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Comparison of SVS CS, CS+, CS Ultra, and Servodrive Contrabass


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#1 of 32 Ned

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Posted September 28 2004 - 06:20 AM

In preparation for the soon to be expiring SVS pre-order, I did some testing of the various existing SVS cylinders. I myself have 1 SVS 20-39CSi. It is a great sub but I need more headroom and extension. So begins the quest.


Sunday 19th

My friend Eric had just received his dual CS Ultras. Our previous bargain had been that I get to borrow his Behringer Feedback Destroyer for 2 months if I showed him how to use it when his Ultras arrived.

His room is in the basement, so the walls and floor are concrete. The approximate dimensions are 15x25x8 and it has an opening near the back to a stairwell leading upstairs. So a fairly large room and not sealed.

The Ultras were placed in the front corners of the room and to start we plugged 1 port on each for a 16hz tune. The amp is a Crown K1 (550 watts x 2).

Next, I measured the response in Eric's preferred seat, middle row, center (he has 3 rows Posted Image ). In the 16hz tune we were getting a 10db hump from 16-22hz and from 22+ it was fairly flat except for a 10db peak at 46hz. No dips luckily. We set a band on the BFD and the peak at 46hz was easily dispatched. So fairly flat now except for this 10db hump at the very bottom.

First up was The Rundown - first fight scene in the nightclub

Posted Image

In the 16hz tune, the dual Ultras measured 108db (c weighting / fast) on the Rundown "bodyslam". It was clean and could be felt through the air and in the chest. Shirts and pantlegs were flapping. So of course the next thing to do was hear it again only louder Posted Image . We upped the volume and tried it again. 109db, but I detected what sounded like the dreaded clack. It was faint but once you've heard it, you never forget. Up went the volume again, 110db measured and very noticeable beginnings of clacking.

Now we removed the plugs to return the Ultras to the 20hz tune. Same volume as the last test and we hit 113db. Clean as a whistle and the first time my hair actually vibrated.

At this point I have to say that the sound character between the 16 and 20hz tunings is significantly different. At the 16hz tune this is probably the best sound quality I've heard from any subwoofer. It was deep but totally composed across the 15-80hz range. It had that silly "tight" description that most "audiophiles" like to tag on their wimpy 10" subwoofers that do nothing under about 35hz. I was actually a little disappointed at how the sound character changed in the 20hz tune. It shifted from being more visceral and tactile to being more of an audible effect. It didn't sound bad at all but compared to the fantastic sound character at 16hz tuning it was slightly less impressive. Louder but not as visceral and deep.

From here on we left it in the 20hz tune as the 16hz tune just ran out of gas too fast in his room.

Next up was Titan A.E - the icefields.

Hmmm.

I have to admit at this point I was a little unimpressed. There was gobs of output but the bass content of this scene is rather one-notey. I counted at least 15 bass FX that sounded the same, as if they had cut and paste the same effect again and again. There is certainly quantity of bass but it just gets boring to hear the same tone over and over.
Similar findings were made on the other subs so it wasn't actually the fault of the Ultras.

We quickly tossed that scene from the demo list.

Next up was The Matrix Reloaded - fight scene with many Smiths.

Posted Image

This really sounded fantastic on the Ultras. I was measuring peaks of 111, 113, 112db all throughout and you could hear the various kinds of bass. Short punchy bits from single kicks and punches to quaking rumbles from the foot stomps. Some of the most impressive bits were the sustained bass when Neo spins in slow-motion with the steel pipe. They only read 108-109db but the sustained nature was totally smooth and controlled. I didn't push the volume any higher at this point but I would estimate that we could easily do 116db peaks with the same composure. 118db is probably the upper limit of a pair in 20hz tune.

Overall impression:

Fantastic sound quality. The 16hz tune was bar-none the best bass I've heard. The output was a bit crippled but for most people it would be plenty. In a smaller room you could probably reach the 112-115db range. Quad Ultras in 16hz tune would truly be awesome. For bigger rooms or SPL hungry listeners, the 20hz tune is the way to go. We were sitting in his middle row, which is about 12' away from the Ultras and you could feel waves of bass. In the Rundown and Reloaded, the Ultras defined the bass notes so that you can appreciate the intricacy of the mixes. That's really what it's all about. Loud, deep bass with the ability to reproduce the subtle differences in tone.


