SVS B4 Subwoofer Product Review!!! - Page 3  

on my CBII, I'm typically around a gain of 35. Sometimes I crank it up to 40 for the heavy bass scenes but I hardly ever go beyond that. When my B4s arrive, I'll probably let her rip for a little bit. But I'm really looking forward to what they'll do at ambient.
Javry

Hi all, saw something posted and thought I might be able to clarify a few concerns:

If a test system is calibrated, then from a frequency response standpoint the type of mic, type of PC/soundcard/digitizer, software settings, and even test signal should not make a difference. I've done extensive sets of measurements in the past for FDA-approval of new Ultrasound systems, and have been "through the wringer" in terms of measurement types.

MLS (MLSSA, LAUD, many others), FM Slide/CHIRP (predominantly TEF), stepped sine (LMS), pink/white noise (RTAs), all will produce the same frequency response given the following:

- Data is properly truncated/windowed to eliminate effects of reflections
- System is properly calibrated.

I've spoken at length with Dr. Johnson in the past, and believe he is properly windowing the data, to eliminate reflections. A good examination of the impulse response shown at his site will show that the data is windowed correctly; there isn't any extra reflections in the data. As is shown in his review of the B4+, it's clean to 60 msec, which would indicate good data acquisition down to 16 Hz.

If there is a discrepancy between measurements, then both measurements should be called into question, until one or the other can be verified as accurate. Given that the only measurements posted have been from Dr. Johnson, and personally knowing how he captures and analyzes his data, I'd say his results are most likely quite accurate.

As far as MLS accuracy showing 12-13 dB of drop at 20 Hz, this is not an artifact of the measurements; rather, this is showing the true anechoic measurement of the system. In-room will of course have room gain, flattening the curve. Properly windowed, MLS is as accurate as any other test signal, from a frequency response standpoint. The difference is the environment where the measurements and the claimed performance are taken.

On another note:

My guess is that the environment being discussed is different. I suspect the B4+ may have the claimed sensitivity when in-room, where 8-12 dB of gain is expected down below 50 Hz. I know Mark is typically working in "largish" rooms (like 4,000 seat theaters), so that free-air sensitivity is truly anechoic. An anechoic efficiency of 90 dB @ 1W, 1m would fall in line with Dr. Johnson's findings of 122 dB SPL @ 1500W (~32 dB of power gain, meaning a 1W output of ~90 dB SPL).

I personally would be VERY surprised to see an efficiency of 100 dB SPL @ 1W, 1m anechoic for the B4 at any frequency, anechoic. If it does perform that way, then SVS has truly shattered the limitations of Hoffman's Iron Law, and should immediately patent when they are doing. An efficiency of 100 dB @ 1W, 1m is 6%, which is extremely high, especially in the bass range. Even large bass horns have a difficult time reaching that kind of sensitivity down in the sub 50 Hz range, free-air. For example, the LAB Subwoofer, a large (32 cubic foot - nearly 3X the size of the B4+) horn subwoofer drops below 100 dB efficiency at 100 Hz. At 30 Hz, still within the cutoff of the horn (and thus benefitting from the loading and directivity gains of the horn), the LAB Subwoofer is down to 95 dB @ 1W, 1m anechoic.

My guess is the difference in claimed efficiency is in-room versus anechoic. I know we've seen upwards of 95 dB SPL @ 1W, 1m efficiency for the Sadhara in our home theater room (2300 cubic feet), but anechoic measurements in our smaller 77,000 cubic foot warehouse (a bit more than 2100 cubic meters) show a true efficiency around 84 dB @ 1W, 1m.

Dan Wiggins
Adire Audio

Wow, nice to see a review/thread of a SVS product generating so much interest I guess?


>>>Hi all, saw something posted and thought I might be able to clarify a few concerns:<<<

Hi Dan, thanks for the concern...


First, I have found soundtechnology(which is the program John Johnson uses) to be fairly processor and soundcard sensitive. If someone thinks they can DL the highest resolution versions into 10 different computers and they are going to measure the same thing in all 10...they obviously have no hands on experience with the program. Next, it is VERY important to realize that using a frequency sweep out doors (ground plaining) is COMPLETLY different from using a MLS method. So when I say no one should expect my data and John Johnson's data to parallel...there is good reason behind that. The more actual experience someone has with the programs in question...the more they would agree.

