Possible for DIY sub design (2 Viewers)

[Rob Ritch]

I have been thinking about making an attempt at a DIY sub. I have a complete woodworking shop already so the wood tools and skills are not a problem. The problem that I have is if I spend any more money on my HT the wife is going to kill me (~about $4500.00) in the past 6 months. I currently have a Kenwood SW32HT Subwoofer that is OK, but not great. I also have 2 10" MTX Blue Thunder subs from a previous auto sub. I have been wondering if it would be possible to use the plate amp from the Kenwood (100 watt) and one or both of the MTX subs to make a decent sub for my HT.

What do you guys think of this idea? Also where is a good source to design the cabinet? I have never done any speaker design so I am a total newbie to this. I have seen alot about the sonosubs, but that will not pass the WAF. I would need to cabinet to be reasonably sized.

Any help with this would be appreciated. If this is a real bad idea please let me know so I don't go careening down the wrong road with this.

 

[Tim Morton]

I think you should step back and chill out a little, wait till you can get wife approval for a real subwoofer. You piss her off now just to switch drivers and you will NEVER get that SVS you want.

 

[Rob Ritch]

Tim,

Which piece of the puzzle does not fit. Is it the MTX subs, or the kenwood plate amp?

 

[Rick Guynn]

Both. I have no idea what the specs are on those MTX subs, but very few drivers specially designed for auto use make good home drivers. More often than not the Fs is way too high among other things.

As to the amp, many OEM subs like that one have some sort of equalization curve built into them. Without knowing what that curve is, (or wheteher it actually has one) you're working blind.

I would wait until you can get something decent to replace your current sub. Keep an eye out for specials over at Parts Express, or try to snag a used Tempest or two. Once the Tumults are flowing freely, you will probably see several used Tempests available.

RG

 

[Aaron_Smith]

I say give it a shot. Get the driver specs, download Win ISD, get yourself $15 worth of MDF and go crazy. If nothing else you'll learn a lot in the process, and you just may end up with something that sounds better than the one you've got now. Car subs may not be perfect for home use, but I'm guessing they're a hell of a lot better than the cheesy drivers in your Kenwood sub.
Anyone can build a great speaker with top-of-the-line drivers and amps... but I think it's as much fun to make less-than-optimal stuff sound pretty good with a little time and effort. There's virtually a religious cult built around $8 full-range radio shack drivers.

 

[Tim Morton]

MTX Blue Thunder subs are not audiophile grade subs, if memory serves they are pretty standard 99 dollar sub with stamped basket and paper or composite cone...so while it might be a little better than the boxed driver...it won't be by much. Plus if i remember right from my old CA days..MTX= BOOOOOOOOOOMY Bass.

 

[Bryan Michael]

they are not that bad they have a rubber suround and are not that boomey but i have mine in a .88 cube box in my trunk and aplying 1000 wats rms to it i can blow it in 2 oni if i wish.

 

[Aaron_Smith]

Stamped basket and paper cone... that sounds a lot like the shivas and tempests that everybody raves about. Don't get me wrong- I have a tempest and it's a wonderful sub, and I wouldn't expect the MTX to be in the same league; it's just hard to judge a speaker's quality based on appearance. If nothing else, you'll have greater displacement with two 10" speakers, and I'm guessing that the voice coil length is probably greater too.
I once had a 10" sub in my car, I think it was an MTX. I remember it sounding pretty good in that environment. If you build it and it sounds like crap... oh well. All it cost you is the materials for the box, and you learned a little bit in the process. You can always pop the plate amp back into the kenwood and go back to what you started with.

 

[Rob Ritch]

You can always pop the plate amp back into the kenwood and go back to what you started with.

That is kind of what I was thinking. I have all of the tools so it would only cost me about $20.00 for the materials. Who knows it might be fun to try, and like you said I could always re-install the plate amp in the kenwood if it is a failure.

Now can anyone suggest a good source for information on how to design a sub enclosure?

 

[Aaron_Smith]

Download WinISD (it's free), and follow the instructions and tutorials. It's pretty well explained. For a better explanation of theil-small parameters, etc. you can go to the LDSG page (snippets.org, do a google search for it). Good luck!

 

[Jeremy Stockwell]

Rob,

I'm not advising you to build a box with the MTX subs and the Kenwood amp as I don't believe that you'll be happy with the results . . .

BUT . . .

IF YOU DO - try to build your box with some contingency plans in mind. Like, don't mount the amp on the box you plan to build. Make the sub passive and wire it to the outboard amp and see what kind of performance you get. If you're happy, build a separateplate amp box for the Kenwood amp.

Also, build your box so that if it doesn't work out with the MTX subs, you can make an easy substitution with a driver that you'll be happier with cough-shiva-cough. That way, you're work on the box won't be wasted no matter how the performance is with the MTX drivers and the Kenwood amp.

JKS

 

[Rob Ritch]

Jeremy,

Thanks for the input. It was your web site that really got me thinking about a DIY sub. Plus this is a good way to combine my two hobbies. I like the idea of making the enclosure so that I can use a different driver, and by using the plate anp box. I will give that serious consideration, that way if that amp does not work out, I can change it fairly easily. What do you think about attaching the plate amp box to the sub enclosure?

I am still stumped about the enclosure design. I have downloaded WinISD and it looks like it will give you the response and the needed port size for a given enclosuer size, but how do you determine the size in the first place. I know this is probably alot to put in a post, but some sources for this information would be interested.

If you are interested here is a link to my woodworking site. It has not been updated in a while so some of my latest projects are not there, but it gives an idea of my shop and woodworking capabilities.

 

[Jeremy Stockwell]

Rob,

My link was to Patrick Sun's website. I'm working on getting my website up, but I don't have one as yet. Though Patrick's site also inspired me into DIY quite a bit. My DIY Tempest sub is a clone of Pat's Sunosub II.

Attaching the Plate amp box to the sub shouldn't be a problem as long as you take vibration damping into consideration. Setting the box on top of the sub, loose without damping, would probably cause unwanted noise from vibrations. Hanging it off the back or side could cause the same problem, just find a buffer between the sub and the amp.

Adire Audio makes their reference designs available for each of their drivers (with build specs. and everything!). Check these out and see if that helps. Other driver manufacturers (Stryke, etc.) may make these available as well, but I'm not sure. I believe there is some link between ideal enclosure size and the driver's Vas (one of a driver's T/S Parameters - make sure you have these for any driver that you consider.)

Good Luck!

JKS