OS Boombox build

[filmslayer]

Re: OS Boombox build

i think i'm there Chris but i dont have measuring equipment at this point , they almost sound as good as the 6" pro surrounds i built for my system but my surrounds need bass support as well . i dont trust myself either so i sent pics of the XO's to Josh (Jbrunner) and between the two of us i believe they're correct
i was looking at this lil guy last night http://www.parts-express.com/tang-ba...oofer--264-831 and playing around in winISD and for a 0.4 ^3 box with a 2" x 15" port i come up with just over 35htz . i'm gonna play around some more today as i don't trust myself with winISD yet either ... ;)

my real concern is will the unbalanced load on the amp be an issue ?

[Chris Roemer]

Re: OS Boombox build

The "1138sm-F" version is half the price and should give better results in 0.35cf w/2"d x 18" port. Can't say about the load, but wouldn't think it'd be an issue at modest volume levels, as long as it's 4-ohm friendly.

[filmslayer]

Re: OS Boombox build

amp is rated 100x4 @2ohm so i dont think it will be a problem either , i'm waiting for one of the car guys to get some free time and i'll ask what they think ... thanks for the F version , i'll check that out ...

**edit** 75wx4 into 2ohms , 50wx4 into 4ohms ...

[filmslayer]

Re: OS Boombox build

car guys said there should be no issues with the amp . so now i have a 6" 4ohm driver wired in and running , gonna let it run for a couple hours and see about any heat issues and also make sure the 9a brick can keep up ...

[filmslayer]

Re: OS Boombox build

yesterday the test went well , 5 hours at pretty good volume and no issues ... moving forward with the 1138sm-F ...

Mr.Roemer , you seem to have a good grasp of what i'm try to do , could you please recommend a simple filter for this sub ? the amp has active controls but unfortunately all four channels get the same filter ...

Thanks
Mark

[Chris Roemer]

Re: OS Boombox build

You'd have to go line-level somehow. Passive on the output (around 80Hz?) would be prohibitively expensive - due to the cost of the large components. Also, w/out using a summing plate amp, you'd either have to run dual (stereo) subs, or use a single dual voice coil driver (probably the best option there would be the 8" Dayton DVC).

[filmslayer]

Re: OS Boombox build

would make the box to big . prelim sketch is 16 x 8 x 8 and that would give me .36 internal . at this point cost is not really an issue , i'm already getting close to the $500 mark . in my 2.5's Josh has the sub rolling off at 125 , what about something like that ?

[Chris Roemer]

Re: OS Boombox build

You'd probably need a coil in the 6-8mH range (and maybe 200uF or more of capacitance - but those could be cheap npes). How would you sum the L/R channels for the single (v.c.) sub? (Dayton's SA25 plate amp is only around $30-40? . . . don't know if you could get it to run on 12vdc though?)

[filmslayer]

Re: OS Boombox build

i'm not clear with what you mean by summing ? the sub is only hooked .... ahhh now i see ... the 6" bazooka subs i used in my lil bass box are DVC maybe one of these ....


i have some 199uF electrolytic caps here in the shop . i'll go pull up Josh's schematic for the 2.5's and see how he handled it

[filmslayer]

Re: OS Boombox build

thanks Chris , i think i got it now . gonna go with the 6.5 DVC bazooka .this will only increase box a lil as they need .5 . looking at the schematic it looks like he just used a 7mH coil ,how would i put the cap in ?

[Chris Roemer]

Re: OS Boombox build

I can't even find T/S parms on Bazooka subs? I could try modeling an LP filter if you can post a link?

[filmslayer]

Re: OS Boombox build

it was like pulling teeth and i never got them (propitiatory) ! after reverse engineering one of their tubes and several e-mails with their head tech he modeled my sub box for me . would any of the info i have help you ?

[Chris Roemer]

Re: OS Boombox build

It might. "Proprietary" doesn't mean "unknown" anymore, that's exactly what the DATS is for. It cranks out all the T/S parms and plots an impedance curve (free-air, or in-box, of individual drivers or complete systems) giving you everything you need for an XO simulator except frequency response data (which you need a mic for). The only parameter that takes even a little effort is Vas (it might take a minute or more for that one, unless you're used to doing it all the time). If someone in central FL had one, they might be willing to measure your drivers for you? T/S is really just for box design (box size, and bottom end rolloff), but if I had those I could model that sub's impedance curve which would help in calculating an LP filter for it.

[filmslayer]

Re: OS Boombox build

got ya ... i'm on the waiting list as soon as PE gets them back in stock ....

[filmslayer]

Re: OS Boombox build

OK , at somewhat of an impasse . but i'm gonna use the bazooka driver , worst case i pull one from the sub box and send it to Josh for modeling he's in south Georgia so not to far away . cause i already have some of these it will let me move forward with box construction if i can get some time . i still have to figure out how i'm gonna mount the USB and AUX in receptacles . the best part of working in a stereo shop is i have lots of tools and materials at my disposal ...