The subject of this review is the Rythmik G25HP, a new model from this venerable subwoofer company. The G25HP is Rythmik's first dual-opposed design so this is a milestone of sorts for them. Utilizing a pair of the company's best 15" drivers, and sporting an 1800 watt amplifier, this subwoofer ticks all the boxes. The G25HP measures in at 24" x 18" x 25.5" (HWD) including the grills. Quoted frequency response is 14-200Hz +/-2 dB when using the LFE input and 14-90Hz +/-2dB if you choose Line In. It weighs approximately 170 pounds.


Rythmik is the quintessential ID (Internet Direct) company, which means you purchase the G25HP directly from their website. Units finished in either matte black paint or oak veneer are $2250. A high-gloss black paint is available for an extra $200. There is a 5 year warranty on the driver and 3 years on the amplifier. Rythmik includes a 45 day satisfaction guarantee as well.


Shipping protection is about as good as it gets. Due to the size and weight of the box it was delivered to my house on a pallet via trucking company.

The box - or more accurately, boxes - the G25HP is packed in are constructed of very thick cardboard. Slicing open the outer box reveals unpacking instructions printed on the lid of the inner box. That's become a Rythmik hallmark of late and I think it's a great idea. Most people don't get something like this delivered to them on a regular basis so it's nice to have detailed information about how best to safely extricate your new toy from its packaging.

Opening the second box reveals your subwoofer, completely sealed in a thick plastic bag. Protecting it on the entire top and bottom is 1.5" of medium density foam, while in each corner are 1.5" edge protectors made from the same material. Package delivery companies are notoriously hard on stuff - I'm looking at you FedEx and UPS - so it's nice to see Rythmik has gone to such great lengths to safeguard their products.

Included with the G25HP is a 2 prong power cord, four 1.5" x 3/4" round rubber feet that screw into threaded inserts in the bottom of the cabinet and a dual sided 8.5" x 11" laminated sheet with a Quick Guide on one side and Installation Instructions on the other. Also included are complimentary furniture mover pads (the white disks in the picture above) for either carpet or hardwood floors, a choice you make at the time of order. That's a rather thoughtful touch that I'm not sure anyone other than Rythmik offers. If the standard rubber feet don't work for you they also sell chrome spike feet.

I Must Break You

With this the 4th Rythmik subwoofer I've reviewed they now have the distinction of being the company I have the most experience with. It started about 5 1/2 years ago with the LV12R , followed by the F8 , then the FV18 and now the G25HP. For almost 2 years my own personal reference sub was their E15HP so I know this companies products better than most. To say we have a positive history would be a bit of an understatement, but will it continue to be that way?

I've often heard 'familiarity breeds contempt'. Quite the opposite is true in this case; familiarity breeds expectations, and mine were sky high. Develop a more potent version of the DS1510 driver used in the E15HP, stuff a pair of them into a single cabinet and then triple the amplifier power and you have my attention.

Rythmik will need to bring more than an impressive spec sheet though as I have seen lofty numbers not translate into real world performance before. Looking good on paper is simply not enough so I intend on pushing this subwoofer beyond what I've done to any Rythmik in the past. Given how I treated their FV18 recently that will take a fair bit of doing but I'm certainly up for the challenge. Let's see if the G25HP is too.

So why is this section titled I must break you"? It's an homage to the movie Rocky 4, and it's also the theme for this review (4th Rythmik, 4th Rocky, get it?). As far as Rocky movies go the 4th installment is pretty forgettable. It's probably my least favorite in this pugilistic franchise, so does that mean this is my least favorite Rythmik subwoofer? I ain't telling just yet. No matter, there is one part of Rocky 4 everyone knows. Dolph Lundgren - aka Ivan Drago - uttering those immortal words to Rocky Balboa before they face off in the ring. Staring into each other's eyes Ivan says, in his baritone voice, "I must break you".

Admit it, you can hear him saying that right now. When the G25HP hit my doorstep I couldn't get the phrase out of my head so a theme was born. That gave me a target, but ironically it was Rythmik who provided the bullseye to shoot for. More on that later.

