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Robert · Joined: September 6th, 2004 Posts: 52 Location: Olympia, WA

RCF ART705AS Subwoofer. Who has used this sub, what are your thoughts? Is there a better sub for the price, keeping size and weight in mind?

I'm seeking the perfect sub to match up with 1 or 2 EV SX-300 speakers per side. Yes, weight and the ability for one person to carry it upstairs alone (some venues here don't have elevators) is important, but so is having bass that sounds good and punches hard when needed.

The EVs will be powered by a PLX3602 and cross-overed using the amps 100HZ filter. The sub will run on its on so I'm seeking powered for the subs unless you know of a great passive sub that has a filter built in for the tops that will match up well with the EVs.

CJ Greiner · Posted: Sun Feb 17, 2008 8:40 pm Post subject:

Hi Robert,

I own a couple of RCF ART522A top speakers -- wow! They're very powerful, and only 40 lbs each.

I really don't know about the subs you're looking at, but if they're of the same quality... I suspect you'll get your money's worth.

TheBartman47 · Posted: Mon Feb 18, 2008 1:17 pm Post subject:

Size/weight, sound quality, and power/volume/efficiency are 3 factors that fight each other (sacrifice two to increase the third). $$$ can overcome a lot of the compromizes with more sophisticated designs, but it still boils down to what area is most important to you. If size/weight is the number one concern, then you may not like the lesser output of a light-weight sub. But if you only need a little suplimental sub sound anyway, then a small sub may work well for you.

Go test drive some subs at a store if at all possible, and pick what sounds best to you and that you can still carry yourself. KV2 has some good stuff. Compact size and awesome clarity and powerful output, but still a bit heavy, and higher price than cheap stuff. Peavey makes some large and heavy subs with great sound and high output at a lower price than competitors of same quality. Bose makes the ultimately small and light weight but at a very high cost and sacrificed sound quality and less output volume.

dokai · Posted: Mon Feb 18, 2008 5:54 pm Post subject:

Ditto what Bartman said.

I'm going to add something else to the mix: placement. Subwoofers are very sensitive to placement in the room.

Some tips...

NEVER place the output end of a sub between 2.5 feet and 8 feet from the wall because the back-wave that bounces off that wall will be 180 deg out of phase and will partially cancel the output of the sub. Closer to the wall and the back-wave is below the frequency of the sub, farther away and the waves are above the frequency of the sub.

ALWAYS try to couple your subs and take advantage of boundary reinforcement. Place the subs side-by-side for acoustic coupling, which will give you up to 6db increase in bass. And if you can point the subs into a corner of the room, you'll see an additional 6db increase. That's a HUGE increase in the output, equivalent to quadrupling your amp power.

Keep all of that in mind when you're auditioning subs. If you have a small/light sub that is REALLY close to what you need volume-wise, you might be able to squeeze more out of it by using those placement tips. However, we frequently don't have any choice about where our subs go, as the venue or client says "Put your speakers over there" and we're stuck with the result. Coupling the subs is usually easier to accomplish at most venues compared to corner-loading. Also, using your subs as bases for your tops is probably one of the worst things you can do, as you're throwing away a lot of output that you could have had if you'd coupled the subs together and put your tops on tripods.

Good luck!

TheBartman47 · Posted: Thu Feb 28, 2008 12:16 pm Post subject:

dokai wrote: NEVER place the output end of a sub between 2.5 feet and 8 feet from the wall because the back-wave that bounces off that wall will be 180 deg out of phase and will partially cancel the output of the sub. Closer to the wall and the back-wave is below the frequency of the sub, farther away and the waves are above the frequency of the sub.

