DIY cube speakers

[alexwakelin]

Some of you may have been reading the threads regarding my DIY kappa 12.1. Having finished that project, and considering it was my first one, I think I would call it a success. I have decided I want to tackle another project. I want to build some speakers for my computer. I don't think I am ready for a project with a crossover just yet. I have been looking at full range drivers to keep these speakers simple. These tang band drivers model quite well and look like a good choice with a sub crossed over at 100-150 Hz. I'll eventually build a sub to go with them, but for now I'll be using the sub from my old logitech system. I'm thinking of putting these in roughly a 6" ported cube. It looks like I can build a pair for under $60.

http://www.parts-express.com/pe/showdetl.cfm?Partnumber=264-811

I have a few questions regarding this project:

For $60/pair, is this project worth building?
Can I use 1/2" mdf, or should I stick with 3/4"?
Does a cabinet of this size need to be braced?
Power handling says 15 watts, I'll be hooking these up to a 2x20 watt amp so I should be good there.

Who knows, if these sound good maybe I can put bose out of business I'd eventually like to build a complete matched 5.1 system, I just need to start small and work my way towards it. If these turn out decent I might try building some two way bookshelf speakers next.

 

[TLS Guy]

Some of you may have been reading the threads regarding my DIY kappa 12.1. Having finished that project, and considering it was my first one, I think I would call it a success. I have decided I want to tackle another project. I want to build some speakers for my computer. I don't think I am ready for a project with a crossover just yet. I have been looking at full range drivers to keep these speakers simple. These tang band drivers model quite well and look like a good choice with a sub crossed over at 100-150 Hz. I'll eventually build a sub to go with them, but for now I'll be using the sub from my old logitech system. I'm thinking of putting these in roughly a 6" ported cube. It looks like I can build a pair for under $60.

http://www.parts-express.com/pe/showdetl.cfm?Partnumber=264-811

I have a few questions regarding this project:

For $60/pair, is this project worth building?
Can I use 1/2" mdf, or should I stick with 3/4"?
Does a cabinet of this size need to be braced?
Power handling says 15 watts, I'll be hooking these up to a 2x20 watt amp so I should be good there.

Who knows, if these sound good maybe I can put bose out of business I'd eventually like to build a complete matched 5.1 system, I just need to start small and work my way towards it. If these turn out decent I might try building some two way bookshelf speakers next.

Whether it is any good or not will be hard to say. Full rangers always catch my interest, and I have pondered that driver before. The problem with that driver is that it is 3" and xmax is only around 1mm. The spec sheet says the power handling is 10 watt. I doubt it would handle quite that. The Fs is 100 Hz, so the F3 will be above that, so it is hardly a full ranger.

On the plus side it seems the cone is small enough that the first break up mode is around 12 kHz, where there is a 10 db peak which should probably be notched.

It is a high Qts driver, which means it will have a loose suspension. Did you model the speaker yet with a ported alignment? In a ported enclosure with those numbers, I would be worried about the unit self destructing. I have not modeled it, but it looks as if that speaker is designed for a small sealed box, so that air pressure prevents the voice coil from flying out of the gap. After all in a ported box that driver will offload from the box above a 100 Hz, and then there will be nothing to restrain the cone.

I would use 3/4 inch material, I don't think you need to brace it. It is best to not make loudspeakers cubed, as the panel reflections all combine to reinforce at one frequency.

Anyhow let us know what you decide, and we will follow with interest.

I will be happy to check your modeling if you want.

 

[alexwakelin]

Hmm, I've been playing around with winisd. I'm having a hard time finding an enclosure that does not exceed the cone excursion of this driver. Response curves look good with 0.1 ft^3 ported and .06 ft^3 sealed, but this driver looks like it needs to be crossed over at around 300 Hz. TB makes some full range 4 inch drivers, I'll see if I have more luck with those.

 

[TLS Guy]

Hmm, I've been playing around with winisd. I'm having a hard time finding an enclosure that does not exceed the cone excursion of this driver. Response curves look good with 0.1 ft^3 ported and .06 ft^3 sealed, but this driver looks like it needs to be crossed over at around 300 Hz. TB makes some full range 4 inch drivers, I'll see if I have more luck with those.

Welcome to the world of no free lunches.

I think you are getting the contagion pretty badly. I'm going to just make comments, constructive I hope, as you continue to doodle. Please keep posting.

Don't worry about exceeding xmax, drivers of this size will. The trick is to know when things may turn out badly and end in damaged drivers. The programs will not tell you that.

The real issue is that, as I was hinting, that driver is not a full ranger. A lot of that outfits claims are specious, and I think a lot of their data likely guilds the lily.

There really are few good full rangers, and I don't think one could be built on the cheap. Good full rangers available and in history are rare commodities.

In my view this was the best of them all, and I use them still to keep me honest.