The DS1520 used in the G25HP is the best 15" driver the company has ever offered, quite a statement considering the capabilities of their other units. It features an anodized aluminum cone with a thick rubber surround, 3" voice coil and 200oz magnet, all of which are anchored firmly to a 10 spoke cast aluminum basket. The linear excursion is +/- 20mm. High-end drivers can't do much unless the amplifier motivating them is up to the task, and the HX2000XLR3 certainly is. Utilizing a pair of Hypex modules the HX2000XLR3 pumps out 1800 watts, effectively giving each driver 900 watts to work with. Tying it all together is Rythmik's patented Direct Servo. They explain the system far better than I can so click this link for information about how the technology works. That's probably the perfect segue to discuss the amplifier in greater detail.

I can't think of another company that provides the level of control and customization these folks do. If you like to tune things you'll be in heaven. Let's skip the features every subwoofer manufacture provides - like volume (gain), phase and crossover - and instead focus on what the others don't have. There's the Limiter switch; turn it on to protect the driver from over-excursion during demanding movie soundtracks. Off is primarily for those who use their subwoofer for 2 channel music. To further protect you from... well, yourself... there's a Rumble Filter as well. That's to keep things in check when playing movies that have really deep notes, for turntables that may introduce subsonic content into the material and/or for owners who are less than sensible with the volume (why are you looking at me?).

Rythmik also includes a 3 position toggle switch used to set both the low pass frequency and slope. In the simplest terms this allows you to adjust what frequency the subwoofer starts playing at and how quickly it becomes audible. Then there's the Extension Filter with toggle switches for both Frequency and Damping. Combined, these two switches adjust how deep the G25HP goes and how 'clean' the output is. But wait, there's more! In addition to all that there's also a PEQ (Parameter EQualizer). Basically this feature allows you to increase or decrease a specific frequency range that may need to be enhanced/diminished for your particular situation.

As is the case with everything Rythmik, you can adjust this in many different ways. The PEQ can be completely disabled via a toggle switch so if you don't need it simply flip it to the off postition and you're done. If you do opt to use this feature there's a dial for selecting the target frequency to be modified, one for gain - how much boost or cut to apply - and a third for bandwidth, often referred to as the Q Value (how much of a range before and after the target frequency will be included when making this adjustment). Whew, that's quite a lot of stuff.

I'm sure some of you have been left reeling with what may seem to be a daunting task. "I just want to plug in my subwoofer and get good bass, I will never be able to figure out how to set all those adjustments". Although a solid understanding of what these options are and how they work is beneficial, it's not mandatory. Rythmik provides both a Quick Guide and Installation Instructions. The Quick Guide explains every switch, dial and knob from a reference standpoint while the Installation Instructions give detailed suggestions about how to set them for different uses. Most of the text for the Quick Guide is in a muted blue font, but for areas of particular importance you'll find those highlighted in red. That makes it easy to see what's critical with just a glance, so even if all this tech seems overwhelming you can rely upon the documentation to help get everything set correctly.

Regardless of whether you feel the amplifier is busy or not, one area you won't debate is Rythmik's implementation of auto on/standby. Put succinctly, it's a thing of beauty. It works exactly how I would design the feature if I had the skill to do so. The G25HP consistently came on when I expected it would and never went into standby when I didn't want it to (like muting commercials, which I always do). The transition from standby to powered up was instantaneous without any clicks, pops or other unpleasant noises; one minute there's no sound and then all of the sudden there is. This is how every company should do it. I realize in past Rythmik evaluations I have said something along the same lines, but given this is a pet peeve of mine I felt compelled to mention it again.

The cabinet is offered with 3 different finishes - black oak veneer, matte black paint and a high gloss 'piano' finish. The review unit came wearing the oak veneer.

{picture courtesy of Rythmik Audio}

Construction was first rate with not a single defect to be found; screws were tight, panels aligned, veneer was unblemished and applied smoothly. The grills fit perfectly and have a beveled edge that softens the overall appearance. Their frame is made from 1.25" MDF, sanded completely smooth and painted with a matte black finish. Material is very transparent and was applied flawlessly.

