New Subwoofer Technology

**SteveCallas** · **10-02-06, 04:48 PM**

tzucc, the dynamic range compression comment was to Chrisbee, sorry for any confusion.

Just seems like there is a lot of room for error in combining three subwoofers and a fan IB into one bass system - potential for lots of phase issues, especially if they aren't all collocated. If your FR at the seat is flat without much EQ though, more power to you.

**Josuah** · **10-02-06, 05:26 PM**

Quote:

Mark Seaton wrote:

I've heard the TRW, and have heard a variety of systems that have in-room response into the 10Hz range. This most certainly is a noticable addition and IMO it is quite beneficial subjectively with all playback.

So, in the shared range of 20-30Hz (or even 10-30Hz), you felt that the TRW was better able to reproduce those frequencies than a traditional subwoofer? I'm not sure if you mean adding the TRW to a traditional sub was a noticeable improvement (because you now have two subs and all the benefits that go along with it, or if you mean the TRW is a better alternative? I'd imagine 10-20Hz the TRW would perform better. Little skeptical about 20Hz and above.

Quote:

Mark Seaton wrote:

As for the 20ms of group delay comment, I don't even know what that refers to or what the context was and I allegedly made the statement!?!

I think you were replying to someone asking about a subwoofer company stating 20ms or less at 20Hz to be a desireable group delay goal.

**10-02-06, 07:27 PM**

Quote:

SteveCallas wrote:

tzucc, the dynamic range compression comment was to Chrisbee, sorry for any confusion.

Just seems like there is a lot of room for error in combining three subwoofers and a fan IB into one bass system - potential for lots of phase issues, especially if they aren't all collocated. If your FR at the seat is flat without much EQ though, more power to you.

agreed, but we got sort of lucky, except for one very high Q notch we suspected was caused by phase mismatch between the WD and the X1's, but we ameliorated that by adjusting the WD phase and then applying positive EQ with the Lake.

**Chrisbee** · **10-03-06, 03:32 AM**

I'm still trying to get my head round the problem of bass sounding deeper when potentially the frequencies involved are completely inaudible. Same SPLs but sounding competely different. Perhaps its a masking poblem? Do higher frequency distortion components mask the lower frequencies? Even that doesn't make a lot of sense when different sounds have different audio spectra. Many sounds have weak fundamantals with strong higher frequency harmonic components. Yet they still sound much deeper on an IB. So much so that sometimes it drags one's attention away from the music.

The important question is whether the (ULF) TRW actually makes things sound deeper than your subs on their own?

**10-03-06, 10:42 AM**

Chrisbee, you can absolutely hear and feel below 10Hz, but understand you need sufficient SPL to get there. Look at the equal volume curve studies done for low frequencies...at enough SPL, your ear will hear even 1Hz, but it must be at SPLs of like 120-125dB. WHich is practically impossible for cone driver solutions.
Sub 20Hz is only thought of as completely inaudible, because they have not been presented with enough SPL in that freq range.

On your question, my perception is not necessarily that things sound deeper than my other cone subs on their own. It's more that there is a whole new sound effect below 20Hz, feelings of pressure and concussion... the difference between watching fireworks DVD in a nice system and watching them up close in person, perhaps is one way to express what I observe.

**Mark Seaton** · **10-03-06, 01:30 PM**

Quote:

Josuah wrote:

So, in the shared range of 20-30Hz (or even 10-30Hz), you felt that the TRW was better able to reproduce those frequencies than a traditional subwoofer? I'm not sure if you mean adding the TRW to a traditional sub was a noticeable improvement (because you now have two subs and all the benefits that go along with it, or if you mean the TRW is a better alternative? I'd imagine 10-20Hz the TRW would perform better. Little skeptical about 20Hz and above.

The TRW only reproduces below 20Hz in Tzucc's system. I stopped by breifly last night before I flew back to Chicago, and there is no question that you sense and experience things that aren't there with conventional systems. Multi-driver sealed or large IB systems that can couple into the room into the 10Hz range and below do give a related impression, but the exceedingly low distortion and effortless reproduction into the low single digits takes it to another level. While the effects still need the upper frequencies produced with authority to have the sharp attack and impact, the addition of the TRW adds a subjective scale, weight and realism by adding the all important underpinning foundation to sound effects. Watching Master & Commander even at healthy but in no way excessive levels (still below reference), so many of the sonic occurences are quite different and just draw you in with greater subjective intensity than without the TRW.

**10-03-06, 01:38 PM**

well put Mark.

**SteveCallas** · **10-03-06, 01:40 PM**

Mark, what was your impression of the implementation of the triple crossover?

**Josuah** · **10-03-06, 04:29 PM**

Cool. Thanks for the info, Mark.

**Chrisbee** · **10-03-06, 06:04 PM**

Thanks tzucc. I am very envious of this new level of ULF audio reproduction you are now enjoying.

I wonder how soon such frequencies, distortion levels and SPLs becomes accessible to a wider audience? Clever as the TRW is, I feel another technology will surface which may take us half way there if not quite all the way. For rather lower cost and simplicity.

There was a DIY subwoofer in the mags several decades ago which used full sized rectangular polystyrene sheet ABRs on all faces of the sub box. I even got as far as making one large ABR myself with a nice floppy rubber roll surround. Somebody should give this idea a modern workover in a wall-sized ABR driven by a number of large longthrow drivers via suitable ports. An IB manifold driving an 8'x4' ABR? Insane? Probably.

**10-04-06, 11:43 AM**

I spoke with Bruce about cost in the future, and he is working on something much more cost effective and installable much as you would an IB DIY kit, in the attic for example. About one year out, so stay tuned to his website and we'll likely see something many more people can contemplate buying and installing.

