Two subs makes my system sing. I recommend it for everyone!!! (1 Viewer)

[Jeff_Rice]

Hi,

I just added an additional sub to my system for the rear speakers. I did not realize how much low bass information goes to the rear speakers. It really adds to the realism to the movie and everybody should consider adding one. I thought with the sub in the front would take care of the room but man when something flys by in the (ie. Phantom Menace) rear all the low is just from the rear. It is low and loud.

What do you think of all this?

My system:

Receiver - Denon 3801

Amp - Harman Karden 2.1 Signature

DVD player - Pioneer DV-525

CD player - Kenwood (low grade stuff)

Audioquest interconnects and speaker wire

Polk Audio Speakers RT800 (fronts), CS400 (center), RT55i (rears), and RT35i (rear center).

Velodyne CT120 sub(front)

Velodyne CT80 sub (rear)

Room size 26 x 13 x 8

Jeff

 

[Legairre]

Jeff,

I know exactly how you feel. I have 2 250 watts subs for the LFE and last January I added 2 150 subs to my surrounds(speaker level connected of course). Man talk about all the bass in the surround channels I was missing. I run my surrounds as large and they get a full range signal. Just like having full range speakers in the rear of the room. Everything sounds sooooo much filled in now. Almost like filling a hole.

Enjoy that bass.

 

[Luis C. Ortiz]

Same here! it's amazing how much information goes unheard with out a Sub it the rear!! I've been using it for months and wont have it any other way!! I recommend everyone try this!

Luis

 

[Neil Joseph]

I haven't finished building my second sub yet but I will try it as a dedicated rear sub and see what I have been missing. Can you recommend some movies that have a lot of rear sub info?

 

[Jeff_Rice]

Neil Joseph,

Movies that will rock you rear speakers are:

Phantom Menace

Saving Private Ryan (tanks scenes)

The Patriot (battle scenes)

Fast and the furious

U571 (depth charge scenes)

Gladiator (I have not tried this yet but will tonight)

Many more I am sure.

Does anybody know any other movies?

Jeff

 

[BryanZ]

Add in JP3 (looking forward to seeing Tom's waterfall chart for that one) and Titan A.E.

 

[Legairre]

Rajee,

The reason for having rear subs is to put the bass where it was originally intended to be. I'm not talking LFE. I'm talking about bass the same way a certain amount of bass is intended to go to your front speakers. With my receiver I can set my fronts to large and have ONLY LFE go to the sub. All non LFE stays in my fronts. By doing this I get a much fuller soundstage than setting them to small and rerouting all my non LFE bass to my sub.

When you add subs to the rears by using the speaker level connections. Th subs get all the frequencies below whatever crossover point you choose(my rear go down to 75hz so I set the rear subs crossover to 72hz). By setting the rears to large you are actually turning your small rear speakers into full range speakers(don't confuse this bass with the LFE signal).

For instance when a movie like the Patriot was mixed with an explosion in the left rear speaker. That sound was ment to be heard in the left rear speaker. Otherwise the person who did the mix would have put that explosion in the LFE if they wanted it to go the the LFE subwoofer. Having that explosion come from the left rear and not LFE subwoofer in the front of the room makes a huge difference in the impact a movie has in terms of realism. Isn't the feeling of actually being there in the battle what were all after.

Also cancellation is not a problem because unlike LFE bass. The non LFE bass is not going off in all the speakers at the same time. You might have bass from the left front or rear at one point in the movie and bass from the right front or rear at another point in the movie.

I'd NEVER put mutiple LFE subs in the front and rear of my theater. This would definately cause cancellations, but turning the surrounds into full range speakers and keeping NON LFE bass where it was intended to be? Yes I'll always do this.

 

[BruceD]

Legairre,

I think a lot depends on the capability of the receiver's crossover, room size, speakers, and the actual crossover frequencies used. Whatever you're happy with is what's important.

But in most cases I do not believe you would be able to tell the difference between bass correctly re-directed by the receiver to front sub(s), which have the ability to correctly deliver the high SPL levels needed by this re-directed bass + LFE, and that of an additional rear sub.

In most cases it is just simply that you don't have enough bass capacity (subs) in the front location.

Bass management (re-directed bass from other speakers) puts a huge demand on a sub, and many subs don't really have the ability to handle this increased load plus the LFE at the same time properly.

Remember re-directed bass frequencies (typically those below 80Hz) are NOT directional, i.e. you can't tell where they originate from. Rajee is also right on cancellations.