The G25HP wasn't as big as I figured it was going be. Relative to my E15HP, the tale of the tape looks like this:
  • E15HP - 19" x 17" x 20.5" (HWD)
  • G25HP - 24" x 18" x 25.5" (HWD)
A quick calculation indicates the G25HP is only 5" x 1" x 5" (HWD) larger than the E15HP, yet it doubles the number of drivers and triples the amplifier power. That's pretty darn impressive. Most subwoofer companies overcome small cabinet dimensions by using DSP (Digital Signal Processing) to boost the low frequencies and extend the effective range. Rythmik does not use DSP, preferring physics and their patented servo system instead of electronic aids. That suggests to me even though the cabinet is not terribly large it's still close to ideal for the parameters of the drivers. As with food, naturally derived beats artificially added.


Rythmik Audio is best known for 2 things, sound quality and their servo technology. The former is directly related to the latter so it's not a coincidence both have become their stock in trade. It should then be no surprise that the G25HP delivers very precise, detailed bass. You probably expected that, but what may surprise some is this; the Rythmik G25HP quickly grew to become my favorite among their subwoofers. The FV18 is a remarkable product, and I would have no qualm living with it on a day-to-day basis, but the G25HP fits my requirements better. Quality of sound, output, depth, clarity, it's all there. I'm not willing to divulge anymore at this point but it's likely I just gave away the conclusion long before we reached the end of my story. If you want to know why I feel that way you'll have to keep reading.


Previously I mentioned the Rocky 4 'I must break you' theme and associated bullseye for this evaluation. Movies are where I will squeeze off my first round and see if I can make the G25HP stumble. After a considerable effort it becomes apparent I'm no sharpshooter; in spite of how prepared I was to pound this thing with my movie selections the first attempt goes wide right. Maybe if I dial in the scope a few clicks I can eventually hit the mark. We'll see.

Edge of Tomorrow (blu-ray)

Say hello to the aforementioned bullseye. The Installation Instructions provided with the G25HP mention a configuration specifically to overcome the brutal opening scene of this movie. Sensing a weakness, can you guess what blu-ray I went out and purchased just for this evaluation? If you said EoT you would be correct. I should probably show some restraint here given the manufacturer is clearly nervous. Nah, forget that! Remember, I have a theme for this review so I'm going to show no quarter; if Rythmik is worried about this soundtrack than I'm excited about it. Unfortunately my joy was short lived. Despite a deliberate attempt to bring the pain, the opening scene didn't faze the G25HP in the way I hoped it might. When your first attempt to force a submission is probably your best shot and it still misses the mark, where do you go from there?

Edge of Tomorrow features Tom Cruise playing someone who is valiantly defending the earth from a merciless race of aliens that are trying to make us extinct. Does that sound vaguely familiar to you? The premise does have some parallels to another oft-used subwoofer test, War of the Worlds, but he's not a dad on the run in this case. Instead, he's a Major in the military with zero combat experience that ends up on the front line after he crosses paths with an unstable General. Like several of Mr. Cruise's movies this one has a punishing soundtrack, one that can beat a subwoofer to death. The very beginning is where the most damage is done, so be careful of how loud you play that part, but the rest of the flick is no walk in the park either. Naturally I didn't follow my own advice and proceeded with total disregard.

The portion I assume Rythmik fears most is short in duration, and if I'm honest it proved anticlimactic. While the G25HP did a splendid job of getting my attention, and making the blinds rattle, it wasn't vanquished as I figured it might have been. It's a weird feeling to be disappointed that something was successful. I did experiment with turning off the Limiter and Rumble Filter in various combinations, just to see what the results would be, and my testing leads to this PSA (Public Service Announcement); I suggest you don't disable either. The beginning of this movie can be very difficult for a subwoofer to handle, especially at volume. With the Limiter and Rumble Filter both engaged the G25HP was nonplussed and fully protected, so if you have a tendency to push things leave both enabled.