Claims can be made about the accuracy of MLS...but in my experiences it just isn't like that in the real world. In case someone following along isn't sure what MLS/gated method means...here is a brief description from my LinearX manual(leap/LMS)...

By using a series of electronic timing, LMS can make quasi-anechoic measurements in reflective environments. LMS gates out reflections by turning the meter on when the signal arrives at the mic and then turning the meter off before the first boundary reflection has reached the mic.

LMS uses an instantaneous detector for gated sweep modes that can capture the signal level in a single cycle, or even less. However, this assumes that when the meter window opens the signal has arrived perfectly on-time to be read. In reality this is quite difficult to achieve, given the delay through the air and transducer response. These quantities are difficult to measure or determine perfectly. The primary limitation on the low frequency limit of gated SPL measurements is the distance to the nearest boundary. the meter gate ON time must be short enough that it does not pick up the first reflection from the nearest boundary. It should be obvious that the smaller the environment, the higher the low frequency limit will be. Gated measurements made in a residential household living rooms usually must be gated to 2-5ms at MOST...which means accurate response down to only 200-500hz.

For more info about LMS, see www.linearx.com

I have measured many of the same subwoofers that I have already reference in my text. HGS series, subwoofer *X* from the Ultra review, the Ultra and the 25-31PCi. The HGS series has been measured by DON KEELE (maybe some folks have heard of him?)using ground plane/2 meter (same method I use) and he found the HGS12 to be very flat down to 20hz. (this is documented) Personally, I would find it very hard to believe Velodyne designed the HGS12 to be flat when measured quasi-anechoically...but the HGS18 is designed to be down by a whopping 15dBs at 20hz? I guess with the Velodyne thread right here in this forum...it would be easy enough to ask?

I guess you can argue that MLS and 2m ground plane aren't the same. I agree! I would take the real measurement( 2m ground plane) over an estimation by a computer every time. Don Keele felt the same way I guess?

I'm not going to argue with anyone who would rather depend on MLS over GP....so to each their own. GP is definitely a lot more work(it can take me almost two hours just to drag all my test equipment and the subs/speakers I want to test outside), but it has worked fine for SVS for many years now. For example when SVS had our 20-39cs reviewed by Tom Nousaine it extended all the way down to 25hz in his super large 7600 cu-ft room. Not bad for a passive unit with absolutely no on board EQing...much better than just about every other subwoofer he has measured except the servo VELs...so IMO using GP methods has shown to be a very good way of doing things. Our competitors are welcome to do as they wish of course.

FWIW...Don Keele has also measured subwoofer X using the same method...again, his frequency response was NOT even close to the way the curve was shown on hometheaterhifi.

I am fairly confident the little SPL800 would NOT be down 15dBs at 25hz either. But all should fee free to ask Velodyne if they designed the SPL800 to be 15 dBs down at 25hz quasi-anechoically.

So you have a total of 6 subwoofers measured with this method. Three SVs, the HGS18, the SPL800 and subwoofer *X*. Two of them are documented to have flat response by none other than Don Keele in his measurements.

When it comes down to a computer simulation vs. real world data (data documented by Don Keele for instance)...I'm going with the real world measurements every time. I have a full CLIO system with dedicated computers, the newest version of LMS and LEAP on twin dedicated computers, v4.32 Soundtechology, a calibrated Audiocontrol RTA with 170dB+ capabilities and in my experiences...MLS doesn't come close to the accuracy of real world ground plane measurements(<100-150hz). The documented graphs from JJ (MLS) and Keele (ground plane) show a HUGE difference between the real world and the computer estimations of MLS which I believe reinforces my POV.





>>> I suspect the B4+ may have the claimed sensitivity when in-room, where 8-12 dB of gain is expected down below 50 Hz. <<<



We really made no *claims* of sensitivity until specifically asked about it...in fact I explained how I didn't even feel it was worth talking about. But when pressed on the issue I took a guess... here is my last text on the issue...


"That works out to >100dB/1w/1m for me...and that assumes absolutely no thermal compression with 1.5 kilowatts poured into the subwoofer...we both know that isn't going to happen. Even assuming just 1-2dBs of compression taking place...we are right at 101-103dBs sens. Which is very close to what I predicted a while back iirc."


So we agree and you are repeating what I already stated. (about 100dB in room sens.) I'm not sure how many competing manufacturers feel that is a good number or not...and I really don't have too much time to worry about it to tell the truth...

