New school subwoofer question?

[Jake321]

So mechanically you have 40mm of xmax each way, but linear xmax is only 15mm. So from 16-40mm you induce some sort of distortion. That said most people don't notice that kind of distortion especially since the bass is generally quite loud at that level of xmax.

That was something on my mind for a while.
So it's 40mm or 24mm equivalency?

 

[Jake321]

Infinite baffle is on my bucket list!

SSA GCON 18"

Currently on sale $60 cheaper = $369. I think it's Black Friday.
I'm not sure how much RMS you're looking for but this is actually an interesting budget (priced) sub that I'm pretty sure can go infinite baffle.


T/S Specs:

• D4 / D2
• Fs. 25.5 / 24.9 hz
• Re 8.0 / 4.0 ohms
• Qms 6.49
• Qes 0.82 / 0.78
• Qts 0.78 / 0.74
• Cms 0.14 mm/N
• Mms 304.5 / 306.5 gr
• Bl 16.3 N/A
• SPL 93.1 / 93.8 dB
• VAS 178.0 L
• SD 1210cm^2
• Xmax 23mm
• RMS 950 watts

SSA GCON enclosure info:

• Overall Diameter 18.5"
• Displacement 0.19 Cu. Ft.
• Cut out 16.75"
• Mounting Depth 9.5"
• Sealed: 4.25-4.75ft^3
• Ported: 6.5-7.5ft^3 @ 27-34hz w/15.25^2 of port per cube

 

[hispls 5,000+ posts]

T/S Specs:

• 
  
• Fs. 25.5 / 24.9 hz
• Qts 0.78 / 0.74

This is the sort of thing you're looking for if you're attempting to do IB. Low Fs and 0.7 to 1.0 Qts.

You can confirm by just modelling a sealed box with 20 cubic foot volume.

 

[mat3833 10+ year member]

This is the sort of thing you're looking for if you're attempting to do IB. Low Fs and 0.7 to 1.0 Qts.

You can confirm by just modelling a sealed box with 20 cubic foot volume.

I completely agree that the theory says .707qts is ideal. In my experience, the QTS/Fs relationship largely affects how the sub sounds/plays so I feel it should be used as one more "tuning" aid.

My 18's have a QTS of .245 and an Fs of 26.5. They will happily play up into the midbass range(500hz eaisely) and it's crazy loud. They will happily play down in the 20's as well, but they need more power to do it. I have them EQed pretty hard in the 45-60hz range to tame them. They aren't playing "flat".

I don't understand the science or whatever behind it, but the last 3 subs I've really liked IB were all low Fs Lowish Qts subs. That may have something to do with my trunk volume being 16 cubic feet(true infinite baffle is minimum 10x the Vas volume.) or it may just be my taste.

MMake a baffle and throw different subs into it. It's pretty awesome being able to swap subs and change how your whole substage sounds/responds.

Matt

 

[Jake321]

I completely agree that the theory says .707qts is ideal. In my experience, the QTS/Fs relationship largely affects how the sub sounds/plays so I feel it should be used as one more "tuning" aid.

My 18's have a QTS of .245 and an Fs of 26.5. They will happily play up into the midbass range(500hz eaisely) and it's crazy loud. They will happily play down in the 20's as well, but they need more power to do it. I have them EQed pretty hard in the 45-60hz range to tame them. They aren't playing "flat".

I don't understand the science or whatever behind it, but the last 3 subs I've really liked IB were all low Fs Lowish Qts subs. That may have something to do with my trunk volume being 16 cubic feet(true infinite baffle is minimum 10x the Vas volume.) or it may just be my taste.

MMake a baffle and throw different subs into it. It's pretty awesome being able to swap subs and change how your whole substage sounds/responds.

Matt

How'd you Tune the IB of those 18s?

And wondering if I could Infinite Baffle my current Sub:


DD712

Speaker Size (In):12
Watts RMS:600 - 1200
Watts Peak:3600
ImpedanceD2 / D4
VCD (In):3
Piston Diameter (In):10 1/4
Fs (Hz):28.26
Qms:4.344
Qes:0.482
Qts:0.434
Vas:39.64
Xmech (MM):80
Xmax (MM):14
Frame OD (In):12 5/8
Frame OD w/Gasket (In):12 7/8
Mounting Diameter (In):11 3/8
Mounting Depth (In):8 9/16
Motor Diameter (In):7 3/4
Motor Depth (In):3 1/2
Woofer Displacement (CuFt):0.17
Ported Enclosure (CuFt):1.75 - 2.75
Shipping Weight (Lbs):38
Price (USD):469

 

[Jake321]

Into the company: SSA (just found it).

 

[mat3833 10+ year member]

How'd you Tune the IB of those 18s?

And wondering if I could Infinite Baffle my current Sub:


DD712

Speaker Size (In):12
Watts RMS:600 - 1200
Watts Peak:3600
ImpedanceD2 / D4
VCD (In):3
Piston Diameter (In):10 1/4
Fs (Hz):28.26
Qms:4.344
Qes:0.482
Qts:0.434
Vas:39.64
Xmech (MM):80
Xmax (MM):14
Frame OD (In):12 5/8
Frame OD w/Gasket (In):12 7/8
Mounting Diameter (In):11 3/8
Mounting Depth (In):8 9/16
Motor Diameter (In):7 3/4
Motor Depth (In):3 1/2
Woofer Displacement (CuFt):0.17
Ported Enclosure (CuFt):1.75 - 2.75
Shipping Weight (Lbs):38
Price (USD):469

I'm still in the process of tuning my system, and it won't be fully finished until I build the enclosure for the pair of 18"s.

I tune my substage mostly by ear, I have a dsp so it's a bit of a mash of different stuff. I know 50hz-70hz is really buzzy and kinda annoying to me, so I usually start by cutting that band by a few DB. I'll take a frequency sweep to grt a response curve and then just add a little or take away a little until it sounds good to me. I can make changes while playing music, so it goes pretty quick.

Any sub can be ran IB. They will all sound different. Some people like a system QTC of 707, others prefer closer to 5, some people don't really care at all. Any sub in an infinite baffle system will have its QTS become the "enclosure" QTC value it's pretty simple.

QTC example chart:

Matt