[muskydusty]

So I was wanting to build a portable subwoofer for my Ipod. I have small speakers for it but i wanted to do this for a little extra "oomph". I figure i could hook them both up to the Ipod with a splitter (one 3.5mm male jack into the Ipod, to two 3.5mm female jacks. With one line going to the smaller speakers and one going to the subwoofer.)


Requirements:

-Must plug into a standard wall outlet for power

-must take a 3.5mm jack INTO the sub for input of music (same size that goes into an Ipod)

Must have a volume control or "bass boost"

I would like everything to fit inside the box so that it looks cleaner, and is mroe portable.


I understand that i am going to need either an 8 or 10 inch sub, along with mabye a 200 watt car amp. Where i get confused is i dont know what components to get to convert power from a standard wall outlet to power for a car amp. Also i need a way to have a female 3.5mm jack for input that would go into the car amp. Lastly, i need all these parts to fit nicely inside the box that i would build the subwoofer for(besides the amp, which i would find a way to attach on the outside cleanly). Unless there would be a clean way to attach everything on the outside.


I think i can handle wiring the sub to the amp along with build a suitable box to house the sub. I am just confused about how to wire everything with those certain requirements. Lastly, this is just for fun, so if it cant happen, no biggie. Thanks

 

[Volenti]

While I know this is a DIY section, and you already have small speakers, I think for this application you may be better off simply buying a good set of 2.1 pc speakers.


There is a massive selection available, they natively accept 3.5mm inputs, most have volume/bass controls, and they have a price/performance ratio that is very hard to compete with even with diy, especially with you wanting a neat "box" solution.


Worth looking into at least.

 

[jkhome]

I imagine most of the parts you are looking for are at your local Radio Shack store.


Does anyone make a self-contained "boom box" with decent sub performance? That's the way I would go, one with a 120vac and 12vdc-power plug option and an auxiliary input. Plus a cable with the proper jacks at each end to feed the ipod into the box, and you are set.


Or maybe check into some of the HQ stand alone headphone amps, which can double as a pre-amp, to be fed by the Ipod, to drive the sub amp. The 120vac to 12 vdc conversion is easy (again see Radio Shack)

http://www.headphone.com/guide/by-application/ipod/

 

[JorgenMan]

It sounds like you'd be better off with a sub plate amp than a car amp. How much were you expecting to spend on this project? The 3.5mm input is no problem, you can get an adapter for that. You may have problems with input signal strength, as jkhome alluded to, if you're running both speakers and a sub from a splitter. I'd just cross that bridge when you get to it, though - it may not be a significant problem.


EDIT: Just get a plate amp with a line-level output and run that to the speakers. Then you won't have to worry about signal strength.

 

[Gir_1337]



Quote:
So I was wanting to build a portable subwoofer for my Ipod.

Anything portable doesn't classify as a subwoofer, rather just a woofer (if even that). You're probably better off just getting an off-the-shelf "subwoofer" that you can plug your ipod into.

 

[BoomieMCT]

If you just want to upgrade the speakers, check this out.


If you are looking to go low and don't mind dropping some coin, how about building something with the Mpyre 65X driver? It is only a 6.5" driver but it can still go low. Failing that, check out the (more reasonably priced) Tang Band W6-1139SG. Either can be powered with a 25 - 70 watt plate amp (well more for the Mpyre) and get enough sound for a small room or near field use. I think a plate amp would be more compact (and lighter) then a car amp and power supply.


BTW, what speakers are you matching this with? It might help bracket how much output from a sub you are looking for.

 

[BoomieMCT]

Just a thought,

This driver
This amp


Cost: apx $80


Put in a (roughly) 1 cubic foot box with a 2 inch diameter, 7.5 inch long port. This should get you 97 dB with an F3 of 28Hz (should keep up with small portable speakers). Put a handle on top and voila!


As far as hooking it up to the iPod, they have 3.5 mm to RCA cable adapters. I'm sure something can be worked out.



. . . maybe a computer setup would be easier . . .

