DIY OB designs?

[Rbrockman]

I've completed a couple of DIY "box" designs now (including the wonderful Modula MT); and am now looking for something a bit different.

I would really like to build a proven OB design and hear the difference. I'm just beginning to learn about these designs, but haven't seen to many of them here.

This style looks interesting (not sure how the baffle can be so narrow?)


Design goals:
Budget: < $1500 (drivers & crossover)
Room size: 17' x 26' x 9'
Freq: 80hz to 18khz (can use sub for <80 hz)
SPL: ~100db
Use: 60% music / 40% HT

If anyone can point me to some designs and/or offer some advice, I'd like to cut some wood soon.. :W

Thanks!

[augerpro]

The main reason (I think) the baffles are narrow is because the woofers are not OB, they are in conventional boxes.

[Rbrockman]

The more you learn.....the more you realize how much you don't know!

I would like to understand more about the baffle width of OB & Dipole speakers. Is this width primarly that of the largest diameter driver?

Can the woofers be oriented 90 degrees facing a side to reduce the overall width? (obviously the may require more depth)

For example, in the picture below - are there reasons why the bottom drivers could not be oriented to the side to reduce the width of the speaker considerably?

[Doug Lockwood]

Is this width primarly that of the largest diameter driver?

No.

Can the woofers be oriented 90 degrees facing a side to reduce the overall width? (obviously the may require more depth)

No.

For example, in the picture below - are there reasons why the bottom drivers could not be oriented to the side to reduce the width of the speaker considerably?

Yes.

I would first send you to Linkwitz Labs
and Music And Design.
To answer your specific question, The Area of the baffle controls the low frequency roll-off of the speaker. This is explained in great detail on both the reference sites.
Basically, at low frequencies, the front and back wave begin to cancel. Also, there is usually a null at 90 Degrees on an Open baffle, where the output is less than either forward or backward.
The reason you do not see more designs is its relatively challenging to make an Open Baffle design with a passive crossover. It can be done, and the AVRO that you pictured is one of the passive designs. Also, OB speakers tend to need more swept volume in the base because of the cancellations. This translates to more and larger woofers in most designs, as well as a physically large unit.

Many talented OB designers hang out here.
Check out the OB threads and ask questions.

Doug

[JimS]

Design goals:
Budget: < $1500 (drivers & crossover)
Room size: 17' x 26' x 9'
Freq: 80hz to 18khz (can use sub for <80 hz)
SPL: ~100db
Use: 60% music / 40% HT

If anyone can point me to some designs and/or offer some advice, I'd like to cut some wood soon.. :W

Thanks!

Follow Doug's advice and read SL's site a few times (and then a few times more).

There are a few choices available on the board that will fit your goals and a few new ones under design.

The pic you posted is the Arvo designed by Jon & Thomas - I've built them along with about 4-5 others on the board (Chuck - ChasW98, Jacob - Soho54, CraigJ and Eric). Highly recommended :T you can get them together for well under $1500 with some judicious parts shopping and they'll be cruising with your freq & spl requirements. Search under "arvo" for many threads. Just like SL's site, read through Jon's design posts a few times until your head doesn't hurt quite as much as it did the first read. 8O

Davey has a nice set-up as well. Don't recall if there's a design thread, but there are enough posts to get a good idea.

Steve Dodds has a well-detailed site for his active dipoles (although I'm guessing they would push your budget a bit).

Paul Carmody (Undefinition) has a great thread on budget dipoles ($250) to get your feet wet - although they use a vented bass like your photo. Search "Aether".

Depending on how much DIY you want to undertake, ThomasW has some good threads on modifying Maggies.

Finally Jon is working on a project called the Isiris which will likely be well out of your price range, but there is a plan in the works to develop a lower-cost version at a later date.

Have fun!!

Jim