In the end, with just about every customer including feedback of dynamic peaks WELL over 125dBs (usually with the RS SPL meter which is going to read low too) in their on line reviews...I guess I can't get too worked up about what the latest computer simulation is telling someone regarding what our product can and can't do. We have a few B4+ subs shipping out within 24-48 hours and several other orders backed up..hopefully shipping by the end of the week. So I really need to concentrate on getting our orders shipped rather than arguing over the latest computer theory/estimation.

Tom V.
SVS

Tom,

Then your problem is with Dr. Johnson's measurements, not MLS. MLS is most famously used in the MLSSA measurement system, which is used in a huge variety of applications by some of the biggest names in the industry. Properly used, MLS is as accurate as gated sine wave approaches, and in fact can be more accurate, since it is much more noise-immune than gates sine waves (as is FM Slide/CHIRP systems).

Personally, having done thousands of measurements, including FDA-life-critical measurements (for example, we designed and validated the entire audio system in the Siemens Antares ultrasound system - speakers, amps, signal processing, mics, etc), I've found wonderful correlation between MLS, gated sine, and CHIRP when properly used. I tend to use CHIRP because of the speed or the signal, but in high noise environments (particularly outside where wind can skew the bottom end) MLS with it's pseudorandom noise pattern is superior. Higher noise rejection. Personally I rarely use gated sine since it is very susceptible to noise.

Gating in a room can be stretched out to 1 msec per foot from the nearest boundary or significant object; in a larger room, it's possible to get 100 Hz. In a huge room/warehouse, or outside, you can get much further. Note that gated sinewaves can have the same reflection issue. if the reflection happens within the measurement window, then the measured data will be corrupt. Regardless of measurement technique, proper setting of the gate window is critical, and will skew the measurements accordingly.

The issue, therefore, is operation of the system, and not the measurement system itself. How was the gate set? If the gate is 60 msec out, as shown in the B4+ measurements, then the data should be clean down to 16 Hz. If the gate was shorter, then the lower end of the frequency spectrum would increase.

So I guess the question is what could be the issue with Dr. Johnson's measurements? Perhaps we should ask Dr. Johnson to join us and explain how he takes his measurements. If Soundtechnology is as difficult to set up and configure as you state, then the issue is with the particular tool used (not the measurement technique), and would mean that results found by Dr. Johnson should be discounted, for all tests so measured. Even "comparative" samples within the same test set should be circumspect, because the potential errors can't at this time be determined to be precision or accuracy.

As far as the sensitivity of the B4+ goes, the SPL measurements of Dr. Johnson (the only published review I can find for the B4+) shows 90-92 dB, and 100 dB in room. Just wanted to clarify. Also, be aware that the RS meter is inherently inaccurate above 116 dB SPL, and is limited to 126. I've seen it swing wildly low AND high at the upper ends of things. Personally I would not trust it at all for SPL levels above 110, but then again I think you and I have access to gear beyond the usual HT enthusiast.

Dan Wiggins
Adire Audio

Dan,

Let me try to make this as simple as possible...

I don't have a *problem* with the way John Johnson measures the FR. I just don't think it is going to parallel a 2m GP measurement. I personally feel 2m GP is the most accurate way of getting quasi-anechoic data. You may disagree...that's fine...I don't really know what all of your measuring preferences are. And to be honest, I really have no interest in them.

I have spent the better part of the last 5-6 summers(May thru Oct) doing nothing but measuring speakers and subwoofers outside...sometimes making hundreds of measurements a day in the process. You have the methods you are comfortable with...I have methods that I am comfortable with. You have equipment you are comfortable with...I have equipment that I am comfortable with. That I am put in a position to defend my measuring preferences by a competitor in a thread solely dedicated to a recent review of a SVS product is a little surprising. Maybe I am just envious of the free time others have...


I have already listed multiple examples of MLS not matching 2m GP data at all in DOCUMENTED cases (Keele) above. And I would like to see the look on Bruce Halls face if someone told him his 18" servo just measured 15dBs down at 20hz quasi-anechoic..:) The fact that these MLS measurements show the smallest PCi and the largest Velodyne having *about the same* FR should be a good indicator that they aren't the most accurate of data.

Tom V.
SVS

Tom,

What bothers me is that when properly calibrated with known conditions and suitable resolution, measurements should be highly repeatable. Outdoors on the ground is one condition that most anyone can easily replicate. While in-room measurements are very difficult to compare with those taken in different rooms, with the exception of temperature and wind, the great outdoors is pretty constant in acoustic loading of low frequency devices.