Now the LFE is something else, because it's defined spec for frequency response is in the 20Hz-120Hz range.

What I'm really trying to say is that you may get the same results by simply stacking both subs in the front corner and letting them share the entire load as you get from adding a rear sub (of course speaker settings large/small will need to be changed). It helps if multiple subs are exactly the same model.

BruceD

 

[Legairre]

Bruce,

I have identical dual 250 watt 12 inch subs for the LFE in the front. Definately not a problem with bass here. I can easily cause maritial problems with my front subs. And the bass in the rears can easily be noticible(dual 150 watt 10 inch subs. One for each pair of surrounds). Real nice full sound in movies. With all the effects where they should be(not redirected). I was skeptical before adding the rear subs. Now I'll never go back. Any of you are welcome to come over anytime. When you leave you'll be shopping for rear subs.

 

[BruceD]

Legairre,

I don't have the actual numbers, but your fronts probably don't provide enough SPL capability (depends on room size and room openings). I remember some comments by the SVS folks that in many cases two humongous HGS-18" subs from Velodyne aren't enough for proper LFE and re-directed bass level SPLs in many rooms.

Bass sound effects below an 80Hz crossover frequency can't really be identified as to source location (front or back).

Again, it's about what makes you happy.

BruceD

 

[Legairre]

Not enough SPL from my fronts subs??????? Tom N. The sub expert has shown that only one of the subs I have will do 25hz at a SPL of 105 dbs and I have two. I can't even get close to running at reference level with my dual LFE subs(yes they are AVIA calibrated). Not because I don't have enough SPL. But because it way too much bass. The house feels like it's going crack it's foundation. As for stacking them. I've tried that and in my room it put way to much bass on one side. So splitting them up worked much better.

I'm not quoting from articles I'm talking real world. Books can tell me how to drive a car, but in actuality it's much different. The same goes for sound. Every room is different and in my room rear subs make a huge difference.

 

[BruceD]

With bass management engaged on a receiver/prepro, I believe the requirement is somewhere around 125dB SPL capability from whatever is connected to the sub-out.

BruceD

 

[Legairre]

125 SPL? And at what frequency? Reference SPL is 115 SPL from the subwoofer. 120 SPL is the allowable bass limit without hearing damage. What sub do you know of that can hit 125 SPL at 20-25HZ? An SVS ultra with the S1000 1000 watt amp has a frequency range of 10hz-20khz at 103db SPL. All this doesn't change the fact that rear non LFE subs are a benifit to home theater. Having rear non LFE subs is the same as having a full range tower or bookshelf speakers for surrounds. I guess full range speakers shouldn't be used in home theater either?

 

[Jerry AZ]

I have a question. I have all of my speakers set to small, and the sub on the sub out of the receiver. If I set the rear surrounds to large, would this effect the operation of the sub like setting the fronts to large?

Thanks.

 

[Legairre]

Jerry,

I'm not familiar with the bass management on the 595. But on my receiver if I set the rears to small it has no effect on the sub. Mine gives the following large options with a sub:

Large Fronts and subwoofer play all frequencies.

Large Fronts and sub plays only LFE.

Also I have to set my fronts to large in order for the rears to be large.

 

[John H]

With bass management engaged on a receiver/prepro, I believe the requirement is somewhere around 125dB SPL capability from whatever is connected to the sub-out.

That's 121dB/at the seats/down to 21-24hz. According to the FAQ's at the SVS site*
John

 

[BruceD]

John,

Thanks for pointing me to the right number.

BruceD

 

[Jerry AZ]

Thanks Legairre. I'll have to play with it somemore.

 

[Bob_A]

Legairre, what kind of main speakers do you have? They are near full range speakers? Thanks.

 

[Jeff_Rice]

Wow, I am really surprised in the responses I received for my statement.

I did a little testing last night with Saving Private Ryan tank scene (near the end of the movie).

When the tank turns into the town and the guys are putting the sticky bombs the bass is coming from all over. But, and I mean but, when the actor Ed Burns is facing the camera the bass is only coming from the rears. When I turned the rear sub volume off the bass is ok, but I turned the volume up it made a world of a difference. It sounded correct with the sub hooked up.

You should not have your front sub do the work because the sound is coming behind. Basically, get a rear sub and set your rear speakers to 'Large'. You will dig it!

P.S. I watched a little of JPIII, the T-Rex and other man eater dino scene was fantastic. Take a listen.

Jeff