SVS 25-31pc Plus. ? (1 Viewer)

[Tom Vodhanel]

Hi Steve,

Well, I'm not here to tell you your preferences are wrong.. We just need to be sure that the system can handle the stress your preferences will put on it...particularly the subwoofer. Based on your text above, it appears as if you push the system to reference levels(and even slightly above) on occasion. This isn't that unusual...many home theater enthusiasts enjoy reference level playback on their favorite DVDs. With all speakers set to small(and everything properly calibrated)...the subwoofer can be required to produce 121-125dB to your key seating positions. If you like the bass 4-5dB on the hot side...this ups it to 125-129dB.

So there is no wonder why the single 25-31PC+ is straining.

Even in your smaller room...the 25-31PC+ might not offer enough output for you. But I would wait until you have a chance to setup the system in the new room before making any final decisions.

Tom V.
SVS

 

[steveGamble]

Tom...
Just to let you know.
I had the SPL meter 4 feet from the sub during the DVD Alien vs Preditor.
It peaked at 105db during most action scenes.
or the mains did ?...hard to say what was moving the needle?
seemed like the sub.... but that's how loud it was.
that is where it started to thwack.. a bit so I turned it down, and began asking for advice to get a bit more SPL.
I will NOT turn it up like that again, just so you know... until everything is set up proper in HT rm.
thought I'd pass that on.
I think 125db would actually hurt ? from what I hear..

 

[TimJC]

125db would do more than hurt, and after that you'll be hearing less anyway...

Please be careful out there.


Tim

 

[Geoff Gunnell]

Steve, I have no experience with Rti's.

Occasional use only for your second row will make everything much easier.
Deaden the rear area as you can -- simple drapes and wall hangings will reduce unwanted reflections.

Absolutely keep your cht-10. Multiple subs are great! You can try one sub in each front corner, or near each main speaker, or co-located. From what you describe of the power of bass you desire, a second 25-31 might be a future upgrade

 

[steveGamble]

I like the idea of multiple subs....I don't know much about "cancelling out" issues ? Is this something I can test and adjust with test tones, or a calibration disc ?
Or is it easier to stack them as far as having them in synch ?
one down firing, one front firing.... might be easier for me to place them in each front corner though.
How many Subs can you have ? different tonal qualities in each would make quite a bang perhaps, or in the end just sound like MUD, or causing everything to sound a little distorted ?

 

[dany]

Stay with one sub,your having a hard enough time as it is.

 

[Geoff Gunnell]

It's not THAT hard to do multiple subs -- in fact you often HAVE to in order to get enough SPL. An example you've just experienced yourself , Steve: You had your 25-31 12" driver going full stroke -- and its a great driver in an efficient cabinet -- but it couldn't fill your big room.
Think of it this way: You've got a little 2" - 3" coil of wire wound on a bobbin connected to to a 12" cone --- and you want this little thing to transfer hydraulic pressure pulses through the air strongly enough you can feel it.
It's not all about SPL, though. You don't want your drivers to have to "excurse" to their limits -- that generally means more distortion. More drivers means each one has to move less for the same SPL -- since it's easier for an amp to control a driver's movements if they are smaller, that means better transient reponse when the driver is not operating at its limits.
Another benefit of multiple subs CAN be a smoothing of the frequency response at your listening position IF the different sub positions excite the room resonances differently. Finally on a more subjective note, many folks say stereo subs sound better, broaden the soundstage. That's tough to justify on a theoretical level -- I don't want to start an AVS thread here --
it depends on a lot of factors.
For quite a while Tom V had two B4's in his room -- that's 8 12" drivers. That's enough radiating area so nothing has to work too hard.
Think of it this way: Back in the 'old' days (I'm in my 50's) we put woofers in our mains. No-one would have thought it excessive to have mains with 12" woofers powered by a big solid state amp -- that's TWO 12" drivers right there -- and even back in those days folks generally got more if strong bass was desired. Nothing new...
Is it hard to blend subs in different positions? Not really -- but I agree with others here that you need to finish your room first
One thing you CAN do now: When you get ready to "nail down" your seating position, drag at least one sub down there and find the nulls in the room. Place the sub(s) where they're likely to go -- front corners or near the mains -- and make SURE you are not putting your seats in a null.

 

[steveGamble]

Yes Dany, I believe your right.
I just went out and bought a monster cable to play both the 25 13+ and my CHT 10. Together.
ok....matrix ch 15 fight scene.
both subs adjusted close, with gain and freq. using my SPL meter 2 feet from ea. sub.ona at a time, ea. sub 12 feet apart. along a wall , 2 feet from a corner.
turning one down...then going to the other....back and forth...
They both give very close spl reading of 108db , master volume at -18.5
But ....The cht 10 , is louder than the 25-31+ as far as what I hear with both playing.
Now...I believe that is because the cht 10 has a MUCH higher tone that you hear....and The 25-31+ has a lower tone you feel... they're both set at 100hz..
SO.....I hear one and feel the other.... but it is hard to feel the svs with the cht10 filling my ears...
They BOTH will start to distort beyond the 108db. but the svs bottoms out.
the cht10 just starts to sound distorted it doesn't bottom out.

