SB 8 inch woofer sounds great on its own.

[tuxedocivic]

Wow you move quickly!!!

I'd start by raising them off the floor. Do you have a bigger inductor? That woofer has pretty flat impedance, but maybe a 10uF cap across it in parallel.

 

[xrk971]

Sootboots,
Nice job with the foam core cabinet. I think you are the first to do a 2 way since I started the foam core thread. Looks like fun and I can tell you like the sound. Speaker cabinets never weighed so little have they?

 

[sootboots]

I have a 5mH inductor here. Any suggestions?

John

 

[sootboots]

Paul Simon's "Rhythm of the Saints" is on right now and the imaging is the best I have heard yet in my 16x 20 living room. I am willing to give all of the credit to the MA 7.3 but the woofer and foam core must figure in there somewhere......


John

 

[picowallspeaker]

I have a 5mH inductor here. Any suggestions?

John

It could introduce you in the realm of OB (open baffle)

Or any other application of a woofer which is 'cut' real low- so it
make happen the extension>sensitivity trade off .

With OB you lose lots of pressure in the bass because of acoustic
short-circuit

Which I doubt is present in foam enclosures, in multiple forms ( transparency
to the lowest frequencies , and selective and depending on the different paths
that sound travels with ...)

 

[tuxedocivic]

Well, I don't know anything about open baffle, but if you also have a bigger cap I'd swap in the 5mH instead of the 1.5mH. I'd then bump up the 22uF for something about 50uF if you have it. Even two 22uF in parallel gets you 44. Once you have that I'd put the 1.5mH and about 5 to 10ohm resistor in series with it, and put that LR across in parallel with the alp7. So 44uF followed by 1.5mH + 8ohm going to ground.

A schematic would make more sense but I'm on my phone.

 

[tuxedocivic]

The 1.5mH + resistor is to compensate for impedance in the alp7's low end which is required for the 50uF cap to do a proper job.

 

[picowallspeaker]

Yeah
5 mH is good for making an HP more robust!
Difficulty arises, as 2nd order makes 180° phase rotation at output.

Just a tought.

BTW I'm using 8 and 10" paired with 2" as mid-tweeter

 

[planet10]

...first order cross over consisting of a 1.5mH inductor on the woofer and a 22uF film cap on the MA 7.3

Somewhere 700-800 Hz (nominally). Part size is going to need to increase.

Try connecting those parts in series and see what happens. It may help, it may not. One thing it does is lock the 2 drivers together so that the LP = HP.

Try with what you have

A series XO has a parameter called Zeta that describes the behaviour of the electrical filters around the XO. Zeta = 1.0 = Butterworth (with the same text book RL values as passive). Raise the zeta you get a depression, lower it a hump.

dave

 

[mor2bz]

u like this better than the pencil? what is an sb woofer ?

 

[xrk971]

I was asking myself the same thing, if indeed that is a Pensil A12 in the picture. Smaller drivers have better imaging in general so not surprising.

 

[sootboots]

The pensil's sound better in the bass department but the crispness of the MA 7.3,even in a foam core box, really shines. I will work crossover experiments while woofers are breaking in.

John

 

[mor2bz]

again, what is a sb woofer? i pasted the numbers and came up with nothing but your post.
thanks

 

[sootboots]

SB Acoustics. You will it at Madisound.

 

[tuxedocivic]

Is your enclosure sealed? Interested to know how you find the bass once they're in a ported or something enclosure.

 

[sootboots]

It was "sealed" but then I cut a couple of crude ports in the front of each. It was an improvement. Inserted paper towel rolls and another improvement! It's a great way to learn but the WAF is a new low.

John

 

[xrk971]

WAF can be high with foam core wall mount cornu horns. Hey at least they are not full BLH with front tractrix horns I read somewhere those were a sure sign of either celibacy or imminent divorce

 

[planet10]

I did some sims of this and decided 55 litres would work well.

dave

 

[tuxedocivic]

Dave, was that ported or sealed? That's a fairly large speaker, so hopefully ported. Lots of bass??

 

[planet10]

Ported, aligned for high aspect ratio vents. actually smaller than what i'd use sealed (60 litre). Sealed Q = 0.5 is over 100 litres.

dave