We have to understand that right now volume is low, as the concept is new, and production costs are high, and installation/integration costs very high... professional installers and acousticians and home theater architects need to learn how to work with this new technology and it's particular constraints.

**Chrisbee** · **10-04-06, 05:54 PM**

Excellent! Thanks.

News of the release of such a product would go round the forums like wildfire.
If he could manage a wider bandwidth that would be a real bonus.

**10-11-06, 11:13 AM**

hi, posted some new output graphs captured during movie sequences.
http://bassment.wordpress.com if you're interested.

**SteveCallas** · **10-11-06, 12:08 PM**

tzucc, can you take a 1-100hz FR sweep? I still have a hard time imagining all 5 bass units getting along very well at the seat since they are located in various spots around the room, but I could just be pessimistic.

**Josuah** · **10-11-06, 01:08 PM**

It couldn't use the same amount of installation space as a single fan. :P

**10-11-06, 03:20 PM**

Quote:

SteveCallas wrote:

tzucc, can you take a 1-100hz FR sweep? I still have a hard time imagining all 5 bass units getting along very well at the seat since they are located in various spots around the room, but I could just be pessimistic.

I think we have one already... a FR of 0-100 based on a broadband pink noise.
Let me find it and post it.
There is, as you suspect, some phase adjustments to do to align everything time-domain wise.
I'd say the 5 woofs are getting along quite well, from what I hear and feel, but from the numbers, there may be more work to do. Phase adjustments don't always seem to do the trick either... it's a complex problem.
You can see that without the TRW's, the output spans down to 18Hz or so in M & C.
With the TRW's the outspans down to 1Hz, BUT there seems to be a deep notch in the 20Hz area.
Phase? Time delay? Both? EQ too? Dunno... some combo of the above should ameliorate the notch.

**SteveCallas** · **10-11-06, 04:14 PM**

Quote:

You can see that without the TRW's, the output spans down to 18Hz or so in M & C.
With the TRW's the outspans down to 1Hz, BUT there seems to be a deep notch in the 20Hz area.
Phase? Time delay? Both? EQ too?

Hmm, when the TRW's are not being used, isn't the 20hz highpass that's part of the crossover still in the signal chain feeding the XS? As for the notch at 20hz with the TRW on, my first assumption would be the crossover again. Do you happen to know what order it is?

**10-11-06, 05:32 PM**

Hi Steve, yes the crossover for the XS highpass is of a low order, allowing plenty of 18-20Hz for a '20Hz' crossover point. I do think it's a notch resulting from phase.

**Ilkka** · **10-11-06, 07:10 PM**

Quote:

tzucc wrote:

You can see that without the TRW's, the output spans down to 18Hz or so in M & C. With the TRW's the outspans down to 1Hz, BUT there seems to be a deep notch in the 20Hz area.
Phase? Time delay? Both? EQ too? Dunno... some combo of the above should ameliorate the notch.

I think the reason is as simple as that M&C just doesn't have any material in that range. It's not wide band pink noise...

**10-11-06, 07:18 PM**

huh? M&C audio track goes well down to 1Hz!!! What I am referring to in the thread above is that when using all five subs, there is a notch at 20Hz that is not there when I turn off the TRWs.

But M&C has excellent bass output well below 10Hz, at least in the cannon scenes. Check out the plots at my blog. Notice that those <10Hz energies also showed up with the TRW's off... but at low SPL levels. Which is unexpected... the crossover should have prevented anything at all in the freq range, at the XS.

**Ilkka** · **10-11-06, 07:27 PM**

Quote:

tzucc wrote:

huh? M&C audio track goes well down to 1Hz!!! What I am referring to in the thread above is that when using all five subs, there is a notch at 20Hz that is not there when I turn off the TRWs.

But M&C has excellent bass output well below 10Hz, at least in the cannon scenes. Check out the plots at my blog. Notice that those <10Hz energies also showed up with the TRW's off... but at low SPL levels. Which is unexpected... the crossover should have prevented anything at all in the freq range, at the XS.

I know that M&C has bass down to 1 Hz, I meant that it might not have very high amplitude material in some small frequency range (for example the wide notch in 3-6 Hz range). But I looked your graphs more closely and you are being correct. There is around 10 dB notch at 20 Hz with the TRWs on. That is very likely a phase issue. What kind of filters (HP or LP) you have there? What are their slopes?

**Ilkka** · **10-11-06, 07:37 PM**

Here's a little comparison I made. Red line is without TRWs and yellow is with them. The notch is very narrow, so it can't be very audible.

**10-11-06, 08:54 PM**

Quote:

Ilkka wrote:

I know that M&C has bass down to 1 Hz, I meant that it might not have very high amplitude material in some small frequency range (for example the wide notch in 3-6 Hz range). But I looked your graphs more closely and you are being correct. There is around 10 dB notch at 20 Hz with the TRWs on. That is very likely a phase issue. What kind of filters (HP or LP) you have there? What are their slopes?

I see. Actually the wide notch between 3 and 6Hz we believe is a room mode of sorts. We are working on figuring out the cause... the next amp Bruce will bring me has EQ capabilities... unfortunately the Lake doesn't let you set EQ parameters below 20Hz.

Regarding the filters, I'll shoot some snaps of the Lake Contour settings and upload later. That should answer some questions about what's going on.

**10-11-06, 08:54 PM**

very short movie clip of the TRW being used at a haunted house in FLA... at the blog.

**10-11-06, 08:57 PM**

added a sig for convenient linking to the blog.

Advertisement