it was "cold".

 

[KEW]

Thanks for the education/clarifications!

 

[Steve81]

As always, glad to be of some use Half the fun of this hobby (for me at least) is sharing what I know.