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kgillies 11th June 2007 11:51 PM

Design Challenge #1
 
Aloha from Hawaii to all you fanatics. I'm new to this gig, so I'll not pretend to be anything but a rookie. I'm a cabinetmaker, so I can handle that part, but need some good design input from you experts out there. Design #1 challenge: I've got dual 10" Peerless drivers front firing from a 8.5"h x 27.5"w x 8.5"d (all dimensions ID) enclosure, which ports out the back left side to a 8.5"h x 40.5"w x 8.5"d enclosure which in turn is ported through a 7.5"w x 8.5"h opening on the back right side into a 8.5"h x 12.5"w x 8.5"d enclosure that finally ports out to the front through a 4.5"w x 8.5"h opening! I understand this is referred to as a "horn" design? It's underdriven passively by my amp, so I bought an Apex Senior Subamp 250 watts RMS@ 8 ohms
350 watts RMS@ 4 ohms S/N Ratio(full rated power) 100Hz(+A) 102db
THD 100hz 0.1%. Questions:
1 - am I better off hooking up both drivers in series or parallel?
2 - is it ok for me to mount the amp in the right side of the cabinet (that's away from the drivers)?
3 - from my architectural experience, I'd think the box would be better off NOT square, but trapezoidal shape. What does anybody think if I mitred the sides of the cabinet at a (15 degree?) angle so that it is wedgeshaped to the rear?
Thanks!

Cal Weldon 12th June 2007 12:14 AM

Hi KG,

Welcome to the forums.

1) What is the impedance of the drivers? That will determine series or parallel. That amp is looking for 4 ohms minimum isn't it?

2) You can mount the amp inside or in it's own cabinet. If inside, make sure your leads from the amp reach the drivers.

3) Correct, square is the least desirable shape but many have done it and many still do. If it were a huge issue, no cabinet would be cubed.

pinkmouse 12th June 2007 12:34 AM

3) Doesn't make a blind bit of difference, as the wavelengths involved are all significantly greater in a sub then any of the box dimensions.

Cal Weldon 12th June 2007 12:42 AM

What he said. :)

pinkmouse 12th June 2007 12:46 AM

It might look prettier though. :)

Sonusthree 12th June 2007 01:08 AM

Quote:

Originally posted by pinkmouse
3) Doesn't make a blind bit of difference, as the wavelengths involved are all significantly greater in a sub then any of the box dimensions.
Isn't the issue that square sides are likely to resonate at the same frequencies? i.e. Panel resonances are not spread? I'd really value some advice since I'm about to build my first subs tomorrow.
Regards,
Martin.

pinkmouse 12th June 2007 01:10 AM

That's what bracing is for. Have a look at some of Ant's (Shinobiwan) build pics for ideas.

MJL21193 12th June 2007 02:56 AM

Re: Design Challenge #1
 
Quote:

Originally posted by kgillies
Peerless drivers front firing from a 8.5"h x 27.5"w x 8.5"d (all dimensions ID) enclosure, which ports out the back left side to a 8.5"h x 40.5"w x 8.5"d enclosure which in turn is ported through a 7.5"w x 8.5"h opening on the back right side into a 8.5"h x 12.5"w x 8.5"d enclosure that finally ports out to the front through a 4.5"w x 8.5"h opening! I understand this is referred to as a "horn" design?

Hi,
The dimensions above do not resemble a horn, they don't increase. They seem to be a kind of T line.
Is this box built allready? Or are you in the planning stages?

To be honest, the way you are descibing it, with these dimensions, it can't be an optimal design.

kgillies 12th June 2007 05:27 AM

Drivers
 
HI everybody - interesting to get responses from all over the globe! I believe the Peerless drivers are 8 ohms - they aren't labeled. Anyway, the question is with that amp am I better off running the drivers at 4 ohms or 8?

kgillies 12th June 2007 05:27 AM

Already Built!
 
HI there - it's already built as a passive sub by someone who was reputed to know, but somehow it never added up to me...but it is there and I was hoping to make use of it. Hence my question about modifying it in some way using information those in the know might have... But I could also start fresh if that's better! I have the amp, I have two 10" drivers, what's the best thing to do? By the way, if anyone's interested enough to run it through your calcs, I could make a drawing of it to post...


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