 

[alexwakelin]

The 4" driver looks much more promising, but is a tad more expensive.

http://www.parts-express.com/pe/showdetl.cfm?Partnumber=264-820&vReviewShow=1&vReviewRand=2295580

This is approaching the cost of the "recession buster" kit, which looks like it would give better results for the same price, but in a much bigger cabinet size. Hmm, I wanted to build something small

It looks like I can fit the 4" in a similar size cabinet as the 3", but the port would have to be folded (winisd recommends a ported cabinet). -3db is at 97 Hz. One pe reviewer mentioned a notch filter, what it this and how do I make one?

 

[jboogie]

Hey alex... I too am getting very hooked on this "hobby". My first build was the Mark III MTM design, and my second was the simple Infinity sub. The former has two crossovers. These are really no big deal. Get a $12 soldering gun from Radio Shack, some solder for $5, and have at it. Don't let the crossovers intimidate you from making a great sounding speaker.

Just my two cents.

 

[TLS Guy]

The 4" driver looks much more promising, but is a tad more expensive.

http://www.parts-express.com/pe/showdetl.cfm?Partnumber=264-820&vReviewShow=1&vReviewRand=2295580

This is approaching the cost of the "recession buster" kit, which looks like it would give better results for the same price, but in a much bigger cabinet size. Hmm, I wanted to build something small

It looks like I can fit the 4" in a similar size cabinet as the 3", but the port would have to be folded (winisd recommends a ported cabinet). -3db is at 97 Hz. One pe reviewer mentioned a notch filter, what it this and how do I make one?

This is the spec sheet of this driver, and it is more promising. The driver piston area has to be in error. That number is impossible for a 4" driver, so I took the diameter to be 100mm which gives it a piston area of 78.54 sq. cm.

I have played with it and can get an F3 of 81.5hz with a 0.3 cu.ft box tuned by a port 2' in diameter, 4.5" long flared at both ends. Vent velocity is 16 m/sec. The driver off loads at around 60 Hz, so you would want to cross to a sub between 100 and 120 Hz.

Yes there is a break up mode at 6.5 kHz. You could notch this out with a parallel notch filter. These are the values: -

C = 5 µF
L = 0.12 mH
R = 2.5 ohms

You would parallel those components and put the network in series with the voice coil of the driver.

Now to make a good small enclosure, you need a relatively heavy cone, with a very compliant suspension in a sealed enclosure. These drivers are outside what seems to be your budget, but very suitable drivers are available from Morel.

As you say the cost of this project is getting close to the recession buster. The drivers, especially the woofer is an outstanding value. If you made the two way in the 0.43 cu. ft. enclosure, as you say you are close to the cost of this system. Really the cabinet is not much bigger, about 30%. You get an F3 20 Hz lower, and much greater power handling. I have experience of the drivers, so I know you will get a good result.

In the unlikely event you make a mistake with the crossovers, you can ship them to me and I will sort it out and test them. I agree that you do not need to be intimidated building crossovers. The headache is designing them, and it really is, and it takes a lot of experience to do it with confidence.

Now you have the pain of choice.

 

[alexwakelin]

This is the kit I was referring to:

http://www.madisound.com/catalog/product_info.php?products_id=8525

It looks like the crossovers come assembled. I'm tempted to order a pair, but I did want something a bit smaller for my computer desk. The tang band 4" driver modeled well in a .1 ft^3 box, the madisound kit will need something at least .25 ft^3. Are there any proven diy designs for a compact speaker out there?

 

[Swerd]

Here is a full range DIY design using another Tang Band 4" driver. Costs a bit more. It includes the design for a board with baffle step compensation to improve the bass and a notch filter to tame a resonance peak at about 6-7 kHz. Read the link for a more detailed explanation.

 

[TLS Guy]

This is the kit I was referring to:

http://www.madisound.com/catalog/product_info.php?products_id=8525

It looks like the crossovers come assembled. I'm tempted to order a pair, but I did want something a bit smaller for my computer desk. The tang band 4" driver modeled well in a .1 ft^3 box, the madisound kit will need something at least .25 ft^3. Are there any proven diy designs for a compact speaker out there?

That set from Madisound is a very good deal. That is a big price reduction. The Bandit looks very interesting.

 

[alexwakelin]

The bandit does look interesting, but the madisound kit looks to be the best bargain available right now. What commercially available speakers is it comparable to?

 

[TLS Guy]

The bandit does look interesting, but the madisound kit looks to be the best bargain available right now. What commercially available speakers is it comparable to?

That's hard to say. I have used that woofer before, and used a very similar crossover circuit, the tweeter was Vifa but a different one. I think you will find those speakers better than the majority of bookshelves around. Remember if we were not in a cluster f*** to the poor house, the parts would cost a lot more, and yet still be very good value.

 

[alexwakelin]

The Madisound kit has been ordered. Actually, my gf ordered them for me I love having a sugar momma that buys me AV gear

 

[lsiberian]

I think I may jump on that deal too. That's an amazing deal. I may get a pair of them. Then I could use one of them as a center.

Very tempting.

 

[lsiberian]

I think I may jump on that deal too. That's an amazing deal. I may get a pair of them. Then I could use one of them as a center.

Very tempting.

Jumped on it. This is gonna be a lot of fun. I know that much. Can't wait to start building. Now I just need some jigs.