New SVS Sealed Sub (2 Viewers)

[brendy]

Dave Alan,do you have some kind of personal vendetta against SVS? Secondly,what qualifies you to claim that your general understanding of sub design may exceed Ron's ? Post for all to see.

 

[dave alan]

Hi Wayne,

I appreciate the report.

Help me to understand. The room compensation control switches between high pass filters at different frequencies. If we keep with the word 'filter' instead of 'choke', it may be easier to make my point.

A filter does just that. It filters the signal to prevent frequencies from being reproduced from it's designed corner down.

I understand that if the filters are 'bypassed', there are no filters, but is that the case? The graph Ron linked looks to have a 2nd or 3rd order filter in-line.

Maybe that graph was made with one of the room compensation filters engaged? IOW, 'bypass' may only mean that you are setting the sub to the default setting of a 2nd or 3rd order HP at 20Hz, but I don't know.

It would be nice to know where and what order the filters are for each of the settings, but maybe we'll have to await Ed's review, ;^)

The interesting part of your post is that you seem to be saying that the room compensation control is not a set of filters, but instead is a set of differing EQ boost curves. This would be a much better solution, IMHO, than different HP filters, but I believe you are mistaken judging by Ed's previous statements as well as the SVS web site info.

Anything you can add would be appreciated, especially having first hand experience with the sub.

Dave

 

[LanceJ]

Not an exact comparison, but close enough I think.

Why some people think ONE subwoofer design is good at all things is beyond me. Though I have noticed that many HT-philes hardly ever listen to music so I think they might lack the experience listening for musical realism, which is different from a movie's special effects. Or another possible explanation, which is they rely totally on spec charts and computer software to tell them what sounds good (FYI: I'm about a 75% objectivist/25% subjectivist audio guy).

It's a very common observation by many people that some of the most accurate speakers available i.e. studio monitors are also thought to sound sterile, thin, uninvolving or bordering on harsh when used to listen to music for non-recording purposes. So its not surprising that most of the home audio world's most loved pieces of gear *aren't* the most accurate.

I don't know if movie soundtrack engineers do this, but most music recording engineers (particularly for rock & pop music) take the mixes they make & go around to various Regular Joe reproduction gear to make sure it sounds good for the majority of people that are going to buy that album. This usually means boomboxes, $200 HTiBs, car systems and mid-fi component systems (and I'm sure the iPod and MP3s are in there too nowadays) playing in a "normal" room i.e. not an anechoic chamber. So when you finally get that CD in your system it is already INaccurate frequency-wise but when played in that normal room via that typical audio system, all that EQ juggling back in the studio compensates for most of that & it ends up sounding pretty good. But when played back in an "accurate" system, the sound can be very disappointing. That's why I finally stopped salivating over $5,000 speakers and $1000 CD players and started buying Advents & Boston Acoustics speakers and Pioneer electronics instead.

 

[Robb Roy]

Jack,


While the terms "guru" and "expert" are more self-proclaimed than anything else, I think this points to a feather in SVS' cap. Not because other manufacturers might or might not have faults, but because every move/post/product of SVS' is so highly criticized. These criticisms are aimed squarely at SVS while ignored for other manufacturers. The argument often goes that because they post on the forums so much they should be subject to these criticisms. Well, they're not the only manufacturer to post (or be represented) on the forums, but they seem to collect the majority of trolls. And that's not to mention the outrageous ads and press releases by the whole industry, whether they post on the forums or not. The more these folks hold SVS to a higher standard than other manufacturers, the more they demonstrate how good SVS' products are.

-Robb

 

[Wayne A. Pflughaupt]

Hi Dave,

I don’t know anything about the SVS graphs or how they were “made.” Unfortunately I didn’t get a manual with the SB12 (not in print yet), and I didn’t correspond with Tom about it until after I had sent it back, so I wasn’t clear on how the room comp feature was supposed to operate while I had the sub. Tom didn’t tell me order of the slopes, and it didn’t cross my mind to ask. However, I think I can answer a few of your questions, based on what I was informed.

Yup. Since I was fuzzy on the whole thing,not having a manual, I didn’t try to evaluate the filtering. I don’t know what the filter orders are, but if it helps I can tell you that in my huge room, the SB12 got flat response (with a little EQ) down to 24 Hz, and fell hard below that point. Didn’t think about it until later, but the signal was probably high-passed by the 18dB/octave 25 Hz filters my Audio Control EQs have (can’t easily access the rear panels at this time to defeat it). That probably contributed to the steep drop; and probably cost us a few Hz in response. I wish I had been able to spend more time with it; I'd sure be looking at some different things based on what I know now. Hopefully Ed can take more meaningful measurements when he reviews the SB12.

