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JTR Captivator 2400ULF vs Rythmik Audio FV25

31K views 71 replies 23 participants last post by  Marc Alexander 
#1 · (Edited)
With the immenent release of the Rythmik FV25HP there will be a new face-off between these ported subs with 10Hz capabilities. This thread is meant for information and discussion of these two ultra-low frequency monster subs.

JTR Captivator 2400ULF
Driver: one 18" driver
Port tuning frequency: 14Hz
Amplification: Speakerpower 2400W RMS
Size: 20.5"(W) x 22.5"(H) x 39.5" (D) or 20.5"(W) x 39.5"(H) x 22.5" (D)
Construction: 18mm baltic birch (13-ply)
Part Sourcing: USA
Assembly: USA
Weight: 165 lbs
Cost for standard: $2399 + freight
Cost for tall: $2499 + freight
*freight shipping only (~$250 for one, $300 for two)
+sales tax for residents of Wisconsin
Official JTR Speakers Subwoofer Thread
Official JTR Speakers TALL 2400ULF thread


Rythmik FV25HP
Drivers: two 15" aluminum drivers (DS1520)
Port tuning frequency: 12.5Hz
Amplification: Hypex 2000W RMS (Rythmik patented DirectServo)
Size: 21"(W) x 41"(H) x 22"(D)
Construction: 18mm MDF for bracing, top, bottom, and sides, 1" MDF for back panel, 1.5" MDF for front panel
Weight: 105 kg, ~232 lbs
Part Sourcing: China
Assembly: USA
Cost for one: $2500 shipped
Cost for duals: $4750 shipped
*freight shipping only
+sales tax for residents of Texas
Official Rythmik Audio Subwoofer Thread

… the FV25HP and the 2400ULF will be very close in performance with each other based on what we know so far. The major difference is footprint:
edit: The dimensions of the taller Captivator 2400 ULF and the FV25HP are nearly identical

Rythmik FV25HP available only in textured black paint. JTR offers matte black paint (std), custom wood (+$300) & automotive (+$500) finishes.
 
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#46 · (Edited)
Driver and amplifier for both models are new components made from scratch. FV18 has DS1820 driver and HX1000XLR3 amp. The FV25HP has DS1520 driver and HX2000XLR3 amp.

Here is a picture comparing H600XLR3 vs HX2000XLR3. The H600XLR3 amp has the same size and layout as the HX800XLR3 that we use in the F25.



Added to Post #3

Note, these are class D Hypex amplifiers but with linear toroid power supplies with large capacitors. The amplifier heat sink, knobs, and connections are not included in the dimensions and require a couple of inches of clearance in the back.

JTR recesses the SpeakerPower amp so you shouldn't need more than 1" of clearance in the rear. No clearance is needed if right angled cabling is used.
 
#47 ·
@jrittz impressions and pics of dual Cap 2400ULFs: part 1
Edit: My apologies, the pictures did not show up sideways on my PC... not sure why they decided to now. I moved these things entirely by myself, from my truck, to the basement. :)

And now I am a proud owner of JTR subs.

My first first impression was "meh". I hooked them up, turned them on, turned down the volume so I wouldn't wreck my ears. I proceeded to play some reference material and I was a little underwhelmed. I wondered why in the world aren't these things rocking my world? The answer is easy... I forgot that after I sold my subs, I ran another calibration and through that calibration, my receiver turned off my sub outputs because it didn't detect any subs. :eek:

Needless to say, on with the show... I just thought i'd share with you my quick moment of stupidity. :)

My first impression was holy f*&k. Ginormous. I positioned them on the side walls with the backs of them in the back corner facing the front of the room. After a quick calibration and several positions later, I settled on having the drivers facing the back of the room, still along the side wall, with about 12-18" of space between the driver/sub and the back wall and about 8" off the side wall.

I did try them on the back wall, side wall, various positions on both, cocked 45 degrees, etc... but it was always towards the corner, never more in the middle of the back/side walls. I kept them at 1/3's and 1/4's... Except the last position where I placed them facing the back corner as described above.

I demo'd my favorite Hulk Chapter 10'ish. The scene where they put a couple gas canisters in the room with him and then he changes all the way through his scowl after saving Liv Tyler.

We decided to watch a movie last night... Battle: Los Angeles. Seen it before but not with these subs. It was a totally different experience and the entire family is in love with the new subs. They really kick ass. Thump you in the chest. Give you that added element that was so needed/wanted.

I will easily say these are worth it. I give it a 12 out of 10 stars.

