Fi IB vs Maelstrom-X

[jagman]

I've seen modelled output of both of these subs when 4 of them are given 2400 watts. More specifically, when 4 of each are hooked up to an EP-2500, the Fi IB subwoofers don't quite reach their excursion limits, while the Maelstrom-X drivers need a hi-pass filter to keep them from bottoming out. The Fi IB subs are much more efficient between 20Hz and 100Hz, while the Maelstrom-X subs are much more efficient from 10-20Hz. Since the output curve of the Maelstrom-X's is flatter, I think it would offset room-gain in most rooms to more or less keep the in-room response curve pretty flat (excluding room nodes, of course). The Maelstrom-X also has XBL technology. Since the Fi IBs are so much more efficient in the 20-100Hz range and less efficient in the 12-20Hz range, I think it helps explain why a lot of guys with the Fi IB subs get humps in the midbass and a lot less ultra low frequencies. That could be nice for having a natural house curve without the need for as much EQ... and it might be better for rooms without a lot of room gain.

So, it seems, if the money is available, the Maelstrom-X is in theory the better IB driver. But, I have a dual Avalanche 18" IB now and the bass "feels" a bit soft. I think, but don't know for sure, that it may be in part due to the lower Qts (0.40). The Something to consider is the Avalanche 18" T/S parameters are very similar to the Maelstrom-X. Since the Fi IB has a higher Qts and more output in the 20-100Hz range, I wonder if the Fi IB has more "slam" in the bass. Remember, this comparison is all based on having 4 drivers fed by an EP-2400. If the measured in-room response of the Maelstrom-X looks better than the Fi IB, but the Fi IB has more slam and impact, then the Fi IB sub might be the better choice.

Have any of you heard both drivers in an IB?

If so, does the sound quality differ between the two?

Does the "feel" of the bass seem different?

The reason I'm asking is I put an offer on a house and if I move, I'll have an excuse for a new IB . This one will definitely need four 18" high excursion drivers. Since I only have two 18" Avalanche drivers, and I'm not blown away by their sound, this a good excuse to go a different direction. BTW, thanks for your input. I realise this is a bit abstract, but your input is appreciated.

[jman]

4 Avalanches do the trick. Today I was watching some bassy scenes and one of them made my eyebrows vibrate (think it was Boogeyman)

Then I watched a Genesis concert and one of the songs the keyboard player hits a low note occasionally, whole body and chair vibration.

Ran the crash scene in Flight of the Phoenix, the room actually does pressurize if the volume is loud enough. You can literally feel the waves setting up in the width dimension of my room (side to side).

Also reminds me, when I had soundemon over last time for a demo, there was one scene where I talked during the bass and you could hear my voice quaver

Bass is fun.

[ThomasW]

It will take considerable time to address this....

As time permits I'll compose a thorough reply.

[ThomasW]

No I'm not aware of anyone doing a hands-on comparison between these two drivers

Computer sims for driver performance are only a part of the equation when we're deciding on what's most important for an IB

As important as the differences in the drivers are room location for the IB, location of the listening posting in relation to the IB, the effects of room-gain, and how well acoustic treatments and EQ have been applied. So I don't believe the conclusions being drawn based simply on the sims are a good criteria for concluding one driver is inherently 'better' than another when we're talking about a multi-driver IB...

But, I have a dual Avalanche 18" IB now and the bass "feels" a bit soft. I think, but don't know for sure, that it may be in part due to the lower Qts (0.40)

I have no idea what "feels soft ' means...

If the bass in your room isn't what you want it's more likely to be a function of the room, not the choice of drivers...

The lower "Q" driver is technically over-damped (tighter) compared to a driver with a higher "Q". This means they'll roll-off a little faster in the bottom end. This roll-off usually isn't a problem given the effects of room gain and use of EQ.

It's irrevelevent to me how much a person decides to spend on their drivers. That said, remember some things. The reason we advocate multiple big drivers is to have so much Vd the drivers are never over taxed. Also human hearing is less sensitive to distortion as frequencies go lower. So drivers like the Maelstom are very good choice when a system is using one or two drivers that will be driven hard. When we're talking about a 4-18" driver IB I think the need for more sophisticated drivers is less important.

Since I only have two 18" Avalanche drivers, and I'm not blown away by their sound, this a good excuse to go a different direction.

I think this is a myopic view of the situation. Your current room is compromised by it's size and the inability to utilitze proper acoustic treatments.