Nevertheless, all things considered, I was really impressed with the performance the SB12 generated for its size, especially in a room as large as mine. Sure, the PB12 bested the SB in extension and dynamics, but it didn't exactly blow it away. (the PB12 is really too small for my room as well). Pretty amazing considering the PB is three times the size of the SB!

Regards,
Wayne A. Pflughaupt

 

[BillHewitt]

Please pardon my ignorance on the matter as I'm no amp designer, but why are differing boost curves that much better than a set of different HP filters? I mean, if you just boost the original signal, can't you shape it down to the desired boost level by switching between filters of different slopes and corner frequencies?

 

[Ilkka R]

Hi all,

I was too a bit disappointed when SVS published the frequency response for the SB12-Plus. The final roll off looked almost identical to their vented subs, which is IMO too steep for a proper sealed sub. It just takes away the only real advantage sealed subs have over vented subs - shallow 12 dB/oct. roll off (and usually somewhat smaller size). And as many of us know, the shape of the frequency response dictates also many other variables, for example transient response (which includes impulse response, phase response and spectral decay). The sharper the "knee" at resonance frequency, the more ringing there will be at resonance frequency. Ed Mullen pondered the same issue here.

The final roll off for the SB12-Plus seems to be around 36 dB/oct., which means there is a 4th order high pass filter at around 23-24 Hz. That gives us 24 dB/oct. slope + natural sealed 12 dB/oct. slope = 36 dB/oct. I assume that the frequency response shown on SVS webpage is measured with the "room compensation" bypassed. Wayne's explanation would idicate that the "room compensation" is an EQ (notch filter), not a HP filter. It will just make the "knee" at ~25 Hz wider by bringing down the overall level below 35 Hz by 3 dB, 6 dB or 9 dB.

Of course all these extrapolations assume that the frequency shown on SVS site is correct and accurate for this sub. We'll have to wait for a couple of 3rd party measurements to be able to confirm this. Ron, you know my address.

 

[Jack Gilvey]

Based on personal hatred disguised as technical issues usually.

 

[dany]

He stayed at a Holiday Inn,what eles could it be?

 

[dany]

Say Ron,how would the new sub compare to a 20-39 pci? My wife begs be to get something not as tall.

 

[dave alan]

Hi Jack,

You've mentioned this point several times at various places and the point is well taken, but not very well researched, IMO.

Some of the 'gurus' you may be referring to have, in fact, had many conversations about this very fact.

In response I would point out that Ed's review mentions this:"As shown in the table below, the UFW-12 can play very loud at/above 40 Hz before distortion reaches 10%. In fact, this is one of the strongest overall performances in the 40-80 Hz bandwidth I have yet measured."

Obviously, headroom and BW linearity in the musical region is very important to music reproduction, as no one says that roll off is everything.

R-DES is also in the package and no doubt has something to do with in-room response.

Then, there is Seaton's upgrade option with measurements of the proto seen in this thread, where it's obvious that feedback has prompted an option for a very smooth roll off vs the steep HP.

And yes, I consider Seaton to be a subwoofer 'Guru'.

Again, your point is well taken, but I think the point here is that, instead of the fanboy backlash and vitriol from the owner, the result was instead an optional upgrade to satisfy those who believe the upgrade will result in improvement in SQ.

Dave

 

[Tom Vodhanel]

>>>While the terms "guru" and "expert" are more self-proclaimed than anything else...

 

[Tom Vodhanel]

Hi Jack,


>>>Shallower is better, sure, but yet it seems a much steeper slope is more than acceptable in a non-SVS model. If posted impressions are to be believed, such a slope can be highly "musical", even to the "gurus".

 

[Jack Gilvey]

No argument. Never mentioned otherwise.

 

[Ilkka R]

I believe one major reason for its claimed musicality (I haven't heard it) is indeed its maximum output capability above ~40 Hz. Although Ed's 10% THD data doesn't clearly show it (one reason why I (and recently Ed too) prefer other way to measure THD), I believe its THD levels are lower for example at 100 dB level (above 40 Hz) than what most other sub's have. You have self said that the SB12-Plus matches with PB10 from 30 Hz and up, meaning ~103-105 dB. That means a single UFW-12 would match with TWO SB12-Plus in maximum upper bass output. And we haven't even compared the THD levels yet. Certainly a major factor when discussing about good music performance.

