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Old 18th November 2004, 07:14 AM   #1
Zeph is offline Zeph  Canada
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Default Quatro Sub Enclosure, Help me decide

I have a dayton quatro 12 here from partsexpress,and a 200w plate amp.

After reading numerous posts on different forums.

I originally wanted to downfire, because I am very limited to space.

I also wanted to downfire because I have noticed, with my old front firing sub, (not active, straight from reciever) It would seem to overpower my mains, in the higher freq. This sub is solely for ht purposes.

Im not to sure on that crossover thing listed on the amp, if i set it to something it should not let the higher freqencys pass through?


Im just not clear on all of these things, right now my front firing sub is facing the wall so it bounces off of that first so i dont get the higher freqencys as much..

any help is appreciated!



Thanks
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Old 18th November 2004, 06:18 PM   #2
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Default If for HT, your receiver should have a crossover.

I presume your receiver is Dolby Digital/DTS capable, correct? If so, it will have a subwoofer crossover built in. Some have adjustable frequencies, some do not, but most have a fairly steep slope. My receiver for example is 80 Hz, 24 dB/octave. I run my receiver's subwoofer preamp output to an external amp with no additional crossover, works great. So, what I'm saying is that if your receiver has a subwoofer output, you can simply disable the crossover in the plate amp, or set it to it's highest frequency if you can't disable it.

With a proper crossover, you shouldn't need to face the woofer away from you to reduce midrange frequencies. Your box can be shorter if not downfiring, since you don't need 3" or taller legs underneath it. I don't know if the Quatro 12" is suitable for downfiring though. I believe Parts Express and Adire Audio both provide formulas for calculating the amount of sag present in a particular woofer if downfiring, a search of their sites should bring it up.


Aaron Gilbert
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Old 19th November 2004, 12:40 AM   #3
jjdche is offline jjdche  United States
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You can also build a tall narrow box and front fire the woofer, that way it will take up the same space as a tube and you won't have to worry about downfiring.
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Old 19th November 2004, 06:47 AM   #4
Zeph is offline Zeph  Canada
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well, My recievers just a cheapo one for now, JVC rx-6042s i do belive it is.

Is there a way to disable the reciever xover and stuff so i can just set it up on the plate amp ?

if i were to make my box tall front firing, it would look somewhat retarded no?

i came up with 2.25 cubic ft ported with 4" circle port, and length was 14.5 or some.

with the braces and the amp's displacement calculated its volume needs to be bumped up to 2.46 cuft. So therefore it is roughly 17.5x17.5x18 ish

so it will look somewhat square


last question:

Port placement, does it matter where i point it?

i was thinking of on one side? since id have to move it away from the wall if i put it on the back, on the front it may or may not cause the need for end correction, and or it may look stupid, and if i mount it on the top, it will get crap in it, if i mount it on the bottom, i need to jack it up 4" off the ground...
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Old 19th November 2004, 07:30 AM   #5
AndrewT is offline AndrewT  Scotland
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Hi, its a while since I last looked at speaker design but from memory; The port end should be at least one diameter from any internal surface and two diameters away from the driver.
The internal shape of the box is usually better if all the L,W & D are different, try ratios of 1:1.25:1.6, the port can go on any face relative to the driver, its the location of the open end that matters.
regards Andrew T.
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Old 19th November 2004, 08:09 AM   #6
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Default Only one way, and it's not ideal.

With that receiver, there is no way you can disable the subwoofer crossover and still use the subwoofer preamp output. You'd need to select subwoofer as 'Off' or 'No' in the setup menu, in which case the signals which would normally go to the subwoofer, would now go to the front left and right speakers. You'd then connect your subwoofer to the receiver using speaker cables in parallel with your front L/R. As far as the subwoofer is concerned, this really doesn't hurt the sound quality. However, the downside is that you now have a full range singnal going to your front speakers, which may overpower them and add more distortion. If they are capable of handling a lot of low frequencies, you may be ok. The exception to what I've just said, is if your subwoofer amp has high pass filters built into it's speaker level outputs, in which case you could connect the front L/R speakers to the subwoofer instead of the receiver. However, even if present, they will likely be only 6 dB per octave, so not a huge help, though better than nothing.

I don't think a tall front firing box looks bad, as long as it has a grill.

Andrew's right about port placement. You don't want it obstructed by a wall either inside the box or outside, other than that, you are free to place where aesthetics request it. The frequencies coming out of the port have such long wavelengths, that it really won't matter from a performance perspective.

As for the shape, given the frequencies a subwoofer will reproduce, it can really be any shape and be successful, even square.


Aaron Gilbert
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Old 19th November 2004, 02:39 PM   #7
jjdche is offline jjdche  United States
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Quote:
Originally posted by Zeph
if i were to make my box tall front firing, it would look somewhat retarded no?
Well, thats really up to you, I've seen quite a few people build them like this.
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Old 19th November 2004, 02:46 PM   #8
Zeph is offline Zeph  Canada
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ah, so i have to either use the settings from the reciever to the sub or dont use them at all?

sounds wierd, most recievers cancel it out.
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Old 24th November 2004, 07:15 PM   #9
Sly-1 is offline Sly-1  Canada
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If you make a down firing sub I highly recommend making an MDF base about 1.5" thick and 4-5 inches from the driver. The sound reflects off the solid base in every direction to fill the room. Mine was so effective that it kept blowing papers off my coffee table. I would still have the sub except for an unfortunate moving accident.
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Old 25th November 2004, 05:58 PM   #10
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Send a message via Yahoo to sidd_raj2002
and if u are going to connect the sub in paralel to the receiver check the receiver 4 the safty circuitry cuz if u connect the speakers in paralel the resistance is gonna drop, and that may causer cause the receiver amp to blow off, and also the power o/p will increase with less resistance see if ur speakers can handle the power, and also that will increase distortion.

so best thing is operate the sub through the receivers crossover.

and y dont u try a sealed bipolar enclosure instead of a vented one or may be a passive radiator that way ur enclosure will be smaller.

i have just finished my sealed bipolar enclosure and it sounds toooooooo good for the 30 bucks i spent on it.

and remember to use 18mm mdf or thicker. dont use anythin thinner than that. also dont put any stuffing , 1st listen to the sub and if u think its boomy then only put some stuffing
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