One or Two Subs

**Tommy** · **05-19-06, 07:21 AM**

Ok NDawag convinced me to return the in-wall sub I purchased but I havent seen him online much since.

I've been hearing different things recently of whether I should do one larger sub for the room or two smaller size ones. Thoughts?

The basement room is 20' x 14' with cement floor and one riser.

**Sonnie** · **05-19-06, 10:57 AM**

E has his hands full right now with a new baby boy.

Remember your room is almost the size of mine and I have two SVS PB12-Plus/2's. I had just one hooked up for a night and then hooked the other up the next night... NO lookin' back! I can't figure out how I ever lived without two... and for those two subs you actually get 4 x 12" subs with about 1800 watts total power.

But I forget... you were originally considering in-wall so you might opt for the cylinder subs... a pair of those would be awesome as well.

Either way... whatever you get... go for two, one in each front corner and you'll never have to ask yourself, "what would two subs be like"... and I won't have to whoop you over and over about not going with two.

**toecheese** · **05-19-06, 10:59 AM**

Get an IB!

**JCD** · **05-19-06, 12:20 PM**

An IB might not be a bad choice for you. If you drink the KoolAid (I love that metaphor) over at the Cult, then I think you have an ideal situation for an IB. It will give you the "in-wall unit" you were originally looking for, but also give you that ohmygawdthat'samazing kind of bass that I think was missing from your previous unit. Given the size of your room, you may need to get 4 or 6 15" drivers.

If you're going to go with the stand alone sub, SVS is the way to go. I'd e-mail Tom V. with your room dimensions and ask for his opinion. He'll tell you what he thinks will work best in your space, with no bias towards the more expensive stuff. He'll also give you his honest opinion on whether or not a dual sub arrangement would be worth it. He'll also get back to you

The IB Pro's
Cleaner appearance-- they're in wall after all
Bass is supposed to be better
Figure ~$250 for the amp, ~$100 for the BFD, then the cost of the drivers. Depending on which way you go, you can spend between $100 and $300 per driver

The SVS Sub Pro's
Much easier to set up
SVS is a great product. I think the IB will be better overall, but the SVS is no slouch.
Great customer service
Cost for their subs run from $429 to ~$1200, well, they also have one over the top ridiculous sub for ~$2000

JCD

**Sonnie** · **05-19-06, 03:30 PM**

If I'm not mistaken I think he decided he has no place for IB. Of course Tommy will know best and will certainly chime in. We discussed in one thread about using the Store room and I can't remember what the reasoning for not using that was... but he did decide he really didn't want to cut into the wall right in that location anyway.

Now that soffit he built on the front (if he leaves it up)... that might be an option for IB... not sure if that's enough volume though for four drivers.

**JCD** · **05-19-06, 04:01 PM**

I missed the earlier thread where he decided he couldn't do the IB.. however, the soffit should have enough volume. The entire volume is supposed to be a minimum of 4 times the Vas of the drivers. I took a look at one of the Parts Express IB drivers. Its Vas was 9.92ft^3 per driver, so as long as the soffit has 160ft^3 he should have enough space in the soffit alone. More, of course, is better.

My main concern is if there is enough distance for the back sound wave. I don't know all of the physics involved, but seems to me that if he flush mounted the drivers on the front side of the front soffit, there would be enough space for the back sound wave.

JCD

**Josuah** · **05-19-06, 04:46 PM**

Sonnie, have you pushed your subs to the maximum to see if you actually need those four drivers? Just wondering. I've got a pair of SVS 16-46PC+ subs in the 12Hz tune, and I will hit 110dB maximum at my seating position, 105dB max at lower frequencies. My room is open to the rest of the house and over 5000 ft^3. So, I will need two more subs to hit 115dB maximum, which is my target for reference level playback.

**Sonnie** · **05-19-06, 05:56 PM**

I could live with one sub (which would include 2 drivers)... but having two subs there is a noticeable difference in overall sound. Maybe less strain on each individual sub and more of a pressurized feeling. I had to cut down the volume on the subs after listening for a short while... it was just too much, but it still sounds better than just having one. Maybe it fills a void or something, I don't know. Somebody probably knows more about the technical advantages than I do. I'm just a hillbilly.

**Phil M** · **05-19-06, 06:55 PM**

I asked the quetion to SVS 2 years ago when finalising (English spelling) my HT. I emailed a drawing and they recommended one sub.
Morale of the story - get in touch with Tom and he'll make an expert recommendation.
The air is different in Hillbilly land - that's why Sonnie needs 2!

**Tommy** · **05-19-06, 08:27 PM**

Quote:

Sonnie wrote:

E has his hands full right now with a new baby boy.

I should have said I'm trying not to pester him because I know he's busy.

Anyway who is this Tom guy?

I havent thought much on it till the guy that came out to give an estimate suggested getting the two speakers instead of the one.

All I know is if I do finish it myself I still need to ask some wiring questions about it soon. Like whether I'm wiring for one or two speakers

what type of wire to get
should I get it with the connections already on the ends or not
and how to get it thru the wall so its not just popped out a hole in the sheet rock...

**Josuah** · **05-19-06, 09:08 PM**

Two subs can certainly result in better overall response depending on placement. I used to have my pair of subs next to each other in the same place, and now I have them separate: one on each side outside of my left and right speakers. This placement got rid of a null and resulted in a flatter overall response.

