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Discussion Starter #1 (Edited)
The Rythmik Subwoofers AVS Forum FAQ

About the author: jwskud

I don’t currently own a Rythmik sub! So why did I spend my time throwing together a Rythmik FAQ? As soon as budget allows (hopefully by the end of 2021), I plan to add a Rythmik FV18 (Paper Cone, Rev2). In preparing to make this large purchase (I’m not one to casually spend almost $2,000), I spent about 12 months reading through thousands of posts (from January 2017 to present) on the Rythmik owners’ thread, educating myself on their quality subs, trying to determine the best subwoofer for my space. Yes, I have more time than cash...!

In so doing, I encountered the same questions being asked repeatedly, and I thought I could do the forum’s frequent posters (who have taught me a lot) a favor by authoring a FAQ which answers some of these oft-asked questions. Moreover, I thought such a document would be useful to you, the potential customer (I know it would have been very useful to me). The AVS “Official Rythmik Audio Subwoofer Thread” already contains in excess of 40,000 posts! That’s a lot of information to sort.

Ultimately, however, if you have a question about a Rythmik product, your best bet is to contact @enricoclaudio (Enrico Castagnetti) and @Rythmik (Brian Ding), the wizards of Rythmik Audio, who are always very gracious with their time and knowledge. They can be PM’d here on AVS Forum, or via their website contact page.

Note that all references herein are to the “Official Rythmik Audio Subwoofer Thread,” so head there to find out more.

I am not a subwoofer expert, so most of the information here is taken directly from very knowledgeable people on the Rythmik thread.

Finally, if you find some fault here, or if there’s something you’d like to add, reply to the bottom of the thread and I’ll edit the FAQ accordingly. Also, let me know if this is useful, or if there are other Q&A entries you’d like to see.

What do I lose in SQ going from a competitor’s sealed sub to a ported Rythmik? What about from sealed Rythmiks to ported Rythmiks?

How do I set up my new Rythmik sub?

Should I use Line-In instead of LFE? How/when can this be beneficial? Can/should I run a Y-splitter to both Line-In inputs?

How do I perform a sub crawl? What is the benefit?

Do I need dual subwoofers? Generally speaking, what is the best/easiest way to integrate duals in a room? What is a miniDSP 2x4 HD and why would it be useful?

Rythmik subs generally have lower power amps (providing lower wattage RMS) than do subs of similar size from other manufacturers. Does this mean Rythmik designs are less powerful?

Should I get the FV15HP, or will the FVX15 suffice? What about two FVX15s vs. one FV15HP?

What does one gain in moving from the FV15HP to the FV18, other than output?

The FV18 Rev2 with Paper Cone utilizes a foam surround, instead of rubber. Is this an issue?

Can I run XYZ smaller Rythmik sub with ABC bigger Rythmik sub?

What is BEQ and why would it be useful?

Why did serith sell his 3x FV25HPs? What does he own now?

Why did muscles sell his 2x G25HPs, and later his 2x FV25HPs? What does he own now?

Why did imureh like the FV18 (paper cone) better than the V1801, the JTR118HT (2019 model), and JTR2400?

A chart of shipping box sizes and weights (larger shipments only).
 

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Discussion Starter #2 (Edited)
SQ sealed to ported?

What do I lose in SQ going from a competitor’s sealed sub to a ported Rythmik? What about from sealed Rythmiks to ported Rythmiks?

Frequent contributors to the thread maintain that the servo technology and designs used in all Rythmik subs allows the sound quality (SQ) of Rythmik’s ported offerings to compete well against other brands’ sealed subs. For example, alongside servo tech, the amps on Rythmik subs allow a level of tuning control not found on other brands. As such, a ported Rythmik set to high damping will often exhibit SQ comparable to competitors’ sealed offerings. A sealed Rythmik sub will sound even tighter and faster (although some maintain that discerning between ported and sealed subwoofers is impossible – e.g. post 40384 by @Madmax67 and post 41363 by @rossandwendy; others disagree based on in-room experience, maintaining that a difference in sound quality is discernible between sealed and ported subs, as in post 41353 by @PlasmaPZ80U).

In the transition from sealed Rythmiks to ported Rythmiks, you can expect to pick up increased TR (tactile response, i.e. floor shake) and low-Hz output (dB). Set to high damping, a ported Rythmik will sound closest to a sealed Rythmik but will roll off faster at low frequencies. Set to low damping, a user picks up extra TR and output.