Point being, that outdoor ground plane measurements of suitable resolution with a calibrated system should be easily comparable. This is nothing new to the professional audio world, or even to designers in the residential/consumer world who are measurement savvy. I hope that reviewers follow the lead of Keith Yates and John Johnson in taking measurements which are in many ways easily compared and repeatable. If measurements are not accurate and repeatable, there's no point in taking them.

Two points need to be considered here. First, John Johnson does not list the level at which his frequency response measurement was taken. It is only a realtive level plot. I'm sure you have seen some of the measurements our friend Deon has taken of the Velodyne and Sunfire subwoofers, and the measurements Keith Yates published also show how frequency response is rarely constant with level. With the sophisticated limiting executed in the HGS subwoofers, I would be that at some output level, the frequency response IS 15dB down at 20Hz quasi anechoic. This would also explain the response of the SPL-8. This is not much different that what is seen with a Bag End sub where it is flat to 8-10Hz... at ~75dB.

Finally, there is nothing in John Johnson's measurements which indicate an included reflection or lack of resolution at the frequencies of interest. This is why I had inquired as to how this response compares to your measurements. Citing that users have reported very high levels of bass on program material measured with a Radio Shack SPL meter on C weighting only tells us the levels are high, not if they are high at low frequencies. The measurements being discussed are not "computer theory/estimation" but rather well understood measurement methods. Nothing in this is hypothetical modeling, but real world measurements. Measurements which somewhat contradict the "Anechoic" frequency limits quoted in the B4-Plus manual. As the measurements differed, I inquired how these measurements correllated to yours.

>>>Tom,

What bothers me is that when properly calibrated with known conditions and suitable resolution, measurements should be highly repeatable.<<<


Mark, I'm sorry you are *bothered*. In my experiences when you introduce a single variable into the experiment, all bets are off. In this case, we have different computers, different sound cards, different mics (I believe), different distances between the mic and the subwoofer, different orientation between the subwoofer and the mic, different input signals, different generators of the input signal, probably different weather conditions (and if you don't think that will make a difference...try measuring the same subwoofer in 90 degrees in the middle of the afternoon and 50 degrees later in the evening) and almost assuredly a minimum of a half dozen differences in the settings of soundtechnology itself. The ONLY constant is both methods had the subwoofer *outside*...and we really don't even know how close each outside environment was. And thru all this...someone is *bothered* that the two methods aren't showing identical results? Please.





>>>Two points need to be considered here. First, John Johnson does not list the level at which his frequency response measurement was taken. It is only a realtive level plot. I'm sure you have seen some of the measurements our friend Deon has taken of the Velodyne and Sunfire subwoofers, and the measurements Keith Yates published also show how frequency response is rarely constant with level. With the sophisticated limiting executed in the HGS subwoofers, I would be that at some output level, the frequency response IS 15dB down at 20Hz quasi anechoic. <<<


Yeah, if the output levels were so high, that the limiters kicked in so SEVERELY...that the big 18" servo fell flat on its face...and ended up 15dBs down at 20hz. That is a huge assumption you are making. I believe John Johnson would take a FR measurement at more standard levels...85-95dBs for example. If you are that bothered by it, I would email him to ask.



>>>Finally, there is nothing in John Johnson's measurements which indicate an included reflection or lack of resolution at the frequencies of interest. This is why I had inquired as to how this response compares to your measurements. Citing that users have reported very high levels of bass on program material measured with a Radio Shack SPL meter on C weighting only tells us the levels are high, not if they are high at low frequencies. The measurements being discussed are not "computer theory/estimation" but rather well understood measurement methods.<<<


MLS is a computer estimation of how a speaker MIGHT measure in a true anechoic chamber. Because it is *well understood* doesn't mean it is more accurate than any other method.


>>> Nothing in this is hypothetical modeling, but real world measurements. Measurements which somewhat contradict the "Anechoic" frequency limits quoted in the B4-Plus manual. As the measurements differed, I inquired how these measurements correllated to yours.<<<


Mark, I think I've made it VERY clear why I don't believe the MLS measurements John Johnson takes are good indicators of the response of a subwoofer. He even indicates that in his text. Using your *logic*...Velodyne should be indicating their 18" servo is 15dB down at 20hz...???

gee, maybe you and dan can jump into the next thread dedicated to an overwhelmingly postive Velodyne review and question the validity of all of Velodyne's manuals, and Velodyne's own design/measurement methods on their own products?