So...I may upgrade as I want to have clean output at about 110 -111db
But will the same tone be in say a PB12 NSD/2.?.. LOW bass you feel not hear ?
I need to get used to clean bass, but I notice the cht 10 plays sounds that dissapear when I switch to the svs, which is why I thought use both subs ?
and....
I tried to put in a blocker and change to 20hz , I heard no difference?
But that may be a testement to the poor room I am currently in.
or the source material.?
I won't make a final decision until Tuesday after I move the sub down to the new room.
I'll post my results then.
I'll be using the Avia disc as well. :>)

 

[steveGamble]

Thanks Geoff.
I should be testing the room Tuesday.
The seating position won't be able to change, Almost 8k, and my wife has been designing the room around them. I have a open spot for two subs front corners just outside the mains.
BUT what about subs of different tones ? They sound SO... different.
By the way...I'm 38 and have speakers with two 12 woofers and a tweeter in ea. I remember the day they were common in living rooms. maybe still are.
they weren't great for dolby digital. so I bought polk RTi 's ....
I thought I'd get more than 106db before risking bottoming the driver..
and I can't get over that missing top end, love the feel of that thud the chest when a door slams in a movie, that isn't there with my new sub ?
Is that because my old sub artificially produced an exagerated sound there.?
It was nice to hear.
does it make a difference front firing, bottom firing ?

 

[dany]

I dont buy the 2 subs gives that much more spl. Really,i'll take 1 good one every time.

 

[steveGamble]

You know,,,I agree one good sub would probably ,sound better, but...
If one monster sub just feels inadequate, then what other choice is there?
Buy two of the monsters...and keep going intil your satisfied. Right ?
There comes a point where you have to say that's all you gonna get...so deal with it..
more to life than subwoofers.
Just not for me .. just not right now..

 

[dany]

I'm running a SVS 20-39pci in a 16X14 room that opens up on one end and the back side to more like 35X25 and i have plenty of LFE.

 

[Geoff Gunnell]

Danv, I'd rather have separate subs for each channel

Steve, your issue with the 25-31 mid bass needs more explanation than I have. The 25-31 should be producing more mid bass than the cht-10. Plug two ports (16Hz tune) -- that will extend low bass frequency-wise but roll it off more level-wise. Move the 25-31 at least 3' from any wall or corner -- that will reduce low bass amplification from nearby surfaces.

As far as using both the cht-10 and the 25-31 simultaneously, it will work fine IF you co-locate them. One key to getting multiple subs working is a continuously variable phase control -- I'm not sure if the cht-10 has one.
You want the wavefront from the main speaker woofers and the sub(s) to arrive at your listening position at the same time -- in practice it is as simple as using the variable phase controls to maximize bass output.

Eventually you may wish to invest in a bass equalization system. One method involves a professional parametric equalizer, a calibrated mic, and usually a computer sound card based program to generate tones and display the frequency response. Another method uses a Velodyne product, the SMS-1.

 

[steveGamble]

Thanks Geoff.
More mid bass from the 25 31 ?..not even close.. cht10 is ALL mid bass 90hz..+.25 31 is ALL 30hz
I really wonder if something is not working right in the sub? because in mid bass 60 to 110hz my cht10 is louder to the ear ?, although not to a SPL meter.
and...
I plug ports...no change...play with phase control knob..no change... use internal x over, and play with that 40hz to 120 hz ...no change in sound no matter what I do...Just VERY low rumble bass, you feel it you can't hear it.

The cht10 has only a switch 0 or 180 degrees.
and when I use the internal x over 40hz to 120 hz....huge difference, at 40hz I don't hear a thing, just shuts off, the higher I turn the freq. knob, it gets louder more intense, the upper bass start to pound hard,(you hear it) although too high starts to sound not as good as I loose the low end.
it is a cheaper smaller sub.
combining the two, keeps resulting in the 25 31 dissappearing a little bit, because cht10 produces bass to my ears, thats what I hear.
maybe the X over is stuck at 40hz.
could the SMS-1 test this ?

 

[Roger-C]

I have a 25-31PC+ in a 17x20 room and there is plenty of power. I think it may be a case of you not use to the sound of the sub. Sometimes i think my sub is not working.... but when it hits... it hits big when it has to. I have mine set a 20hz. It does not add emphasis on bass that should not really be there. I think that is what you are use to. Keep in mind that LFE is an effect and if you do hear sound... it is flat.