I bought this movie for the sole purpose of tripping up the G25HP and it didn't. It's starting to feel like my whole theme is blown already and the review is barely more than half done. OK, so now what do I do?

Flight of the Phoenix (blu-ray)

This is a remake of a 1965 movie which originally starred the incomparable Jimmy Stewart. The storyline centers on a plane that crashes in the Gobi desert of Mongolia. The survivors must try to overcome the harsh conditions and each other. Truth be told, I only bought it to test subwoofers as I heard the crash landing scene was pretty intense. Then I started watching it and noticed a distinct parallel to something I've been doing for years; primitive survival.

Since I was a lad I have been tent camping and backpacking. About a decade ago I decided to take it down a notch and drop 95% of my gear. When I hit the woods now I only allow myself 5 items and none of them are food, water, a sleeping bag, tent or anything else most associate to outdoor living. Remember the old Les Stroud TV show Survivorman?

That, but without exotic locations or fancy video gear. There is a distinct psychology to a survival situation, a dire predicament where you have almost nothing and must rely upon ingenuity and perseverance to stay alive. In my case it's only a few days at a time, certainly not anything like what was depicted in this movie, but the concept is very similar. Having years of experience with the real version of 'roughing it' I wanted to see how they portrayed that part, so instead of just queuing up the crash scene and using it I watched the entire movie. They portrayed the survival aspect fairly well - by Hollywood standards at least - but in the context of this review the only important part is how the G25HP fared, so let's focus on that instead.

Dennis Quaid plays pilot Frank Towns. After an experimental desert oil field is shut down he's hired to fly the workers home. Shortly after takeoff they encounter a haboob, a massive sand storm (essentially a hurricane in the desert). The storm is so severe it forces them way off course and eventually they crash in the middle of the Gobi desert. Unlike Edge of Tomorrow, where the noted subwoofer test scene lasts but a few seconds, the lead-up and subsequent plane crash in Flight of the Phoenix goes on for significantly longer so it provides plenty of material to evaluate. As they're flying through the haboob there is frequent low-level grumbling and pulsing sounds, all of which the G25HP produced with both power and precision. That helps draw you into the action, and lends a sense of realism, but the crash itself is where this thing sealed the deal. As the plane strikes terra firma and bounds across the sand the G25HP sprung to life, producing waves of bass that made for a thoroughly entertaining experience.

No matter how much you spend on a HT sound system, isn't that the goal? You don't want to merely watch something, you want to be drawn into it. Mission accomplished.

Olympus Has Fallen (blu-ray)

Gerard Butler stars as Mike Banning, a disgraced Secret Service agent who finds himself trapped in the White House when terrorists attack. What a unique premise, eh? Unlike the less than riveting White House Down - another film released in 2013 that has a similar plot - this one is actually not too bad. It has the typical cliché scenes you expect to find in a movie such as this, but Gerard Butler rather convincingly plays a remorseless individual I found to be somewhat refreshing. He's not very PC and I can relate to that, but then I've always been the type to buck convention so it's not surprising I enjoyed his character.

When things go bad Banning is only there by happenstance. He's been relegated to a desk job with the US Treasury after being unable to save the President's wife during a car crash 18 months earlier. The attack on the White House is conducted by North Korean insurgents and it just so happens he sees the chaos unfold from his office. Initially he rushes into the streets purely to help the injured, but as the situation escalates he finds himself in the middle of the action.

The scene most often cited as the best material for a subwoofer test is during a battle between the North Korean rebels and US troops determined to retake the White House. The Americans launch their assault with helicopters but the North Koreans are ready for them, possessing a secret US weapon known as the Hydra Six. One by one the choppers are picked off with the Hydra Six, exploding in the air and crashing to the ground. Each gun blast and explosion the G25HP was tasked with reproducing had a percussive kick to it, adding an unmistakable sense of realism to the action. The crescendo is when one of the helicopters crashes into the White House, an effect that caused an eruption of bass to fill my room. What I found the most satisfying was not the intensity of what this subwoofer had to offer, it was the depth of sound it produced. By "depth" I don't mean extension - although there was plenty of that - I'm referring to what can best be described as 'richness'. There was a distinct weight to the effect that was both heard and felt, yet it wasn't the least bit overdone or pretentious. Ferocious and polite at the same time, as odd as that might sound.