Monday 20th

Now of course the first thing we all do after hearing/seeing something impressive on someone else's home theater is to try it at home.

My room is 10x12.5x8 with only 1 door that can be closed. My theater is on the first floor however so the floors are wood joist and the walls are plaster (old house).

I have a single SVS 20-39CS powered by the Samson S700 and eq'd by the ART351.

This is where things get depressing. On the Rundown I could reach about 101-102db on the "body slam" but the sound quality was getting ragged. It definitely did not have the punch of the Ultras.

The Matrix Reloaded sounded better but peaks were still only in the 103db range and above that it was losing control.

Titan A.E reached similar levels and I noted again how little the bass notes vary in the icefield scene.

I turned everything off and left in relative disgust Posted Image

Luckily (for me), while at my friend Eric's place, we measured the frequency response of the dual Ultras with and without his old 16-46CS+, which was at the back of his room. Our hope was that it would help to smooth out the response of the dual Ultras at the front. Unforturtunately, it just made the response worse and it added very little to the output. Theoretically, the best it could do is add 3db if placed at the front and that was not physically possible so it had to go at the back. In light of the excellent performance of the Ultras by themself Eric decided that he had no use for the CS+.

Being the generous guy that he is, he offered to let me try it in my home theater in case I wanted to buy it before tossing it on Ebay.

Wednesday/Thursday

The first thing I did was to run the 16-46CS+ by itself to get an idea of what it was capable of. It is a significant improvement over the CSi. The better driver has greater control in the 16-25hz range and I was able to hit about 104-106db with reasonably low distortion (not a lot of harmonics). It was significantly better than the single 20-39CSi but it wasn't quite reaching the levels I wanted.

So next up I experimented with having both subs connected. 1 in the front right corner, 1 at the back left corner (I don't have too many placement options in my little room). That sounded rather crappy as even at 80hz crossover I could detect a sub behind me. I settled on having them together at the front right, which nicely blocks the door from opening fully Posted Image

The other tricky part is the mixed tunings. Normally I filter at 19hz and down on my ART351, but the 16-46CS+ should be filtered at 15hz and down. I compromised by setting the subsonic filter at about 18-19hz and I reduced the gain slightly to the 20-39CSi so that it isn't pushed as hard.

Result? Clean peaks of 108-109db in the Rundown "body slam". I hit as much as 110db but I can hear the sound quality diminishing. Neither sub was clacking at all but you could hear the loss in definition. In my room the slamming bass type effects tend to ripple through the floor since it's a wood joist construction. It certainly makes body slams and foot stomps seem real but you lose that in-air, wave of bass effect. It could also be that the CS/CS+ combo is unable to move enough 15-20hz bass to get that effect. Can't say unless somebody brings over a pair of Ultras Posted Image

Friday

What better litmus test than a pair of Servodrive Contrabasses backed with 1400 watts Posted Image

His room is also in the basement, 11x21x7 (goofy low ceiling in basement just like my 1950's house)

Before listening, I measured the frequency response of the 3 main seats. The 2 seats in the middle of the room had fairly lumpy response, humps from 20-25hz, valleys from 30-45hz, another peak at 45-55hz. The seats at the back near the wall however, were virtually perfect with even a slight house curve established (shelf from 20-30hz, sloped down 8db to 80hz). This is where I sat for most of the SPL measurements.

To start, I asked my friend Andrew to turn off one of the Contras. This made it easier to assess what 1 was capable of.

As always, we started with The Rundown. The bodyslam registered 114db. Yowsa! So of course we now increase the volume Posted Image

116db!

More.

The needle swung past +6 to what looked like +8 if that's possible.

"so why do you need a pair of these again?"

I went and turned the 2nd Contrabass on.

This time the needle nearly snapped off. I had to set the rat shack meter to 120db range and we played it again.

122db! The ceiling is creaking, walls are bowing/rattling. Basically anything not made of cement is making a nuisance of itself. The Contras are laughing at us, "we can do more".

