Zigmahornet

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I am looking for the inside dimension of these cabinets. The plans I got with my merrill drivers are very vague. Done quite a bit of research but everyone seems to have a different way to build them. The issue is if you put the sides in between the front or back or if you put the front or back over the sides. This will change the inside dimension. I am just curious what the original plans call for. If you put the front (baffel) in between the sides( like it looks on the review for 6moons) this would only leave 1/8" on each sides by the time you cut the hole for the driver. If someone has built these as they were intended I would really appreciate a response.
 
zigmahornets

Thanks for the relpy but those are the plans I have. I am looking what the inside dimension is..depth and with.This changes on how you put these cabinets together. I am interested in the correct way these were designed to be put together as described in my previous post.
 
frugal-phile™
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Re: zigmahornets

flippinjaz said:
those are the plans I have. I am looking what the inside dimension is..depth and with.

Those are a legible copy of the original plans...i think there are a lot of better boxes to build, so i didn't put any more effort into them.

If you can subtract the internal dimensions are obvious... ie internal width = 120 - 2x12 = 96mm.

dave
 
Re: Re: zigmahornets

planet10 said:


Those are a legible copy of the original plans...i think there are a lot of better boxes to build, so i didn't put any more effort into them.

If you can subtract the internal dimensions are obvious... ie internal width = 120 - 2x12 = 96mm.

dave


Thanks Dave,

I understand . I built a couple prototypes of these and the one out of 3/4 hardwood sounded much better than the 1/2 birch ply.
I narrowed up the inside demensions and the bass is quite tunefull instead of just a low tone I got from the original plan. Much clearer, cleaner sound also.
 
Hi flippinjaz, can you estimate where the bass rolls off, e.g. with a test tone CD? The vertical dimension corresponds to a ~35Hz QW resonance which obviously seems a bit low for a driver of this size.

I read on Bob Brines' site that when a cab is tuned too low for the driver, you may hit the QW resonance but the price can be a sag above that. It would be interesting to know the Fs, Qts and Vas of this beefy little champ. Aesthetically it's pretty sweet.
 
Hi Dave, thanks for posting the measurements. Oh dear, it's tuned more than an octave below Fs. So this cab is going to behave roughly like an infinite baffle? It looks like a much smaller box would get better bass. This driver does look like it would be fun to play with, though it would take more watts than I have at the moment.
 
Hmm, this little guy is interesting.

I see now that the 59" dimension is a quarter-wave of 57Hz. As strictly a learning exercise, I took a stab at it in MJK's worksheets (being a novice did not stop me).

I approximated the port size by treating it as two sections, the "front" one at 1.625" x 1.875" x 3.875" = ~ 11.8 in^3, and the back one at 2" x 5.375" x 3.875" = ~ 41.65 in^3. So I added them together and got 53.45 in^3. Not sure if summing their volume is a valid simplification.

Translating that volume into a cylinder shape:

V = pi * radius^2 * height
53.45 = 3.142 * 4 * height
53.45 = 12.568 * height

So height = 4.25" and so the equivalent port tube is a 4" x 4.25" tube (if any of this math is right). I used a Zdriver of 57 (rough figure).

In MJK's worksheets, the infinite baffle response falls off gently under 100Hz at ~12db/octave. However, I could not get a nice flat response -- the driver and port summed in a spikey fashion that I could not flatten, and man, I tried. Perhaps it's the high Q of 0.98.

(OT but with a Q that high, it might be fun to try that driver on OB.)
 
bainjs said:
Flippinjaz: What type of hardwood did you use? Were you able to compare to one made with MDF?

Thanks


Hi Bainjs,

You know I was just making a rough one to start with and I used 3/4 popular which really is not a very musical wood. I think after my drivers break in I might plane down some mahogany, spruce or maple to 1/2" and try that. I was just surprised at the difference in sound. To my ears the hardwood sounds more real on the stringed instruments and the piano was much more forward and true to life. These are just my opinions. The 1/2 birch plywood sounds good but kind of hollow to me. Now using 3/4 that changed the depth and width of the inside measuments and I think that is why I have a more tunefull bass note. Just my guess, I am a amature trying to have some fun and learn some things about these boxes. I am running a BH Paramour,FPIII with Tjoeb cd player. My reference discs that I am using are Tony Rice "Unit of measure" which is just great on these Ziggys and Marian McPartland Live Jazz Trio. Also killer.
 
After reading everyone's opinion on wood types (plywood, mdf, etc) to use, I think I'm going to chicken out and go with 1/2" MDF and then veneer them using 1/4" spaulted cherry.

I think Dave Merrill's speakers (DCA4's) will go well with my Bottlehead SEX amp and powered subwoofer.

I understand he was scheduled to have a heart transplant. Has anyone heard anything?
 
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