After all the testing had concluded I did sense a bit of warmth on the amplifier heat fins. There are certainly enough of them - 5 horizontal rows, each consisting of 14 1/8" vertical slats - so there is a great deal of surface area to convect heat, but you probably want to keep the amp at least a few inches away from any walls.


All the while I kept thinking "I must break you, I must break you" as I was selecting songs, and just like with movies what you see published is merely a small sample of what I used to evaluate the G25HP. A best-of type thing. When it came to movies I went all in, nothing but heavy hitters, and that was my intention with music as well. At least initially. By this point I had begun to get somewhat discouraged; I wanted to trip this thing up but thus far it had proven virtually immune. As you will soon find I came out of the gate strong, just like with the movies, but in the end I... hey wait a minute, I'm not telling you anything more than that. You'll have to keep reading to find out what happened.

Bass I Love You, Bassotronics (CD)

Who's your daddy? Actually who's your granddaddy, as in the granddaddy of all subwoofer tests. That would be the Bassotronics number Bass I Love You. Regular readers of my reviews may notice that I used this exact same song during the evaluation of Rythmik's FV18 about a year ago. Think that's a coincidence? Think again, it was deliberate. In the FV18 article I wrote "this was quite possibly the cleanest and most detailed version of the song I've ever heard". To my ears the G25HP turned out to be even better than the FV18, no small feat mind you. This synthesized number has been used to pummel subs since it was first released. Bass I Love You couples extremely deep notes with sustains and assorted pulses, material that is quite difficult for any subwoofer to reproduce cleanly ("cleanly" being the operative word here). So what happens when you add lots of volume? You expect the sub to lose composure, or at least that's what typically happens anyway. Not this time I'm afraid.

Because Bass I Love You is less than 4 minutes long I ran it a few times using different volume levels and settings on the subwoofer amplifier. The first pass was with both the Rumble Filter and Limiter disabled, not advisable for this material. With the volume at what I would consider a comfortable level there were no issues whatsoever. Same when I turned it up louder than I prefer. It was only when I hit a ridiculous level did the G25HP get a little unhappy, sounding as though there was a bit of run-on in the really deep throbbing notes; they went from perfectly blended to somewhat thick and less accurate. There were no mechanical sounds, so I don't think I reached a physical limit, but there were indications the G25HP wasn't all that pleased with what I was doing.

I experimented with various combinations of the Rumble Filter and Limiter and found it was the Limiter that cured the problem; once engaged I could twist the volume knob with reckless abandon and no longer heard any protesting. Some of you might say that constitutes me breaking the G25HP, but I beg to differ. I deliberately turned off the protection mechanisms to see how effective they were. Rythmik includes them for a reason, giving you the option to tailor things to your particular situation. Unless I was intentionally being careless I left both enabled and never heard a bad sound, despite how unforgiving I was at times. It was only when I disengaged them and raised the volume did I hear anything untoward. If nothing else my tests prove the protection mechanisms work as intended.

Congo Square, Sonny Landreth (Streaming)

When it comes to reviews I seem to have two predominate avenues to travel, themes and whatever comes my way. Most of you know I love themes, something that ties seemingly disparate bits into a cohesive whole. Frequently they just happen, without any effort on my part. This review has a theme, the number 4 or the 4th in a series. I'm not the least bit adverse to let things flow all by themselves however, to coalesce into something without any intervention on my part. A whatever. This song is a whatever.

On a recent Sunday I was puttering around the house doing all manner of domestic chores. Streaming in the background through my TV was the last installment of Eric Clapton's fabled Crossroads Festival, this one circa 2013 (there were 5 Crossroads Festivals in total, the first was in the late 1990's and the last being the 2013 version). The telecast lasted over 5 hours so there was plenty of music to go around. The soundtrack is mixed surprisingly well so it's definitely worth a listen. Even though the music was only in the periphery while I was occupied with menial tasks one song immediately caught my attention - Sonny Landreth's Congo Square - so I sat down and watched it from start to finish.