Tom V.
SVS

I could give a rats ass about the measurements..my ear is the one that counts...If I'm happy and with the way SVS backs their products, I'll be svs for life. Johnson must have thought the B4+ was worth testing....was it a mistake...I doubt it...get in line.

Didn't have a chance to do much this weekend other than subjectively compare scenes from The Matrix Reloaded with and without one port plug (20hz). Having one plug definitely enhanced the bass you could "feel" in the freeway sequence and others and did not require too much upward adjustment in level with Avia. I will know more after I do my freq. sweeps in preparation for BFD programming.

BTW, what's wrong with a red subwoofer? I wonder if Tom could chime in and let us know what color (roughly) SVS ships the majority of B4's with?

Post your B4+ pics!

http://home.mchsi.com/~toml/wsb/html...ID-283652.html

A photo shoot...it isn't like this in my room:)

Now Brian.....don't go gettin your ti.......'s in a wringer! A red subwoofer is a very nice thing....sure to be loved and admired by all. Why, just the other day, I was strolling through the park....and whaddya know.....a cloud came floating by in the shape of a red subwoofer....just kiddin, of course. Actually, It sounded kind've cool. TV just sent me some samples to pick from and guess what......mercury red is on my list of potentials. Now, aren't you ashamed?.............don't answer that.

Now on to more serious matters. I noticed that 3 has his ports pointed in several different directions re: his photos. Does this matter? In other words, does the relative position of the ports [outward vs facing the wall, et al] impact sonic performance? How about the drivers? Maybe TV can weigh in here, as well.
Javry

Then someone's measurements AREN'T CORRECT. I think that's what Mark is getting at. If they are different, then one (or both) are incorrect.

I'd suggest a quick read of http://www.purebits.com/mlsteo.html to understand that MLS is NOT a computer estimation. It allows you work in closed environment because it has the ability to gate echoes out (which are much more difficult to do with CW signals).

To summarize: MLS uses a pseudorandom noise pattern that has the wonderful property that when it is cross-correlated with itself shifted by one sample, you get back a perfect impulse. In other words, it's a way of creating a VERY high S/N impulse.

Now, take an impulse, and run it through a Fourier Transform. You get the frequency response over the time window input. Provide a 1 second impulse response, you get 1 Hz out as the lower limit.

And, because you cross-correlate (a true mathematical function, in that you get a unique output for any unique input, thus there is no "estimation" involved), you get time domain data to work with. Which makes gating out echoes a LOT easier.

There's no "estimation" of MLS at all; it's a wonderful, highly-noise-tolerant test signal. If it's an estimation, so is gated sine. So is a CHIRP. I can assure you that all 3 have their uses, but MLS and CHIRP are used in most high-end measurement systems (such as TEF, MLSSA, Audio Precision One and Two, etc). Gated sine as done by Linear X/LMS is rapidly being dropped because of it's susceptibility to noise, and inability to effectively deal with echo-filled returns.

There's several other signals and systems books I can direct you to, if you'd like to learn more about use of MLS and CHIRP in measurement systems. Both approaches are used heavily in some of the most advanced acoustics measurement systems on earth - ultrasound and SONAR. High resolution of extremely small signals in high noise environments are why these types of signals - and not CW (gated sine wave) pulses - are used.

MLS is at least as valid as CW, if not more so, for the audio professional. The freedom from noise, and the ability to easily identify echoes (readily apparent in the time domain) prior to frequency domain transforms is very beneficial in ANY situation (including true anechoic chambers, such as the one at Siemens Medical in Issaquah, WA). CHIRP has the same benefits over CW as MLS, but because of the shorter pulse length is slightly more susceptible to noise (but still quite a bit better than CW).

I'll ask Dr. Johnson to pop on by, and see if he can clarify his measurement technique.

Dan Wiggins
Adire Audio

at least as I understand MLS according to JJ's reveiw of the Ultra but I think it would be similar to the B4 or other non-front ported subs.
Below is a quote from the Ultra review and shows the problem as I see it.

"Since we don't have an anechoic chamber, we used MLS filters, which simulate anechoic response. I placed the microphone 8" from the subwoofer, and used white noise with MLS filters, and a 65 ms window, which means that everything which the microphone receives 65 ms after it starts receiving sound is eliminated from the measurement."

