I'm using these parameters for the 1354:
Fs 51, Vas .5 ft3, Qts .46, Qms .537, Qes 3.46,
Pd 40W, Re 7, Diam. 4.75, Xmax 0.1 (??)

From PiAlign I got: Vol. .23ft3, Fr 46
From Box Plot: Alpha 2.2, H 0.9

The Box Plot alignment was: vol. .8ft3, Fr 44 Hz
Alpha .62, H .97

The Box Plot alignment Amplitude plot has -3dB at 40Hz
and a flat 0dB line from 60Hz up.

The Pi Alignment Amplitute plot has -3dB at 70 Hz
and a hump from 90-250Hz.

Some questions:
1) Am I entering things correctly?
Assuming this is correct
2) Why the differences in the 2 alignments? How
will the sound compare?
3) How are the cylindrical port sizes determined for
each alignment? This has got me confused.

Tia, Craig

From Loudspeaker Design by Vance Dickason

For a tubular vent flush-mounted on a speaker,
calculate the length by:

Lv = ((1.463*(10**7)*(R**2)) / ((fB**2)*VB)) - (1.463*R)

Lv = length in inches
fB = tuning frequency in Hz
VB = box volume in cubic inches
R = radius of the vent in inches

My favorite calculator is the Python interpreter. A
Windows version is available at:
http://www.activestate.com/Products/Download/Get.plex?id=ActivePython

I wrote a function to calculate port length for me:

def portlen(diamInches,tuningFreq,boxVolCubFt):
radiusInches = diamInches / 2.0
cubInchConv = 12.0 * 12.0 * 12.0
boxVolCubInch = boxVolCubFt * cubInchConv
num = 1.463 * (radiusInches * radiusInches) * (10000000.0)
denom = (tuningFreq * tuningFreq) * boxVolCubInch
term1 = num / denom
term2 = 1.463 * radiusInches
len = term1 - term2
print 'calc port len diam.=',diamInches,'freq=',tuningFreq,'vol=',boxVolCubFt,'len=',len
return len

Example output:
calc port len diam.= 0.5 freq= 54.0 vol= 0.23 len= 0.423228647155
calc port len diam.= 0.75 freq= 54.0 vol= 0.23 len= 1.2265769561
calc port len diam.= 1.0 freq= 54.0 vol= 0.23 len= 2.42441458862
calc port len diam.= 1.5 freq= 54.0 vol= 0.23 len= 6.0035578244

calc port len diam.= 2.0 freq= 46.0 vol= 1.0 len= 2.53815084366
calc port len diam.= 3.0 freq= 46.0 vol= 1.0 len= 6.80808939824
calc port len diam.= 4.0 freq= 46.0 vol= 1.0 len= 13.0786033746

I calculated Pi Align for RS-1354 some time ago, but not built them.
Where I was confused was a really small port dimensions.
In the Pi align, there is another factor to be considered, which
is the ratio Qe = Lp^2/Ap. For RS-1354 in 0.234 cu ft Pi aligned
box tuned to 41.6 Hz, this ratio is 2.206. The only possible port dimension I found is Dp=0.414" and Lp=0.545" - not a huge port, it
risks to produce some noise, IMHO.
I do not understand exactly how important is to keep this ratio close to calculated Qe value. What's more important: use such a small
port or make the port bigger and then keep right values for Qe or rather for Fre?

O'tor