Speaker Box

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Hi everyone

I recently came into the possession of two very well built speaker boxes. I know it is not recommended to start a design with the boxes but I really would like to make use of them. Their inside dimensions are H:21.5" W:12" and Depth:9". There are 3 holes in the baffle; 7.5" 3" 2.75". Any help anybody can give me would be greatly appreciated.

Thanks

Ian
 
Your biggest problem will be finding a woofer or a mid-woof that will work well in the box you have. I would rather start with a good woofer and then design an appropriate box for that woofer. This topic has come up before, try searching the forum. You might also want to search the Internet and download WinISD - its a woofer simulator that can help you match a driver to a box.
 
Ex-Moderator
Joined 2002
Hi Ian,

I know how it is when you don't have the resourses or time to make your own boxes. You tend to latch on to something good when it comes along.

You could check any number of sites on the web that can offer you kits complete with crossovers, that would fill the holes in your boxes.

Here are some of the more popular sites:

http://www.partsexpress.com/index.cfm

http://www.madisound.com/

http://www.zalytron.com/

http://www.northcreekmusic.com/index.html#LoudspeakerKits

I know Madisound will talk to you and help you to select the right components or kit to work in your boxes.

Let us know how your search goes.

Good Luck,
Rodd Yamashita
 
diyAudio Moderator Emeritus
Joined 2001
Do you have anywoodworking tools at all? I have a nice 10" spekaer that requires an 8.5 inch hole to fit in. I recommend it a lot because it has a long throw throw for deep bass, plus goes all the way up to 2,000 Hz to meet a tweeter. It also has a symmetrical magnetic system, which is nice.

Here is a simulation of this woofer in a 1.3 cubic foot box. It is the Peerless CSX 10". $63 at Parts Express. Madisound has it too. A bargain.
 

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diyAudio Moderator Emeritus
Joined 2001
Here is a graph of the unenclosed CSX 10". Forget the lower end-that will straighten out when we put it in the box. Take a look at the upper end.

Most tweeters do not like to crossover under 2,000 Hz. At the crossover point, both woofer and tweeter should be 6 dB down for a 12 dB/octave crossover.

As can be seen from the graph, the CSX 10" rolls off naturally at 2,000 Hz. All you need is a tweeter with a 12 dB/octave crossover and you should be all set.
 

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diyAudio Moderator Emeritus
Joined 2001
Kinsale:

Vented box, tuned to 27 Hz.

Do you have any woodworking tools at all? You might try a 3" PVC pipe, if it fits. You might also try a flared 2" port, but might have to enlarge the opening. The flared 2" port will give performance like the 3" straight PVC pipe, but will be shorter. We can work out the details later.

You do have the option of gluing a piece of plywood over any ports from the inside and making any new ports that are necessary, right? If you paint the plywood black once it seals the hole, it won't look bad. And hey, there is such a thing as grill cloth.

Can you give us a brief description where the holes are located on the front speaker board and the distance between the centers of the holes? Doesn't have to be exact. Just want to see if the speaker hole can be enlarged without encroaching on space that would be necessary to fit a tweeter
 
diyAudio Moderator Emeritus
Joined 2001
If worse comes to worst, you do have the option of cutting off the front board and putting on a new one with the holes cut the way you want. This would still be much easier and cheaper than building and finishing a new box. Most good woodworking stores will be glad to cut their particle board for you-even using circles-for a very very reasonable charge.

But my guess is that we can probably make the present holes work, if you have a small reciprocating saw, a little patience, and are willing to put up with a slightly home made look. Under the grill cloth, who can tell?

We might even be able to use the two smaller holes intact, without modification.
 
Kelticwizard:

Yes I do have some woodworking tools. I'm at work so I can't give you the precise locations but I don't think enlarging a hole would encroach on any others.

When I get home I'll take a picture of the box and post it for you. Are there any other drivers I could check out with my box? I downloaded winISD pro and have been playing with it. Its real easy to use. Just don;t know which drivers to try! I design IC power amplifiers for mobile phones and wlan so I'm used to simulation software thankfully. Anyway thanks again.