The advice is spot on, but the frequency part is reversed. Closer to a wall and the reflected out of phase frequency is higher, and further away the frequency is lower. At about 3.5ft. from a boundary (floor, wall, other) makes 80Hz out of phase (chest pounding thump frequency), and about 7ft. from a boundary will result in 40Hz being nullified (the low rumbly felt frequency). Most subs start rolling off lower than 40Hz, so this is why at MINIMUM 8 ft. from any wall, and a sub's high frequency limit can be anywhere from 100Hz to 150Hz (I don't recomend anything higher than 150Hz as it tends to start mudying the vocals). If you got subs that can go down to 20Hz, then you'd have to keep them at least 14ft. away from a wall.

Quote: ALWAYS try to couple your subs and take advantage of boundary reinforcement. Place the subs side-by-side for acoustic coupling, which will give you up to 6db increase in bass. And if you can point the subs into a corner of the room, you'll see an additional 6db increase. That's a HUGE increase in the output, equivalent to quadrupling your amp power.
If you put a sub in the corner, you actually get about 9dB increase... 3dB from the floor, + 3dB from the side wall, and +3dB from the back wall. Also, don't "point" it in the corner, but place it in the corner facing outward.

Coupling two subs together in front gets +6dB increase; +3dB from the coupling effect, and +3dB because you also doubled the total power devoted to subs.

dokai · Posted: Thu Feb 28, 2008 7:40 pm Post subject:

TheBartman47 wrote: Closer to a wall and the reflected out of phase frequency is higher, and further away the frequency is lower. At about 3.5ft. from a boundary (floor, wall, other) makes 80Hz out of phase (chest pounding thump frequency), and about 7ft. from a boundary will result in 40Hz being nullified (the low rumbly felt frequency).

Oops. :oops: Yeah, that's what I meant. Good catch, Bartman! 8)

Quote: Most subs start rolling off lower than 40Hz, so this is why at MINIMUM 8 ft. from any wall, and a sub's high frequency limit can be anywhere from 100Hz to 150Hz (I don't recomend anything higher than 150Hz as it tends to start mudying the vocals).

I always recommend 120hz as a limit, with lower being better as long as your tops can support it. It's less important if your subs are near your tops, but much above 100hz and you can start localizing where the bass is coming from. You don't want that disconnect and the mud that results. Most decent tops can get down to 100hz without too much effort.

Quote: If you got subs that can go down to 20Hz, then you'd have to keep them at least 14ft. away from a wall.

Or put them really close to the wall.

Quote: If you put a sub in the corner, you actually get about 9dB increase... 3dB from the floor, + 3dB from the side wall, and +3dB from the back wall.

I wasn't counting the first 3db because I was assuming the sub was sitting on the floor already if you're corner loading it, so it'd be a 6db increase over just sitting on the floor. But you're right, it's 3db per boundary and corners count as three boundaries.

Quote: Also, don't "point" it in the corner, but place it in the corner facing outward.

That depends on the size of the sub. The driver on some larger subs would be greater than 30" away from the boundaries if you corner loaded them facing outward, resulting in some cancellation, as mentioned earlier. In the case of horn-subs, you'd have to measure from the boundary to the mouth of the sub, and you can easily exceed the 30" limit on larger horns.

Here's a great article on sub placement, courtesy of Bill Fitzmaurice's website. It focuses on horn-subs, but the ideas still apply. (Corrected. Thanks sddj!)

sddj · Posted: Sat Mar 01, 2008 3:24 pm Post subject: Re: The Perfect Sub?

Sorry Dokai... you meant "Bill Fitzmaurice"...??

dokai · Posted: Sat Mar 01, 2008 5:21 pm Post subject: Re: The Perfect Sub?

sddj wrote: Sorry Dokai... you meant "Bill Fitzmaurice"...??

DOH! Yes, I meant Bill Fitzmaurice. I have a client named Fitzpatrick.

Man, I just keep shooting until there's none of my foot left, don't I? Just don't tell Bill! :oops:

TheBartman47 · Posted: Mon Mar 03, 2008 5:46 pm Post subject:

Yep, folded horn subs you can do even more tricks with wall placements and get crazy results!