 

[muskydusty]

Thanks for the replies guys. This project was starting to look impossible. I'm hoping to keep the project under $100. but if i could find some portable hardware that would perform awsome, I might have to spend more. Again, this is just for fun, i love to build stuff like this. I am trying to pair this sub with the Virgin Electronic Boomtube EX speakers. Also, does anyone know a way to make this so that it can be hooked up to mabye a computer or a TV for more usage?


A few more questions

- why do you recommend the Tang Band W6-1139SG? Is it a respectable sub for its size, vs others?

- Can I use a car Sub woofer with a plate amp?

- Is a six and a half inch sub really going to produce some respectable low notes? I feel like it would be better to go with an 8 inch sub. althougth that would sacrifice portability.

- what does it mean to bracket how much output from a sub you are looking for?

 

[JorgenMan]



Quote:
Originally Posted by muskydusty /forum/post/0


Also, does anyone know a way to make this so that it can be hooked up to mabye a computer or a TV for more usage?

The adapter that you use to hook up the iPod will also work for the computer. For TV, you just use a stereo RCA cable.

Quote:
Originally Posted by muskydusty /forum/post/0


- why do you recommend the Tang Band W6-1139SG? Is it a respectable sub for its size, vs others?

Yes, the Tang Band 6.5" and 8" subwoofers are popular for small subs.

Quote:
Originally Posted by muskydusty /forum/post/0


- Can I use a car Sub woofer with a plate amp?

Yes, just make sure the impedance isn't less than 4 ohms, as this is the lowest most plate amps (and surely anything you'll be interested in for this project) can handle.

Quote:
Originally Posted by muskydusty /forum/post/0


- Is a six and a half inch sub really going to produce some respectable low notes? I feel like it would be better to go with an 8 inch sub. althougth that would sacrifice portability.

Well, that will have to be up to you. You're exactly right, an 8" sub will give more output than a 6.5", but be less portable. A 15" sub would give you some very "respectable" low notes. Or four 15-inchers.

But, that wouldn't be too portable. You'll have to decide what's right for you. Try to decide about how big you want the whole thing to be - that will help people give you more specific advice.

Quote:
Originally Posted by muskydusty /forum/post/0


- what does it mean to bracket how much output from a sub you are looking for?

BoomieMCT just means that knowing what speakers you're using will tell us how much output you'll want from a sub.

 

[JorgenMan]

After looking at the TB W6-1139SG, it looks like a pretty respectable driver. I think I'd do something like soundbite did in the HTGuide "Missions Accomplished" DIY Subwoofer Showcase:

Tang Band W6-1139SG
Dayton 70W Plate Amplifier


12 liters internal volume, tuned to 36 Hz (13.75" port). soundbite's external dimensions were 10x10x14.75 inches, plus some short legs he had on the bottom. You could put a handle on the top, if you wanted. That would come out to a little over $100 after you figure in shipping and building materials, but it would be worth it, I think.

 

[BoomieMCT]



Quote:
Originally Posted by muskydusty /forum/post/0


A few more questions

- why do you recommend the Tang Band W6-1139SG? Is it a respectable sub for its size, vs others?

I picked it because it's small and has a very respectable xmax (esp. for its size). It is also very shallow so it shouldn't take up as much box volume as other drivers (since size is so important here). The price isn't too bad either. Sure, there are plenty of 8" drivers that will walk all over it in terms of performance but I felt for low power portable use it was hard to beat.

Quote:
Originally Posted by muskydusty /forum/post/0


- Can I use a car Sub woofer with a plate amp?

If you wanted to, yes. They tend to not be designed to play as low but there is nothing that says you couldn't use one if you found the right one. A pro-sound driver with suitable specs would also be good as they tend to be a bit more durable. Also, be careful as many car drivers are 2 ohm - this will fry most plate amps for HT use.

Quote:
Originally Posted by muskydusty /forum/post/0



- Is a six and a half inch sub really going to produce some respectable low notes? I feel like it would be better to go with an 8 inch sub. althougth that would sacrifice portability.

There are some small drivers that can perform impressively low for their size. The Mpyre 65x driver can supposedly produce an F3 of 19 Hz in a small vented enclosure. A larger driver will tend to require a larger enclosure which seems counter to your needs. Sure the Tang Band W6-1139SG is small, but with an xmax of 13 mm it can move a lot of air for its size!