Sealed subs also have slower roll-off at ultra-low frequencies, whereas ported subs roll off very quickly below their port tune. As such, per post 33381 by @enricoclaudio, sealed subs are recommended for small- or medium-sized sealed rooms, where room gain can result in deeper extension relative to a ported sub. Regardless, due to servo tech, Rythmik ported subs offer very low distortion compared to other ported subs. Sealed Rythmiks are even better in this regard.

For HT (home theater) use, ported subs are often recommended. For music-only setups, sealed subs are often recommended. For mixed use, a ported Rythmik sub set to mid- or high-damping seems to provide the best of both worlds based on forum discussions. Ultimately, it is up to the end user to decide, as a sealed sub(s), properly integrated into a room, can certainly deliver a full home theater experience (post 41346 by @audiofan1).

One final note: because Rythmik subs often have reduced distortion (and thereby less “ringing”) relative to cheaper “one note” subs that are available (e.g. sub-$500 subs like my Klipsch R-120SW, which has plenty of punch but is a bit "bloated"), the bass impact may initially feel lacking. This is the trade-off for cleaner, more accurate bass reproduction. It may take some getting used to, but most forum posters never go back. The low damping amp setting can bridge the gap between higher distortion subs and Rythmik subs, but the Rythmik will almost always still sound “cleaner.” The paper cone of the FV18, which provides additional mid-bass output (+3 dB) relative to the aluminum cone, is therefore recommended for HT use.
 

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Discussion Starter #3 (Edited)
Sub setup

How do I set up my new Rythmik sub?

First, each Rythmik sub ships with accompanying literature which explains some of the amp features and offers advice on how to set the amp initially.

Second, it is recommended that you read @laulau ‘s “Dialing in Rythmik Audio Subwoofers,” a guide he authored for the express purpose of helping you cope with all the dials and knobs. See it here.

Third, with respect to maximizing performance, it is recommended that you read @mthomas47 ‘s “Guide to Subwoofer Calibration and Bass Preferences,” which you can find here.

If you’re still having problems, a PM to @enricoclaudio or @Rythmik will put you in direct contact with the Rythmik gurus, Enrico Castagnetti and Brian Ding, respectively. They have a track record of quickly responding to new owners.

Finally, the folks on the AVS Official Rythmik Audio Subwoofer Thread are very knowledgeable and are willing to spend their time helping you out – just post your issue(s) and someone will get back to you.

With regards to initial setup, I would offer the following general advice based on what I’ve learned on the thread:
1. Perform a sub crawl and position your sub
2. Set for 2-port mode, 12 Hz, and low damping, with the Rumble Filter off
3. Run Audyssey/YPAO/Dirac/AccuEQ
4. Now you can play around with other settings (it is recommended that the Rumble Filter be turned back on and left on)

Note – when using a miniDSP 2x4HD (or the equivalent), it is recommended that you optimize with the DSP initially (with the subwoofer amp settings listed above) prior to running Audyssey/YPAO/Dirac/AccuEQ. This way, you leave Audyssey/YPAO/Dirac/AccuEQ to simply tweak and level small dips/peaks.
 

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Discussion Starter #4 (Edited)
Line-In vs. LFE? Y-Splitter?

Should I use Line-In instead of LFE? How/when can this be beneficial? Can/should I run a Y-splitter to both Line-In inputs?

First, by utilizing Line-In vs. LFE, you will get faster upper-frequency roll-off (similar to a low-pass filter). This can help improve SQ, providing a “cleaner” upper ULF sound signature (YMMV, as the best crossover frequency will vary with respect to your mains, i.e. L/R speakers, and their bass extension).

Second, Line-In goes through the crossover and phase adjust circuitry on the amp (among other things), while LFE does not. If you are not using an AVR, Line-In thereby gives you greater control over SQ.
In the words of @Soulburner (post 36046): “The decision of LFE vs Line-In depends on your setup and usage. Some of us have preferred the steeper upper roll off associated with Line-In as it cuts the frequencies that are way above the crossover that may be localizable and not sound great coming from a sub. Others use the LFE input and don't notice the difference.”

In the words of @DonH50 (post 36051): “Line in allows you to cascade crossovers for more roll off (less highs in the sub, less lows in the mains) and access to more of the controls. However, most AVRs handle all that stuff automagically, so unless you know how to tweak things I'd just use LFE and let the AVR handle things at first. You can always change later, but most of us simply want our new toys to be playing away without hours of fiddling or weeks (plus) of learning. I would use LFE, set the crossover in the AVR to 80 Hz, and listen for a while.”