 

[Tom Vodhanel]

>>>I believe its THD levels are lower for example at 100 dB level (above 40 Hz) than what most other sub's have.40hz most subs will be coasting...(esp sealed subs) with VERY low distortion. So for your theory to be accurate, you would be suggesting the difference between 1% and 2% THD is so significant it will overwhelm all of the negatives you introduced earlier when criticizing the SVS SB12plus design (group delay, phase, impulse, ect). Doesn't make much sense at all(imo) No one who understands low frequency acoustics is going to claim that the difference between 1% and 2% THD is going to be make the difference between one sub being "very musical" and another sub being "disappointing". . Also, your theory doesn't explain why the UFW10 is also considered extremely "musical" either. Or are you now suggesting the UFW10 has as much >40hz output as the UFW12?


>>>You have self said that the SB12-Plus matches with PB10 from 30 Hz and up, meaning ~103-105 dB.

 

[Ilkka R]

I'm extremely sorry about that. I do remember seeing that comment, but it wasn't from you, somebody was just misquoting you. Here's what you said:

"In comparison to the PB10...

In terms of sheer output... SB12plus will have slight advantage >45-50hz. In the 40-50hz range it is close. And the farther you drop under 40hz, the more of an advantage the PB10 gains."

108-110 dB above 40 Hz should be very comparable with the UFW-12, so it will be an interesting race. Especially when noticing that there is such a huge size difference between those two. Of course some 3rd party reviewer has to confirm those numbers before. Many of us still remember what kind of numbers were being shown prior UFW-12 launching...

 

[Tom Vodhanel]

>>>I don't necessarily agree with this. Most rooms have very little room gain above 40 Hz. There will be some boundary gain (~3 dB per boundary) depending where the sub is placed, but if one is sitting very far from the sub, that added distance can actually make subwoofer work harder than it would work at 2 m GP. IMO the upper bass headroom is one of the most undervalued variables.

 

[LanceJ]

The audio biz ain't doing so well these days and I'm sure sometimes solid philosophical considerations take a back seat to keeping the business viable enough so they can pay their bills.

 

[dave alan]

"For anyone following along who is wondering how "bad" the sb12plus must sound because of these *evil* highpass filters(that are only bad when SVS uses them?)...please search through the threads that have dozens of people offering their listening impressions of the SB12plus in recent "get-togethers". See if their opinions of the Sb12plus match up with the "gurus" (who have never heard/seen a SB12plus of course) who are criticizing the design. That might give everyone a little insight into what is REALLY important in sound quality."

Tom,

I have said and will repeat it here, that I personally think you are among the top subwoofer designers out there. It's public relations I think you are terrible at.

I've been following along and I actually had to re-read the entire thread to find where anyone said that HP filters are "evil", or that anyone said the SB-12 sounds "bad", for any reason.

I don't believe that I've ever said any subwoofer is 'musical', in any context other than to quote someone else who said it. A subwoofer is either accurate or it isn't. It adds to the signal either to a greater or a lesser degree. It has the features to arrive at as flat an in-room FR or it doesn't. It is closer in time to the rest of the presentation, or it's farther away in time. It has headroom for a given app, or it doesn't.

There's no reason to sidetrack. I wish the AV123 subs were not brought up as this thread should be about your SB-12, but since they have been brought up and you've commented on them, the UFW-12 is a more efficient design at 3X the size and sports a larger power plant. With R-DES and the upgrade option, the SB-12 simply can't compete with it, nor do I think it was intended to.

I also obviously agree with Ilkka regarding the headroom issue as soundtracks and music program are anything but static and continue to become more and more dynamic as technology allows, as well as varying greatly from one disc to the next. This fact doesn't allow a subwoofer to 'coast along at 100 dB', IMO.

To stay on topic, I wonder why you haven't corrected Wayne's idea that the SB-12 doesn't use HP filters but rather EQ notch filters, or otherwise varying degrees of EQ boost?

It appears that there is an EQ boost curve applied to extend the natural response to 20Hz with a high order HP below that when in 'bypass'. The 'small', 'medium' and 'large' positions on the room compensation control are selectable HP filters that change the anechoic FR, the Q of which filters isn't specified or reflected in any graphs.

I think this is an excellent feature, as anyone who knows me already knows. I simply said I was 'a bit' disappointed that HP filters were used to accomplish the goal.

It's a personal opinion. I could be mistaken, as in-room response is ultimately most important and dictates GD numbers to the end user.

I wish you'd be less defensive and tell more about the feature so we could move on to the other features.

Or, we'll just have to wait for 3rd party reviewers, as Ilkka pointed out, and that's OK, as it's your call. Honestly, if you perceive any ill-intent in this post, please just don't answer any of it and I'll move on.

Dave