Another PB10-ISD review

Discussion in 'Speakers & Subwoofers' started by CurtisSC, Oct 28, 2004.

  1. CurtisSC

    CurtisSC Screenwriter

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  2. EdNichols

    EdNichols Second Unit

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    How does having what he calls a slow decay effect the sound? Does that mean that he doesn't consider this sub "tight"? The fact that he calls the sound "boxy" is subjective. But a "slow" decay means something doesn't it?
     
  3. Tom Vodhanel

    Tom Vodhanel Cinematographer

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    Panel decay will be primarily determined by the area of the panel, the thickness, and the material used in the panel construction. When you consider the SVS has about 4x(!) the panel area as the only other subwoofer compared to it...having 50% more decay time shouldn't come aa a surprise. Also remember, the decay in question is being measured all the way down to an *extremely* low 38dB level.

    Tom V.
    SVS
     
  4. kevin tate

    kevin tate Stunt Coordinator

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    Tom, does SVS have any plan to add the bracing to the cabinet in the future? (per the reviewers' recommendation)
     
  5. Tom Vodhanel

    Tom Vodhanel Cinematographer

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    Well, as we've only started shipping in the past 24 hours...I'm not sure how quickly we'll start updating things..[​IMG] One thing SVS is known for though...is making constant improvements to our products thru the last 5 years.

    I think when put in context(that is, compared to *like* sized/priced products that also fairly loud/clean bass down to the 20-25hz range...our panel *decay* would compare very well.(in fact, I know it will from my own testing)

    We sent a early test sample to *COF* because we felt he would be *very* demanding on our performance. Constructive feedback like he has offered is always taken very seriously at SVS. He has proven to be just that...tough, but fair(imo). I hope we can have more products sent to him in the future!

    Tom V.
    SVS
     
  6. paul clipsel

    paul clipsel Stunt Coordinator

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    [​IMG]

    I was reading both PB-10 ISD reviews and I could be wrong but does the 93.9dB relate to 20Hz on the chart? If so why does the chart show 105dB at 20Hz?

    PC
     
  7. kevin tate

    kevin tate Stunt Coordinator

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    Thanks Tom, for your reply. With that kind of dedication, it's no wonder that your products are so well know among the enthusias crowds and selling like "hot cakes".
     
  8. jephdood

    jephdood Stunt Coordinator

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    Would internal bracing be the only method to combat any decay that might be present? Or would some other addition of internal damping material help at all?
     
  9. Tom Vodhanel

    Tom Vodhanel Cinematographer

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    Hi Jeff,

    It might, but it would depend on just how you were measuring...and just what you were trying to measure too. There are so many variables to this...there is lierally an infinite number of ways you can try to measure it. Some methods would be so strict, they can make almost any enclosure "look bad". Some methods can make almost any enclosure look good. Since there is nothing close to an industry standard in this regard...it makes it tough to compare one enclosure to another with only one method considered.

    Tom V.
    SVS
     
  10. Max F

    Max F Second Unit

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    The best review yet IMO. For around $400 you can't expect it to do everything and this review shows a few weaknesses while still proving this is one hell of a sub for the price.
     
  11. SVS-Ron

    SVS-Ron Screenwriter

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    Max,

    At the risk of putting words in Franklin's mouth, that's exactly the point I believe he was making in this article.

    Sure he found something he perceived as a flaw, but he's also known to be one of the pickiest guys in the business (one reason we picked him to review us). Of course, the same old 3 or 4 SVS detractors we all know have elsewhere latched on to the very few nits "COF" had to pick with the PB10-ISD. (Curiously, enough these same guys are oblivious to how "their" brand is going to perform on some of the tough non-standard tests we submitted to. I think if other subs were... you would mysteriously see "decay" drop off their map as some sort of flaw with this SVS too.)

    No doubt naysayers would rather you skip over the following key parts of Franklin's reivew that really seem to sum up his feelings about this very early PB10-ISD sample:

    "The 10" driver is one serious component. I was shocked at what they (SVS) could offer in a $400 subwoofer.... I made some measurements of the woofer, and to save space I will simply say 'WOW!'"

    ... I was extremely impressed with the low end extension of the subwoofer....

    ... I don't think I have ever heard any commercially available subwoofer in this price range that could shake a room like this. It also blended better than most subs with the main speakers, something I contribute to the constantly variable phase control which is absent on way too many subwoofers. I had a hard time recognizing where the sub took over the sound reproduction duties. This is rare even for high-end subwoofers, some of which are considered to be the best on the market."

    ..."The frequency response was stunningly flat and extended. The +/-3dB window response was 17hz to 300Hz.... Imagine getting a useable 18Hz out of any subwoofer that costs less than $500!!! Very impressive."

    ... "I was able to generate 100dBA SPL at 20 Hz from this beast with less than 5% THD, which is stunning to me. Again, at this price point, nothing else can touch the bass extension and output of this subwoofer."

    ..."Suffice it to say, this sub should meet the bass needs of anyone shopping for a sub in this price range."