For Congo Square Sonny was joined by none other than Derek Trucks. Depending upon the type of music you listen to the name Derek Trucks might sound familiar. His uncle Butch Trucks was a founding member of the Allman Brothers, a band Derek joined at the ripe old age of 20. Derek is a skilled blues player in his own right but where he really excels is with a slide, almost a lost art today. His ability with the slide is probably why he sat in on Congo Square because there was a lot of opportunity for him to showcase his talent.

This song has a good groove and a lot of energy, perfect to test the Rythmik. As is my wont I cranked the volume and sat back to enjoy, and enjoy I did. The sound coming from the G25HP was simply brilliant, with plenty of power and precision. The bass was intense and evident, yet it was never overbearing. I was treated to all the detail you could ever ask for from a live show, at least a show where the person on the mix board knows what they're doing. I wish I had hit the record button on my DVR because I would have certainly loved to hear this one again, it was that good.

Dark Side of the Moon, Pink Floyd (CD)

The goal with all the movies and music I had chosen was to put a hurt on the Rythmik G25HP. By the time I had gotten this far it became apparent I wasn't going to break its resolve so I gave up trying. Accepting defeat I decided to queue up something I just felt like listening to. For those who know me you probably saw this one coming. Using Dark Side of the Moon in a review is essentially my seal of approval as only a select few products ever get to be tested with this one. The Rythmik G25HP had earned the right, and my respect. Is it possible to enjoy being whupped?

From a band of virtually unknown musicians came a concept album the likes of which may never be duplicated. Arguable the best rock album ever created, Dark Side of the Moon was released in 1973 and reportedly went on to sell about 45 million copies. That's more than the population of New York and Florida combined. Dark Side appeared on the Billboard Charts for more than 900 consecutive weeks, a record that still stands today. Calling this album ground-breaking would be an understatement. Although Pink Floyd has produced some outstanding work since then a lot of their diehard fans consider this to be the pinnacle, the zenith of their career. It was also recorded very well, so not only is the music exceptional the mix is as well.

Floyd opens with Speak to Me and a deep heartbeat sound, one that starts out low but quickly intensifies. The G25HP had some fun with that effect. Or more accurately, I had some fun with it by way of the volume knob. Breathe and On the Run come next and the G25HP ate up the challenge, not that either song posed much of a challenge. Then comes Time, my second favorite Floyd song (Comfortably Numb is still numero uno for me). With Time not only does a subwoofer have to deal with Roger Waters' Fender Precision bass and Nick Mason's drums, it also has to contend with the rototom that Nick decided to add into the mix. "deal with" is probably a bit of an overstatement as the G25HP didn't give this material a second thought. From the metronome that starts this song - which is probably playing in your head right now - to the wind down after David Gilmour's guitar solo, it was all there. While writing this section I actually listened to the entire CD twice. 'nough said?


I must break you. By now it has to be painfully obvious that was my goal while evaluating the Rythmik G25HP. Ultimately I didn't break anything and failed to reach my objective. I tried, I honestly did, but I simply wasn't successful. The G25HP proved to be all but unflappable; no matter how intense the movie, no matter how much I cranked the volume, no matter how complex the material, this subwoofer never missed a beat. It wasn't only proficient at movies and outright volume however, it was able to handle music with both poise and accuracy.

If the situation warranted power and output both were there, if a more subdued approach was called for it was able to do that equally well. Rythmik spared no expensive with the hardware as they packed the G25HP with a pair of their best drivers and most powerful amplifier, then tied it all together with their unique Direct Servo control system. In the end the impressive spec sheet did result in an equally impressive subwoofer, one with no real weaknesses. It just works, period. With both high quality and high performance in a single package, what's not to like about the Rythmik G25HP?

{previous 3 pictures courtesy of Rythmik Audio}

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