It should be noted that this still doesn't sound harsh or ear-splitting because the majority of the SPL is infrasonic bass that is felt, not heard. If you hit these levels at 500hz+ your ears would bleed. With bass, it's just a room-rumbling, shirt/pant flapping affair.

Did we go louder? No. At this point it was just getting silly and the room was adding so much rattling rubbish that it maybe even detracted a bit from the presentation. Having heard Eric's super tight basement, I like that the best. Nothing rattles and you get almost the full force through the air. It is pure bass at it's finest.

Now of course the ultimate question, which sub is the best?

I won't make a judgement like this since they were all used in different rooms. Each was measured and equalized for a reasonably flat response but the size and room construction vary too much.

I can make some conclusions on each.

1 CS - enough for small rooms or those who don't listen at reference level

1 CS+ - absolutely worth the extra cost. Greater control, stronger extension, just better sound quality all around.

CS & CS+ - this is where you start to get that true bass impact. No movie theater I've been to comes anywhere near the 20-30hz output of this combo.

2 CS Ultras - bloody good. The 16hz tune puts them at the top of anything I've ever heard. The 20hz tune isn't quite as defined and deep-digging but it can hit you with impressive impact and waves of bass, even in a fairly large room.

1 Contrabass - similar to dual Ultras. Has the extension of the CS at 16hz tune but the output of the 20hz tune (probably more even). Not quite as good sound quality, but that's difficult to peg down given different rooms.

2 Contrabasses - you better have a well built house or you'll be hearing so much vibration and rattling it will be somewhat distracting. Easily the king of output, maybe not quite the best sound quality. Hard to make a rock solid conclusion when they are in different rooms.

1 20-39CS - $429
1 20-39CS+ - $575
1 20-39CSU - $899
1 Contrabass $3000-3500

2 CS Ultras matched up well against a single Contrabass, although the Contra has a very big edge below 18hz. 4 CS Ultras in 16hz tune are probably in the same ballpark as 1 Contra for a total price of $3600. I doubt most people would hear much difference or care at this level of performance.

The CS and CS+ combo is not something I would recommend. Mismatched tunings is also something I would absolutely avoid. For small to medium rooms a pair of CS+ will definitely kick a lot of ass. This is why so many people are happy with the PB2+. The Ultras are absolutely worth the extra money however. The price premium is significant but the payback in performance is worth it. The regular CS is still a great sub, it really just depends how loud you like your movies, budget and room size.

#2 of 32 Ned

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Posted September 28 2004 - 06:26 AM

Hopefully this all makes sense, but there is so much to say that I have to draw the line at where to stop on certain subjects. Please let me know if anything needs clarification.

#3 of 32 Matt G.

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Posted September 28 2004 - 08:13 AM

Ned, sounds like you had a lot of fun doing that. Thanks for the good info. I pre-ordered a PB2-Ultra and I am encouraged of what you have to say about the dual Ultras considering it will be similar. Thanks again.

#4 of 32 Edward J M

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Posted September 28 2004 - 09:05 AM

Ass kicking write-up, Ned. Backs-up much of what we've been saying for a few years here - ya get what you pay for and as you move up the SVS line, you'll get more clean output, impact, and SPL capability. Probably the PC-Ultra with the infrasonic filter would have been even more capable in Eric's basement, possibly avoiding the slight clack you heard in the 16 Hz tune. Nevertheless, your experience with plugging a port demonstrates what happens to the overall dynamic compression limits.

The Contra-Bass - phew it's a monster and Mark should be proud of its performance. Not much out there can run with a Contra-Bass below 16 Hz. But it was also operating in a 1600 ft3 room with a low ceiling. The Ultras were running in a 3,000 ft3 room - big difference both in terms of boundary effects and room gain.

I would expect the Ultra's in that 1600 ft3 room to have substantially more output (in the native 20 Hz tune) below 20 Hz from room gain alone, as well as considerably more output overall. If my experience with the PB2-Ultra in an 1800ft3 room is any indication, dual Ultras a 1600 ft3 basement should be able to break 120 dB on the Rat Shack meter. IIRC, I was getting about 115 dB on the RunDown body slam at around -8RL, with plenty left in the tank.