    ..."It is very clear the team at SV Subwoofers has created a stunning sub for the money. The low frequency extension and output capabilities of this beast are beyond anything I have ever heard for the money. I would wholeheartedly recommend this subwoofer to anyone shopping in this price range with the space to install it in...."


    (C) 2004 Sound Environments

    That's the real story here.

    So, perfect? No, Franklin did indeed find one aspect he felt fell short of that. The lesson being apparently that not even an SVS at this price will tick off every block for the toughest, most "irrate guy" out there.

    We'd be happy to see some of our competitors subjected to the same "gnat's ass" scrutiny and see how they fare.

    That sound of silence you hear?? That's the lack of other OEMs lining up to be turned inside out and examined by that most dangerous of reviewers. A golden ear, with instrumentation he's not afraid to use.

    If there's a better $400 subwoofer it's pretty clear Franklin's never seen it.

    You can choose other brands, just don't expect them to volunteer for constructive criticism like this.

    Ron
     
  12. Max F

    Max F Second Unit

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    Franklin's review did convince me that I'll need to spend at least $800 (for the tube subs) in order to get a sub that will do everything that i want (great at both music and theater).

    Or i can build my own - which i'm seriously considering. That driver does look pretty awsome BTW [​IMG]
     
  13. Edward J M

    Edward J M Cinematographer

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    The COF/IG's review was a very good read.

    He essentially duplicated the FR I measured, with some minor variances. I'm not sure how far away from reflective boundaries he was; I learned the hard way you need to be at least 60 feet away (preferably 75 feet) from any large reflective boundary in order to obtain the true FR. Otherwise you can get minor cancellation and/or reinforcement at various frequencies.

    And I'm not sure how he measured 100 dB (dBA is incorrect) @ 20 Hz @ 5% THD. He didn't give any other specifics about distance or spectral breakdown. For my data, the 1 meter equivalent (simply add 6 dB to the 2 meter value) @ 20 Hz would be 100 dB @ 8% THD @ 1M. In the absence of additional information, I'm assuming this was a 1 meter ground plane, in which case this would correlate well with my data. He is still showing a slightly better performance, which could easily be attributable to weather conditions (temp and humidity can vary the results by 1-2 dB).

    I liked his twist on impulse response, with the decay time being altered by bracing the cabinet. If he has the capability to show this decay as a 3D waterfall plot, it would show where in the bandwidth the resonances were occuring. My only caveat would be that he should subject himself to double blind testing to determine if he can hear the bracing differences under those conditions. Since he was the one who applied the bracing, and measured the reduction in decay time, and knew which version was playing, he cannot claim non-bias.

    This is not to say I don't believe what he was hearing (his peers judge him highly credible in all respects), nor that his discovery lacks merit. I'm simply saying a proper DB study will lend substantial credibility to the audibility claim. If he (and other listeners) can tell the two configs apart with high statistical confidence under proper DB testing, I'd be right there with him suggesting SVS adopt internal bracing as a running production change.

    Overall, COF/IG certainly confirms my findings about the FR accuracy, extension, and clean output of the PB10-ISD being class leading at this price point.


    Hi Paul:

    The 104/105 dB FR sweep in my review represents the maximum sound pressure at which the curve remains linear with a short duration sweep. Above that point, the curve starts to compress or exhibit various anomalies.

    Because I use straight sines to measure THD, the amp can sometimes limit the output before distortion reaches 10%. This occured with the PB10-ISD at 20 and 22 Hz. This is perfectly normal, and the amp will react differently to sines than it will to normal music/movie transients. Hence the ability of the PB10-ISD to generate a 104/105 dB FR sweep, but only hit 94-97 dB at 20-22 Hz on sines before the amp limits out. SVS also uses straight sines for testing THD, and Tom V has encountered the same phenomenon.

    Furthermore, as Tom V has stated in the past, all subwoofers have a disparity between the maximum uncompressed FR, and the THD limited output. As Tom states: "remember, the measured FR of any speaker may or may not be related to the THD produced. Tom Nousaine has published dozens if not hundreds of examples of just that. Velodyne, SVS, MK, ect.,..they all show the same thing. No matter how flat the subwoofer measures (FR wise) you aren't going to be able to ensure it shows the same THD for each frequency vs level check...it is just impossible."

    Regards,

    Ed
     
  14. paul clipsel

    paul clipsel Stunt Coordinator

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    Thanks Ed. Trouble is my logic has me lost. [​IMG]
    It seems that both are measured on a 2 mtr Ground Plane, with the FR numbers using a 10%THD limit, while the FR graph doesn't seem to have a measurement limit of 10% THD? I guess I am still trying to work out how the sub measured 94dB with a sine, yet measured 104dB for FR chart. Thats a 10db difference which is quite a big variation. Are all FR charts measured like that?
    Yet from 32Hz up the results are replicated on both.

    PC
     
  15. Edward J M

    Edward J M Cinematographer

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    FR is typically measured with some type of closed loop sweep. The MLS type software can be extremely short (on the order of 100 ms). The TrueRTA QuickSweep is much longer, probably around 750 ms if I were to guess. Then there are really slow sweeps (in the 30 second region) like LMS.

