follow up on ZA 14 vs Fountek

[r-carpenter]

Re: follow up on ZA 14 vs Fountek

here's what the output looks like roughly after padding was added. Note: the over all level was changed in the process.

[r-carpenter]

Re: follow up on ZA 14 vs Fountek

now, this is what happens then you put padding on the walls. a fundamental standing wave is still there (equal in length to the longest dimension, about 11 inches in this case) but lower in magnitude. Padding is only so effective. I also find stuffing such as accustuff only marginally effective in the ported loudspeaker. Unfortunately then you keep on adding it, the usable output drops down in magnitude together with the ripples. Ahh no luck in life.
Peter, don't jump the gun I did.
Anyway, here my to blonds and 2 redheads.

[Pete Schumacher]

Re: follow up on ZA 14 vs Fountek

Here's CSD of the port output. Left is again, port behind the driver and rite is upper section vertical center placement

Now, do it again with some of stuffing . . . ;)

[r-carpenter]

Re: follow up on ZA 14 vs Fountek

Here's CSD of the port output. Left is again, port behind the driver and rite is upper section vertical center placement

[r-carpenter]

Re: follow up on ZA 14 vs Fountek

looks like with the port moved away from the center line the magnitude of usable output slightly drops and ripples move slightly but don't decrease or increase significantly. it appears that the worst port positioning is directly behind the driver, lower magnitude of what we need and relatively higher and wider mid range leakage.
Green=directly behind the driver
Red= centered vertically in the upper section.

[DDF]

Re: follow up on ZA 14 vs Fountek

I wonder if Martin King's spreadsheet could model port output changes with placement in a BR box? It models (accurately) port o/p in an MLTL

[r-carpenter]

Re: follow up on ZA 14 vs Fountek

from the left

port in the center upper section
port in the upper section close to the sidewall in the midle
port in the upper left corner

[r-carpenter]

Re: follow up on ZA 14 vs Fountek

Each panel is just clamped in for measurements. Microphone is about 1/4" in the port.
Levels remain constant throughout and only the backs are changed.
Speaker does not have any padding or stuffing, just a thin layer of elastomer.
First take is with the port located in lower section, vertical center.
gating, 500msc distance set at 0.

[r-carpenter]

Re: follow up on ZA 14 vs Fountek

4 back panels are made
one with port pretty much behind the driver, vertical center line
second has the port in the upper section also vertically centered
one with the port moved in the corner
and one with the port close to the side and 2/3 up from the base

[r-carpenter]

Re: follow up on ZA 14 vs Fountek

made 3 dummy panels to play with port placement but that will be done next week.

[r-carpenter]

Re: follow up on ZA 14 vs Fountek

ZA14/ProAcVifa combo= Zavic?Prozac?Fazac?

[r-carpenter]

Re: follow up on ZA 14 vs Fountek

back panels are ready for binding posts.

[r-carpenter]

Re: follow up on ZA 14 vs Fountek

Thanks Peter. I was going to place the port in the upper section of the cabinet, somewhat behind the tweeter. But now my curiosity is running wild. I'll make 2 or 3 dummy panels and move port from the very corner to a vertical center line and measure the output.
Then I build these speakers
http://techtalk.parts-express.com/al...pictureid=2038
port (2x9) was placed directly behind the RS180. It had an interesting effect and the speaker sounded somewhat "dipolish"
I also build this one a couple of years ago with down firing 2x9 flared port.
http://techtalk.parts-express.com/al...pictureid=2023
and that one had the best imaging that I've heard ever from anything else in my life.
So, I think port placement and how it relates to the sound especially in a 2 way design are worth playing with.

[Pete Schumacher]

Re: follow up on ZA 14 vs Fountek

Thanks.

Did anyone experimented with asymmetrical port placement? I mean in relation to a vertical center of the panel. I wander what kind of the effect it has on the midrange leakage.

The speakers are 4.5L after the drivers and brace.

Excellent question and astute conclusion. It has a MAJOR impact on midrange output in the passband of the woofer. Not only does the port resonate at a particular frequency, causing a ripple in overall response, it can allow a broad range of output that can mess with the sound.

If possible, get it away from a position directly behind the woofer. An unobstructed pathway will allow much more information out than one where absorptive material is in the path. Loose fiberfill in the enclosure helps reduce the effects as long as airflow from the port is maintained.

[evilskillit]

Re: follow up on ZA 14 vs Fountek

Nicely done, very nice. Don't see mitered joints around here very much what with most of us being **** joint kinds of guys.

Dave