DIY SUB. I got the amp, I got wood(you can laugh), opinions on whats next?

kawizx9r

Face wrote: »

You're going to need 2-3 coats of primer over MDF.

ben62670 wrote: »

The first few coats of primer need to be light too. They are called tack coats to keep the primer from soaking too deep into the MDF.

Thanks for that you guys. Over here I'm trying to help someone out with their sub build and still needing some advice myself lol.

Face

Coating the MDF if a 50/50 mix of wood glue and water will also do a good job sealing MDF.

polkanddie

Qms: 7.0, Qes: 0.62, Qts: 0.57, Vas: 0.85 cu. ft., Sd: 54.25 sq. in..... Can anyone tell me what the Ideal sealed inside volume of my box should be using this info? I really would like to know since my sub will be here in about a day or so.

polkanddie

Thanks for all the advice about painting the box and getting it sealed... But alas.... I have to build the box first... lol

Face

Download WinISD(it's free) and enter those parameters into it.

Does your amp have bass boost?

polkanddie

It has a low pass xover with gain control, phase switch, and EQ. I dont think it would have a bass boost since its a plate amp made for a subwoofer. But I may be wrong.

polkanddie

Does 1.57 cu ft sound right?? thats what I got when I put in the info that I found... Eh, thats pretty small. but then I have to mount the amp and take out some for that as well.... Amp is about 5 inches deep. 10x10 cut out.

kawizx9r

polkanddie wrote: »

Does 1.57 cu ft sound right?? thats what I got when I put in the info that I found... Eh, thats pretty small. but then I have to mount the amp and take out some for that as well.... Amp is about 5 inches deep. 10x10 cut out.

You can use a volume calculator or something on that forum I posted to find out the volume your bracing will take as far as anything else going inside the box.

1.57 cu ft sounds about right for your sub, mines over 4 cu ft (at about 17" wide x 21.5" tall x 25" deep).

Double check your plateamp, it might have bass boost like Face suggested, I know several Dayton amplifiers do....and all of them have a chart of what resistor to use in place of R27/R28 in case you manually want to add a bass boost yourself.

Face

If this is for HT, you need bass boost for a sealed sub.

billbillw

Dude, you really should be looking at a ported box for that sub if you want to do home theater with it. In a sealed box, you loose most of the response below 45Hz. In a HT setup, you want decent response down to 25Hz or lower.

Look at the plot below comparing a ported vs sealed box and you can see how much you are giving up. Sealed is yellow, ported is red.




In a 10" size, a sealed box really only works for car audio use. This is because you are trying to minimize box size, but have the car's 'cabin gain' to help boost the low end.

In case you don't see it in the image, the ported box is 2.7 cu ft with a port tuned to about 26Hz. You could shrink the box down some if you used generous amounts of polyfill, but you should read up on that first.

everpress

Face wrote: »

Coating the MDF if a 50/50 mix of wood glue and water will also do a good job sealing MDF.

Face, I'm prepping a couple of RT1000p's that someone gave me. I peeled that rubber stuff off (I would have done this even if some wild cat hadn't started that before I got them- that stuff is ugly), and I'm left with bare MDF.

If I seal the MDF with the WoodGlue/Water mix, should I still use 2 coats of primer? I mean I guess it can't hurt, but since you know what you are doing and this is my first project, it'd be worth asking.

Sorry to jack the thread...

Face

I would still use primer.

Be sure to give the glue/water mix and a good sanding beforehand though.

jinjuku

polkanddie wrote: »

This is my amp, Just got it in a trade. Dayton HPSA500 500W Subwoofer Amplifier. I was thinking about changing it up and using a dual 2ohm woofer, either a kicker L5, Infinity Kappa, Or possibly a Polk?? Any thoughts...

For the $150 mark get the Shiva-X from diycable.com. Most likely one of the best bang for the buck subs out there.

I would say go for the Infinity Kappa 12VQ if they were still in production. I haven't seen the specs for the the Kappa 120.w9 that is (I believe) it's replacement. They blinged the 120.w9 up and it looks terrible IMO.

jinjuku

Face wrote: »

You're going to need 2-3 coats of primer over MDF.

MDF especially on the cut edge will soak primer. One trick is to hit the edge with a thin film of glue. Just use your finger or a small .5 or 1 inch paint brush to apply it and let it dry then primer.

The finished side of MDF won't need as much attention. I still use Killz oil based primer on MDF.

Krazyz1

Part Express.com will have everything you need including books on speaker design. A un ported sub is best but takes a big amp to move it. A slotted port tends to make less "chuffing" sounds then a single round port due to area of relief.

jinjuku

Krazyz1 wrote: »

Part Express.com will have everything you need including books on speaker design. A un ported sub is best but takes a big amp to move it. A slotted port tends to make less "chuffing" sounds then a single round port due to area of relief.

A sealed sub isn't better or worse then Ported/Passive Radiator/Band Pass/T Line/IB subs. It's different for sure. Better/Worse is just subjective. It depends.

Not only does a sealed sub take more amp, it takes eq.

kawizx9r

billbillw, +1 on the ported enclosure.