The best way to evaluate subjective impressions and SPL levels is in the same environment. I know that wasn't possible in your case, and you still did us a great service with a very thorough review of several different subs - and it sounds like you had a blast too. Posted Image
Ed Mullen
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"What we do in life, echoes in eternity."


#5 of 32 frank manrique

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Posted September 28 2004 - 09:28 AM

Hi, Ned,

Terrific stuff! Really enjoyed reading it.

Say...what sort of software do you have on your PC that produced those charts? Thanks in advance...

-THTS

"...hi, my name is Frank...and am an SVS bassaholic..."

#6 of 32 Shane Martin

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Posted September 28 2004 - 09:34 AM

Quote:
Titan A.E reached similar levels and I noted again how little the bass notes vary in the icefield scene.
I thought Titan AE was better at the beginning(a demo scene if there ever was one) over the Ice Fields section.

Being that my purchase has had to be pushed back for a few more months Posted Image I'm getting some more time here to see these types of comparisons and find out what I really want/need.

One question though: Is the Crown amp he is using that much better than the Samson that SVS is using with their packages? Would it result in a bit more spl?

#7 of 32 Ned

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Posted September 28 2004 - 11:45 AM

Ed-

Forgot to mention we had the SVS/Marchand box with the Dual Ultras. The subsonic filter was set as recommended for each tune point. It was only on the Rundown fight scene that the 16hz tune ran out of gas. We didn't try it with Reloaded (damn, damn).

Frank-

The program is Spectrum Laboratory, which is actually freeware. I added the arrows and text in Photoshop though.


I also forgot to mention that we tried Titan A.E on the dual Contras. Again, very one-notey bass. The only 2 good FX in the icefield scene are when the big X shaped crystal flies past the screen and when the camera pans down the front of the spaceship to show the other ship escaping below. Oh well, it's officially out of demo rotation Posted Image

#8 of 32 SteveCallas

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Posted September 28 2004 - 12:10 PM

I don't know if your friend would let you do measurements again or not, but why don't you try testing the CS Ultras again collocated in one corner instead of one in each corner? With one in each corner it kinda seems like one is being wasted.

#9 of 32 KeithY

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Posted September 28 2004 - 12:38 PM

Great work Ned!!

#10 of 32 Kevin C Brown

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Posted September 28 2004 - 12:50 PM

I also pre-ordered a PB2-Ultra in black. Ned's info as well as the thread where SVS Tom posted the differences between the drivers is making me feel really good about convincing myself to move up from the PB2+. Posted Image
If it's not worth waiting until the last minute to do, then it's not worth doing.

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#11 of 32 Ned

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Posted September 28 2004 - 01:02 PM

Steve-

Putting them together has a theoretical boost of 6db, opposite corners is ~+4.5db. Unfortunately it's not possible as my friend has an 8' wide screen inbetween and he has an aversion to asymmetry Posted Image

#12 of 32 MingL

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Posted September 28 2004 - 01:19 PM

Beautiful write up!

#13 of 32 Shane Martin

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Posted September 28 2004 - 01:44 PM

Quote:
Unfortunately it's not possible as my friend has an 8' wide screen inbetween and he has an aversion to asymmetry
My friend is doing the same thing and it works better for him than colocating.

#14 of 32 ChuckRG

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Posted September 28 2004 - 03:11 PM

I'd love to see how dual SVS B4+s stack up against the ContraBass!!

#15 of 32 Brian Corr

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Posted September 28 2004 - 03:34 PM

Good read!

#16 of 32 alan*T

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Posted September 28 2004 - 04:30 PM

I see quite a few is using this review to make inferences on the PB2U. But I noticed that Ned prefered the 16hz tune of the CSU over the 20hz.

quote
I was actually a little disappointed at how the sound character changed in the 20hz tune. It shifted from being more visceral and tactile to being more of an audible effect. It didn't sound bad at all but compared to the fantastic sound character at 16hz tuning it was slightly less impressive. Louder but not as visceral and deep.
endquote

Considering that the PB2U is stock tuned at 25hz, won't that be a problem?