    Even with a relatively long 30 second sweep like LMS, the PB10-ISD amp still allows for the higher output. Tom V measured the same thing I did with his LMS rig: A stable FR up to about 104 dB, where he then noted the onset of compression.

    The continuous sine used for measuring distortion triggers a limiter in the PB10-ISD amp, only allowing 94 dB at 2 meters GP.

    So that's the difference, Paul: The FR is measured with a sweep, and the THD is measured with a continuous sine. The amp allows a higher output with the sweep than it does with a continuous sine.

    If you wanted to measure the distortion at 20 Hz at 104 dB, you would need some type of software that can generate a short duration sine burst and measure the distortion.

    To answer your question - yes - all subwoofers have a disparity between the maximum uncompressed FR, and the THD limited output.

    The fact that the PB10-ISD's distortion limited output and its dynamic output limit achieve parity above 25 Hz is actually quite remarkable; most subwoofers will exhibit a far wider disparity across the board, especially at the lowest frequencies.
     
  16. ChrisBee

    ChrisBee Stunt Coordinator

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    Given the very narrow bandwidth of subwoofers in use. And the difficulty the human being has in recognising distortion at such low frequencies. Is coloration very likely?

    Or would the (supposed) panel resonance be at a higher frequency and therefore more easily detectable?

    It occurs to me that a simple halving-jointed, cruciform brace of MDF or chipboard. Wedged (edge-on to the drive unit) somewhere in the middle of the panels... would be a simple "aftermarket" fix for owners seeking (theoretical) perfection.

    But what is SVS' attitude to unsolicited entry into their enclosures by owners making such modifications? Would it invalidate the guarantee?

    ChrisBee
     
  17. Ilkka R

    Ilkka R Second Unit

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    I would love to see another review from this guy, maybe PCU or PB12-Plus/2. Will he find something bad also from those models? That is interesting point that he is the first reviewer (point me out if I'm wrong) who has said something bad from SVS subwoofer (boxy, slow, cardboard like sound etc.).

    For example Ed didn't say anything bad from PB10-ISD's sound. Is this the first REAL review of SVS sub? Don't get me wrong I love Ed's reviews, but not once I have read anything bad from their sound and I know they can't be perfect. I've read the discussion from Ed being biased to SVS, I didn't believe it at first but now I have to think twice.

    This is also interesting point. (a quote from S&V forum) "Personally, I would just go with a sub until I could afford one of the Tube subs" (IG/COF, guy who made the review). Interesting becouse I have get the feeling that people are placing PB10-ISD above the normal PCi line subs, especially in sq. He also points out that he would definetely buy one $800 sub (for example PC+) than two PB10-ISD and that is quite the opposite to what some people have done.

    http://www.soundandvisionmag.com/ide...um=20&pageNo=1
    This is a good thread, especially page 4.


    This review has made me definitely think twice before I buy the new PB10-ISD sub.

    I don't want to start a war, but I had to bring this up...

    ps. (I have heard 20-39PC+ at my friends home and did like it, atleast with movies)
     
  18. Robb Roy

    Robb Roy Supporting Actor

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    Ilkka,

    I wouldn’t let the lack of panel decay measurements in Ed’s reviews make you think the reviews are biased. Just how many reviews contain measurements of panel decay? I know of one. How many have a double blind listening test for panel decay? I don’t know of any. What are great about Ed’s reviews are the measurable, repeatable tests he puts the subs through.

    I like the subjective portion of reviews, but put less stock in them. There are simply too many factors that can account for them. I had about a dozen people (representing owners of cylinders, PB12-Ultra/2s, PB12-Plus/2s, and non-SVS models) at my house a week ago today listening to a PB10-ISD, and I sincerely doubt even one of them would describe the sound as "'cardboard-like'".

    -Robb
     
  19. paul clipsel

    paul clipsel Stunt Coordinator

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    Thank you Edward, you always do a good job on explaining your reviews. I have a much better understanding of it now.
    Does Nousaine use continuous sine for his FR which he says he caps at 10% THD? Is there a standard time for the sweep that allows you to compare graphs from reviews? Or are they not comparable?


    PC
     
  20. Ilkka R

    Ilkka R Second Unit

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    Robb,

    Yes I would like think this same way you do, but I am still conserned. Part of SVS's success is based on this "hype" going around the net, I'm not saying that SVS subs are not good, but maybe not as good as many people think. Partly becouse of these "zero-critic" reviews floating around. Now we have first review that actually says that sub has some flaws and people are immediately start having second thoughts of buying it (you can confirm this from S&V thread).

    I've read the report from your "get-together". Almost all of you were proudly owners of SVS sub(s). How non-biased can we then think your opinions were of those both subs? It scares the hell out of me that you couldn't make a difference between those subs (moderate levels), that means that either your ears are not trained enough or PB12-Ultra/12 has these same flaws as it's smaller brother (boxy, cardboard-like sound), right?

    That's why I WOULD LOVE to see some more expensive model(s) get reviewed by this same guy.

    Dacay tests are basic tests (at least here in Finland) that HI-FI magazines do when they test subwoofers.
     

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