This is the requested info about the new sub.

Stuart Wright

AVForums Founder
Staff member

Tom Vodhanel

Hi guys,

A moderator can delete this thread if this is breaking any rules. I apologize. I thought a manufacturer offering information (repeatedly)requested by other forum members was ok.

We won't have time to update the website for a few days so rather than keep everyone here who asked for more details in the dark even longer---I linked a post Ron made in another forum. If that is also breaking a rule...I once again apologize and request this thread be deleted.

If anyone has any questions about SVS products in the future(questions they would appreciate feedback from me on)---it seems it would be best to keep them private and just email me,thanks.

Tom V.


Standard Member
don't see any problem with you handling enquiries regarding SVS if you are an official representitive of that company... isn't that what John Dawson does for Arcam?
He provides an excellent service to Arcam owners and potential owners. I can't see how offering that kind of service provides anything other than benefits for users of AV FORUMS. I would certainly welcome it (although I am not in charge... maybe one day!!:devil: :D )

Ian J

Originally posted by James45
don't see any problem with you handling enquiries regarding SVS, isn't that what John Dawson does for Arcam?
He provides an excellent service to Arcam owners and potential owners. I can't see how offering that kind of service provides anything other than benefits for users of AV FORUMS.
John Dawson answers questions about Arcam products that have been raised in the forum which is not quite the blatant advertising that this thread is, a practice for which Richer Sounds were told to desist when they did it.

Stuart Wright

AVForums Founder
Staff member
Ian the difference is that Richer Sounds are a retailer, Tom is the manufacturer.
Yes they are both out to make money, but manufacturers are in the best position to inform us about their product information.
I actually want to encourage manufacturers to post here. Though answering questions is preferable to making announcements while making announcements is still ok if done without using 'advertising speak'. Product announcements would also have to be done at the same time or before official press releases or website updates.

Tom you are very welcome to answer questions here re your products.

I may change the rules to specifically allow manufacturers (not distributors) a little more freedom.

Bone Daddy

Active Member
Looks very nice Tom,now from reading the link, I and it seems every other sub-human would love to know the specs - ;)

Tom Vodhanel

Hi guys, thanks for allowing me to answer questions about SVS when appropriate, much appreciated. From now on I won't link any information---I'll just post it here. (sorry about that Ian).

Here is a little feedback from me regarding some of the questions I've received on the "b4" to date.

Really it's nothing but a Blown BBC(Big block chevy) in a world busy putting a chrome air cleaner on their 4 cylinder. Just a big ported enclosure.

Could it be considered *under ported*? Absolutely, there are always design compromises that must be considered.The question here should what output level will the ports begin to *audibly* compress and how will that relate to what the rest of the room will be doing at those levels?(walls and floor flex for example ) I'm not sure how it will look on *sims*---I've been experimenting with this design for over a year now and can't remember running a simulation on it yet. We've just been so damn busy actually building and rebuilding about 6-8 variations on this and then spending hours and hours measuring each---how *old school* of us

I think our Ultra design has been verified to offer good output? (see the independent objective data gathered by John Johnson and Brian Weatherhead for details).In ground plane testing using a 1500w amp(Crown K1 bridged) here is how the B4 compared to a single Ultra/500w.(running max output tests at each 1/3 octave using a 10% thd limit)

FYI ~We use Soundtechnology V4.32 with an assortment of LinearX and AudioControl mics for testing. We have 1/96th octave resolution and calibrated mics capable of 176dB readings.

Ultra set to 20hz/B4 with all ports open

20-80hz avg ~ B4 was +9.9dB
25-63hz avg ~ B4 was +10.4dB

Ultra set to 20hz/B4 with two ports blocked

20-80hz avg ~ B4 was +10.4dB
25-63hz avg ~ B4 was +9.6dB

Ultra set to 16hz/B4 with two ports blocked

16hz B4 + 6.4dB
20hz B4 + 8.0dB

Please note---most of the B4 output readings were limited by the amp. While the Ultra would max out at 10% thd at just about every frequency before the amp(half a S1000 gave out)...the B4 would routinely show <10% thd at the output levels listed above until the amp clipped. Since then SVS has purchased a 5 kilowatt Crown Macro reference amp to find the 10% limits of the B4 at every frequency/tuning configuration. I don't have that notebook in front of me(so I can't reference the exact data numbers)...but we only saw a 1-3dB increase in output levels before 10% thd was reached in just about every instance. Given that, I would recommend anything from 600-3000w is fine with this...and 1500-2500 is what I would call optimal.I've been running one of these in my HT room for a couple of weeks now with a K1 bridged and I think that is fine. Going from the 1500w K1 to the 2500w k2 would give you another dB or so of clean output...but I doubt that would be needed(or audible) unless the room is very large.

I also took 1,2,5 and 10% THD checks on the B4 at each frequency/tuning configuration. I'm note going to sit here and type out what amounts to a notebook full of info...but here is one example.

ULTRA(with 500w) with all ports open/40hz

B4(with 1500w)with all ports open/40hz

The B4 had 8.7dB more output at 1% thd than the Ultra had at 10% thd.

The frequency response is very good with all four ports open but begins to push the +/-3dB window with one port blocked. In MOST rooms, this unit will remain relatively flat with 2 ports blocked. I do recommend using a good parametric EQ with this unit though. This is so powerful, adding something like the PE17 is a natural progression imo.(like adding headers to a 454 chevy) are just able to maximize everything a little better. With the EQ, you can tame room induce peaks with a couple of channels AND use the other channels to really dial in the subwoofer for each tuning point---then use the adjustable subsonic filter to tweak everything and you are all set to enjoy a little bit of bass.

Tom V.

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