Differences between Rythmik FV15Hp and F25

[N Boros]

I would really like to bring an F25 to the other house (as it is a better test environment than my own) to directly compare the subs, but the F25 isn't exactly portable.

I think you are absolutely right. The room and placement of the subwoofer within the room makes a huge difference. The best way to compare them would be to bring one subwoofer to the other person's house and place it exactly in the same position. This takes the room and placement out of the equation.

I agree with you about not wanting to F25 all that far either. I bet the PB2000 is more portable. Maybe you can convince your friend to bring it to your place, to compare the two.

[Sivar]

I've been trying to get him to do that, but I doubt it will happen.
My friend did finally demo my setup at a party.
Keeping in mind the caveats I mentioned in my previous post:

1) After the demo, he said, "Thanks for jump-starting my heart!"
2) One of the first songs he played on his system was from a test disk I made for him: Time Stretch by Bassnectar. He said "where's the bass?" -- a criticism of the song, not his sub (since it was performing pretty well).
That was the song I played at my place which got the response above. I don't think he remembers.
3) When I demod that same song to another friend about 3-4 months ago, a light fixture fell from my ceiling and shattered all over the floor.

The F25 is more than a capable subwoofer, but the SB-2000 is a great subwoofer and should be plenty of power for most home theaters. A single F25 should outperform it in every way except price and space taken. I happened to choose sealed so I needed to be more flexible with both to get good response, but I'd be happy with an SVS, too. I'd also have been happy with a pair of FV15's. Just about anything from Rythmik, SVS, HSU and others should perform very well and be priced very reasonably. I chose Rythmik because my research indicated they were slightly ahead of the competition.

[N Boros]

Thanks Sivar. Just to be clear, here you write his sub was the SB-2000. In the previous post you said PB-2000. Does he have the small sealed sub, or the bigger ported sub?

I would expect the Rythmik F25 to be superior to the SB-2000 in every way (except of course size and the larger price tag). The PB-2000 would be an interesting comparison, since it might not be too far away from the F25 in terms of output and extension, at least not as far away as the SB-2000 and F25 will be. However, the natural question is how much better is the F25 in terms of sound quality? This is a tough question to answer, because as you say it is not easy moving subs from one house to another to be able to compare these.

But, I completely agree with you, that if we go with Hsu, SVS or Rythmik, especially in the same price class, the differences should likely be pretty small and I don't think that any would be a bad decision. Though, I too lean slightly towards the Rythmik likely being slightly ahead of the other two in terms of price to performance. All of this is probably meaningless, since I have not been able to compare all three in my room, but looking over detailed measurements on data-bass and comparing professional reviews that is the impression I get.

[Sivar]

My apologies for the confusion. He has the PORTED sub, the PB-2000.

[curtis]

But, I completely agree with you, that if we go with Hsu, SVS or Rythmik, especially in the same price class, the differences should likely be pretty small and I don't think that any would be a bad decision.

I think it would depend on how discerning your hearing, and how "picky" one is.

I have not compared subs in a while (5-6 years?), but have heard and compared subs from all three mentioned manufacturers in my own room. They are all good, but definitely sound different.

[N Boros]

I think it would depend on how discerning your hearing, and how "picky" one is.

I have not compared subs in a while (5-6 years?), but have heard and compared subs from all three mentioned manufacturers in my own room. They are all good, but definitely sound different.

I think most of us on forum would likely fall in the "picky" category. Since you have heard all three manufacturers would you share your thoughts, from what you remember? What were some of the strengths and weaknesses of each?

[RythmikAudio]

Actually Sivar's depiction of the whole thing is very interesting. Here is my take-away: 1) Our sub blends better and it sounds like on and off. When it sounds as off, it is not because it is turn off, or it has less output. Rather it is because it blends so well that it does not draw attention. When it is on, it is because the bass effect is so much so that someone cannot believe the sound is from a pair of 8" woofer front speakers. On the other hand, PB2000 draws attention all the time reminds the listener it is there. The analogy of subwoofer/front speaker integration is like team work. The two blend well together and from outside you cannot see individuals. 2) When we have a better sub with higher resolution, we get more confidence about judging the music we hear. With a lesser sub that does not play well, it is always a question if it is the song, or it is the equipment (not just sub). So why not get the better sub? The difference is not subtle.

For anyone skeptical of the sound quality of our servo subs, I have no problem sending a unit for comparison. I can even pay for shipping. I did it once before for an AVS forum member. He was skeptical. I sent him a unit so he compared it with Ourlaw. He said he cannot tell the difference on music he played. However, in one of the demo tracks used by Danley Sound with a sound recording of a train seemingly with a lot of randomly orchestrated sound from rail, cart moving, metal striking.. etc. Our sub sounded much cleaner and believable than Outlaw. So much as that even his young son agreed. Now why he cannot hear the difference in music has to do with the type of music he likes. But that aside, our subs are not just for music. Customers can hear more believable sound from movies too.

