Ported or Not? SVS PB16 Ultra or SB16 Ultra? (1 Viewer)

[Mike Frezon]

I figured it was real...but it seems so "big" that you never know. But given your proclivity for "big" DIY projects, I figured you would be on the up & up!

32" subwoofer. Wow. You haven't gotten your hands on one? Are the specs ridiculously low?

 

[DaveF]

You are happy with the bass and the wife is happy there isn't a large, black box in the room.

I’ve got friends, the husband brought to the marriage a DIY cylinder sub that’s about 2 feet dia and 4 ft tall! It’s a monstrous black ... thing... in the basement.

The wife is not a fan.

 

[theJman]

From my reading, ported subs will go lower which makes them ideal for movies. The sealed sub is good for films, but leans more toward being ideal for music because the is tighter if not quite as low.

At one time you could make the statement that sealed subwoofers were more articulate than ported, but that's not really the case any longer. While things like group delay and impulse response do generally favor the sealed alignment, frequently the differences are no longer audible. Measurable, but rarely audible (assuming all things are close to equal, like comparing the SVS SB16 and PB16). The amplifiers, DSP's and drivers of today have blurred the distinction for the most part.

With regards to extension, as it relates to ported versus sealed, it's actually the opposite; sealed tend to go lower. They have a more shallow roll off slope, so with reinforcement from the room - which all rooms provide - they typically extend deeper. The benefit of bass reflex is the contribution from the the rear of the driver, via the ports. That increases the output in the passband, so performance above port tune favors that alignment.

 

[Race Bannon]

Package received -- still need to get it going and calibrated this weekend. Do you guys think the bass management in my Emotiva UMC-200 is probably fine? I was looking at all the adjustment features the app provides, but I don't think I need to mess with that if I'm using the LFE from my Emotiva with active bass management. I don't much about all that slope and stuff -- I suppose if I were getting a pronounced effect that I needed to go away I'd mess with it.

But I mainly just need level adjustment and my calibration will do that. I don't get into crossover and stuff.

What do you think?

 

[Mike Frezon]

You'll get a million different answers to that, I suspect.

I'm all for plugging it in...running the receiver's calibration and looking for your favorite bass demo scenes! (For me, LoTR: RoTK - Pellennor Fields. )

 

[Robert_J]

Not performing the proper calibration is like buying a Ferrari and putting regular gas in it. Yes, it will run but you will not get the full performance out of it.

At minimum you need a $60 calibrated mic and free software to at least know you have a relatively flat in-room response. If you need to EQ it, a Behringer Feedback Destroyer is about $70 on the used market or $150 new. The Mini-DSP EQ is about $200.

After building my subs, I ran the auto calibration on my receiver, they were set very low. I thought they sounded pretty good on music but lacked low end bass on movies. When I measured the in-room response I saw a 15 db peak at 55hz. Your auto EQ will read the loudest frequency and set the level based on that. Based on my sub's response curve, I added some filters to my BFD to pull down that huge peak and a couple of smaller ones. Now my sub is + or - 3 db from 120 hz to 17 hz with usable output to 15 hz. When I re-ran my receiver's auto calibration, the level on the sub was raised close to what the other speakers were and now it sounded great on both music and movies.

 

[Race Bannon]

Not performing the proper calibration is like buying a Ferrari and putting regular gas in it. Yes, it will run but you will not get the full performance out of it.

At minimum you need a $60 calibrated mic and free software to at least know you have a relatively flat in-room response. If you need to EQ it, a Behringer Feedback Destroyer is about $70 on the used market or $150 new. The Mini-DSP EQ is about $200.

After building my subs, I ran the auto calibration on my receiver, they were set very low. I thought they sounded pretty good on music but lacked low end bass on movies. When I measured the in-room response I saw a 15 db peak at 55hz. Your auto EQ will read the loudest frequency and set the level based on that. Based on my sub's response curve, I added some filters to my BFD to pull down that huge peak and a couple of smaller ones. Now my sub is + or - 3 db from 120 hz to 17 hz with usable output to 15 hz. When I re-ran my receiver's auto calibration, the level on the sub was raised close to what the other speakers were and now it sounded great on both music and movies.

If I'm hooked up single LFE, isn't it the case that I can't do any of this at the SVS subwoofer? Do I need to hook up L-R separate line outs in order to calibrate at the subwoofer? And I suppose I could do the same adjustments at the preamp.

I have no idea how to make sense of something like "15 db peak at 55hz." Does that mean not enough volume when the bass signal is strong in the movie?

 

[Robert_J]

If I'm hooked up single LFE, isn't it the case that I can't do any of this at the SVS subwoofer?

It does not. My LFE output runs into the right input of the Behringer Feedback Destroyer which applies the EQ. The right output of my BFD runs into splitter and the 2 outputs from the splitter go into a two channel pro amp.

I have no idea how to make sense of something like "15 db peak at 55hz." Does that mean not enough volume when the bass signal is strong in the movie?

Take a look at the graph below. Your input signal is pink noise. Pink noise has the same energy at each frequency across the spectrum of sound you are testing. You set the volume knob so that all things being equal, that means your amp is pushing 20 watts at 200hz then it will push 20 watts at 20 hz and all frequencies in between. But because a speaker can't reproduce each frequency at the same level, the output will vary. The speaker also interacts with the room to boost (peaks) or pull down (nulls) different frequencies.

Below, at 100 hz, the output is 105 db.
At 50 hz, the output is 115 db.
The peak output is at approximately 38 hz and that is 120 db.
The problem is that at 20 hz, the output is only 90 db.

The marketing department would emphasize that this sub is capable of 120 db!!!!! That sucks watching an action movie because the very low frequency information would be 30 db lower than the peak output.

The measurement below is much better. At 100 hz, the output is 93 db.
At 50 hz, the output is 92 db.
At 20 hz, the output is 95 db.
The sub's output is limited to 20 hz to 120hz in this example. So the deviation across that range is only 4 db. On the graph above, the deviation is 30 db. The sub below would not sound boomy at all. It would sound natural no matter what the material being played through it from an acoustic bass to a spaceship rising up from under Los Angeles.

 

[Race Bannon]

Well, thanks for all the technical insight and patience -- I got it in last week but it took me a while to get it tested and calibrated. I have found that once you have a subwoofer that is first class, you become obsessed with tuning and messing with it, to see if you have perfection for the room. I've auto-calibrated it a bunch of times, tried different movies, etc.

It sounds fantastic. I just constantly wonder how it does under every load. I may have to buy a sound-checker-ma-jig.

 

[Mike Frezon]

I may have to buy a sound-checker-ma-jig.

You order those from here: