Foam Core Board Speaker Enclosures?

[xrk971]

Originally Posted by Cal Weldon

Pics:

I see there is still a little glue string and a grill cloth tuck needed in the middle pick. Oops.

Wow! Very nice looking. The oil turned out very nice and adding the trim frame with fabric really makes it look polished and professional looking. Congratulations on being done!
Now relax and enjoy the sound!

[Cal Weldon]

Originally Posted by xrk971

Cal,
Thanks for the minute play by play with your adjustments.

Except for the fact that my dinner is getting cold, I am happy too.

Are you using a spectrum analyzer? Even software one using the computer mic is helpful.

WTF is a spectrum analyzer? Sounds like something that should be left to a doctor.
Software is what my wife calls me when I can't...umm...you know.

I am listening to mine now and think that I must have just gotten lucky with the light stuffing i put in the throat.

I will experiment over the next few days, but at this point we are good, not great, but really, really good good.

[Cal Weldon]

Originally Posted by xrk971

Wow! Very nice looking.

Thank you. I have enjoyed the journey.

Now relax and enjoy the sound!

OK, those are instructions I can follow.

[klampykixx]

Originally Posted by Cal Weldon

Software is what my wife calls me when I can't...umm...you know.

made me LOL

[6L6]

Cal - those look great!

How far did you jam the stuffing in the throat? Was it getting really tight or still kind of loose?

[Cal Weldon]

Tight, that's what leads me to believe is was getting close to aperiodic.

[xrk971]

Originally Posted by Cal Weldon

Except for the fact that my dinner is getting cold, I am happy too.

WTF is a spectrum analyzer? Sounds like something that should be left to a doctor.
Software is what my wife calls me when I can't...umm...you know.

I will experiment over the next few days, but at this point we are good, not great, but really, really good good.

That's hilarious. Not sure if you are sharing too much there Cal

I use FrequenSee for the spectrum analyzer, works on Android phone or tablet. There is probably a pc version, but gives you instantaneous real time graph of sound pressure (arbitrary units) vs frequency. Pretty handy for checking speaker response.

https://play.google.com/store/apps/d...equenSee&hl=en

[xrk971]

Originally Posted by Cal Weldon

Tight, that's what leads me to believe is was getting close to aperiodic.

Do you mean bass is tight or stuffing is tight? When you say aperiodic, you mean there is no resonance peak?

[Cal Weldon]

Oh god, all these questions...

Tight meant both. There was too much insulation in the throats so the bass was literally sucked out. With it removed there is the 200 peak again but not too bad. I am guessing that a light stuffing might do the trick.

[Don Hills]

Originally Posted by xrk971

... How do you model the split lengths?

Like this:

                     Throat              +-- Horn 2 -- Radiator
Radiator --Driver -- Chamber -- Horn 1 --+
                                         +---- Horn 3 ---- Radiator

Originally Posted by xrk971

... Do you mind scaling it to 20 in (50 cm) and running it with the Vifa tc9fd ...

See attached. I assumed 6 cm depth. It doesn't look good... I think the volume (depth) is too small and the horn is tuned too low.

Originally Posted by xrk971

... Also, at the 70 cm, the longest path should get down to about 38 Hz, the sim shows falloff below 50 Hz. ...

It is what it is. The impedance and excursion graphs (of the 70x70 cm model) show resonances at 61 and 119 Hz. I suspect the bifurcated horn is the problem. The longer of the two "output" horns is 138 cm, which is 1/4 wavelength at 62 Hz. That's why I want to re-sim with equal length horns.