#17 of 32 Kevin C Brown

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Posted September 28 2004 - 06:15 PM

You can tune the PB2-Ultra to any of 16, 20, or 25 Hz.
If it's not worth waiting until the last minute to do, then it's not worth doing.

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#18 of 32 MingL

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Posted September 28 2004 - 06:22 PM

But tuning any PB2 to 16hz would limit SPLs as well as increase the likelihood of port noise acting up at SPLs lower than cylinders.

But there is alot of real world compromises that we should balance. Ask yourself "Do I need SPLs or depth in my HT room?" The right choice of sub will present itself to you.

#19 of 32 frank manrique

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Posted September 28 2004 - 09:25 PM

quote:
__________________________________________________ ____

Frank-

The program is Spectrum Laboratory, which is actually freeware. I added the arrows and text in Photoshop though.
__________________________________________________ ____

Great news! Will try downloading it into for my PC. I just hope I can make some sense of it if it works (Ed, Mark, Craig...that's where you guys will come in! Posted Image ).

Thanks for the information, Ned. Keep up the good work...

-THTS

"...hi, my name is Frank...and am an SVS bassaholic..."

#20 of 32 Mark Seaton

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Posted September 29 2004 - 01:58 AM

Hi Ned,

Great write up and anecdote on your experiences and impressions. I also applaud your attention to, and notation of the frequency response and room details.

It does sound like Andrew might benefit further from careful use of an EQ and some serious attention to room rattles. I think your point about rattles and buzzes is largely overlooked by many who are initially amazed that their subwoofer can rattle things/everything. Rattles are flat-out distracting, and they remind that you are in your room, and not in the scene of the movie or engrossed in the musical score. I direct you and Andrew to Blue-Tac, foam tape and some weather stripping with a healthy dose of test tones or very slow frequency sweeps!

It should also be noted that Andrew's room as you described is rather problematic for any subwoofer with solid basement walls in such a narrow and low space. If it was possible (doubt it) it might be interesting to co-locate the pair of Contra's on their side under the screen in the center of the front wall. EQ would help in either case, and you could probably get great results either way. I also wanted to caution that the response you describe at the back seat is quite an extreme "house curve" which I would expect to sound a bit like you describe. 8dB down at 80Hz relative to 30Hz is pretty extreme, and many don't realize how important smooth response at higher frequencies is, as the upper range and the integration with the main speakers largely dominates the "tonal" perceptions. The lower half of the typical subwoofer range will also largely effect perceptions as excessive low energy can serve to subjectively "mask" much of the subjective detail.

Again, there is no question that system setup and optomization is a major key to sound quality. In most of the systems I have measured, it is the rare case and a bit of luck when things look quite good with conventional setup. It is highly common for the main speakers to produce too much energy below 120-80Hz, subs will often have a huge peak or dip above 60-65Hz, and if you have a measurement system which is not "time-blind" ie you can look at energy with respect to time, we also see that most subwoofers are "late to the party" with respect to the mains, resulting in a significant discontinuity. Think about it, why else is there a delay feature for your subwoofer? The relative level with your mains is another major issue where people need to realize that other than for pure SPL, you can't really make many useful subjective evaluations without the main speakers properly calibrated. The scarry part is how much the main speaker's response can affect the subjective perception of the sub.

Now I'm not saying that Ned's evaluations are not useful. Quite the contrary. What I am saying is that you need to carefully read the details of the SYSTEM and setup being evaluated, and take such input as relative feedback, not absolute determinations. In the case of this review, we should keep in mind that room size can have some very powerful effects on the response. Also note that larger rooms will tend to have a much better dispersion of modal issues where the real problems shift lower in frequency relative to smaller rooms. Basically in a larger room you need more output from the subwoofer to fill it properly, but it is often easier to achieve good sound. Also solid walls like a basement foundation wall will better confine and reinforce low frequencies, while at the same time making modal peaks more prominent as there are less losses.

Keep up the great discussion and postings.

Cheers,
Mark Seaton
Seaton Sound, Inc.





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