OK to Share Chamber????

[Flyhalf 10+ year member]

Here's what I am planning, what would you do if it's all you had to work with. I have 200 W rms x 2 @2ohm to work with.

I'm getting closer to building a box for my new setup. I'm planning on running 2 8's ported (Possibly Assassin's). The box should have an internal volume of roughly 1.2 cubes after port/sub displacement. Thinking tune should be from 35-40 hz for the 8's. Box will be in the cab of my CC truck where my center consol between the front seats used to be. Also thinking about downfiring the subs.

Would it be ok to have the subs share the same chamber?

If so, where should I locate the port in reference to the subs for best sound? Any thoughts on downfiring in a ported box?

Box shold be 41"Lx9"Hx8.5"W. Will probably use .5" mdf or birch...Will probably use 4" pvc for the port.

Hell, here is the space I've got...what would you do with it???

Click to read more...

 

[Flyhalf 10+ year member]

bump...anyone?

 

[Relax 10+ year member]

1. It is okay for you to have the subs share the same chamber.

2. Try to have them on the same plane, although in bass frequencies it hardly matters. I would have subs up or down firing, and the port out the front or back.

 

[TeoTorriatte 10+ year member]

Just make sure you are sending the same signal to each driver... you may need to bridge the amp and run it @ 8-ohms with a pair of SVC 4-ohm drivers (which the Assassins are).

 

[Louisiana_CRX 5,000+ posts]

If the subs share the same chamber you can do about a 20% decrease on the interior size of the enclousure //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

 

[Flyhalf 10+ year member]

Just make sure you are sending the same signal to each driver... you may need to bridge the amp and run it @ 8-ohms with a pair of SVC 4-ohm drivers (which the Assassins are).

Thanks...They will be getting the same signal. The amp is an Alpine MRP-M450. Mono and puts out 400 W rms at 2 ohms. So, wired in parrallel, 2-4 ohm svc subs will produce a 2 ohm load. Right??? Each sub getting roughly 200 W rms.

 

[Flyhalf 10+ year member]

If the subs share the same chamber you can do about a 20% decrease on the interior size of the enclousure //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

Sounds like it's OK. I always thought on sealed enclosures, it wasn't recommended. Didn't know about ported. Also didn't know about the decrease in box volume. Thanks...

 

[TeoTorriatte 10+ year member]

Thanks...They will be getting the same signal. The amp is an Alpine MRP-M450. Mono and puts out 400 W rms at 2 ohms. So, wired in parrallel, 2-4 ohm svc subs will produce a 2 ohm load. Right??? Each sub getting roughly 200 W rms.

OK, that makes better sense... you confused me when you stated this way...

I have 200 W rms x 2 @2ohm to work with.

Made it sound like you had a 2-channel that you wanted to run @ 2-ohms per channel.

 

[helotaxi 5,000+ posts]

If the subs share the same chamber you can do about a 20% decrease on the interior size of the enclousure //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

Not exactly sure where you heard that...

I am building one myself right now and getting a relatively low tuning (36hz is what I'm going with and that is lower than the AA 8 wants) with a fairly flat response, the internal volume I ended up with was 1.2cf plus port and sub displacement. I went with a slightly smaller box than what I wanted (.52cf per sub) and a very slightly higher tuning and after all was said an done the final design is 35x13.5x9.5. With the space you have to work with, the design is going to have to put both drivers in one end of the enclosure firing up or down and the port coming out the opposite end of the box. I would use birch instead of MDF if you plan on going with 1/2" and would either double up the speaker baffle area or use a piece of 3/4" for that part. Brace the back panel to reduce flex. Figure out your 1.2cuft internal volume and put a 4" port 17.75" long in it and the net should result in 1cuft tuned to 40.5hz. It should play into the mids 30s on the low end. You shouldn't have audible port noise but you will have to worry about overexcursion below about 25hz at full power.

 

[Flyhalf 10+ year member]

Not exactly sure where you heard that...
the internal volume I ended up with was 1.2cf plus port and sub displacement.

What is the displacement for each sub?

With the space you have to work with, the design is going to have to put both drivers in one end of the enclosure firing up or down and the port coming out the opposite end of the box.

That is exactly what I was thinking.

I would use birch instead of MDF if you plan on going with 1/2" and would either double up the speaker baffle area or use a piece of 3/4" for that part. Brace the back panel to reduce flex.

Good tips. Wasn't sure if I would have to worry about that only giving each sub 200 rms.

Figure out your 1.2cuft internal volume and put a 4" port 17.75" long in it and the net should result in 1cuft tuned to 40.5hz.

So, 1.2 internal volume after subs, but before port?

It should play into the mids 30s on the low end. You shouldn't have audible port noise but you will have to worry about overexcursion below about 25hz at full power.

Thanks...

 

[helotaxi 5,000+ posts]

The sub and port displacement should be right at .2 total giving the numbers that I quoted above.