Regarding the use of a Y-splitter and connecting both ends to either the L/R LFE or L/R Line-In connections, several knowledgeable posters (e.g. @laulau and @jsc79, see post 34714) have stated that Yamaha receivers tends to have low voltage from their pre-outs. Thus, by splitting the signal, you boost the voltage to the L/R inputs on the sub and this can result in a superior signal.

For AVRs with higher-rated pre-out voltage, using a Y-splitter can result in clipping (overdriving) the sub and/or negatively impacting the limiter’s function, and is not recommended (post 32140), especially if you are already running your subwoofer “hot” (see post 25514).

More info: posts 24545 by @PlasmaPZ80U and 24550 by @JimWilson.
 

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Discussion Starter #5 (Edited)
Sub Crawl

How do I perform a sub crawl? What is the benefit?

A nice video explaining the process can be found here:

In brief, the process allows you to maximize subwoofer performance by finding an ideal location for subwoofer placement. You place your subwoofer in the MLP. [Note – it may not be wise to place Rythmik’s larger, heavier subs in a chair – use caution!]. Then, while listening to deep, repetitive bass output, you crawl around the room, trying to find the spot(s) where the bass is deepest, smoothest, and most even. Once that spot has been identified, put your subwoofer there, and you’ll get the best bass possible from your sub.

Note that @DonH50 prefers a less-subjective method, as per post 41400:
For the record I am not a fan of the subwoofer crawl, at least in its simple version. Too easy to fool the ears and pick a spot based upon inaccurate information and/or bias leading to poor sound. I prefer measurements, but alternatively get a test CD and use single tones or sweeps, preferably with an SPL meter (a C-weighted version is good to about 30 Hz and is a decent start), to help optimize placement and sound.
 

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Discussion Starter #6 (Edited)
Dual Subs and MiniDSP

Do I need dual subwoofers? Generally speaking, what is the best/easiest way to integrate duals in a room? What is a miniDSP 2x4 HD and why would it be useful?

Almost everyone on the Rythmik Owners thread will maintain that dual subs are absolutely necessary. Why? Only dual subs, with proper placement, can conquer room nulls. Thus, if you desire even bass response across a room and multiple listening positions, it can normally be achieved only through the use of multiple subs, properly phased/aligned/tuned.

This begs the question: what if I already have good/ideal bass response at the MLP and nobody else in my family cares about bass (as in my own situation)? In this case, I maintain duals are not absolutely required, although you’d still benefit from higher SPLs at the MLP (and throughout the room) with duals.

Now, if duals are purchased, good for you (I am envious of your AV budget)! Be prepared to spend a bit of time integrating them, however – it may not be easy. There are dozens of videos and pages of information on this topic out there in Google-land. Based on my reading, integration of duals is made immensely easier through the use of a miniDSP 2x4HD, as most AVRs do not allow for multi-sub EQ, so that is all that will be covered here.

As per post 36278, @enricoclaudio recommends the following process:
“I don't like to use SubEQ HT when using miniDSP as I do prefer to time align the subwoofers on the miniDSP then show the subwoofers as one to Audyssey or Dirac or whatever room correction system your receiver or pre pro comes with.”

Thus, it is recommended that the duals be time-aligned with the miniDSP first, in order to present them as a “single sub” to the room correction system. Another benefit here is that you can conquer the largest peaks and dips using the miniDSP first, then allow your AVR to "fine tune" the final EQ. For more information on this process, ask on the forum or check out the miniDSP thread on AVS.
 

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Discussion Starter #7 (Edited)
RMS Wattage

Rythmik subs generally have lower power amps (providing lower wattage RMS) than do subs of similar size from other manufacturers. Does this mean Rythmik designs are less powerful?

As @tvuong states in post 41679, and @yodog discusses in post 41704, Rythmik’s highly efficient drivers coupled with servo design allows Rythmik subs to achieve high outputs at lower wattage. In other words, Rythmik subs have similar or superior output (SPL in dB) at lower wattage than less-efficient designs, and output is what matters.

For more information, check data-bass.com for measured SPLs - this will provide you with insight into what output levels are for each model tested at specific frequencies.

Also, as pointed out by @darthray in post 41705, in order to increase SPL by 3 dB, a doubling of power is required.
 

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Discussion Starter #8 (Edited)
FVX15 vs. FV15HP

Should I get the FV15HP, or will the FVX15 suffice? What about two FVX15s vs. one FV15HP?

