Designing mid-high speakers to match SUB

**Spadez** · **10-17-09, 12:49 PM**

Hi,

Im building this sub:
http://www.geocities.com/adrian_mack/

I now need to start looking into creating my 5 additional speakers for the mid-high frequencies to give me the 5.1 setup.

At the moment I have bose cube speakers, their sound isnt fantastic but the size is perfect. How possible is it to make my own "cube" speakers that will give good sound quality / performance? Can anyone recommend a driver for such a purpose?

James

**evilskillit** · **10-17-09, 01:31 PM**

There are plenty of small designs out there you could use.

Zaph has 2 at zaphaudio.com
The Hi-Vi BS3 Single Driver System and The Budget Mini

There are a few posted on the partsexpress project showcase

There are a few posted here like the Overnight Sensations or the Orient Express
http://undefinition.googlepages.com/diy

Brando at the htguide just came up with a 5.1 channel mini cube design recently.
http://www.htguide.com/forum/showthread.php4?t=34341

and probably mini more to be found if searched for.

**Spadez** · **10-17-09, 01:57 PM**

Thank you for the links, im reading through them now. I dont think I was specific enough when I said cube speakers, I meant like the "bose" cubes which are around 4" cubed. Do these style speakers have the capability to produce good sounds or is the size needed.

**evilskillit** · **10-17-09, 06:11 PM**

Making a very small speaker that uses a 3" or 4" full range driver in a very small cube may be possible and might sound better than what you would buy but most DIY designs use slightly larger speakers because if you are going to spend the time to build something usually it is worth your while to make them slightly larger 2 ways, as they will usually sound better but not cost that much more than a very small speaker.

Things to take into consideration is when building speakers you usually have to use MDF at least 1/2" thick, where as manufacturers may use very thin plastic allowing more inner volume in a smaller enclosure. Also they can have the speakers designed to the specification of the small enclosure where as DIYers do not have that luxury and have to find a small full range speaker that does not sound horrible and can work in a very small enclosure. Usually due to the small inner cavity and the thickness of the building materials this precludes fitting in a tweeter and suitable crossover. I guess what I'm saying is there may be a design out there that would work for you and it would certainly be a good idea to ask around if you want a design that small and are worried more about size than sound quality and value you might be better of sticking with your bose system untill you have more space or more of a budget, or both.

**Spadez** · **10-18-09, 06:40 AM**

Thank you for the reply. I don't want to stick with the bose because I want surround sound with a custom sub. I can go for a bigger speaker design, but if I can help it I would prefer to keep it small. I used to have iPod speakers that used a tiny 1 inch driver and these sounded incredible, is there nothing like that out there for the diy's?

Also is it possible to use a passive radiator design with tweeters to keep it compact and keep the sound?
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**evilskillit** · **10-18-09, 01:55 PM**

These might be your best bet.
http://zaphaudio.com/audio-speaker18.html

Also check out these.
http://rjbaudio.com/Bandit/bandit.html

Check out these little cubes
http://www.hometheatershack.com/foru...-speakers.html

Look at these little fostex cubes
http://diyaudioprojects.blogspot.com...-speakers.html

They should both be incredible small full range speakers. I know you're looking for something more cube like in nature, you could make them deeper but less tall. It might be possible to make them a little wider too but you would have to ask the designers as changing width is normally a big no no as it can throw off frequency response quite a bit.

Part of the reasons the boxes on these are larger than your bose cubes is because they're designed to actually be able to play low enough to properly mesh with your subs, smaller boxes would roll off the low end much more quickly and if the speakers drop off too much before 100hz there will be a funky area between them and the bass of the sub that causes them to sound like small speakers + a sub, instead of just one really big nice speaker.

Trying to make a really small 2 way cube probably won't be doable, look for very small designs that use a full range driver and see if you can find one that fits your bill as far as being small enough and cubelike enough.

**Spadez** · **10-18-09, 02:36 PM**

Hi Evilskillit,

Has nobody tried a passive radiator Mid-High range speaker? Would that not give the bass required to mix into the sub and keep the size down?

Those cubes are still large than I was hoping for. Im going to have to look into how I can get around this? Perhaps two small tweeters for left and right with a larger mid for the center? (Im thinking about how I can place this setup for my desk, rather than a whole living room).

**evilskillit** · **10-18-09, 03:31 PM**

Peerless does offer tiny little 3.5" passive radiators. I guess I could model the box for either of the designs I posted and see if they could be made smaller using a passive radiator tho to fit a 4" driver and a 3.5" PR into a cube it would have to be at least 5x5x5 outside to accomodate the driver, the pr, the terminal cups, the thickness of the lumber and maybe some crossover components. I'm not sure how small of a driver you really have in mind. Maybe if you could post a picture of your current bose setup it might give someone an idea and another sugguestion could be made but at this point I'm about out of ideas.