[N Boros]

I know that in general the transient response of sealed subs are supposed to be better than that of ported subs and ported subs are supposed to have quite a bit more output at the lower end. But the output seems very similar between the FV15Hp and the F25 and the F25 should have better transient response than the FV15HP. According to the Rythmik website:

"Output comparison

At 20 Hz, our subs vary in their maximum output capability. The output at 20 Hz is shown relative to F12.

F12: 0db (baseline)
F15: +2db D15: +2db
LV12R: +2.5db
E15HP: + 3.5db
F15HP: +4db
FV15: +7db
FV15HP: +9.5db
F25: +8db"

So the FV15HP has a slight advantage of output at 20Hz. However, since the F25 is sealed it should roll off more gradually, so below 20Hz output should be higher on the F25. If the differences in output are only slight, will I hear much of a difference between the two with music? What about with movies? If a sealed sub has the same output capability as a similarly priced ported sub, wouldn't the sealed sub be the better of the two?

I compared my new Sierra 2s with other similarly priced speakers exhibiting flat frequency response on axis as well as quite far off axis. I could immediately hear the difference between the Sierra 2s and the other speakers and I attribute this mostly to the faster transient response of the ribbon tweeter in the Sierra 2s. A better comparison is the folks that have upgraded the Sierra 1 to the Sierra 2 and preferred the difference in sound quality for almost double the price. I wonder if the same will hold true in the below 80 Hz region with subwoofers?

With music, i would be more concern with the higher frequencies rather then the lowest, in which based on the discription of the f25, has more power than the FV15.
It will be most likely hard to hear the difference as frequencies below 20hz are rather sensational.

I guess the reason I was bringing up lower frequencies, is that sealed subwoofers will have the most difficult time getting the same output at 20 Hz in comparison to a ported sub in the same price class. So if the F25 and FV15HP have nearly the same output at 20 Hz then we could expect the same to be true up to around 40 or 50 Hz, where the F25 probably has a little bit more output than the FV15HP, as you mention. So the FV15HP has a slight advantage below 40Hz and the F25 has a slight advantage above 40Hz.

My concern is more with respect to home theater, as the F25 would likely have the advantage for music. If the frequency response is quite similar between the two, and I am okay with the size of the F25 and slightly higher price, then which of the two would have the advantage for home theater? Also, will I be able to hear faster transient response of the F25 and is this something more desirable for home theater use? I cannot see why a main speaker with faster transient response wouldn't be more desirable for home theater or music use, but there seems to be some who prefer the sound of ported subs for home theater use.

Brian,

Since you are here would you be able to enlighten us with the differences between the F25 and the FV15hp? Nobody was really able to answer the original thread questions.

[RythmikAudio]

F25 has absolutely the least amount of phase shift or group delay (even though group delay is meaningful only for low pass filter). But it is large because it is a sealed design.

FV15HP has all the characteristic of ported subs. It is more efficient and hence output more. Normal nonservo ported subs give us this boomy bass sound. Our servo ported subs greatly reduces that signature and gives us a bit of more "fully body" sound. The instructment may sound slight larger compared to the sound from F25. For anyone with HT application, we recommend FV15HP. For anyone with music as a higher priority, F25 is a better candidate. That does not mean F25 will be bad for movies. It is just that it has less coloration associated with other nonservo subs and can really "disappear" a bit better.

[Sivar]

Rather it is because it blends so well that it does not draw attention. When it is on, it is because the bass effect is so much so that someone cannot believe the sound is from a pair of 8" woofer front speakers. On the other hand, PB2000 draws attention all the time reminds the listener it is there. The analogy of subwoofer/front speaker integration is like team work. The two blend well together and from outside you cannot see individuals.

I think this wording better conveys my experience, especially the "it is because the bass effect is so much so that someone cannot believe the sound is from a pair of 8" woofer front speakers." (although my fronts have dual 5.25", but you get the idea).
It really is difficult to tell that the bass is coming from the subs (or from anywhere in particular) whereas the SVS is like a mean little Tasmanian devil in the corner (which is exactly how some people like it).

For anyone skeptical of the sound quality of our servo subs, I have no problem sending a unit for comparison. I can even pay for shipping.

I'd be happy if you guys would post the F25 specifications on the website. It's been under construction since my first visit months ago. Even though I shouldn't care, I always like to compare numbers.