When he was performing other 8" microphone measurements he said
"The red line at the top is with the calibrated microphone placed 8" from the subwoofer output region (bottom of the subwoofer)." There's no reason for me to think the microphone was anywhere else for the MLS test than located at the subwoofer output region.

Herein lies the problem. The microphone is over 3 feet from the ports.

Perfoming the 8" test with my Ultra and RS meter (C-weighted slow), a 90 db reading at the sub output area yields a a 99- 100 db reading at the port area.

As you go higher in frequency, you will get a blended response between the ports and speaker. As you get to 50 Hz it is all speaker.

While the B4 is tuned naturally higher than the Ultra, I think the same logic applies. Assuming of course what I am saying is logically.

In a nutshell, a single microphone may not be enough when measuring output that close to a non-front ported speaker. I think you would need one 8 inches directly in front of the ports and another 8 inches by the speaker. With a sealed or front ported speaker I don't see an apparent problem with using a single microphone.

As you get further away, such as with ground plane measurements, the ports and speakers blend better, giving a more accurate indication of what the frequecny response is. With my Ultra at 3' and 20 hz, the output is still greater above the ports but it is only ~ 2 dbs instead of 9-10 dbs. At four feet therer is not much of a difference.

>>>Now on to more serious matters. I noticed that 3 has his ports pointed in several different directions re: his photos. Does this matter? In other words, does the relative position of the ports [outward vs facing the wall, et al] impact sonic performance? How about the drivers? Maybe TV can weigh in here, as well.
Javry<<<

How guys, sorry for getting side tracked.

One thing we should have done was to take pictures of each of the finished B4 subwoofers. I think we've built at least one in every standard veneer option on our website...and some colors like Mahagony...man, we must build some variation on that color at least once a week now. We've shipped a bunch(between 1-2 dozen I would guess) of black units...one we hand delivered to Big Mick Hughs...ring a bell? He is the chief sound engineer for Metallica. (has been for about 15 years I believe). He contacted SVS a while back because he wasn't real pleased with the bass in his (fairly large) home (he had a large pro style bass bin) One thing lead to another...and we were building a B4+ for him before we knew it. Ron had the pleasure of roaming around back stage at the Denver show a couple of months ago when he personally delivered the B4+ to Big Mick....meeting everyone...just hanging out in general I guess.

Cherry seemed to be the hot finish at the start...I bet we shipped out some variation of *cherry*...10 of the first 20 units we shipped(about the first month or so the model was available).

We are also doing a lot of custom/ matched to customer sample units lately. I would say we are shipping an average of 2 a week that are custom in some regard. We have done more than a few matched to the *rocket* finish. Not sure how many...but I bet at least a half dozen in the past 6 months.

I really wish we would have had time to get pictures of each, but I have seen a lot of pictures on line so hopefully more and more customers will showcase their B4+ subs as time allows..:)


Tom V.
SVS

TRC,

I think you have found one of MANY potential details that have been ignored during this debate. As much as I like the little $549 25-31PCi...the thought that is going to have about the same anechoic FR as a Velodyne 18" servo is a stretch to the extreme. I covered some of these issues in general when I said *mic distances*. There is also the effect that driver orientation can have on the measurement. When I test subwoofers that have a driver/port/PR on different baffles...I orient the subwoofer so that the port/driver will be approx the same distance to my mic (which I keep at 2m). Just rotating the subwoofer 45 degrees can make a big difference in the measurement.

I have seen quasi anechoic data from at least a half dozen sources now...Don Keele, All the audio ideas guide reviews, my own, two close friends of mine I can't name(they work for large companies that probably wouldn't like them sharing data :), and a nice cross section of FR measurements in AUDIO magazine that weren't performed by Don Keele. There is also a ton of quasi-anechoic stuff in all the old SB magazines...and some data in the misc audio critic.

NEVER, not once has any of sources shown identical measurements when measuring the same subwoofer. I have gotten close to Keele's measurements...but never identical. And i have seen big differences between MLS and 2m GP in the past...this isn't anything new.

The myopic view of this would be to simply say everything must be "wrong" then. But that isn't the case. The data I measure is correct...it is correct in that it is how I CHOOSE to perform my measurements. This doesn't make everyone elses data inaccurate. Their data is just as accurate to THEM...as they are obviously not going to copy every piece of gear, and every measurement method someone else uses. All of Don Keele's data isn't suddenly "wrong" because someone measured something different using a COMPLETLY DIFFERENT METHOD.

Tom V.
SVS

has johnson tested anything by adire audio?

