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Discussion Starter · #1 ·
Hello everyone, I've got a Alpine MRV-M500 500W 2Ohm Mono Amplifier and a dog **** prefab pioneer sub and enclosure. So I'm looking to upgrade my sub and enclosure.
I've already pretty much decided on the Alpine R-W12D2 12" Woofer. It was between that and the Rockford Fosgate P3. And based on my music taste (mostly rap and hip hop, occasionally rock) and because of price Im choosing the R-Series.

I've also decided to build my own box.
Sub Box Design
That's what i came up with
I used Information and recommended specs from Crutchfield Manual for the speaker as well as some information given to me on a reddit Car Audio Page. Im pretty certain about the 2 cubic feet of internal net volume, but im not sure about the port dimensions and stuff. and tuned to 33Hz. Alpine recommends 32-35?

This is my first time ever designing or building anything related to speaker boxes and i'm looking for some of you highly experienced and knowledgable people to maybe take a look and tell me if its gonna be crap or not.

Idk what sort've info you'll need, its being installed in the trunk of a VW Beetle. and I think i'm going to put it facing up, so its not pointed directly at the trunk lid. I'm also going to do a double baffle on the front, and some 45's on all the corners inside the box to help with airflow.

Anyways I'd love to hear what you all think of it, what changes you'd make, if i should just scrap it and start over lol.
Thanks, Adam.
 

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What jumps out at me is the D2 ohm... final load will either be 1 or 4 ohm with that sub = no bueno. Get the D4 and run parallel will be 2 ohm final load. Your amp will be much better matched with this simple change. This assumes your only using 1 sub.
 

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Discussion Starter · #3 ·
Okay
My amp will run it at 4 Ohm, but only at 300W. I don't think running a 750W rated speaker with only 300W would be a great idea. especially not when i could be running it with 500W by just getting the other model
 

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You generally want the same or more watts in your amp than what the speaker is rated for.

No 1 killer of speakers is overdriving the amp into clipping (sends bursts of DC straight to the speaker and burns out the voice coil)

I have always fed my drivers clean unclipped sound and even though the amp is rated higher than the speakers i have never blown one because the signal is always clean and unclipped.
Of course you still can overpower the thermal ratings of the sub but that would be your own fault for pushing it to hard but usually you can start to smell it before it's too late as the enamel coating on the voice coil wire gets hot and starts to give off a particular smell.
 

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Discussion Starter · #5 ·
You generally want the same or more watts in your amp than what the speaker is rated for.

No 1 killer of speakers is overdriving the amp into clipping (sends busts of DC straight to the speaker and burns out the voice coil)

Alpine’s website says the type R is rated for 300-750W RMS. And it says 500 is perfect. Do you think that’s right? Or am I wasting my time and money screwing with the speaker when it’s really the amplifier that needs replacing.
It does make sense now that you say it like that. My problem with distortion has been because of clipping in my amp. I think it has anyways. So by upgrading the speaker I still won’t be able to go any higher with the gain on the amp.

but this doesn’t really explain my my current set up sounds so dogshit. The amp and sub are a perfect match as far as ohms and watts and everything.
So what do I do?
 

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Discussion Starter · #6 ·
And also, let’s say I can put my gain at 3/4 on the amplifier before I can hear any sort of **** like clipping or whatever. If I were to upgrade to the type R and that custom box, would I even notice a difference in volume between the two? Cuz I’m still giving it the exact same power I’m giving the current one?
I designed the box with the knowledge that I will be upgrading to 1000W sometime in the future, so if I went ahead and ordered the new speaker and built the box, just using the same amp for now, would I at least get some more volume from that without upgrading my amp just yet?
 

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You need to be setting your gains correctly from the beginning... something tells me they have not been setup correctly... its easy to do, but it can't be done by ear...

 

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You need to be setting your gains correctly from the beginning... something tells me they have not been setup correctly... its easy to do, but it can't be done by ear...

Setting gains by ear is just as effective, and by far my preferred method. It can be done with a multimeter, but absolutely doesn't need to be.
 

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Wow didn't know that it could be done as effectively... I had always been taught you can get it close if you really really know what you are doing, but that it should always be checked with a DMM, especially if you can have problems when you are listening to the system.

Maybe this was because at the time I was being taught, I was an idiot teenager...
 

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Discussion Starter · #10 ·
Wow didn't know that it could be done as effectively... I had always been taught you can get it close if you really really know what you are doing, but that it should always be checked with a DMM, especially if you can have problems when you are listening to the system.

Maybe this was because at the time I was being taught, I was an idiot teenager...
So just to be very certain I’m doing everything right, and to make absolutely sure that I’m not sending a clipped signal to my sub, I can connect the dmm to the speaker output of my amp, turn all the **** off, like bass lvl bass boost and whatever else, and then play a 50 Hz test tone, and the reading on the dmm should be the root of 500x2? (My amp watts multiplied by resistance which is 2 ohms) and that’s where my amp is happiest. And if I’m still hearing something then it’s a problem with the woofer not my amp.
 

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So just to be very certain I’m doing everything right, and to make absolutely sure that I’m not sending a clipped signal to my sub, I can connect the dmm to the speaker output of my amp, turn all the **** off, like bass lvl bass boost and whatever else, and then play a 50 Hz test tone, and the reading on the dmm should be the root of 500x2? (My amp watts multiplied by resistance which is 2 ohms) and that’s where my amp is happiest. And if I’m still hearing something then it’s a problem with the woofer not my amp.
It is not unheard of to have it all set fine and dandy, and then turn on the bass boost later and overdrive it.

A ported enclosure has more output near the running frequency, and selecting where to set the tuning frequency is a good step #1 to start with.

Many turn it up to the maximum they can get out of it, but a better method is to have an SPL target goal, and then make sure that the sub/box/amp can easily meet that target goal, and run it under that level. That requires one to have an SPL meter or know what SPL level that they want, and desigñing it all to meet that level. Or they just take a stab at it.
 

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I used subox to build a box for my jl 12w3v3. Modeled the response in WinISD and everything sounds great so far to me. I used a side slot port but happy with the results.
 
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