As per @drh3b in post 41631, “The only difference between the two is max output, so if you don't think you need it, save the money.”

A more difficult question: two FVX15s or one FV15HP? The general guidance on AVS is to get the best subwoofer you can afford, then save up and get a second later. So the true answer would be: get 2 FV15HPs when you can afford it! Start with one now and get a second later... But I refer you to the 2 sub Q&A above.
 

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Discussion Starter #9 (Edited)
FV15HP to FV18 upgrade

What does one gain in moving from the FV15HP to the FV18, other than output?

In post 41771, I stated, “A while ago, when some folks on here upgraded to the FV18 from the FV15HP, they noticed a greater weight/heft to the ULF. That's not to say the FV15HP is lacking, it's just pointing out that there's a definite and noticeable distinction between the two.”

Also, as per @kyzer soze responding in post 41777, “I experienced the same increase in weight/heft when I borrowed @Marc Alexander FV18 for a few months. I don’t care what the numbers say I could tell a difference immediately. The FV18 is a great sub.”

In post 41880, @iamsabit313 states, “Yeah, I upgraded from FV15HP to Gen2 FV18 Aluminum cone ones. Quite a massive upgrade I would say. More headroom, more tactile response but bass definition is quite similar which is not a bad thing since FV15 is such a capable sub.”

In summary, moving to the larger cone gives slightly higher output (dB), especially below the port tune, but elsewhere in the spectrum also seems to give extra “weight” to the ULF.
 

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Discussion Starter #10 (Edited)
FV18 Foam vs. Rubber Surround

The FV18 Rev2 with Paper Cone utilizes a foam surround, instead of rubber. Is this an issue?

Per @enricoclaudio in post 41807: “The foam we use on the SW1825 driver is not even close to the foam that was used 20 year ago. The foam on the SW1825 driver is a new composite material with about 40% rubber and 60% foam which will last more than the life of the subwoofer itself. The surround on the DS1820 driver is pure rubber and of course more stiff. The new fiberglass and carbon fiber drivers will use foam surround like the paper cone driver.”

Whether or not the foam surround is cat-proof is a separate matter...:rolleyes:
 

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Discussion Starter #11 (Edited)
Mixing Larger and Smaller Rythmik Subs

Can I run XYZ smaller Rythmik sub with ABC bigger Rythmik sub?

As per @enricoclaudio in post 40207, “If you have patience, time and a miniDSP 2x4 HD, it can be done and the results are pretty good.” As with any dual-sub integration, it will take some time and effort to achieve. Normally, the smaller sub is placed closer to the MLP to even out the responses. In other words, you want the larger sub to work harder than the smaller sub, and this is most readily achieved by having the smaller sub closer to you.
 

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Discussion Starter #12 (Edited)
Beq

What is BEQ and why would it be useful?

The best thing to do is check out the BEQ thread here on AVS (Bass EQ for Filtered Movies), but in a nutshell, BEQ utilizes a miniDSP 2x4HD to restore ULF effects to soundtracks where they have been attenuated (which is especially common in Ultra 4K HD discs, but also in Blu-ray). People have studied the original ULF track and it can be restored by boosting via the miniDSP.

In the words of @PioManiac: “Bass EQ or BEQ has been talked about on Data Bass forums... since ~2014 for restoring some Blu-ray/4K UHD movies that have had their lower frequencies severely filtered...especially recent releases from Disney/MCU/Lucasfilm/Pixar/Buena Vista... The ULF content is still there on the disc for the taking, and with the right software tools the levels can be restored. This is not made up content or filler, it's real low frequency material that "some" sound engineers decided no one needed to hear/feel. So the lowest frequencies were just reduced to soundbar levels, but are still ripe for the picking with the right software.”

If you want the ultimate ULF in your movie soundtracks, BEQ is a must. But make sure you turn it off after watching any particular movie - you can damage your sub otherwise!
 

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Discussion Starter #13 (Edited)
Serith's 3x FV25HPs

Why did @serith sell his 3x FV25HPs? What does he own now?