Interestingly, he did.

http://www.hometheaterhifi.com/volum...rs-3-2003.html

The kosala speaker. Adire lists it as...

"""Bandwidth ±2 dB 55 Hz to 20 kHz, anechoic."""

When John Johnson measured it using his MLS method...it had a huge bass rolloff starting at about 125-150hz...by 50hz it was about 10dBs down(compared to the 125-175hz range). John Johnson stopped the graph at 50hz in this case. It also had a huge 8dB dead zone at 500hz. That isn't on any of the graphs on adires site?

Since Dan has already gone on record insisting this method of MLS is correct (and implying anything else must be *wrong*)...the question begs...why does adire have "wrong" info about their own products listed on the website? Shouldn't adire just remove their response graphs on the kosala and copy/paste the MLS graph of John Johnson...after all...dan has CLEARLY outlined in the above text how very accurate this MLS method is...???

Or better yet, why is Dan so worked up about the differences between a SVS spec and Johnson's MLS measurements...when Johnson's MLS measurements have differed against EVERY manufacturers specs...including adires?

Talk about the pot and the kettle...what a waste of everyone's time.

Tom V.
SVS

I'll post pictures of mine if you post pics of the production line. I, for one, would love to see the process by which one of these suckers gets constructed. BTW, I turned my B4+ on the non-driver side (gently) last night to access the pedestal. Unfortunately, I went too small on the furniture sliders I picked out, so I will have to try again with larger ones. However, I took the opportunity to pull off the recessed grill (the one covering two drivers) and discovered that the interior well (where the two drivers sit) is veneered and finished as well--unbelievable attention to detail!

Thanks Vet...do post them! Glad you are FIRED UP!

Jav...I just took pics of all sides to show it...great job on the finishing...I think you'll be impressed!

Dan, quit knocking the hell out of our fun...talk your bullsh@t somewhere else...I'm tired of having good threads ruined by people of your caliber..knocking someone elses attempt to create good products just shows how worried and thoughtless you are...would I buy a audio adire product? I had the chance, and somehow knew my money was better spent elsewhere..glad I made the choice..now I KNOW I made the right decision...I wouldn't be suprised if you argue with your customers the same way.....Back to B4+ talk...in the way this thread was meant to be! 3C

Not quite a B4 but I had a 25-31 PCi in my dorm last year. And yes it was awesome.

Yes, what a waste of time. I guess you've never heard of smoothing, have you? We use 1/3rd octave smoothing (per industry standards), Dr. Johnson's measurements were raw. And if you look at the trends in the two measurements (ours and his) they are quite similar.

If you want to spew vitriol go ahead - I wasn't attacking you or SVS (apparently you can read things that aren't written) but was clarifying measurement issues. I thought someone considered a professional in this field would appreciate a compare/contrast and clarification of measurement techniques - including appropriate use of test signals - but I guess that was not the case.

Dr. Johnson's review of our product is perfectly fine, when read AND TAKEN as is. Don't add in, or "read between the lines". Dr. Johnson is a serious researcher, and writes what he means. He doesn't play reviewer games. No need to add to it. Apparently you don't like that. Then your issue isn't with me - it's with him.

As far as that "huge 8 dB hole" you talk about? It's a 4 dB dip from average - way to really use the hyperbole there, Tom! Even you guys use the "+/-" SPL spec. I guess that you won't allow that for others, then, will you?

As far as being all worked up about your spec versus Dr. Johnson's measurements - PLEASE tell me where I do? I explained to Mark what I thought were the differences in claimed SPL. In fact, I thought earlier on in this thread you and I agreed where the differences came from (in room versus anechoic). Somehow that is attacking you? I know you have some personal problem with me, but geez if I can't even explain simple technical questions about measurements - and NEVER even degraded or down-talked your product - then you really need to rethink your approach.

I guess I can live with Dr. Johnson calling the sound spectacular, with an extremely wide soundstage, and appealing.

Hey, here's a thought. If you think Dr. Johnson's measurements aren't accurate, then why do you have his reviews all over your site? Pot? Kettle? Black? Look in the mirror...

Dan Wiggins
Adire Audio

Dan..if ya didn't get the hint..your continued attacks are unwanted here...you can see many of us are happy svs owners, and don't want to be rattled by some Bs that you bring to this...I can tell ya this..your making your company look foolish to me...and I can tell you, I, nor any one of my friends reading here will buy one either.....I've tried twice to get this thread back in order....next step will be to close and I'll reopen a new one....