Also... what movies have you demo? I know when i first got my sub... i was use to hearing bass rather than feeling it. I think that's what is happening in your case also.

 

[steveGamble]

so the bass I used to hear, in the say 60 to 100hz area...I should forget about it. Get it from my mains perhaps. feel only low bass from my sub, because that is the way it supposed to be.?
I like how the upper bass from a sub can make even the dialog sound deeper. the car engine sound deeper. that door slam sound louder, and hit you...
So....?...you don't miss that at all with your 25 31+ ?? Or you have BIG mains to provide those sounds, so you don't miss them at all.
which is why I was considering. RTi 12's polk,
PB NSD/2. +EQ ?

I was deciding at one time between SVS and Earthquake super nova12
But SVS Customer service is SO good, had to give them my business.

 

[dany]

I'm getting the feeling you need to take a few hours to do a proper setup and dial in the right x over. I never here anything coming from my sub,it always sounds like its coming from my mains. To many think if they dont hear it from the sub or surrounds,turn up the spl. Doesnt work that way. Got to get the right setup and then see whats up.

 

[Geoff Gunnell]

Yes, the SMS-1 will show you bass frequency response in your room and allow you to correct it noticably. A Stereophile report starts on this page:
http://www.stereophile.com/musicinth...itr/index.html
I prefer (and own) the SMS-1 -- I think for you this would be a good choice because it is relatively easy to use and sounds good -- but as a person who loves EQ it's only fair to tell you there are many EQ options out there. Still I think the SMS-1 is the best choice for you.

If you have spent $8k on your room already, you are trying for a level of bass performance that can only be achieved by EQ. The reson this is true is this:
The wavelength (in feet) of a sound frequency in air is about 1127 divided by the frequncy in Hertz. For example the wavelength of a 100 Hz tone is 1127/100 = 11.27 feet.
As you can see we all have the bad fortune to live in rooms that have dimensions that are the same as bass frequency wavelengths and half wavelengths. So you can take a sub whose frequency response in the middle of a parking lot is as flat as a flounder and when you put it in a room -- got EQ?
So what I would do is get the SMS-1 now -- in addition to EQing your final sub setup it will help you acheive that setup because you'll be able to see the frequency response curves. If your 25-31 is rolling off above 40Hz you can see it at a glance. Get the Avia calibration disk too -- SVS sells them or Amazon etc.

 

[Roger-C]

Hi Steve,

I guess I did not really explain it very well. I am not very good in expressing my thoughts with words. Before I got the PC+... I was using a passive sub. Man... i thought it was the most awesome sounding sub in the world. Keep in mind that I had nothing else to compare to. The best way I could explain the sound now that I can compare it to the PC+ was it was more boomy. I was use to the mid bass so much... I kind of felt like maybe the new sub was a bad choice. I actually felt depressed (ya i know... pathetic) because I felt the sound was lacking. After everything was calibrated... it added more depth (not boomy) and richness. Everyone's opinion on what sounds good is very subjective.

Just take more time to calibrate it along with your mains. I hope it works out for you as i kind of know how you were feeling. Good Luck.

 

[steveGamble]

Goeff $8K was the seats. The room is up over $30K, including the gear,, and I feel I stayed to reasonable costs with each piece. It adds up so fast.
But soon has to stop, Only (I want a projector screen to slide down in front of my 61" DLP HDTV, just for movies 92" 1:85 to 1 ) One thing at a time here though.
Basically had a $1,000.00 U.S. subwoofer budget, give or take.
I definately feel like Roger did. A bit bummed, as I thought plug and play would BLOW me out of my chair, the way folks were talkng. I ABSOLUTELY neet to take tomorrow evening to calibrate, as I will start moving stuff downstairs tomorrow. Avia disc in hand.
After that....I'll see about a SMS-1 ? .....

Roger, I hear ya.....I do feel the richness, and nice smooth, clean bass, subsonic feeling, for sure......but not blending with the mains yet.
My old sub did indeed feel like it blended with my mains, and it was 15 feet away. my new one is in the front corner, beside my left front..
It is pretty strong down low. but doesn't blend with my mains as they drop off at a higher frequency than where the sub picks up , so there is a missing gap, so I feel ? ...which the ol' cht10 seemed to blend and pick up right at the 100hz and carry on. But had NOTHING to offer down low. two totaly different sounds, I prefer SVS If given a choice, but like what both had to offer and miss what both seem to miss ? strange? that is why I suggest an EQ, or blending both subs. or both...?
I am definately " NOT " a pro at this as you can tell, I know... But when something sounds darn good, I really sit and appreciate it. :>)
I appreciate your input as well guys.
in about thirty hours I'll have a brand new extensive opinion of what I was able to acomplish.