**Spadez** · **10-18-09, 04:36 PM**

Ill post a picture of my setup tomorrow as I am currently away from my desk. I like the idea of a 3.5" driver and twin 4" radiators for the small left and right front drivers. Ideally I'd like them as small as they will go whilst keeping good SQ. My Bose cubes are two 5" cubes stacked on top of each other.

I read about a problem with passive radiators where the radiators are out of phase with the driver, and this can be audiable at high pitches. Do you think this would be a problem with this kind of setup?

If you would be kind enough to model it I would appreciate it, otherwise I'll have a crack at learning the program at work tomorrow.
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**evilskillit** · **10-18-09, 05:58 PM**

After doing a bit of modeling none of these very small designs seem to lend themselves well to passive radiators, there is almost no advantage because no passive radiators are tuned high enough to actually help increase the volume in a range that matters for these small speakers. eg 70-80hz.

I figured a cube with an inside dimension of 5x5x5 would give you 125 cubic inches of internal space. a 4x4x4 cube would give you about 64 cubic inches. Anything less than 125-130 makes all the small speakers I modeled have a hump in the response between 100 and 250hz so the sound in that range would be over emphasized, everything higher or lower than that would sound thin. The frequency drops off very quickly below 100-150hz which would require that you run your subs high enough as to sound directional and no longer blend seamlessly.

A 5x5x5 cube built out of 1/2" mdf would be almost 6x6x6, and a 4x4x4 cube made out of 1/2" mdf would be almost 5x5x5 so these are all a bit larger than what you are wanting. You could build something this size or smaller, it would probably sound at least a bit better than what you have right now. But maybe not that much better, and will cost your time and money so its up to you to decide if you want to take a stab at it or not. The other thing to do is ask around on the other DIY audio forums like diyaudio forums, http://diyaudioprojects.com/Forum/, htguide diy forums and others and see if anybody else has any ideas. I'm pretty much out

**Yad** · **10-19-09, 01:33 AM**

Quote:

Spadez wrote:

I now need to start looking into creating my 5 additional speakers for the mid-high frequencies to give me the 5.1 setup.

James

I think, the ScanSpeak 18W8546 + SS R29 or Vifa XT25 will be good. But? unfortunately those tweeters are too narrow ...

**Yad** · **10-19-09, 01:36 AM**

James, why did you choose so heavy driver with not big Bl to Mms ratio?

**Spadez** · **10-19-09, 04:49 AM**

Quote:

James, why did you choose so heavy driver with not big Bl to Mms ratio?

Im not really sure what this means! If your refering to the subwoofer project, I am replicating another persons passive rad sub project which seems to give very good results. Ive already brought the subwoofers so its too late to change

Quote:

I think, the ScanSpeak 18W8546 + SS R29 or Vifa XT25 will be good. But? unfortunately those tweeters are too narrow ...

The scanspeak speakers look very cool, what do you mean about the tweeters being too narrow? If you mean narrow in size, In which case, why is that a problem?

Quote:

After doing a bit of modeling none of these very small designs seem to lend themselves well to passive radiators, there is almost no advantage because no passive radiators are tuned high enough to actually help increase the volume in a range that matters for these small speakers. eg 70-80hz.

I figured a cube with an inside dimension of 5x5x5 would give you 125 cubic inches of internal space. a 4x4x4 cube would give you about 64 cubic inches. Anything less than 125-130 makes all the small speakers I modeled have a hump in the response between 100 and 250hz so the sound in that range would be over emphasized, everything higher or lower than that would sound thin. The frequency drops off very quickly below 100-150hz which would require that you run your subs high enough as to sound directional and no longer blend seamlessly.

A 5x5x5 cube built out of 1/2" mdf would be almost 6x6x6, and a 4x4x4 cube made out of 1/2" mdf would be almost 5x5x5 so these are all a bit larger than what you are wanting. You could build something this size or smaller, it would probably sound at least a bit better than what you have right now. But maybe not that much better, and will cost your time and money so its up to you to decide if you want to take a stab at it or not. The other thing to do is ask around on the other DIY audio forums like diyaudio forums, http://diyaudioprojects.com/Forum/, htguide diy forums and others and see if anybody else has any ideas. I'm pretty much out

Ive looked into my bose speakers a little more. My estimate was a bit off, the interal volume of the bose mini cubes is just 27 Cubic inches. To my mind, these actually do sound very good but I do understand what you are saying about the gap between the high frequencies and the low, there isnt really any mid. I dont want to use the bose cubes anymore because I only have two and I want a 5.1 setup. It will end up costing a lot for the cubes.

In the interest of good sound quality im going to make the cubes a little bigger but im going to try and find a comprimise. Im going to set my target for 80 cubic inches. Ill do this by enlarging the size and also using a different material like plywood (or even hardwood) rather than MDF to keep the thinckness down and ensure it is strong. It shouldnt resonate but if it does at these frequencies Ill play around with the weight to fix the problem. Im going to try and search the forum for a speaker which is optimised for this size box, or at least is designed to come with a smaller enclosure better.

