Newbie Help

[makksus]

hey everyone,

im new to this audio and generally speaker DIY in general. Im a dj and producer and wanted to start diying. Ive been reading up and read vance dickson's book and have some questions..

all of my questions are for the following driver:
p.Audio challenger series c12-300mb
diameter= 312cm
P(rms)= 300
sensitivity= 98
range= 35-3200
fs=50hz
re=5.4
Sd=.543m^2
Qms=4.99
Qes=.27
Qts=.26
Vas=79.41 litres
MMs=52.36 gr
xmax=3.5mm
xmax peak=12mm


i will be using a vented enclosure.

- when talking about alignments i don't . I've got different values for differently alignments, but i don't know which means there best eg. Fb for SBB4 is the same as the driver, is this good? Vb is 23 litres. What is the comparison. I.E. what numbers am i looking for to say," yes this is the alignment im gunna use"?

-becaus the size of my driver most calculators (including LDC7) will give me these box dimensions 29.5 x 47.8 x 18.23 (cm) but that wont fit the driver, and if i change it to fit the driver, won't i have changed the alignment?

-I have a computer (Mac) and a sound card and an amp, is this enough to test the speaker. and find the SPL graph?

-Crossover:both my mid and bass Have the same frequency range, to maximize output would it be feesable to actually design a 2 way xover and just make two similar branches for both oF them. In the absence of this i have designed a 3-way crossover that is fairly simple it is a first order one because there are no significant dips or peaks in any of the responses (apart from a dip of a couple of db at 2khz for the bass but it wont get that far i've concluded) the tweeter has a series notch filter and an L-pad
the mid has a zobel circuit and a l-pad and so does the bass. is there anything i havnt considered? i have not considered the box in anyway while designing this crossover. should i have? and how will it have affected my design?

I have a background in engineering and know some(not alot) about analog electronics.

If you've gotten this far i thank you for reading this. any help would much apprecated.

thanks again
Makks

[richie00boy]

The alignment just comes down to personal taste and how you want the speaker to be used.

As long as you don't go mad with dimensions (direct multiples or long thin etc) , then it's only the volume that matters, so design your box to suit the speaker physical size and vent physical size.

Bit unsure what you mean about the mid and woofer having the same frequency range. If you are going to use this speaker for sound reinforcement then you won't get away with 1st order crossovers as they will allow too much out of band signal through which coupled with you playing at max will blow the drivers.

Ideally you should consider the box during crossover design to think about baffle step.

If you want to test frequency response and SPL you will need a calibrated mic.

[makksus]

thanks for the quick and helpful reply,

so a higher level crossover to get them band off. What is baffle step? and how does it affect my crossover?

and i do have a mic, can u recommend any software for this?