SVS 25-31 cs+ review (long)

McLoki

I have finally secured a few hours to myself at home and decided to make good on a quick review of the SVS 25-31 CS+ subwoofer that I purchased from Mazeroth. It was supposed to be in mint condition, never abused (overly anyway ), and ship in the factory box.

I am comparing to a polk psw-350 as well as an MTX 10" - (both cabinets are ported to peak at 38 hz.)

The CS is an unpowered subwoofer. Since I think the amp makes a huge difference in the sound - this is what my Cinepro amp is rated at (currently running the front stage and the sub)
500 wpc @ 4 ohms (1100 watt peaks)
120 amps peak to peak (per channel)

It Arrives –
After a week of waiting (very impatiently) for the sub to arrive and checking the UPS tracking number multiple times per day I went to lunch the day it was supposed to arrive and it showed up shortly after I got home. I was moderately fearful for its condition as the box was leaning pretty severely to the right. Upon opening it though the internal packaging was intact (foam was crushed in a few areas) and the sub was in great shape. Being the patient person that I am, I stuck it in the location of one of my other subs (removing them from the system), hooked up the sub to my amp, did a quick rat shack meter adjustment for sub level (setting it as close to flat as possible) and started listening. (Ok, so I was a little late getting back to work that day )

Calibration –
I did download some bass test tones. (A few sweeps as well as frequencies from 10 – 160hz) and found a spreadsheet that included the correction factors for the radio shack sound meter as well as some built in charts. In my listening room I had 2 major dips that look horrendous when charted but I have not really heard in any of the movies or music that I have played. With the sub running in the 25hz tune (all ports open) I had a 5db plateau from 30-23 hz and the sound tapered off pretty quickly after that. At the 20hz tune the sub was flat except for a small 2-3 db bump at 22 Hz or so. (Below that bump it tapers off quickly but stays above the 25hz tune by about 6db) I think I could control the dips better by moving the sub, but it is in an inconspicuous location right now and sounds really good so that is where it will stay. (The wife likes it there and it’s not worth the battle it would take to move it to another location.)

Sound –
I use my setup for about 90% HT. With the addition of the Lsi speakers as well as the SVS subwoofer I am listening to more music, but it is still used mainly for HT. Since my setup is in the living room, and I have small children (3 and 5 years old) I tend to watch A LOT of Disney/Pixar/Dora /Thomas (the tank engine)/etc. When I do get to watch something else, it must be family acceptable or watched after the kids go to bed (at low levels). I work close to home and often am able to come home for lunch. This is when I can turn up an action movie and watch the scenes I like or break up a movie over multiple days to watch the whole thing.
My normal listening levels are pretty tame (even over lunch hours) with absolute peaks (explosions and such) in the 90db range. (Very loud for me would be a 100db peak) at this level even with 1 port blocked on the SVS (20hz tune) you really cant feel hardly any air coming out of the ports. I did perform the Darla test from a previous thread just to see where I would fall. My old dual sub setup peaked at about 95db with a lot of distortion. The SVS starts to distort at about 111 db and bottoms at 113 db (uncorrected). (The only time I have or will ever bottom the sub) It did not distort or bottom on each tap, I turned it down when it started distorting (on the first tap or two) and backed the track to the beginning of the scene. It was playing clean then on the 3rd or 4th tap bottomed. (Scared the hell out of me) That marked the end of my Darla test and I played some other movies to make sure I didn’t break anything (all was fine). I never listen to movies at this level though so I am not worried about it happening again. A high pass filter may have helped here also. Also keep in mind that removing the 20hz tune would have added another 5 db or so to the tap test. I did check the ports during this phase of testing and there was a lot of air coming out of the ports at these levels.
I started playing movies at normal/loud levels (for me – 100 or so db bass peaks) There were a number of surprises in store for me with the movies I was familiar with.

Blade: footsteps - I had never actually heard these before. I thought they were just normal/loud footsteps with my old sub. Very cool. "Footstep", Scene 4 (7:15)

Toy story 2 – every bit as cool as I was hoping it would be. Exactly as expected. Much better than my old setup was capable of. When the cement tube falls off the truck as they are crossing the street, the sound lasts much longer than I thought. (Now until the street light falls, my old subs stopped as soon as the tube was off screen)

LOTR – just an awesome experience, my TV resonates (and clouds the picture) with bass peaks around 40-50hz. My old sub was pretty peaky in this area and much of the bass in LOTR affected the picture because of it. The SVS is both louder and lower bass but affects the picture on the TV less since it is below the level where it resonates. Fighting the cave troll and the balrog are both an experience that makes the movie much better to watch at home rather than at the theater.

