# Building a Monitor?

Discussion in 'Amps and Cabs [BG]' started by Hategear, Nov 12, 2001.

1. ### HategearWorkin' hard at hardly workin'.

Apr 6, 2001
Appleton, Swissconsin
Chances are, this has been discussed already, but my searches aren't turning anything up.

I have a pair of 12" speakers that I want to put into some homemade enclosures, to be used as stage monitors. Is there a formula that will tell me what dimensions I should use, to get the best sound, or doesn't it even matter since they're only monitors? It would be nice if I could build 'em so that they sit at about a 45-degree angle. Also, should they be ported and how do I wire them so they can be daisy-chained together? If one monitor is 8-ohms, and each of these is 8-ohms and I chain 'em together, isn't that a little more than a 21-ohm load*? That would be no good, eh?

*8-ohms x 8-ohms x 8-ohms, divided by 8-ohms + 8-ohms + 8-ohms = total resistance in ohms (21.3), right?

2. ### merlin

Erm i had a magazine on how to build your own monitors. Pity its gone missing. Have u tried searching the internet? I wanted to build my own cab and did some research. There's loads of sites.

There's also loads of freeware programs where u enter in the parameters of the speakers u have and it calculates the correct box dimensions for both closed and ported.

Just look around. Sorry i couldn't be any more help.

Merls

3. ### leper

Jun 21, 2001
search under amps for "cabinet building 101" or something like that...lotsto learn there.

4. ### Rockin John

Dec 20, 2000
Leicestershire, UK.

http://www.linearteam.dk/

Download the "winisd" prog from the bottom left hand side of the homepage.

Monitors, though, have angled sides. I've no knowledge as to how the "Golden Ratio" as used to determine the proportions of the usual cube-style box can be modified for angled sides. But I'm certain that a number of other guys on here do.

John

5. ### Player

Dec 27, 1999
USA Cincinnati, OH
This site helped me alot.
http://www.kbapps.com/audiodesign/calculators/index.htm
Probably want to port it and put in a crossover and horn.
For wiring. It's probably best to just put 2 jacks wired in parallel. You can run at least 2 on each side of a power amp 4 if it handles 2 ohms. (I don't know of any that don't go down to at least 4 ohms and a lot go to 2)

6. ### Rockin John

Dec 20, 2000
Leicestershire, UK.
I agree with Player. I've used the site, too, and found it really good.

John

7. ### HategearWorkin' hard at hardly workin'.

Apr 6, 2001
Appleton, Swissconsin
Player: That site looks like it needs more info than I am able to supply.

What if I took the dimensions of the box these speakers are currently in and just divide it in half? Let's say the box is 3' x 2' x 2'. Wouldn't it be "good enough" to build two boxes that are 1.5' x 2' x 2' and then port it?

8. ### embellisherHoly Ghost filled Bass PlayerSupporting Member

This isn't exactly about Amps, but the speaker gurus(Joris, Bgavin, etc) over there would be able to help you. That's why I'm moving it.

9. ### HategearWorkin' hard at hardly workin'.

Apr 6, 2001
Appleton, Swissconsin
Thanks, embellisher!

10. ### bgavin

May 3, 2001
Orangevale, CA 95662
If it is a bass monitor, the shape is of no consequence. The waveforms are far too long to cause standing wave problems inside the cabinet. Build it any shape you want.

If you want golden rectangle for appearance, that is fine also. Use the Windows calculator in scientific mode to find the cube root of the volume, and find the approximate golden dimensions as 0.618x by 1x by 1.618x, where X is the cube root.

You can run a monitor as a sealed box, as there is no real need to have full bass extension. This will give you a smaller box than a ported one, plus it will have the natural driver loading and protection inherent in a sealed box. And without measuring or calculating any port tuning.

There is a very nice sealed box calculator here:

http://xsspl.tripod.com/Audio/SealdBox.htm

11. ### Deman669

May 11, 2001
Caldwell, ID, USA

Actually, three 8 Ohm cabs in parallel equals 2.67 ohms

because others are even better at this than me, a little digging... *rummage, rummage*

CLICK

Enjoy

12. ### HategearWorkin' hard at hardly workin'.

Apr 6, 2001
Appleton, Swissconsin
You're right, Deman669. Thanks for setting me straight!

13. ### Player

Dec 27, 1999
USA Cincinnati, OH
What kind of speakers are they?
You can probably find the parameters on the web somewhere which will help with any of the design calculators. You'll get the most out of them by matching the box to the speakers.