Quote:
Originally Posted by muskydusty /forum/post/0


- what does it mean to bracket how much output from a sub you are looking for?

When I say this I'm asking you what you expect to get and what you expect to pay. If you want reference level output down to 15 Hz with no distortion for under $100 all in a 1 cubic foot box I'd tell you to pound sand - it's not possible. The setup above will get you an F3 of 28 Hz at 97 dB in a cubic foot enclosure for under $100. This should be more then enough for portable music listening however it will be a bit quiet for movies in all but the smallest rooms.

 

[muskydusty]



Quote:
Originally Posted by BoomieMCT /forum/post/0


I picked it because it's small and has a very respectable xmax (esp. for its size). It is also very shallow so it shouldn't take up as much box volume as other drivers (since size is so important here). The price isn't too bad either. Sure, there are plenty of 8" drivers that will walk all over it in terms of performance but I felt for low power portable use it was hard to beat.

Boomie, do you think that I could get the Tang Band 8" subwoofer (120 watts RMS)with the same 70 watt plate amp and still get similar volume but with lower notes vs the Tang Band 6.5" subwoofer(70 watt RMS) with the 70 watt plate amp. Or will running a larger sub on the same amount of power decrease the volume compared to having the same power to a smaller sub?

Quote:
Originally Posted by BoomieMCT /forum/post/0


When I say this I'm asking you what you expect to get and what you expect to pay. If you want reference level output down to 15 Hz with no distortion for under $100 all in a 1 cubic foot box I'd tell you to pound sand - it's not possible. The setup above will get you an F3 of 28 Hz at 97 dB in a cubic foot enclosure for under $100. This should be more then enough for portable music listening however it will be a bit quiet for movies in all but the smallest rooms.

I dont understand why the internal volume needs to be one cubic foot for that subwoofer. The website says the Vas is only 0.41 cubic feet, which to my understanding is the required internal volume.

-Were you thinking that this sub would perform best if it was ported, which would increase the internal volume?

-Could I keep this subwoofer in a sealed box and still get good performance out of it, and mabye even put poly-fil inside to further decrease the internal volume?


Thanks so much for the help, it is very much appreciated

 

[BoomieMCT]



Quote:
Originally Posted by muskydusty /forum/post/0


Boomie, do you think that I could get the Tang Band 8" subwoofer (120 watts RMS)with the same 70 watt plate amp and still get similar volume but with lower notes vs the Tang Band 6.5" subwoofer(70 watt RMS) with the 70 watt plate amp.

Sure, the Tang Band W8-740C 8" subwoofer will go just as low in about the same volume and will get a peak SPL of about 102 dB with 70 watts. So you'd be getting 5 dB mre output for a slightly larger box and more expense. The W8-740C is a great driver, I was just trying to keep this as small and cheap while still getting the job done!

Quote:
Originally Posted by muskydusty /forum/post/0


I dont understand why the internal volume needs to be one cubic foot for that subwoofer. The website says the Vas is only 0.41 cubic feet, which to my understanding is the required internal volume.

When I'm saying the size, I'm talking about the external dimentions. This includes the internal volume, the volume of the amp, the driver, the enclosure and the port. It's a rough estimate.

Quote:
Originally Posted by muskydusty /forum/post/0


-Were you thinking that this sub would perform best if it was ported, which would increase the internal volume?

Yes. Although porting will make the enclosure a little bit larger, it is more efficient then a sealed box. This allows you to use less power for the same output (in the enclosure's passband that is). I felt that for a small, cheap system that might be used outside (no room gain) ported was best.

Quote:
Originally Posted by muskydusty /forum/post/0


-Could I keep this subwoofer in a sealed box and still get good performance out of it, and mabye even put poly-fil inside to further decrease the internal volume?

Define "good peformance"? You certainly could put a driver into a sealed box and it would work and sound good. You'd be loosing about 3 dB of output compared to the same driver in a vented box but it would be teeny tiny. In a small room it would sound good. In a big room (or outdoors) with no room gain to reinforce the low end you'd be missing some extension.


To answer some of these questions in a more authoratative / complete way, check out this web page . I think it does a great job of explaining the strengths and weaknesses of the different enclosures.