Matrix – this is a real test for subwoofers in my opinion. There is a lot of bass going on and my old subs used to just cloud everything together. In the lobby shooting spree the bass track became very muddy with all the gunfire going on. It now all sounds very distinct and the bass track actually adds to the scene instead of just being an annoying distraction. When Neo is dodging the bullets on top of the building (right after the lobby scene) there is a low rip as the bullets come flying past him. I had no idea that this was there at all since I had never heard it before.

Saving Private Ryan – I had always thought the beach landing was a great test of a subwoofer with lots of low bass. This is one that surprised me. The other movies mentioned above have much lower bass than this. My sub does not distort at all on this, and it is as chaotic as it ever was (good surround test), There is just not as much bass here as I thought there would be.

Star wars – AotC : pod race – this was really an experience. The bass is loud and low for the entire race. It really sounded just awesome. (movie still kind of sucks, but it sounds great while doing it….. )

Music:
Fleetwood Mac – the dance: Great sound! bass never calls attention to itself, but is always there as good reinforcement. Really impressive. The sound really does sound live.

Various jass samplers – sounds very good. All drums are very quick with almost no overhang on the sound when the drums are hit.

Eagles – hell freezes over: great sound. Some of the best I have heard from any system. Bass is very quick but never calls attention to it self.

Conclusion: For my current setup, I am very happy with the sub. If I had a dedicated HT room, I do think I would spring for the ultra and tune it to 16hz. For my living room the sound level as well as the size of the 25-31 make it the best choice for me right now. (the 8 extra inches in height would greatly limit the subs ability to hide in my living room.) The sub never calls attention to itself. There is no material that I have heard that the sound seemed to be coming from the sub. It always seems to be coming from wherever it should. Looks are very subjective, but the cylinder does seem to fit in much better than I thought it would. It sounds awesome and most people don’t know what it is. (and oddly enough, therefore don’t ask) It is not a design my wife would have chosen, but then again, she would be fine with a bose system so she doesn’t count for sound quality. She only voiced her opinion of it once (upon first seeing it said it looks like a giant air cleaner) but has not complained about it since. That is as close to an endorsement as you will get from her for any speaker that you can see.

I would have to rate it as one of the best enhancements I have made to my home theater and am very happy with it. I have all settings as close to flat as I can make them and music and movies both sound much better than they ever have in my home. (even flat, it puts out more low bass than my old system ever could) I have not decided what my next upgrade will be, but I may be happy for awhile just adding movies rather than equipment.

Mazeroth

I'm so glad to hear that you're satisfied with the sub! Thanks again and I hope it brings you years of joy you can FEEL!

Tour2ma

Very nice write-up...

At what point are you crosing over to the SVS?

McLoki

At what point are you crosing over to the SVS?

My AVR will only cross over at 80hz and I am running all speakers set to small. I would like to get an AVR with a variable crossover and set the front stage to 60hz (to hopefully remove one of the room dips) and the rear stage to 150hz. (where the RM-6600 start to roll off.)

More likely though I will purchase slightly larger rear speakers (that has a -3 db point of at least 80 hz) and leave the electronics alone. The polk LSiFX is WAY to large a speaker for my living room so I am looking at one of the smaller polks or maybe a small set of paradigm's. (looking at the ADP-170 - about the size and roll off that I was looking for)

Glad you liked the review.

Michael

Dr. Spec

Great write-up! Good mix of subjective and technical. That amp is like Thor's hammer - be careful!

The lack of a steep infrasonic filter will make the CS+ more susceptible to bottoming at high vols; adding one might be prudent for demo's, etc.

Also, as you note, plugging a port makes the sub work harder and the 25 Hz tune will add a few more dB to that reading (probably 116 uncorrected).

McLoki

That amp is like Thor's hammer

Here is a review of my amp. (only 4 of the 6 channels are currently hooked up and running.

Secrets of Home Theater and High Fidelity review

Owners Reviews

When I purchased it I wanted the ability to run the front stage of my HT (planning on the LSi15's or SDA 1C's not the LSi7's I have now).

The price was great on it and the ability to run a sub was a bonus. It really does sound great and I can add almost any speaker I want to it without fear of not enough power. The downside of this is that stupidity or lack of restraint will cost me a set of speakers.

Michael

opus

sorry, but I don't know how to place a quote in my message yet.

Dr. Spec said " plugging a port makes the sub work harder".
Is this a bad thing? Will it do any damage to my sub (pc+ 25-31)? I figured I could use the lower freq and not miss the few extra dB. Am I correct?

gatemplin

To quote, click the quote button at the bottom of a post.

Plugging a port lowers the tuning frequency and makes the sub work harder above the tuning freq. It will be easier to bottom it at say 30 Hz if it is tuned to 16 Hz, than 25 Hz. The driver is coasting at the tuning frequency.

Tuning the sub lower by plugging a port increases low end extension and output, but you sacrifice overall output. This may be fine for you, my sub is tuned to 16 Hz because I wanted extension and do not need a lot of output.