Zigmahornet

[rjbond3rd]

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.)

[flippinjaz]

Originally posted by bainjs
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.

[bainjs]

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?

[rjbond3rd]

Hi bainjs, wow, I hope Mssr. Merrill will be well. I'm not sure the Bottlehead will have the watts to power an 85dB-rated driver (I have the same amp).

P.S. Oops, in my post above I said "Zdriver of 57" when I meant "Zport".

[bainjs]

I know several Bottleheads using the Merrills with great results. I believe the SPL is 92 on the DCA4's.

[planet10]

Originally posted by bainjs
I know several Bottleheads using the Merrills with great results. I believe the SPL is 92 on the DCA4's.

Actual measured is 85 dB

dave