My initial impression as compared to my dual Hsu VTF-15H MKII's... There's no comparison. They aren't even in the same realm.

I still have to use REW and miniDSP for an actual calibration. But, I set the subs to this:
I'm sure I set the subs a minimum of 6db hot... it's probably even closer to 12db's. :)
Control for LF Adjust, I set it right in the middle. If I turned it all the way up, it was a little boomy.
I kept delay at 0ms. I don't even know if this is something I would use or how I would use it properly.
I turned the cutoff up to 120Hz and turned up the cutoff on my LCR's to 80. They were set to 40/60/40.

Here are the pics I took:












 
#48 ·
@jrittz impressions and pics of dual Cap 2400ULFs: part 2
Edit: Funny thing is, I didn't read the last day or two of posts... so how appropriate is this when the thread turned to "should I get dual 2400's...". I can answer that one... YES! :D

Some more pics... tomorrow will be 3 weeks since I brought home my Dual 2400's...

I have other pics in post #758 of this thread... page 26.

Here are more pics of the room and placement of the subs.






















Just a few bonus pics of where my receiver/movies are as well as how I have all of the wiring situated for the room. Half the basement is finished (the HT room). :)

 
#49 ·
@Adamg (Ret-Navy) 's unboxing and initial impressions of dual JTR Cap 2400ULFs:
Subs arrived today. Pics follow:

Currently Calibrating. So no impressions yet. They did arrive in good condition, no shipping damage.

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Post Calibration demo impressions to follow....They are quite large. Same width and height as the SVS Ultras, but obviously much deeper. Seems to be working good. Wife came home and said "Good Job"! So that is several levels above "Oh my God, No way". I think I'm good :)[emoji23]
Disclaimer. I have barely scratched the surface of the capability of these "Monsters". I only watched one movie (Oblivion) and listened to some Music. Most of my time and attention was focused on tweaking the gains with the AVR trim post Audyssey calibration.

Movie observations. Oblivion has some nice deep effects. It is a movie I am familiar with and I know how it sounded with Dual Ultras. Last night I had the Sub Gains on the third hash mark up from low. I did not know the subs were there until they were. That is a high mark. I hate a sub that is always heard. If that makes sense?

Jeff advised me to set the sub gains to middle hash mark. But I could not bring myself to do that. Like I said previously, this will be a slow walk. I'm in no hurry to destroy stuff in my house.

My Wife joined me about half way into the Movie. MV was -20, Sub AVR Trims were -9.0db and -10.5db, Sub Gains were on the 3rd hash mark out of 11 or in the 9 O'clock position.

On a few specific Scenes my Wife reflexively lifted her feet off the floor. She looked at me and said "Wow, that was cool" Yessssssssssssssssss! G.......O.......A........L...........

Cat ran from room sideways.........

I smiled in bliss and took it all in.

I did not use a SPL Meter to ascertain actual SPL Levels. At this point, with the universal gain structure as configured. These Subs are barely Awake. Musically they are wonderful. Tight and responsive, but disappear when hey should and announce their presence at the right moments. I was a little apprehensive these monstrous 18" drives and 2400 Watt amps might not have the finesse and tenderness I desire from Music. My apprehension was put to rest. So far "Musically" these dual 2400's are masterful, responsive and hit with authority. Clean, tight, precise reproduction. Blown away would be an understatement.

Again I have much to explore here. Today I will begin "dialing up" the Gain structure. I can only imagine what's to come of this. I actually have butterflies in my stomach at the thought of it.

I do have Company coming tonight. My Wife's Older Sister and her Husband. This may put a damper on further progress and experimentation. So, if I don't report back until after the Weekend, you know why.

I have two sleeping "Black Dragons" in my Livingroom. We must all tiptoe about, in fear of awaking them! Shush..........be............................very, very..........................quiet........................................................:eek:
Apologies for the delay in posting this update. Yesterday was a busy day and I was preoccupied.

Saturday Wife and Guests go out exploring. I remained behind, to further tweak the Subs.

Long story short. Lots of tweaking and getting distracted. Subs gain structure ended up as thus:

Sub Gain(s) both set to the 4th hash mark up from off. I believe there are 11 hash marks. Representing off, 10, 20, 30, 40% and so on. So using this analogy I was set at 30% on both Subs. Jeff or others correct me if I am misrepresenting the Gain values above.

AVR Sub Gains were -5.5 and -6.5.

Movie selection: I took "Hacksaw Ridge" out of the rotation for personal reasons. Group decided on: "Pacific Rim" UHD"

This Movie is loud and non stop bass from start to finish. MV was at -18db. After about 15 mins we were being brutally handled by the Dragons. I started to dial AVR Sub trims down. Finished the Movie with AVR Sub trims of -10 & -11.