**Sonnie** · **05-20-06, 12:41 AM**

Quote:

Tommy wrote:

Anyway who is this Tom guy?

Tom is one of the owners of SVSound (SVSubwoofers). All of those guys are very helpful and you'll never hear them downgrade another company nor anyone who doesn't wish to buy their subs. Their customer service is literally second to none.

He is a member here and I'm sure he'll chime in... but I would recommend giving him a direct call... or email him.

Quote:

Tommy wrote:

All I know is if I do finish it myself I still need to ask some wiring questions about it soon. Like whether I'm wiring for one or two speakers

what type of wire to get
should I get it with the connections already on the ends or not
and how to get it thru the wall so its not just popped out a hole in the sheet rock...

If you are going to purchase a sub or subs like the SVS subs, then you will need to decide where you are going to locate them... generally as far into the front corners as possible. If you decide on this location then you can run some RCA cables in wall from where ever you will have your BFD located (don't think for a minute you aren't gonna own one

who knows... you may get lucky and win one... either way plan on a BFD) then run them to where you will locate the subs. You can get some good cable from Apature (link in Components forum up top). Or you could get some RCA plates (N-Dawg can probably help you there) and mount them ... have your installer terminal some cable for you. Then you'll need a short cable to go from the plate terminal to your sub. Or... if you want to eliminate that extra connection in the wall plate you can get a solid plate and drill a hole and run the cable through.

**kingkip** · **05-20-06, 11:22 PM**

One sub, especially a SVS, will probably do, but two will almost always sound better. Subs are all about displacement, double the drivers and your subs no longer have to work as hard to put out the same spl and that means less distortion. ie an ib

BTW if an ib is an option I will side with the other guys and say go for it.

**JimP** · **05-20-06, 11:48 PM**

Quote:

kingkip wrote:

One sub, especially a SVS, will probably do, but two will almost always sound better. Subs are all about displacement, double the drivers and your subs no longer have to work as hard to put out the same spl and that means less distortion. ie an ib

BTW if an ib is an option I will side with the other guys and say go for it.

....and if you check some of the test where the frequency response is plotted at various SPLs, you'll find that many subwoofers loose their bottom end the louder they're played. The workaround for this is to use multiple subs so that when you reach those sound levels, you're still at the flat part of the subs operations.

**Josuah** · **05-21-06, 01:02 AM**

An infinite baffle supposedly requires double the drivers because you are throwing away the reverse excursion? This is what I've heard at least. It's supposed to sound cleaner also as a result, because you never deal with the reverse excursion, which is not going to be identical to the forward excursion.

As JimP mentioned, all drivers have a harder time reaching higher SPL at lower frequencies. So you either need a lot of surface area to move back and forth a little (multiple drivers) or less surface area to move back and forth a lot (greater excursion). Since drivers are physically limited in their excursion, multiple drivers is a simpler solution.

If a driver attempts to move back and forth past their physical limit, that's called bottoming out and you'll hear clanks or clacks. That's okay if it happens once or twice, but if you keep pushing your sub that hard you can do permanent damage. I'm led to believe that a sealed subwoofer cannot bottom out because the sealed volume within the enclosure will prevent that, if properly matching the enclosure, driver, and amplifier. But I'm not entirely sure of that.

**Tommy** · **05-21-06, 07:44 AM**

For 2 subs, how is it wired?

**pierrebnh** · **05-21-06, 12:19 PM**

How many sub outs do you have? Many AVRs have 2. Otherwise a Y-splitter with each sub having their own EQ I would think gives the best results.

**Josuah** · **05-21-06, 01:09 PM**

A lot of people seem to want to EQ each subwoofer independently. I haven't been convinced of any benefits to doing so instead of EQing all subs in aggregate.

Gene (I think) over at Audioholics indicated his preference would be to EQ a single sub to avoid introducing delay problems, but I'm still not sure what he was getting at there. An EQ in the path will certainly introduce some further delay, perhaps not constant across the modified bands, but I'd imagine it would be easier to deal with that if that delay was introduced to all subs rather than one.

**JimP** · **05-21-06, 01:46 PM**

If you do that, you also benefit from using the exact same sub, which is probably not what most people are doing.

**Josuah** · **05-21-06, 01:52 PM**

Why would using the exact same subwoofer matter? Phase differential as a function of frequency will be different between the two regardless. Unless by some magic the delay introduced by the EQ unit makes one sub's group delay function match the other sub's, except in amplitude. ???

**Sonnie** · **05-21-06, 03:04 PM**

I have identical subs symmetrically placed in the two front corners. I eq them simultaneously with one channel of the BFD. I believe I added one foot to the distance setting to compensate for the delay (per brucek's instructions in his review and testing of the BFD).

**pierrebnh** · **05-21-06, 04:45 PM**

My apologies, I should've said most flexible instead of the more sbujective best. Obviously there are arguments for doing it either way.

**rcarlton** · **05-21-06, 09:38 PM**

For an interesting take on two subs see: two subs

**Sonnie** · **05-21-06, 10:29 PM**

Hey Ron.... he seems to recommend stereo subs... but this would be hard for most wouldn't it? Most sub pre-outs are mono I think aren't they?

I still question too how much stereo sub information is present in the LFE channel... I've always thought it was mono...

Maybe I'm confused... which wouldn't be a surprise.

Advertisement