Rythmik Audio F15HP Subwoofer Preview

Steve81

Steve81

Audioholics Five-0
The Rythmik F15HP is a medium sized subwoofer boasting a 15" servo controlled aluminum driver and 600W RMS class H amplifier in a sealed enclosure. Priced at $1,224 in either matte black or a black oak vinyl finish, and $1,399 in piano black, Rythmik claims a frequency response of 14Hz-200Hz (-2dB @ 14Hz), which is rather impressive on the face of things. So how does the smaller sealed brother of the overachieving FV15HP stack up in the brutally competitive world of ID subwoofers? Read on to see my thoughts.



Executive Overview

Rythmik is a company with some history of delivering true high value products; the FV15HP reviewed here at Audioholics and also measured by Josh Ricci is an absolute beast considering its modest cost. Utilizing the same driver/amplifier combination as its bigger brother, the F15HP would appear to have the components necessary to deliver considerable output in a smaller package. Measuring at 19" H x 19" W x 21.5" D (with grill), the F15HP isn't exactly what most would qualify as truly compact, but it is usefully smaller than its larger ported brother, and coupled with the optional piano black finish, shouldn't have too much trouble passing the WAF test.

Moving on to performance related subjects, the F15HP utilizes Rythmik's in house DS1510, a 15" driver with an aluminum cone and sensing coil for use in their servo system. A quick visual inspection of the driver reveals a healthy looking motor structure and a beefy surround, which suggest big output. Shooting a query off to Brian Ding at Rythmik, I was able to find that the driver has a useful xmax of 25mm (defined as the 10% THD point at Fs, aided by the servo mechanism), and an xmech of 35mm. It's also worth noting that the DS1510 driver is a soft bottom design, i.e. the driver is constructed such that you cannot physically bottom out the driver and cause damage. Overall, these numbers mean that the DS1510 is capable of relatively high displacement, necessary for producing prodigious deep bass output. This is doubly important in a sealed design, as the F15HP's driver will receive no augmentation from ports.

Rythmik's H600PEQ3 servo amplifier is the other side of the performance equation. Rated at 600W RMS, the H600PEQ3 is a fairly efficient class H design which boasts a massive toroidal transformer; I'd opine that Rythmik might consider a transparent acrylic cabinet as an option some day for those that are into the visual stimulation the heavy duty parts provide. Of course, the amplifier also contains Rythmik's secret sauce, their patented servo mechanism. Rythmik claims this reduces memory effects and counteracts thermal compression and other non-linear behavior; judging by the FV15HP's measurements, the system works quite well. To see the servo in action, you simply need to look at the long term power compression sweeps (specifically the compression magnitude) performed by Josh Ricci. Simply put, the servo mechanism allows Rythmik subwoofers to hold their response shape tightly up to the design limits.

So what about actual performance? Can the F15HP really deliver 14Hz @ -2dB? Yes and no. Depending on the settings you choose on the amplifier, response can be extended down to 14Hz; however, as output levels rise, even the heavy duty DS1510 driver will run out of useful excursion far sooner at 14Hz than it will at say 40Hz. Of course, this isn't meant to take away from what the F15HP can do; it's quite likely that from 50Hz on up, the "compact" sealed Rythmik can keep up with the extreme output capability of its bigger brother. Of course, as you go down in frequency, the small sealed cabinet will take its toll, and Rythmik suggests that the F15HP will deliver about 5dB less at 20Hz versus the bigger ported FV15HP. In plain English, the F15HP can deliver a heck of a lot of output, though it would be best suited to a small or medium sized space where room gain can help lift the bottom end of its response curve.

Summary

Overall, I would wager that Rythmik has an exceptional value on their hands with the F15HP. The high excursion capability of the DS1510 coupled with Rythmik's servo controlled 600W RMS amplifier should equate to powerful, high fidelity output. Further, the smaller sealed cabinet should be a boon for those who might not be able to slip a huge ported subwoofer into their living room. The change in enclosure of course comes with some tradeoffs; for example, you can't expect as much output at 20Hz from the F15HP as you can from its big brother. Still, if you've got a small to medium sized space to fill, it's quite conceivable that the F15HP will deliver strong linear response down to 20Hz and below. Considering the cost, the F15HP looks to be a solid value.

So what do you guys think? Anybody own one (or two?) of these puppies? Any interest in a review from Josh?

F15HP Driver.jpgF15HP Grill.jpg
Quick Specs

Driver: DS1510 15" high excursion with custom sensing coil
Amplifier: 600 RMS class H patented servo controlled
Frequency Response: 14 - 200 Hz (-2 dB @ 14 Hz) with LFE inputs; 14 - 90 Hz with LINE IN
Dimensions: 19"(W) x 19 " (H )x 20 "(D) - (21-1/2" D with grille)
Shipping Weight: 108 lbs
Warranty: 5 years warranty on driver and 2 years on electronics
 
slipperybidness

slipperybidness

Audioholic Warlord
I got one in a rather large room (open floor plan).

This was the largest dimensions of a sub that would fit my space.

Got it as B-stock with just a slight nick at the back edge (Rythmik does not have B-stock very often).

I don't have a lot to compare it to, but I can attest that it is a solid performer. Brian was very friendly and I think he really enjoys his work. This is obviously a fairly small operation.
 
S

shadyJ

Speaker of the House
Staff member
That is one gorgeous sub, I love the look of that cone. It looks so much better with the grill off. One small improvement they might make is using a magnetic grill instead of pegs, then they could get rid of those peg holes and streamline the look even more. One quick comment about the write up, 'soft bottom design', how does that work to prevent bottoming out? If it is like an underhung driver, bottoming out can still cause damage, but to the spider instead of the voice coil or backplate.
 
Steve81

Steve81

Audioholics Five-0
Re: soft bottoming, yes Brian mentioned that the spider & surround will keep the former from physically tapping the back plate. Presumably it's still not something you'd want to abuse.
 
R

rnatalli

Audioholic Ninja
I would definitely like to see Josh review this puppy. Looks like a real competitor to the SB13-Ultra.
 
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