I thought about mentioning this as well to polkanddie since that sub doesn't seem to get very low by itself, a ported enclosure would help in this situation. Since he's looking for a 'small enclosure' his best bet might actually be a sonotube imo.

polkanddie

The amp has an EQ. Its 540w max. which matches the driver I ordered. it should arrive tommorrow or saturday the latest. Also Im not looking to get kicked out of my apartment. So I think sealed will be good... and simpler... Also. I think ill make it downfiring to somewhat match the look of my towers.

kawizx9r

polkanddie wrote: »

The amp has an EQ. Its 540w max. which matches the driver I ordered. it should arrive tommorrow or saturday the latest. Also Im not looking to get kicked out of my apartment. So I think sealed will be good... and simpler... Also. I think ill make it downfiring to somewhat match the look of my towers.

If you're going sealed then I suggest you use solarseal caulk for the inner seams to completely seal things up. This by no means is "the best" but with personal experience I love the way it sealed everything up in my sub.

Downfiring can affect the subwoofer depending what the floor is underneath it. I'd say front firing is a little more forgiving in that respect, but it's your subwoofer so totally your decision. Don't try to compromise your box just to make it "look better" or "smaller" than it should be.

Face

Unless you're concerned about the cone being damaged, go front firing.

polkanddie

Points taken. Front firing will allow me to show it off a bit... instead of saying hey look i got this box and it makes boom boom sounds. I kinda like watching the woofer move. It will be a carpeted floor so... Quite right. Thanks to everyone for all the advice, and I WILL be taking pics of all the progress in building this... even though it wont be as exciting as an ubercomplicated box. The woofer is only one state away... I should be seeing it tommorrow!!!

kawizx9r

polkanddie wrote: »

Points taken. Front firing will allow me to show it off a bit... instead of saying hey look i got this box and it makes boom boom sounds. I kinda like watching the woofer move. It will be a carpeted floor so... Quite right. Thanks to everyone for all the advice, and I WILL be taking pics of all the progress in building this... even though it wont be as exciting as an ubercomplicated box. The woofer is only one state away... I should be seeing it tommorrow!!!

DO take pictures of every major step you take

I've gotta add that pic I posted up on this thread onto my thread just to keep things updated......now I just need to go pick up my woodglue I left at a friends and do the 50/50 mix of water/glue. Would that be easily sanded down with 400grit, 200grit or wet/dry sandpaper because I can imagine the glue/water mix might need some sanding.

polkanddie

I think if you read back someone said that it definitely would need some sanding. Now I cant wait til the sub shows up so I can get everything together. This is gonna be fun.

kawizx9r

polkanddie wrote: »

I think if you read back someone said that it definitely would need some sanding. Now I cant wait til the sub shows up so I can get everything together. This is gonna be fun.

That was in regards to primer/paint, not the glue/water mix but I'll sand it anyway. Got plenty of 400grit paper left, so its not coarse enough to get rid of the improvised sealant but enough to make it smooth if need be.

You figure out the box dimensions you'll be using? You have all the materials needed for completion of the box?

polkanddie

I put the specs in that program and it told me 1.57... but i took a look at the polk manual on the sub I have and it says recommended .66 in a sealed enclosure....curious....

kawizx9r

polkanddie wrote: »

I put the specs in that program and it told me 1.57... but i took a look at the polk manual on the sub I have and it says recommended .66 in a sealed enclosure....curious....

Manual for that sub suggests a smaller box because it's taking into consideration the fact that it'll be inside a trunk/etc which will pretty much act like a big enclosure IE 'cabin gain'

Just disregard it, I think that was said earlier about using a car sub

polkanddie

Makes sense. Thanks again
So what are you gonna do with those rt1000's??
I just recently got some and I love em.

kawizx9r

polkanddie wrote: »

Makes sense. Thanks again
So what are you gonna do with those rt1000's??
I just recently got some and I love em.

Honestly? Most likely just get rid of them....I've had them for what over 8years now? They are my first Polks, and I don't even use them since they just sit here as 'rear surrounds' but they're not hooked up to anything.

polkanddie

Just wondering are yours black or rosewood? and blue or black woofers? I really wish I could find someone who would like to trade bc I have the rosewood cs1000p. You know what you could do... put em up on CL and use the cash to get the HPSA1000 for your sub!!!! Now that would be an amp....Think about it....4x the power you have now....can you imagine...

kawizx9r

polkanddie wrote: »

Just wondering are yours black or rosewood? and blue or black woofers? I really wish I could find someone who would like to trade bc I have the rosewood cs1000p. You know what you could do... put em up on CL and use the cash to get the HPSA1000 for your sub!!!! Now that would be an amp....Think about it....4x the power you have now....can you imagine...

I built my sub properly, and it pounds like hell. Even if its only a 250watt amp....or if I used a 500/1000 watt amp, at the levels I use my sub I wouldn't be using all that power. It hits deep and I mean deep bass that I didn't know existed on some movie soundtracks and music.

As for the RT's, all the P series use black drivers and the i series use blue drivers. Mine are black, and have a black finish on them. Still in pretty damn good shape too. As far as selling them though, just too lazy but if I did I'd just use that money to either save up for a better tubed preamp later in the future or just buy some nice IC's.