the "ibox" custom ipod speaker system-PLEASE HELP

[oddjob7]

Hi, I am a high school engineering student, and I am starting a project to make a dockable sound system for the new ipod video. I have done some research on speaker building, and my (approximate) plan includes the following: 1 12-18" subwoofer, 2 tweeters, (maybe 2 midrange speakers), 1 2-way crossover, 1 100-200 watt amp for the subwoofer, and 1 100 watt amp for the tweeters/midrange. I am planning to build everything into 1 "box" (speakers, amps), although the subwoofer will be seperated. My system is called the "ibox", and will be approximately 3x3x3. The subwoofer will be seperated by a wall that will be halfway through the box. Behind this I will house the amps for the sub and the tweeters/midrange, along with the crossover (and possibly a cd player I have lying around) . the inputs will be connected to an ipod dock that will be mounted on the top. The "box" will be raised off the ground by three inch spikes, and I also plan on adding a neon green light to the bottom (for aesthetics), as well as a green computer fan to the area containing the amps/cd player.

Here are a few general questions I have:
1. How to wire an active crossover? I have seen many pages on the subject, but none have been helpfull or include pictures. Do they use speaker wires, or rca cables?
2. Will the vibrations from the sub ruin the system? can they be in the same "box" as the other speakers without a significant effect to the sound?
3. How many watts should the amp for the sub be? do I need to buy the 240watt amp, or will 100 watts work?

I am planning on documenting the entire process, and updating weekly with photos, so if anyone has a good location/site for me to post this information please let me know.

In addition, I will be sending emails to companies/makers of ipod sound systems and accesories to see if they have any interest in the prototype, or potential sponsorship

If anyone has spare speakers, amps, parts,
-or-
usefull tips, suggestions, critiscims (constructive)

please let me know!
email: oddjob7@gmail.com
AIM: iiiiii1984iiiiii

[mike.e]

1. How to wire an active crossover? I have seen many pages on the subject, but none have been helpfull or include pictures. Do they use speaker wires, or rca cables?

Active crossovers work at line level. Involves opamps with +/- power supplies.

2. Will the vibrations from the sub ruin the system? can they be in the same "box" as the other speakers without a significant effect to the sound

It can be in the same. I would prefer a seperate sub though,as the enclosure should be thick MDF(heavy)

3. How many watts should the amp for the sub be? do I need to buy the 240watt amp, or will 100 watts work?

Double the electrical power,3dB more SPL,which is slight,not huge.

The plate amp will have an active filter.

Feel free to join myspace or geocities to show what your building

I would suggest buying partsexpress drivers that are used in a kitset,so that its not all unknown.

A 'clari t' Class T amplifier for $30 or so,could be an idea also.

http://www.partsexpress.com

Its nice to have a business idea,but you have to consider your competition - cheap labour in 3rd world countries,and mass produced plastic units.

Youl probably have to aim for a different market than the majority.

Choosing the right subwoofer involves checking specifications, reputation ,auditioning etc

Look at the TDK tremor speakers. The cheapets one only uses a ~4" super cheap midbass speaker with flat panel top speakers

[angsuman]

Seems kind of overkill for Ipod. 12-18inch subwoofer kind of insane.
A small problem is you can't just combine the two tweeters with those subwoofers even with a midrange driver. It'd be best to go with a small two way speaker with two bass modules. Do you need the active crossover? Is that part of your engineering project. A passive crossover would be much cheaper unless you had an active one on hand. Not sure how to wire them up. I know you'll need a few amplifiers atleast. The subwoofer and speakers can be in the same "box" provided that they are seperated physically in different enclosures. 100 watts for the plate sub amp is more than enough for what your looking to build considering the SPL limitations of the main speakers.

So is this like some sort of school asignment??
good luck with that.

[joe carrow]

Whoa, that sounds like quite a project. Can we break it down?

I'll preface this by saying that I recently graduated from RPI's product design program. I'm not exactly a hotshot designer, but I've been where it sounds like you want to go after high school. I'll try to take it easy on you, but you're going to need a thick skin to be a successful designer.

I've entertained the notion of designing an iPod dock on and off for a while. It's tempting to think about, but if you really want to take a stab at this it will take a lot of work.

Originally posted by oddjob7
Hi, I am a high school engineering student, and I am starting a project to make a dockable sound system for the new ipod video.

There are a lot of dockable sound systems already on the market. If you're looking at designing a new product, you will first need to study the existing state of the art. I recommend starting a notebook, and don't be afraid to devote a page or two to each docking station you can find- start with "just the facts" before recording your additional ideas and opinions about each.

I have done some research on speaker building, and my (approximate) plan includes the following: 1 12-18" subwoofer, 2 tweeters, (maybe 2 midrange speakers), 1 2-way crossover, 1 100-200 watt amp for the subwoofer, and 1 100 watt amp for the tweeters/midrange.

Ok, back up- let's establish a few things before we pick components.

I am planning to build everything into 1 "box" (speakers, amps), although the subwoofer will be seperated. My system is called the "ibox", and will be approximately 3x3x3.

That's huge! Do you really mean 3 feet by 3 feet by 3 feet? Keep in mind that a standard internal doorway for a new construction is 32 inches. Wheelchair accessible doors are generally only 36 inches. You said that this was for the video iPod- is this meant to be a TV stand?

