SUPPORT FORUMS FOR DECWARE SPEAKER PLANS >> PRO 12 loudspeaker support forum >> Starting to build Pro 12M

Message started by Wakanda on 06/02/09 at 02:35:22

Title: Starting to build Pro 12M
Post by Wakanda on 06/02/09 at 02:35:22

The drivers have arrived from Parts Express and I am picking up the particle board from the store tomorrow.  I have built home audio speakers before, but this will be my first Pro Audio Cabinet. I am excited and a little scared.

Where should I look for some good advice on marking, cutting, gluing and clamping?  I try not to assume that I know the best way to do something.


Title: Re: Starting to build Pro 12M
Post by asiquis on 06/02/09 at 03:58:26

Greetings Wakanda,

I have had the idea to build these too. I was a little concerned about the qulaity of the drivers from PE, they seem to have some bad press on their reviews.
Do they look well made to you?

I was thinking of using 3/4" Russian Birch plywood for my cabinets.


Title: Re: Starting to build Pro 12M
Post by dank on 06/03/09 at 13:15:44

I have built 6 of these for a DJ friend who thinks they are the greatest.  We have never used the Goldwood GW-12120 speaker.  We've used a pair of the Cheeplights look alike (p/n 411-WF12120 at ) and also the Pioneer musical instrument speaker from Parts Express:
We have never used the recommended crossover either, running the woofer full range and using a cap and a coil for the horn to cross it over at 2200 hz (6.8uf, .87mh).

I would not recommend anything but 3/4 plywood for the construction unless you don't ever plan on moving them.  They are quite heavy by the time you get done (especially with the pro woofer in them).

Also, they are very lacking in bass.  With the Fs of the Goldwood at 68 hz, you basically don't have bass.  This is not a bad "feature" though when you add subs.  Just don't expect them to be very impressive before you add a sub.

I wound up running the tuning board in through the bottom, so the tuning board slot would not be visible.  After adjusting the tuning board to sound best, I measured the opening and then drilled a couple holes in the tuning board to get the same square inches of openning.  Then the tunning board was installed permanently, all the way in.


Title: Re: Starting to build Pro 12M
Post by asiquis on 06/04/09 at 02:17:21

With the other drivers you mentioned  and the tuning board is there more bass?
I am looking to build a pair for my adult son and daughter in law that have a 3 acre piece of property with a small gravel pit and a small cabin in the gravel pit area. They like having people over and listen to mostly 70's and 80's rock and pop music (outside).
Might another speaker be better suited? I do not want to get into a sub, but would like some "hit in the stomach" bass.

Suggestions? Looking at a pro amp too (suggestions)Thanks

Title: Re: Starting to build Pro 12M
Post by dank on 06/05/09 at 12:12:11


The 12" drivers and the crossovers I've used have been cost motivated.  I had the Pioneers lying around from another project.  All 12" drivers I have tried in these cabinets have produced very low bass output.  If cost is a concern, you can probably save enough by using the Pioneer 12's and a coil/cap to buy a plate amp, I like this one a lot :

and a couple 10's for a WO32.  That would be my recommendation.  I don't think you will be happy with the Pro12's without a sub, especially outside.


Title: Re: Starting to build Pro 12M
Post by Wakanda on 06/05/09 at 12:52:03


I am using 3/4" MDF and the parts listed in the Pro 12M plans.  I don't expect much low base untill I add a sub.  In the description Steve says:

Notice that the peak at 80 Hz is 6dB giving the speaker warmth and great low end punch. The 60Hz figure is -4dB which will actually be referenced against the peak. This gives a total reduction of apparent 60 cycle hum from amplifiers of 10dB or half as much hum as most other speakers.  A neat trick resulting from this woofer and cabinet combination.

To add low end punch Dan's suggestion for a WO32 or perhaps a WO36 seems like a reasonable solution.

The build quality of the Goldwoods seems very good.  I expect to get years of service - but I don't abuse equipment.  The new horn driver, the Selenium D220Ti-8 seems to be excellent - I expect it to perform well also.

Still looking for general gluing and assembly tips and instructions.

Title: Re: Starting to build Pro 12M
Post by asiquis on 06/10/09 at 02:58:02

Not to harp on this but: is the cabinet "tuned" to a certain frequency like a ported box- that is I mean without using the tuning board the cabinet is tuned to 65 hz.

Steve mentions to use 1.1 cu ft as box size when doing calculations.
If I wanted to get down to 40 hz would that be possible with this cabinet if I were to use a different woofer and would that then throw off the crossover?
Do I need to use the tuning board with any other woofer used in this cabinet?

My hope is to get a little fuller range out of the cabinet. Right now we are using some old 2 way KLH bookshelf speakers with an 8" woofer /1" dsoft dome tweeter and an efficiency of 88dB with a 100 watt yamaha integrated amp.

We dont want to blow the neighbours away, just a little more uuumph.

Only partly confused and still learning.  [smiley=10.gif]


Title: Re: Starting to build Pro 12M
Post by dank on 06/11/09 at 16:11:55

You would need to find a woofer that has a low Vas (1.1 cu ft is ideal, up to 2-3 might be ok), a moderate Fs (40 hz or less I would think), high enough efficiency to be useable without going over the woofers power rating, and still have a useable frequency range up to at least 2000 hz.

You will find that low Vas, moderate Fs, and reasonably efficient 12" speakers tend to be subs with a frequency range of Fs - 500 hz or so.  This will not work in this design unless you add a 3rd speaker/horn to pick up the midrange (500-2000/3000 hz).

If you can find such a speaker you would then need to do some power calculations based on efficiency and power capacity to be sure it will play as loud as you want with the amount of power you intend to use.  Then a little modeling with WinISD (or I prefer ProBox) to be sure it will play low enough, and then your good to go.  If you can find the speaker and let us know what the Vas, Fs, SPL, and frequency range are we can help with the rest.


Title: Re: Starting to build Pro 12M
Post by asiquis on 06/14/09 at 22:41:28

Thanks for the offer!

How about this driver:

Selenium 12WS600 12" 600W Woofer

I tried it winISD alpha in a 37 liter box ( I think this is the volume Steve mentioned to use for calculating) tuned to 35Hz and got a +4dB hump in the mid 70's and it -3dB is about 46Hz.

Could I use this and the crossover that Steve suggests along with the Selenium 210ti suggested and the tuning board?  Or....?


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