Do I need a subwoofer? If yes, one or two?

I have a pair of Focal Supra N2 in my 15 X 13 X 9 feet dedicated 2-channel listening room. The speaker is rated 34Hz +/- 3dB and 28Hz -6dB. In my room, when measured using the RadioShack SPL (slow, C-weighted) at my listening position, the frequency response is pretty flat from 40-200 Hz, +/- 1dB, then 31.5Hz -4dB, 25Hz -10dB, 20Hz -18dB. I listen to all kinds of music, solo voice, solo instruments (listen to many piano and violin), chamber, full scale orchestra, jazz, pop, etc, exceptions such as hard rock or heavy metal. Do I need a subwoofer? If yes, one or two sub? One example of a sub spec, sealed acoustic suspension, 20-200Hz, adjustable low pass filter 40-150Hz, a fixed 24dB/octave crossover, and 1200 watts amp. Thanks in advance.

Recommend reading Floyd Toole’s book “Sound Reproduction”. It will explain why it takes 3 or 4 subs to get proper bass in a residential setting. It has to due with how bass waves propagate in a ‘small’ room.

I have (3) 10" inexpensive subs, 2 professional ported that each connect my DSJ to JBL 708P monitors, the 3rd is a nice sealed unit that is located 2/3rds the way back along the left wall. The professional subs are located near front left corner and 4ft from front right corner along side wall. This dispersed bass source is the key for flat. response across the room.

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Considering the existing setup, and environment in which it’s in, I would question if there’s a point while listening to music that you felt the bass insufficient? If You did feel that you wanted to augment existing bass response, I’d suggest something in the lines of a sealed sub-woofer system with no more than a 10" driver, possibly with a Passive radiator, such as the Definitive Technology SuperCube 6000 series.
Have you tried relocating the speakers or re-arranging the furnishings?

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I have conceded the notion that subs, when implemented correctly, always improve the overall sound. That’s not to say going without subs can’t be enjoyable or without slam.

Best of luck to you.

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Subs are like Lays potato chips, not one can just have 1.


Two of my basic premises for high fidelity is to play the full frequency and volume range of music (feel free to exclude deep organ music). So at a minimum a stereo system must be capable of 30-20,000 Hz at up to 110 dB. But the room and setup must also be taken into account. Big floor standers can seemingly often bass overload a small room, but the reality is that they are poorly positioned to generate a flat in-room response.

Most will concede that the best location to generate mids/highs from is away from walls, yet the best locations for generating bass is not. That’s where sub(s) come in. If you read Toole you’ll find out that to even out in-room bass response across the full range of frequencies you need multiple subs, ideally setup near the corners of the room.

Getting back to my premise the challenge is finding affordable, domestically friendly sized subs that go deep (with multiple subs high output is secondary). My favorite is the Rythmik L12 (a small sealed $539 audiophile sub). A good alternate for me has been the PreSonus T10 (a small ported $400 professional sub that allows use of XLR input/pass throughs). If you’re open for DIY, CSS makes very nice drivers/amps.

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IMHO… yes you do need one. Two is perfect if you have the budget and space but one is good enough and improves the sound a whole lot compared to “no sub”

I only use one 12in sealed sub in my system.

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I also have dual Rythmik L12, highly recommended.


Yes you need subwoofer(s). The most important thing with subs is, as Jim mentions, output. The more linear the subwoofers output at your desired listening volumes, the better it will sound. If you can hear the presence of a subwoofer it is having to work too hard to do the job you want and distorting. When subwoofers distort the harmonics range upwards into frequency ranges you can locate and also muddying up the mid bass that is so critical to the overall sound.

Most people think systems like the IRS Vs are overkill, but one reason they sound so good is the subwoofers d not have to work very hard to do the job, they are walking not running, most of the time.

Your room is over 1750 cubic feet in volume. If you have door ways that you cannot close, you add to that space. Subwoofers are effected by the entire space they occupy.

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Whether you end up with one or more, I find a continuously adjustable phase knob invaluable to blend with my mains. It’s as if not more important than gain.

I had one and it was okay. Now I have two and it is wonderful.

I recently added an inexpensive 10” REL sub and it has made a tremendous difference. Would’ve gotten the Rythmik but shipping to Hawaii was really expensive and Amazon shipped the REL for free.

The sub has tied together recent upgrades of speaker cables and the Matrix. The sub has proved to be my favorite upgrade since the DSJ itself.

Subs simply extend the range of your speakers, and you usually should not “hear” them. If set up properly, your speakers just sound freakishly bigger than their physical size would suggest (with your eyes open).

Two, sealed, which can (and should) be placed where they sound best (i.e. do not reinforce the room’s humps) if possible, never in the corners, preferably (at least to begin with) at points a quarter or third of the long dimension of the room along the side walls, as they interact with the room (with respect to the listening position) massively.

Also - placing them nearer to the listening position has the added potential benefit of the ability to time-align them with the mains, as opposed to simply phase-aligning (x-cycles behind). If the subs are placed further away from the seating position than the mains, you cannot time-align them without DSP, which adds an unwanted layer of shizz vs. achieving it physically/acoustically.

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Why does REL say to put them in corners?

They all say to start there but that hardly ever works. Plus it’s get’s them out of the Wife’s direct line of sight so you can buy more.

There are many philosophies. Not sure what their notion is on that. It is all the more surprising in that many if not all of their designs are ported, which is another thing I typically can’t subscribe to in a sub. But this is my thing based on my experiences and taste. Putting them in corners used to be seen as the best way to get the most apparent output from any sub, as the reinforcement of three surfaces jacks up the room response. Boom for the buck. It also multiplies the resonances, so - dunno why they would say that.

Imagine how much DSP would be required to “fix” the room response of corner-placed subs. Boggles the mind ; )

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What are your favorite subs? In your opinion, is the hi level input something to seek out?

I suppose this is one of the other primary differences in sub philosophy - run off the amp, or line level? I get the idea of having the amp feed them, but don’t feel that it is as big of a deal as either being a sealed design or not placing them in corners, which to me have a far greater effect on the sound. So it isn’t a criteria that I think is that important one way or the other.

Don’t have a lot of current experience with what’s out there, but have been a JL Audio fan for a long time, as they are musical (can produce deep bass notes that actually sound like deep bass notes rather than low-frequency effects) are built like tanks, and have a fair amount of built-in adjustability. I also have a pre with two sets of line outs, so feeding them isn’t an issue. I’ve certainly heard RELs sound fine as well. Another of these taste and synergy things, ultimately.

If you were talking about REL subs, none of them are ported. I may have read your post wrong though.

Hunh - could’ve sworn they used to be. Owned one once. Don’t keep up with it though.