I've heard Cliff's (kadiddle) 4-18" Fi drivers and they sounded quite good. That said, if the additional $600+ to move to 4 Maelstroms isn't a problem then why not? But don't expect them to be a magic bullet that eliminates the need for acoustic treatments and EQ.

To be continued, I suppose.....

[jagman]

Thomas... thanks for the response .

I have lots of strategically located bass traps (more than probably 95% of people with acoustic treatments) which made a dramatic improvement in the bass. I had to take them down once to paint the walls and taking them away really showed ho much they helped. So, I doubt that could be helped much. I also re EQed the room with BFD and REW so that I only use 5 filters (as opposed to the 10 I previously used), and even though the response is a bit more jagged, it sounds a heck of a lot better. I still have equal output at 10 Hz as I do at 70Hz, and the 20-30Hz range is about 8dB hot.

Having said all that, I soft bottomed the Aves with WOTW, and it has made me gun shy about doing it again. I had a relatively large and wide boost dialed in at 20Hz at the time, which I'm sure contributed and probably caused this, but at the same time, I just don't want to ruin these speakers since getting them fixed now is probably impossible. My other complaint is even though I've seen these move about 3" peak to peak (when the bottomed), I didn't feel the impact I wanted. I'm probably sick in the head, but I just want more. My thought process at this point is... have two 18" woofers centered at the front and two 18" centered at the back (a la the Harman white paper). Doing this should do four things. It wouldn't necessary add dBs (in theory) since the four woofers wouldn't be coupled (which I don't need), but they would increase the air displaced (thus I'd feel the impact more), they might help even out standing waves, and they should decrease my worry about bottoming them. I've heard from a couple people who have done the proposed centered front and back locations and both were thrilled with the results. Since my room is rectangular and enclosed, I'm quite confident it will work.

Does this seem reasonable to you?

[ThomasW]

Hi,

WotW has ~3-6Hz stuff. That's tough on 'smaller' IBs. Very few DVDs have such low info.

We seen more people going the front/rear IB route with good success. It certainly evens out the in-room response.

Yes the acoustic coupling output is lost, but there's certainly a fair amount of headroom gained with doubling the total Vd.

So yes if you have the space for a second manifold I think it's a good idea.

[jman]

2 avalanches aren't enough for <20hz content at higher volumes.

Adding 2 more 18's at the back can theoretically increase headroom by ~4.5db max, where co-located can do upwards of 6db. You'll need a way to adjust phase.

Jag- are you using a high-pass filter? I have my ART351 engaged at about 13hz to skim off the really deep stuff.

[jagman]

I'm going to look around for while for a couple used Avalanche 18's. If that doesn't work out, I might add a couple Maelstrom-X's or sell the Avalanche's and convert to four 18" Fi IB3's. I'm not in a rush so we'll see what happens.

As for protecting the low end, I'm also going to get a receiver fairly soon (if it is ever released) that has adjustable hi and low pass filters for the sub as well as phase adjustment for the subwoofer signal. Of course that doesn't account for the phase difference between the two manifolds, but I e-mailed the author of the Harman white paper a few months back and he said he thought it was best not adjust for the difference. He said he thought the difference between the two is what evens out the frequency response, and that if I was really concerned, just center the subs on the left and right wall instead of centering them front are rear. He said the in room response should be the same as front and back if the room is symmetric, and if the crossover is low enough (60Hz or below), they shouldn't be localized. I would expect the phase to be most critical with music. Since the main seated position is equidistant from the two potential side manifold positions, then the phase difference wouldn't be an issue. If I did that, I think I would be the first do centered right and left, which definitely warrants experimentation with dual boxed woofers. It makes sense in theory... but there is no way I'd cut holes in the ceiling without testing it first.

[jman]

Weird theory. The phase of the direct sound from the sub should be the same for both subs. Having them partially out of phase is not going to smooth out frequency response. The flatter FR comes from how each "sub" interacts differently with the room and the combined result.

You could probably use 2 Maelstroms at the back and it would blend well with the 2 Avalanches.

[ryans]

For subs that are not co-located, the only way to keep them in-phase for all frequencies is to have a perfectly symmetrical layout. Otherwise you could get them in phase at any single frequency you're interested ... say 20Hz. But then 30Hz would be out of phase since the wavelength has changed and the distance between the subs and the listening position is no longer the same number of wavelengths. So they'll always be partially out of phase.

Setting the phase between your subs and your mains is a whole different matter though. In this case, you really only need them to be in phase near the crossover point where both the subs and the mains have significant output.