Threecard,

WHAT attacks? Where? Please point them out so I know what I can't do next time!

I was asked into this thread to clarify some measurement questions, and that's what I did. If that's an "attack", then I really need to have someone explain the AVS Forum rules to me.

WHEN did I attack the B4+? When have I said it was a bad performer? When did I say it wasn't good? I haven't - all I've done is explain where the measurements came from, and how MLS, CHIRP, and CW can all be equally accurate when properly used.

If that rattles your cage...

Dan Wiggins
Adire Audio

>>>I guess I can live with Dr. Johnson calling the sound spectacular, with an extremely wide soundstage, and appealing<<<

Yes, excellent...and SVS "can live with"...

"From my listening experiences with the B4-Plus, it is obviously the most powerful subwoofer ever constructed for consumer use. SVS has done it again. For anyone who wants to have the Darth Vader of subwoofers, the B4-Plus is it. With almost unlimited power and low distortion, the B4-Plus is definitely one of the Masters of the Universe"

Funny, no one saw SVS jumping into any Kolasa threads on the internet ramming our opinions down the throat of adire about the proper way to measure their own products...

Tom V.
SVS

Tom and Dan,

Why don't both of you CHILL OUT!!!!

You guys are going back and forth like a couple of Jack Asses.

Buki,

Point taken.

Dan Wiggins
Adire Audio

Thank God I didn't buy a adire sub...All I can say....now back to our regularly scheduled thread of B4+'s, and info to boot!! TV...shed some light on the question above about placement from VET....he had one WAY back when:) I have had good success about 3 inches from both wall corners.....I willtry having the ports out just for kicks..looks cool....then again...my cats may get stuck!

Jav...you corner loading and going side by side with them...or other?

Hey 3,
Actually, I haven't recieved them yet. I'm guessing I'll get them in around next Friday. We're still working out issues with the finish. Those finish guys are real pros. They're almost insisting that they won't do the finish until they're sure they understand what I want. Like the McDonalds commercial says, "I'm lovin it"

I was just sittin back, waitin for things to cool down and hopefully get back to the issue at hand.

Dan,
your points about measurements are well taken. It's just that we are all having a real good time discussing a very expensive piece of gear with the guy that made them....and, at first, it appeared that you were raining on our parade. I'm sure your intentions were otherwise. In short, we would like to keep TVs attention focused on our questions......since we're his customers. Afterall, that's what this thread is about. Any unbiased comment you care to give that will make our purchase more enjoyable is certainly welcome.

Now...........back to the important stuff.
What I was asking about earlier was whether there are advantages to pointing the ports in any particular direction [against the wall, pointing outward, ect]? I've seen several photos of the B4 in HT setups and it looks as if they all point the ports in different directions. I was hoping to have TV discuss this a little further before the discussion got...... "out of phase". Feel free to chime in Dan. Helpful "un-biased" comments are always welcome in this thread.
Javry

3,
I just read over my last comment...and I don't think I answered your question. When my subs get in, I plan to have them sit side by side at the back of the room. DaveN's going to come over and help me unpack them on the front porch...and then we'll man-load them inot the house. We're definitley goin to have the beer flowin but we're taking Brians advise and waiting until things get setup before chug-a-luggin. I'll keep them in the back for about a month and jot down some notes while playing with phasing and port positioning. I have a few other locations in the room I want to try but that will happen as time goes by. My guess is, if my past experience with new gear is any indication, I'll be moving those things around for a few months...until I lock into an optimized setting. No problem there......thats' the part I like.

...and you know darned well I'll be posting a review of sorts with every setup....so stay tuned. BTW, I ordered Titan AE off Ebay yesterday.
Javry

Sounds sweet, and well done getting us back on thread:) Yes, I actually spoke to Jeff, the cabinet owner himself per Tom V. about my finish...it took a few back and forths to get things right...heck, pictures wouldn't cut it..I mailed them samples and they mailed me samples..it was a blast getting things from them to see the quality...A+ to them for that!

Sounds great on the titan dvd...I can't wait to get things up and running again...I'm at a standstill till my 12 gauge gets here...looking forward to your posts man...join us in the other thread if ya can...MRL is over there too...HEY JOHN DORAN...get in on this....(opne of the first B4+ owners fyi:) I believe BrianK is around too...2 good guys for answers...all in all, you will , with a bit of tweaking, be in good hands with the B4+ ' ES :) 3C