open baffle project

[mastarecoil]

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]

Would any of these be a good place to start:

http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=295-600
- 5 1/4"
- Qts: 0.54
- Looks great!
- $49

http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=297-420
- 6"
- Qts: .51
- Looks okay
- $64

http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=295-605
- 6"
- Qts: .83
- Looks so-so
- $26

http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=296-190
- 6 1/2"
- Qts: .59
- Looks great!
- $54

http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=296-192
- 6 1/2"
- Qts: .70
- Looks so-so
- $18

http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=264-422
- 6 1/2"
- Qts: .80
- Looks so-so
- $21

http://www.madisound.com/cgi-bin/index.cgi?cart_id=6931163.5636&pid=1832
- 3"
- Qts: .86
- Looks good
- $10


http://www.madisound.com/cgi-bin/index.cgi?cart_id=6931163.5636&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]

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

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

Nick.

 

[mastarecoil]

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]

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]

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]

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]

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]

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]

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?

 

[mastarecoil]

Partsexpress sells a finished 3-way crossover for $18, but is it just junk?
http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=260-210

or these?

http://cgi.ebay.com/ELAN-3-WAY-PASS...89QQihZ018QQcategoryZ3276QQrdZ1QQcmdZViewItem

http://cgi.ebay.com/1-PAIR-3-WAY-PA...6QQihZ017QQcategoryZ50552QQrdZ1QQcmdZViewItem

 

[holdent]

Sorry I can't advise you well on crossover design. Generally, however, you get what you pay for.
- The first eBay xover, the Elan xover, has 1st order slopes (6dB), lower power handling, is set-up for a 4 ohm woofer, and has what looks like iron-core inductors = cheap and not very good.
- The second eBay listing is for a car audio crossover but the specs (other than general fequency range for each driver) aren't given. If I had to gues it also appears to have a 1st order slope for the woofer and 2nd order (12 dB) for the midrange? It also appears to have better (but low gauge?) air-core inductors = ??? who knows
- At least with the PartsExpress xover they provide almost all relavent info = probably a good deal for applications in an inexpensive OB

The more expensive Dayton and PartsExpress xovers are much better.

NOTE - this thread has strayed far from Fullrange application - You should look for and ask for help in the Loudspeaker diyAudio Forum (http://www.diyaudio.com/forums/forumdisplay.php?s=&forumid=6)

 

[justpoor]

Holdent,

Would you mind sharing your crossover for the Silver Iris' plus the Alphas that you are using. I am planning to do the same with passive crossovers instead of spending money for plate amps.

Also you've mentioned using woofer with high qts - what does high qts do. Is it better for open baffle to select woofer that has high qts.
Thanks.

 

[Viridian]

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.

Mastercoil,
You should check out this forum, all OB stuff. And lots to read other places.
http://www.audiocircle.com/circles/index.php?board=90.0
Stay away from metal. if you want something cheap and quick, just use a piece of sheetrock. You wont have the problems with vibrations/resonances whatever with sheetrock that metal would have. Metal would transmit sound and be a source, which you don't want.
Many folks have highly recommended the hawthorne SI's as being a nobrainer and sound fantastic. I am trying to decide myself. In general you really want to stay away from passive xovers though. Check out this article about biamping that will really open your eyes about this. It is a fantastic site to read: http://sound.westhost.com/bi-amp.htm
Best of luck. A little more money now and you won't end up spending more on the "upgrade path".
Cheers,
Erik

 

[Viridian]

Also you've mentioned using woofer with high qts - what does high qts do. Is it better for open baffle to select woofer that has high qts.
Thanks.

Do you mind if I chime in?

Yes, for open baffle it is better to use higher Qts spec drivers. I believe that Qts is basically the balance of mechanical Q and electrical Q, in other words it is the Q total. This means that a driver which has a high Qts has less damping which translates to a gentler rolloff of efficiency as you approach Fs. Better bass extension. In OB, bass is a little hard to get, so you want something that doesn't roll off sharply.

Does that help? That is what I have gleaned so far on the subject.

Sincerely,
Erik

 

[Geoff H]

Also, on an OB, there is little point going low in FS, particularly on smaller baffles. On the small ones I have been playing with, I got more bass by pushing FR up. These are 460mm high, 300mm wide, plus short tapered wings. FS is now at 76Hz.

What happens, I think, is an increase in efficiency where the baffle can work.

There was mention of putting these on a desk. You will have problems if the desk is against a wall. OBs like to be out in the open.

Regards,
Geoff

 

[justpoor]

Thanks Viridian for your explanation. Sound like the Eminence Alpha 15A is the only inexpensive that have high qts and would work well with open baffle.

 

[Viridian]

Don't forget to look at the Goldwood 18"s. qts of around 1.0 Available at Partsexpress.

I actually have 4 of them on their way to my door.

Woohoo!

 

[AdamThorne]

I was doing some finishing work on regular cabinets for my TB W3-871s and so I stuck them in 2'x2' OBs and I was suprised how nice they sound for the vocal range and up.

So now I wonder about bass for them. The eminence 15" comes up often enough. I was wondering if someone could talk about filtering them, or point me to a good OB bass (not sub) beginner resource.

Thx!

 

[holdent]

JustPoor

Would you mind sharing your crossover for the Silver Iris' plus the Alphas that you are using. I am planning to do the same with passive crossovers instead of spending money for plate amps.

Sorry, I just checked this thread for the first time in a while.

I 'm running the Silver Iris fullrange (its actually a coax driver with a crossover that comes with it) and using the Alpha to augment the bass. I've rolled off the Alpha around 270 Hz using a 4.7 mH inductor (http://www.partsexpress.com/pe/pshowdetl.cfm?&DID=7&Partnumber=266-924)

Unfortunately I'm still playing with baffle size and not completely happy with the lower midrange. I'm using a baffle of 18" x 37" with the drivers centered vertically (the Alpha 8" up from the bottom and the Silver Iris 24" up). The bass is excellent but the speakers must be pulled out at least 1 m from the rear wall.

After talking about passive filtering I'm now thinking that using a plate amp or an active crossover and amp is probably the best idea. It gives you much more control over the bass drivers than possible just using passive components. By the time you've purchased and tried various components you've probably spent close to what a good plate amp would cost (like this one http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=300-804).