Which 12"

I am working on a 3-way system with 2 enclosures. The LF enclosure is basically a pair of 12"ers in a 3.76cuFt box, with each driver in its own 1.88cuFt area and a vent of it's own. I was hoping to get this to work from 30Hz to 300Hz.

The HF enclosure is a baffle-less MTM comprising two Vifa P13's and a Vifa XT25. They operate 300z upwards I got that part pretty well settled. The problem I have is with the bass unit.

I initially had two PPI Pro12's as the Bass units. However regardless of what PPI says that the Pro12's liked small enclosures, .... they don't! The output at 100Hz is maddening.

Each driver is in 1.88cuFT and tuned to 37.4Hz.

Now I am looking at other drivers that give me a more flat response, heck even exaggerated response below 60Hz is acceptable to take care of the bafflestep. I WinISD'd 3 drivers all in the same price rage of $150 per driver or so.

1) THe PPI Pro12
2) Peerless XLS12
3) Dayton Titanic Mk.III (12")

and got the following results... which one would you guys choose for the given application? Should I consider other 12"ers in this application with the enclosure around 1.9 to 3cuFt? In the same price range?

I always prefer deep bass ... My vents are more or less fixed $" by 10"...


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Now I am looking at other drivers that give me a more flat response, heck even exaggerated response below 60Hz is acceptable to take care of the bafflestep. I WinISD'd 3 drivers all in the same price rage of $150 per driver or so.

Unless your baffle is very wide, baffle step usually starts around 4-500hz and flattens out close to 100hz, so a peak at 60hz is not really going to address it. If you don't mind a peak at 60hz thats fine.

Out of those 3, I would choose the purple line. However, I would not port any of those drivers that high, may as well go sealed, at least then you won't be bottoming them with sub-30hz material all the time. If you really want them ported I would go with 1 12" a side, otherwise do 2 12" a side sealed.
B&W claims on their website white papers that one 15" woofer was "better" and "more coherent" than two 10" or 12" speakers. B&W mentioned that new low mass cone materials and new magnet motor structures really improve larger diameter woofer transient response. B&W sells both a single 15" and dual 10" Nautilus speaker, so they don't believe that one size fits all.

A single 15" JBL class woofer in your total cabinent volume might be worth simulating.
have you thought about lambda woofers???

their 12s and 15s are unmatched

if you're looking for 15s... the TD15x is a good route... and it's fairly cheap

a pair of 12s of these (these sound slightly worse than the 15" version in SQ) could easily get you to -3db down at 25-27hz with a tune of around 30hz

also everyone knows what those faraday rings do :) :D :D


diyAudio Member
2004-02-25 9:13 pm
K-amps said:
If I choose the Peerles XLS12 (Purple plot in the previous image) and go with the sealed version, I get these 2 plots:

Purple = vented
Yellow = Sealed

Both 1.88cuFt... the sealed does not look very promising here.

Don't put to much faith in the ISD plots, this is one example where they are just plain wrong.

The XLS is suited to sealed and performs well.

BK electronics in the UK has a sealed design here:



The measurements tell of a -6dB at 17hz using the XLS10 sealed in a 1cuft enclosure.
morbo said:
Well I don't have modelling software in front of me but that curve looks suspect to me, f3 above 60hz? Is that in winisd?

I'll try modelling the peerless at least later. You could always port lower, certainly IMO it would be far preferable if the 12"ers are going to see a full range signal.

Win ISD pro..... Yes. The XLS will be actively crossed at 300Hz.

kan3 said:
the ppi pro shouldn't even be in the comparison - at 5mm xmax its going to be extremely output limited compared to the other two

Except that I already have them and installed.... Basically I am looking to sell and get one of the others. So far I have not gotten complete answers.... I think morbo will do some plots as my WinISD is not showing the XLS12 plot correctly in a sealed 1.88cuFT enclosure.
OK there are 3 sets of graphs below. All of them model one driver in 1.88 cu ft, with 200w input power. The effects of your crossover on the response is not simulated.

In each graph red line = your ported box, blue line = sealed box, and yellow line = your ported box, but port extended to 27" (tuned to 24hz).

The response is all 'bumpy' not because of the modelling, but because this driver was already in the bassbox pro database with real measured response.

This first graphs is anechoic. This is very similar to what winisd is giving you. But you need to consider room gain as well. I'm not sure if you have an idea of what the gain in your room is like, but the next two graphs will have room some arbitrary gain factored in to give an idea.


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Thanks morbo, in the first pic (red line) what did you choose the port dimensions to be? I can either do 4" D with 5" length or 10" length as these I already have installed.

I don't have an idea of my room gain, but the sealed plot with room gain looks sweet!

How about the TC sounds TC2+? Any experience with those?
Some random info/thoughts

Assuming 200w input per driver:

- your ported design exceeds xmax below 25hz, and excursion goes up very fast below that
- your sealed design exceeds xmax below 23hz (but, the cone is still under control by the 'air spring', not unloaded like the ported one, and excursion inscreases more gradually)
- the adjusted ported design exceeds xmax below 19hz, and excursion goes up very fast below that
- both ported designs exceed 20 m/sec vent velocity, yours peaks at 30m/sec @ 35hz, the adjusted one peaks at 24m/sec @ 23.5hz.

You said you are crossing actively... you don't by chance have an extra highpass section that could be used as a rumble filter maybe? Because that would open up some nice possibilities.


diyAudio Member
2004-02-25 9:13 pm
K-amps said:
I think I need to look into the XLS in a sealed cabbie. Tell me what is the optimum cabbie size for the XLS12 for F3 at 25Hz? or Even F3 at 29Hz with better power handling?

Ah, well there's the trick.

I can't :D

As you've shown, modelling suggests that you completely dismiss the sealed loading.

I can tell you that the XLS10 is superb in 1cuft sealed enclosure and will have an F3 of around 25hz. That of course isn't much use though since you have the XLS12.

If you fancy giving sealed a go, try a 1.5-1.8cuft. I would just build something rough to make sure you actually like what you hear. Another point would be to make the box actually 2.5cuft and then have a removable top panel that would allow you to place a seperating wall within the cabinet to reduce the volume to what you think sounds/measures best, That way you don't have the hassle of making a couple of proto boxes.