The Bass was intense and hard hitting. It may be the Movie here, but the Subs were overtaking the room and the movie. Guests started flinching. Once I dialed AVR trims back things got better. The Movie was still plenty loud and impactful. Bass seemed more in tune with the action on the screen.

The sheer amount of deep displacement these beats have on tap is impossible to explain. With these Subs, as compared to my Dual Ultras, you Feel them much more than hearing them. The Ultras were heard and rarely felt. The Black Dragons are Felt as much as heard. Feeling the bass this much was much to process. I liked it and then I did not like it. Once I turned the trims down to the final above settings it became enjoyable again. The deeper tune point and lower Hz produced was a new sensation that may take time to become accustomed.

I guess I was dancing around too much Bass for the Space! Never though that would happen? As I said, it could also be the Movie mix as well. Lots to learn and the tweaking Journey continues.

This is great fun and my impressions of the 2400's. So much raw power on tap is unbelievable. To have them set to only 30% and they can run me out of the room! The floor vibrates! Thats right, solid Concrete, with Hard Tile on top. The Recliners vibrate, the walls, damn near everything in the main room and adjacent rooms would vibrate and rattle. When I compare the footprint with that of the Ultras. Its hard to believe that Jeff has produced so much more spl and low frequency ability from a box that is the same Width and Height and just longer than the Ultras.

We all felt the bass! In your chest, arms, hands, legs....The sensation was familiar to me, from my experiences in the Navy, but never in my Living room! I was astonished to say the least.

The subs are amazing. Extremely satisfied with the Product. Now I just need to figure out what may be happening in my room at the higher gain levels. I did have a "Ratshack" SPL meter out. It was set to 120db scale. It pegged a few times and that was when it became uncomfortable. I really have no clue as to the SPL levels we were hitting. But I know I did not like it that loud. In retrospect, this is a good thing. It means I will probably never need or want MORE Bass than what I now have available.

I may run Audyssey again just to see if perhaps I did a bad calibration run the first eighteen times.....:D Perhaps toe in the left Sub and reduce some of the corner loading that seems to be going on here. I am not certain what to do next, but the process is familiar to me and I will find my "Happy Place" eventually.

Thanks Jeff. I have Z...E....R....O... buyers remorse and am extremely satisfied with the Dragons you sent me.

Mike, the wait no longer matters, as you already know! Most of the wait was not Jeffs doing anyway. Weather conditions caused 4 to 5 day delay. All out of Jeff's control.

Jeff, question. Both Sub's LF Adjustments are in the middle (12 O'clock position) Will adjusting the LF down help tame the sub in the corner? As I understand the LF now, it will. Am I correct ?

A warm and gracious "Thank you" to all you who helped guide me towards buying some JTR subs. This is a wonderful and giving group. I am proud to be a Member and JTR Sub Owner ;)
 
#54 ·
Not trying to take away from other subs on the market... The dual 2400's have impressed everybody who have come over to watch. The wife is a very "cost minded" individual... and she couldn't be happier with the cost of these two subs. She considers them a great investment in our home theater. :)


There hasn't been a single second of buyers remorse on my part... I'm thoroughly impressed and completely satisfied. :)
 
#55 ·
Nobody could possibly be more impressed with the 2400ULFs than I am but I simply don't have room in my setup for even one of them. It's 40" length makes it a nonstarter for me. Too bad, too, but there it is.
 
#57 ·
It looks like Jeff is seriously considering a tall 2400ULF with a smaller footprint.

Meanwhile, @gwsat purchased dual Rythmik FV18s. We have yet to see a FV25 in the wild.
As much as I admire both the JTR 4000ULF and 2400ULF, the more modest Rythmik FV18s that I bought instead have turned out to be just what I needed. They have given me a lot of bang for my buck and turned out to be powerhouse performers. The FV25s will of course be even more powerful but are also going to be significantly more expensive than the FV18s.
 
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#62 ·
i will be interested in how the 2400 mates with 1400. I have 3 different sized subs now and I cant stand the looks in my room so I took out the 2 smaller sized ones...still havent decided what will be my 2nd sub, think maybe a 15hp in cherry as I hate too many black boxes in room.
 
#63 ·
I will be exchanging the 1400 for the 2400 unless Jeff says they would pair well, I would have to sell what left of my soul to my wife to get approval to buy the 2400 out right. :eek:
 
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#71 · (Edited)
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