I would also like to pitch this idea to you. What would it sound like if I went for this setup:

1x Sub
1x Small cube for front left [~80 CI]
1x Small cube for front right [~80 CI]
1x Larger box for front mid [~140 CI]
1x Larger box for back left [~125 CI]
1x Larger box for back right [~125 CI]

This way im still getting plenty of mid, but the sound from the front left and right will be slightly biased to the higher frequencies, but it will allow me to keep the space on my desk. Feel free to shoot this idea down if it is bad, it is just a possible solution.

**Yad** · **10-19-09, 10:39 AM**

Quote:

Spadez wrote:

The scanspeak speakers look very cool, what do you mean about the tweeters being too narrow? If you mean narrow in size, In which case, why is that a problem?

I mean, they radiates too narrow directed soundfield. (sorry for my english)

**Spadez** · **10-19-09, 10:40 AM**

Ah, I understand now.

EDIT: B&O have produced the speakers below. These are tiny and are said to have very good frequency responce and sound quality. How do they do it!?

http://www.audiojunkies.com/blog/506...und-small-size

**Yad** · **10-19-09, 11:08 AM**

I was compared R29 & XT25 with other SS tweeters/ (9500 9700) some Seas exel tweeters... So, it seems to me that R29 & XT25 have less colouration & have good reaction. 6600 could also be a good choice. Morel MDT 33 - are good, but sounds similar with SS 9700

**Yad** · **10-19-09, 11:13 AM**

to my ear, most dome tweeters sounds like to each other. My choice - ring radiators & True ribbons. They have the best BLM/Mms ratio. & light membranes with small number & level of their own resonances

**Yad** · **10-19-09, 04:04 PM**

Quote:

Spadez wrote:

Ah, I understand now.

EDIT: B&O have produced the speakers below. These are tiny and are said to have very good frequency responce and sound quality. How do they do it!?

http://www.audiojunkies.com/blog/506...und-small-size

Well... Such acoustic lens is good idea for making sound field wider. But, notice, that it increases demands for your listening room.

The second thing - (IMHO)- that it's not necessary to use R29 for lens application. XT25 will be better idea. (it's much cheap & Lens will make it's own parameters)

**Spadez** · **10-19-09, 04:34 PM**

Hi, thank you for tehe reply. Its benefit not only getting a wide sound field, but also a small container.

It is the small container I am most interested in. It looks like the XT25 is very nice, but it needs around 125 Cubic inches (i think?), but the B&O seems to need a lot less space.

This is what I want to achieve, as long as I can keep performance high.

**Yad** · **10-19-09, 05:20 PM**

do you have a special idea to place it in your room design? or any demands to dimentions ? You can tell me. I'll think about it more specific.

**Yad** · **10-19-09, 05:34 PM**

I have B&O catalog here. Let me see... aha BEOLAB 3 model dimentions: 16.2 x 13.5 x 22.3 centimeters. For example, XT25 diameter is 10.5 cm.

**Spadez** · **10-20-09, 04:23 AM**

Unfortunatly my design is very constricted. My left and right channel speakers have to sit upon my desk, so the bigger my speakers are, the less space I will have on my desk and the less space there will be between me and the speaker.

Im suprised at how large the BEOLab3 is actually. In an ideal world I would like to have the left and right side speakers at around: 80 cubic inches. This could be in a formation of about 4.5x4.5x4.5 inch outer diamter. If I can get it any smaller and still have it sounding good then fantastic!

What cubic inch does the XT25 recommend?

EDIT: Also I can stuff the internal to help compensate for the small cubic inch size.

**Yad** · **10-20-09, 07:01 AM**

Well, there is another choice. You may use coaxial 2 way drivers. It will be better at the small listening distance, that 2 separate drivers.

It will sound not such detail and reference, like XT25+SS18W, but be sure - they ll give you perfect localization and phase response like "real point source".

Look at this link: here is 5" coaxial http://www.madisound.com/catalog/pro...oducts_id=8494

here is data sheet with filter & possible construction

You also could make a smaller box for it (!):
http://www.madisound.com/catalog/PDF...pl%20notes.pdf

but this is good idea to. http://zaphaudio.com/audio-speaker18.html (i've seen this link above). But my audiophile's nature tells me about 2 problems: 1) Doppler distortion at hi-frequencies; and 2) this driver will not give a crystal-clear hi frequencies. (too heavy diffusor for HF)

**Spadez** · **10-20-09, 07:06 AM**

Thank you for the link. Ive looked into it, but the recommended size of this box is 5Liters (305.050 Cubic Inches). This is huge compared with what im trying to do. Im trying to keep it small!

**Yad** · **10-20-09, 07:22 AM**

I know... (but i did not know, how deep is a rabbit's hole

)

well try this one: http://www.madisound.com/manufacture.../fullrange.php

http://www.madisound.com/catalog/pro...oducts_id=8585

it may operate with 1...1.5 liters of net. volume (closed box) with hard damping inside (wool or fiber-glass) .

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