Ian
 
diyAudio Moderator Emeritus
Joined 2001
Oops, sorry Kinsale.

You mentioned that you would like rcommendations for other drivers for your enclosure, and I was just sitting back a day or two to allow other members to post on this.

The Peerless CSX 10" is one of my favorites, you see, and when it comes to where an 8" or 10" is called for, I tend to go for that one.

I think your box is an old one. Nothing wrong with it, and no reason you cannot use it, but I think it is an old one. Like from the seventies.

I think it was probably an acoustic suspension system in there-that means sealed, and not ported. I think it probably had a 3-way system, with a 2" or 3" midrange that came in around 800 Hz and a tweeter that came in around 4,000 Hz. That was a common arrangement back then.

We can build a 2 way using the Peerless and a tweeter. Or we can change or enlarge the holes to go to a more modern idea.

The notion of crossing over at 800 Hz, while not unknown, is not used often today. Most of the music you listen to is in the 200 Hz to 1000 Hz range. That is where most of the delicate voices and instruments are centered.

Most loudspeaker designers feel that no matter how good you make a crossover, it will still spoil that delicate area. So the thinking has switched to where you want one speaker to cover from 200 Hz, (or lower) up to at least 2,000 Hz. That way the most important, detailed octaves are carried by one speaker, unencumbered by the various phase shifts, etc. of a 3 way that crosses over at 800 Hz or so.

So a 3 way today usually consists of a bass speaker from 8" to 12", a 4" to 6" cone midrange that comes in between 100 Hz and 200 Hz, and a tweeter that comes in between 2,000 and 5,000 Hz.

Crossover components tend to get fairly expensive in the 200 Hz or lower range. They are considerably cheaper in the 800 Hz range. A crossover in the 200 Hz area might run you $50 per channel, for instance. The benefit is that the delicate voices and instruments are carried by a midrange unencumbered by the need to carry bass.

When a speaker carries low notes as well as high notes, the speaker actually synthesizes new notes that are not on the program material. This is known as intermodulation distortion. Bad news. The higher the notes, the greater the distortion. The louder the volume, the greater the distortion.

The bass reflex principle cuts down on this effect by requiring the woofer, in the lowest range, to move only one quarter as much as it would in a sealed system. Less cone movement = less intermodulation distortion. Sio if you are going to go 2-way, bass reflex, (ported) is the way to go.

Of course, you do have the option of putting in a 2 inch midrange to cross over at 800 Hz also. The crossover would be considerably cheaper, and it isn't like the sound is necessarily THAT bad. It will knock down the intermodulation distortion, for sure.

So basically, the choices are:
A) 2-way using a 10 inch bass reflex crossing over at 2,000 Hz to a tweeter
B) 3-way with woofer crossing over to 2 inch or 3 inch midrange about 800 Hz, and to a tweeter at 2,000 Hz-5,000 Hz
C)3-way with woofer crossing over to 4", 5" or 6" midrange at 200 Hz or below, and to a tweeter at 2,000 Hz to 5,000 Hz.

C) is the most expensive, B) is the middle, and A) is the cheapest.

Your thoughts?

And the thoughts of anyone else reading this thread? We are certainly open to driver suggestions-the Peerless is not the only driver made, after all.

One thing-if you are going to go bass reflex, I strongly suggest a driver with symmetric drive. That means a Faraday ring or "shorting ring", or a pole piece that cuts down on second order harmonics. For a discussion of symmetric drive please go to the following thread:
http://www.diyaudio.com/forums/showthread.php?threadid=4524


The Peerless CSX 10" has symmetric drive. I am not sure if the rest of the CSX line has it-I don't think it does. Other drivers from other makes have it on some models, and not on others.
 
Kelticwizard:

Thanks for getting back to me. I figured the boxes were old but they are so well constructed I thought it was a shame to waste them. Saying that though, do you think the box will affext the sound much? I'd rather bite the bullet and build new boxes if I'm going to sacrifice the sound.

I would go with the bass reflex approach. Can you recommend any good tweeter to go with the Peerless woofer?

Ian
 
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