Back to that notebook I mentioned- you ought to outline (ok, if you disregard the notebook then at least make a mental note of) the existing products. You might go through and see that you can classify things like, "People who buy THIS one are using it as a boom-box." You might think of little improvements on the presently available products- like a good handle for that speaker set, or a shoulder strap. These don't seem important right away, but that's why you write them down in the notebook. You may come across a problem or opportunity later on in your own design that is well served by something you saw there.

Now if you really meant such a large box, it doesn't seem like you had a boom-box in mind. The problem you seem to address is that the video iPod could fit in to the home theater better.

The subwoofer will be seperated by a wall that will be halfway through the box. Behind this I will house the amps for the sub and the tweeters/midrange, along with the crossover (and possibly a cd player I have lying around) . the inputs will be connected to an ipod dock that will be mounted on the top. The "box" will be raised off the ground by three inch spikes, and I also plan on adding a neon green light to the bottom (for aesthetics), as well as a green computer fan to the area containing the amps/cd player.

Again, compare your idea to existing products and make lists of "Pros" and "cons". You will probably figure out reasons why things are done the way they are.

Here are a few general questions I have:
1. How to wire an active crossover? I have seen many pages on the subject, but none have been helpfull or include pictures. Do they use speaker wires, or rca cables?
2. Will the vibrations from the sub ruin the system? can they be in the same "box" as the other speakers without a significant effect to the sound?
3. How many watts should the amp for the sub be? do I need to buy the 240watt amp, or will 100 watts work?

1- it's signal level, small wires are fine.
2- they can; vibration isolation or cancellation would be wise
3- depends on SPL goals. Run sims in WinISD or similar to see what you get. No need to get insane SPL from the subs if the rest of the system can't keep up.

Keep searching the forum, and searching google. One of the most valuable skills you'll develop is the ability to research what's already out there so you can learn from other people's mistakes and avoid reinventing the wheel.

I am planning on documenting the entire process, and updating weekly with photos, so if anyone has a good location/site for me to post this information please let me know.

I believe that blogger.com is accepting photo uploads now.

In addition, I will be sending emails to companies/makers of ipod sound systems and accesories to see if they have any interest in the prototype, or potential sponsorship

If anyone has spare speakers, amps, parts,
-or-
usefull tips, suggestions, critiscims (constructive)

please let me know!
email: oddjob7@gmail.com
AIM: iiiiii1984iiiiii

Don't underestimate phone calls to companies asking for samples. I can't tell you how many awesome samples I've seen people get (or managed to receive) from a simple phone call explaining what's going on.

So, what are you really building this for?

[oddjob7]

thanks for the comments!

After more brainstorming/research, the deisgn will be a 2ft cube instead of 3, for size concerns. The amp I have been looking at seems to have a built in corrover, and an output for the satillite speakers, does this mean it will also power the tweeters?

here is the link for the amp

http://www.partsexpress.com/pe/pshow...=300-792&DID=7]http://www.partsexpress.com/pe/pshowdetl.cfm?&PartNumber=300-792&DID=7[/URL]
(that one or the 100 watt)

also, will this amp be compatible with this driver?
http://www.partsexpress.com/pe/showd...number=290-177

If not, can someone let me know what driver/amps I should be looking for if I want REALLY loud bass for under 150$?[URL=

[angsuman]

No that's a sub plate amp. It won't power the tweeters. By tweeters i think you mean a full range driver that will crossover to the sub. Your design sounds kind of like a "Ghetto-Blaster" for the ipod. I really doubt you should have hopes for a market. But it should be a fun project nontheless.

[edjosh23]

Madisound sells some 2.1 channel amps here

I would suggest those. The variable crossover doesn't go very high, so I would suggest some 3" full ranges. The amp is rated 50 & 25 x2. at 4 ohms. I think 50watts can be sufficient if you get some efficient subs and aren't planning on blowing up the house.

If you want to keep the efficiency up, you can run two full range, like some TB W3-871s in parallel. The sub(s) should also be efficient, you can try saw two Hi-Vi M12s in parallel as well.

By the way, I too am a high school student (in a couple months an NCSU EE student). I have just used my sound domain page to post pictures and a little documentation of my projects, or you can just use geocities page.

Josh

[mike.e]

oddjob = I sent u an email

http://www.partsexpress.com/pe/showd...number=300-952
this for the main speakers

Get a 12" pro woofer with a lower Qts,nearer 0.3 so it wont boom so bad.

If you want a two cubic ft sealed enclosure, a low fs,high xmax HT or car style woofer might be in order.

It depends if you want hard kick or proper low bass to 50hz and below.

[oddjob7]

It will not be 2 cubic feet, If you do the math, 2x2x2 equals 8 actually. Anyway my final design is a 2x2.5x2.5 "cube", with a beveled upper edge where 2-4 tweeters/ midrange will be located

I have chosen the 15" dayton woofer (low qt and 30hz), It almost looks too good for the price.
http://www.partsexpress.com/pe/showd...number=295-560

I have also chosen a 100 watt amp, but am not sure if I should get a 120 instead, because the driver is 300
http://www.partsexpress.com/pe/showd...number=300-802

My next question is picking out midrange/ tweeters. I already have an amp that will sufficiently power 4, and now I need to chose the combination of speakers (2 tweeters 2 midrange, or 4 midrange), and also the speakers themselves. can anyone tell me what their (low) hz should be? should it be 100, or more like 300? I am also trying to keep down costs, so under 15$ per speaker is ideal.

thanks!

[angsuman]

Hmm for under $15 a speaker you could try the tangband fullrange 3 in drivers. http://www.partsexpress.com/pe/showd...number=264-810
try these for the main speakers.