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-   -   open baffle project (http://www.diyaudio.com/forums/full-range/100170-open-baffle-project.html)

mastarecoil 16th April 2007 07:03 PM

open baffle project
 
Hi all,

I am looking to do my first DIY speaker. Done subs, but want to try a nice pair of speakers now to use in 2 channel for mostly music, maybe 12-18" tall, so its easy to sit on desk at work.

I have access to a CNC mill, which means I can whip up some pretty cool stuff easily, so I am thinking of doing an open baffle design, so I can cut something out of sheet metal easily.

I would like to do it all with some speakers from partsexpress, madisound, or similar, and not be too expensive.

Does anyone know any existing projects for open baffle speakers?

I would also consider mixing open baffle with a closed section, since I know open baffle you sacrafice a lot of low end. Maybe put one of those 5" or 6.5" tang bands in it. I am not really sure how to design a speaker, so any help anyone has would be greatly appreciated!

Thanks.

mastarecoil 16th April 2007 09:17 PM

Would any of these be a good place to start:

http://www.partsexpress.com/pe/showd...number=295-600
- 5 1/4"
- Qts: 0.54
- Looks great!
- $49

http://www.partsexpress.com/pe/showd...number=297-420
- 6"
- Qts: .51
- Looks okay
- $64

http://www.partsexpress.com/pe/showd...number=295-605
- 6"
- Qts: .83
- Looks so-so
- $26

http://www.partsexpress.com/pe/showd...number=296-190
- 6 1/2"
- Qts: .59
- Looks great!
- $54

http://www.partsexpress.com/pe/showd...number=296-192
- 6 1/2"
- Qts: .70
- Looks so-so
- $18

http://www.partsexpress.com/pe/showd...number=264-422
- 6 1/2"
- Qts: .80
- Looks so-so
- $21

http://www.madisound.com/cgi-bin/ind....5636&pid=1832
- 3"
- Qts: .86
- Looks good
- $10


http://www.madisound.com/cgi-bin/ind....5636&pid=2170
- 4"
- Qts: 1.08
- Looks good
- $19



I was trying to find good sized drivers with high Qts. I am not sure what other qualities will be good for an open baffle design. Also, I do not know what to look for in a tweeter for open baffle. Am I getting myself anywhere?

Grumpy_Git 16th April 2007 10:46 PM

I would personally advise you to avoid sheet metal for the baffle.

but thats just my opinion, and what do i know?

Nick.

mastarecoil 17th April 2007 01:57 AM

The reason I went with sheet metal is becuase I can get scraps of it cheap and use it on the CNC. I would go with some very sturdy, probably 1/4 or 3/8 in thick.

It should be sturdier than wood, but is there some reason to lean away from it?

tade 17th April 2007 02:06 AM

I see no reason to avoid the use of metal. It has tremendous stiffness. That of course leads to high Q resonances which must be damped. Fortunately the damping of high frequency high q resonances can be very effective and lead to a very inert material. My turntable platter rings like a bell before i lay its mat down. Then it is impressively dead.
Try a constrained layer scheme. I would suggest trying roofing felt.
Tade

holdent 17th April 2007 02:13 AM

Depending on your budget, I'd look at the following:

Low budget:
A. Eminence Alpha 15A for the woofer
B. a fullrange driver of your choice such as one of the following:
- HiVi B3N (but add the notch filter Zaph describes for the B3N)
- Fostex (FE103E or FE167E)
- Tangband W3-1364S
Crossover fairly low such as 500 Hz


Mid budget:
A. consider two Eminence Alpha 15As per side, or one 18" pro audio woofer, or Hawthorne Augie (other 15" woofer) with a plate amp
B. mid and tweeter of your choice, or the Hawthorne Silver Iris, or the Visaton B200, or other similar fullrangers (Hemp Acoustics?)

High end:
Martin King suggested two Eminence woofers per side with Lowther drivers here http://www.quarter-wave.com/Project07/Project07.html
or
build the Linkwitz Orion
or
???


Using the higher Qts Alphas means that you can stay passive and don't need to EQ the woofer to get adequate bass response. I stayed away from 18" woofers only because they force the OB to be too wide to have any WAF around here! If you can manage to get around this an 18" woofer would be a better choice (given a similar Qts spec).

I am currently playing with two OB set-ups:
Silver Iris' plus the Alphas which provides excellent sound and a "poor man's" OB using the HiVi B3N and Goldwood GW-215/8 (very cheap 15" woofers). The HiVi/Goldwood combo is surprisingly good mostly because the B3N is such a good driver for its price. Pairing the Alpha with the B3N is even better.

Good luck!

mastarecoil 17th April 2007 03:05 AM

I would like my max budget to be 200, ideally spending around 100. I am not going for anything huge, just some nice small speakers (maybe 12 or 18 inches tall) to sit on my desk. Maybe that helps with perspective.

mastarecoil 17th April 2007 03:05 AM

Lets say I were to go a similar route, some B3Ns (and what about the 4"?, or the M3N?), Foxtex, or Tangband, and then find a smaller woofer, like a tangband 6.5" or 8" for example. Wouldnt I want some kind of tweeter to go with it?

holdent 17th April 2007 03:25 AM

OBs 12 to 18" tall? Unfortunately OBs this small will likely roll off very high and have little to no bass. The OBs I've been playing with are all 18 x 32" or taller. You could make them very small and provide lots of EQ to fix this. (Or would be better off just be building some small BRs or sealed speakers).

I've mentioned using a tweeter for a mid-priced or more OB. I didn't suggest one for the lower priced OB to avoid the cost and complications of additional crossover components and one more driver. Personally I can't hear above 16kHz so I find that a smaller fullrange is more than adequate.

mastarecoil 17th April 2007 03:33 AM

Mostly I wondered about a tweeter becuase the B3N dosent look like it will go very high.

How much more complicated (expensive) is a crossover with a tweeter compared to without?


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