[Ricci]

Nope. I always use one way and get 12.5mm for 300w into the 9ft cab. Vc's in series for 3.84 re.

Parts,

That cab idea sounds fine. Make sure you get enough vent area. 6" port per driver should be ok.

 

[Parts]

Can someone else show their WinISD results with TS parameters showing?

Edit things are looking better, I have re-installed winISD and adjusted the TS parameters again, running a butterworh second order at 17hz with a 506 liter cab tuned to 20hz, looks reasonable?

Qts 0.504
Vas 6.039
Fs 25.00Hz
Re 3.840 ohm
Le 0.50mH
Xmax 8.5mm
Z 4.00 ohm
Qms 6.080
Qes 0.550
SPL 93.00 dB
Pe 300w
BL 8.20000 Tm
Dd 13.00 in
Sd 132.83

 

[Mike P.]

Ok, I got it figured out, I had the wrong BL enterd for a 4 ohm load. It is indeed 13mm excursion with 300 watts.

 

[Parts]

So are the RE and BL figures I entered above correct? Why does the JBL brochure state 0.96 for VC Dc Resistance? is this different when both are wired in series for a 4ohm load hence the figure 3.84 you guys mention?

With the above figures I have used, and a 600w input I am looking OK in WinISD, even with a 700 litre cabinet I look OK, it seems to have a more even maximum SPL line with less tail off than 506 litres? An extra 2 to 3db around 20hz? 114dB at 50hz down to 113db at 20hz with come excursion peaking at 7.9mm at 14.90hz and port velocity peaking at 13.572 m/s at 18.77 hz with four 4.02" + 10.85" ports

Cabinet size and design seems quite a lot of work, so I am still busy calculating what braces and battons and such equate to what volume........

 

[Mike P.]

JBL lists the specs for a 1 ohm load. Changing the Re to a 4 ohm load also changes the BL. Here's the file. Save it to the Drivers fold in WinISD.

View attachment JBL GTO 1502D.wdr

 

[Parts]

Thanks Mike,

Your file gives me that same dip between 45hz and 22hz in maximum SPL I was talking of earlier, is this a good or bad thing? Any way to smooth it out?

Cone excursion looks bad as well? I can keep it level with 300w signal, cabinet tuned to 19hz with a filter at 20hz? Any more and it gets out of hand.

 

[Mike P.]

You're using the wrong graph. Switch to the SPL graph, that shows you what you get with the input power and HPF that you use. In 9 cu.ft. tuned to 20 hz you should be able to get away with 200 watts input and a 2nd order HPF at 18 hz.

 

[Kenneth Demeester]

Hello, does anyone have exact building schemes for the 4642A ? Thank you

 

[derekpittx]

I have always gone with separate subs, it allows more placement options.

 

[willis7469]

I have always gone with separate subs, it allows more placement options.

I’m assuming you mean multiple subs? I agree that multiples is they way to go but not at the expense of output and extension. IE: if you have a bunch of smaller subs with an f3 if 30hz, they still won’t be able dig very deep. I know there’s more to HT than extension, but imo it’s at the top of the list. For movies especially.