Serith famously owned 3 FV25HPs and used them in his basement theater. After owning them for about a year, he sold them. In his own words (posts 39078, 39082, 40189):

“yes, the subs were at the rear of the room. I no longer have them though as I sold them back in December 2018. I loved how they felt & sound, I just want more and I found their limits is all. here are a few pictures that might help show how far away the subs were from the seating (it's about 6' from the seating to the front of the cabinets, never-mind the first picture as I had pulled them out a ways to play around with the TR). you can also see the difference between dark grey/light black painted drywall & black velvet on the walls”

“I had them for about 1 year collectively, and if you do the math they effectively cost me $83/month for a 12 month lease. it was worth every penny! I’ve kept busy since selling them back in December and I’m now trying to make the room whole again. I have a number of options I’m exploring to make that happen soon!”

“I sold the trio because I have an illness and want more tactile energy. my room is in the basement & on concrete so I have everything working against me. I tried a diy 18" vented sub that did an okay job but won't be my endgame. I’m torn between trying the new tv36 or a cap4000, or perhaps there's something else coming on the horizon”

In summary, due to the concrete floor and walls in his space, Serith felt the FV25HPs lacked some tactile response (TR), or “floor shake.” Concrete flooring provides a high damping effect to TR (as compared to a suspended, wooden floor). Whether or not Serith can find something that delivers more TR but maintains the high SQ of the Rythmiks…remains to be seen. 2 x 21" drivers?? :eek:
 

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Discussion Starter #14 (Edited)
Muscles' Journey

Why did @muscles sell his 2x G25HPs, and later his 2x FV25HPs? What does he own now?

Muscles went on a subwoofer odyssey recently, moving from a pair of G25HPs to a pair of FV25HPs, and finally to a pair of F18SEs. Why the changes? Was he unsatisfied with his purchase(s)? In his own words (posts 40104, 40186)

“Kind of a crazy story. I was chasing the output dragon. I went to 2 FV25HP's after the G25HP's to really see what massive output was about. After having them for a few days my Home Owners Association president came over and said that they had to go. She reported that the whole community could "feel" it, and that I had to find a way to tone it way down. I sold the FV25HP's and decided to try the F18's to lower the output a bit. They are awesome for music, but for movies I do miss the G25HP's output, especially down low.”

“I have owned probably 9-10 subs in the past 2-3 years. After discovering Rythmik I have stuck with this brand exclusively. I sold my G25HP's in the hunt for more output down low, I wound up getting the FV25HP's which was too much output for my town-home. I received a lot of complaints from neighbors and the HOA (home owners association). This prompted me to sell them and get the F18's. I wanted to get the sound quality of Rythmik while dropping the DB's a bit in the lower octaves.

For the record, my favorite sub I have ever auditioned is the G25HP. It really has no weaknesses other than sheer size/weight. It is the best sounding sub I have ever heard.”

In summary, Muscles sought greater low-Hz output by moving from the G25HPs to the F25HPs, and he found it! In fact, he found so much that neighbors complained and he was forced to “downgrade” to the F18SEs. With monster subs like these, it is important to consider how far low-Hz sound waves can travel. There have been reports of larger Rythmik subs disturbing neighbors across the street! :eek:
 

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Discussion Starter #15 (Edited)
Imureh's Auditions

Why did @imureh like the FV18 (paper cone) better than the V1801, the JTR118HT (2019 model), and JTR2400?

Imureh has authored an entire thread on this topic: see here.

In summary, in his own words, “As you can imagine, I ended up keeping the FV18s, returning the 118s and selling the V1801s. These subs look the best and easily sound as one the best. IMO anyone considering a ported sub should look closely at the FV18 paper cone. They offer the Rythmik sound with plenty of TR and extremely low distortion.

I can tell you that in my house, things are falling off shelves they never had with any one of the subs I had including the JTR 118s. I deem that as success! These subs are a no-brainer for anyone looking for a ported sub and especially if living with driving distance of Austin where you can save on shipping costs.”

He also auditioned the JTR2400: “The driver in the 2400 ULF is very different than the 118HTs, it looks and sounds totally different. The 2400 driver has a thick and a very room filling sound which makes it an ideal sub for large rooms. However what Todd and I noticed is that the 2400 lacked clarity in my small room and interfered with the other speakers regardless of the position of the LFA adjust knob. It seemed like the bass from the 2400 would keep hanging around and therefore did not seem to be as clear as what we had heard in Todd’s open room. It then became clear to me that the 2400 would not work for me in my room. @Marc Alexander had predicted that especially after having listened in my room which is said to be like a closet with tons of room gain.”
 

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Discussion Starter #16 (Edited)
Shipment Box Dimensions

A chart of shipping box sizes and weights (larger shipments only).

FV18 = 29 inch x 27 inch x 41 inch

Other model box sizes pending...
 
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