Please critique my new speaker design


2008-11-01 4:00 pm
Now that I have your attention please take a look at the rendering of my next project. I have a few questions though before I get into that I will explain my design intent and constraints.

So most of my furniture is mid century modern/Danish in style so I came up with this timeless design to replace my RB kit.

Design Intent/constraints
-33” x 8” x 8” white oak “museum pedestal” base made of MDF and covered with white oak finished in tung oil and wax.
-Bottom firing port
-Pedestal volume up to .64 cu ft (can be reduced though not increased by much)
-Rear firing 6.5” woofer with grill for a diminutive look (max woofer size 6.5”)
-4 satin black spikes on bottom for port clearance
-3 satin black spike on top of pedestal to balance vase/speaker
-Full range speaker enclosures are existing vases with max volume of .20 cu ft
-Max full range speaker flange is 4”
-Cork plugs to seal the vases
-External “umbilical cord” connecting the full range to the crossover in the pedestal
-Must be 8 Ohm
-Powered by 28 “real” watts per channel (not bi-amped)
-Medium size living room
-I listen to Zero 7, Ray Lamontagne, George Michal, Morcheeba and similar
-Crossover point 200-250Hz

-My design is rendered with a HiVi B3N, though that full ranger is not efficient, needs a notch filter, and in my case (passive crossover) I think needs a impedance flattening circuit. My question is there a better 3” full range out there that suits my design better? Paper sounds like it may be the way to go? I am open to any suggestions…
-I was thinking of running the 6.5” Dayton classic for bass duty, thoughts, concerns?
-And finally would anyone be able to help me with a crossover design that fits the bill? I have not had too much success on my own.

Depending on where your planning to cross over the speakers i would be concerned about the distance between the two speakers i would suggest inverting your base and bass speaker so the the two drivers are a lot closer and have the small woofer facing forward. I looks good but its the sound thats more important than anything else.

try modelling a few different drivers using one of the many sim programs available and see where different 3 inchers and 6 inchers play and cross well together this would be my first step.
Nice design,
the pedestal volume will be determined by the bass driver you choose, so you'll need to do some simming in Unibox or a similar program;
Consider the Mark Audio FR drivers, you may be able to use these without any notch.
Depending on how loud you play, a first order xover would be a good place to start,
particularly if you use the baffle step freq as the xover freq & your woofer has a flat response above the xover point. Ideally, the woofer will be a couple of dB more sensitive than the FR driver.
I'd be inclined to put the port on the rear, a down firing port will be affected by the space under the pedestal & so it will be harder to get the tuning freq right.
Nice looking work.
I agree the cross over point is important. If you can get to a public (or Uni Engineering) Library that has back copies of "The Journal of the Audio Engineering Society" (JAES) you'll find some very relevant work by guy named Allison. I think it was the 70's or 80's. He did a lot of measurements of woofers near boundary layers (floors, walls etc) which achieved some nice reinforcement. From memory I think the data suggested a lower cross-over point than 200c/s but I'd have to check.
Good luck, Jonathan

Read up on baffle step compensation.

A very nice 3" driver is

Your bass unit should be mounted near the top and have a sensitivity
probably near 4 or 5 dB higher than the fountek. A first order series
crossover higher up could then work well, Ideally the fountek needs
some correction at the top end, see Zaph|Audio .

Given box to driver ratios and you seem to be going for sealed bass
two bass drivers in near 0.5 way might be an idea, the transition
frequency of the top "egg" is going to be fairly high.

(Two parallel bass drivers are +6dB over one, double box size.)

rgds, sreten.

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