Lavoce SSF153.00 15" based dual opposed subwoofer project

[glideslope]

Now let's see those measurements!
All measurement were done in the MLP

Sub with zero correction:
View attachment 342025

Sub crossed with mains at 80Hz, 24dB/octave, min. phase (using Jriver's DSP)

View attachment 342026

Dip appeared at 90Hz

Now let's see what Dirac could do with the situation:

View attachment 342027

Dip at 90Hz remained - I guess I will play around with the crossover (potentially trying linear phase too) to see if I can further remediate that
For the time being I am fine with these results

Let's see the Group delay:

View attachment 342028

Pretty good down to 26Hz or so

Waterfall (set to 400ms)

View attachment 342029

I might try some notch filters to fight those resonances later on - but again, I think this is not too bad

Spectrogram:

View attachment 342030

There is a 10ms peak energy time delay - I have seen many system with subs with way worse results

Distortion (%):

View attachment 342031

There is one peak at around 30Hz, other than that I am happy

Distortion (SPL):

View attachment 342033

Overall, I am pretty happy with these results
I am now fiddling around with setting a low shelf ('target curve') to taste - that will take days or even weeks

Further next steps:
- Once the shock absorber feet arrive in the coming days I will listen and measure if they make any difference at all
- Continuous fine-tuning of the low-end + considering the notch filters

At this point I think this beast is a keeper - in that case I will also need to fix the aesthetics as mentioned in post #3
Note: I consider the above results especially great if I take into account the fact that the whole thing cost me less than 500 EUR....

I calculate that you should have a baffle step at 45.5Hz, and there it is clear as day. Due to the cabinetry beside the sub enclosure. I think above that there is some cardioid thing happening and interaction with the front and side walls.

Would you consider losing the side cabinetry and the TV. Rotate the sub enclosure 90° so the MDF faces forward. It should run omnidirectional until 101Hz. Still cross it at 80Hz. See how that measures.

You can always wall mount the TV on an articulating bracket that will let you swivel left to center it (due to the window).

 

[neRok]

I calculate that you should have a baffle step at 45.5Hz, and there it is clear as day. Due to the cabinetry beside the sub enclosure.

How did you work this out (as in, what is the equation)?

 

[glideslope]

How did you work this out (as in, what is the equation)?

It's just a quarter wavelength distance around the cabinets, cone-to-cone. At which point it becomes bi-directional.

 

[ppataki]

And finally the aesthetics are in place too!

Overall I am extremely happy with this project, one of the bests I have done so far
I can strongly recommend the Lavoce drivers, mind-blowing price/value ratio!

I consider this project finished now

 

[Wolf]

I would have flipped the polarity on the mains and seen if the dip at 90Hz went away. Usually a 180° change is all it takes, and requires less group delay to become a factor than your active filtering.

I also would tend to agree that the bass response will be cardioid in nature due to placement. If you were to make it face side to side with a small slot loading the drivers between cabinets, say 3-4", you'd have a 3 piece setup with no drivers showing through that patterned face. Your response would likely be easier/better to deal with too.

I hate the ringing nature of plywood, and have to damp and mass load the snot out of it to make it go away. I prefer the damping qualities of MDF.

 

[Keith_W]

I hate the ringing nature of plywood, and have to damp and mass load the snot out of it to make it go away. I prefer the damping qualities of MDF.

The video in post #7 seems to indicate that plywood has better damping properties than MDF.

 

[Wolf]

After working with it in acoustic projects, I would tend to disagree. The ply panels are stronger, but also can survive flexure. While MDF may be more porous and need sealing more than ply does, I find it to be better damped, weigh more as in mass loading, and be stiffer than standard plywoods. Baltic Birch is stiffer than MDF, but still does not weigh as much and tends to ring more readily than MDF.

I used standard poplar ply in a short tower build a couple years ago, and I was only able to nuke the ringing by gluing/applying 4" marble tiles alternated with mass loaded Sonic Barrier and reinforced bracing in the corners. I don't have to go to that length to make MDF cabinets satisfactory for speaker builds.

Of note, I do apply epoxy resins to both materials a lot of the time. This is even with that application.

 

[ppataki]

I would have flipped the polarity on the mains and seen if the dip at 90Hz went away. Usually a 180° change is all it takes, and requires less group delay to become a factor than your active filtering.

I tried that yesterday evening, a huge peak has appeared + two more dips that were not there before
The group delay and the spectrogram curves became much worse too (even after correcting the FR)

I am happy with the sound (and the curves) using the crossover techniques I described in post #20
I keep switching between linear phase and minimum phase modes, depending on my mood

 

[glideslope]

Curious if you have tried no furniture cabinets beside the sub? I was asking this previously because I think with those furniture cabinets it is effectively one giant baffle with the drivers several meters apart. There's WAF and then there's the physics of it.

 

[ppataki]

Curious if you have tried no furniture cabinets beside the sub? I was asking this previously because I think with those furniture cabinets it is effectively one giant baffle with the drivers several meters apart. There's WAF and then there's the physics of it.

No, unfortunately this is not an option.....