Dipole Plexiglass Speakers - need advice !

[Ozne]

I am trying to gather information and thoughts from experienced people about building my own dipole speakers.

I have done a lot of research (A LOT!) and I do believe that making my own dipole speakers (often called open or infinite baffles I believe, but please correct me if I'm wrong!) would be best for my use, budget, and as a first DIY project in this field. I'm pretty handy and am a music lover. My dad and uncle are audiophiles and have made their own speakers when they were my age. Well, I'd like to do better and nicer!

I know it might sound weird but I want to make the "open enclosure" in plexiglass. I do know that the sound quality will decrease considerably but I'm ready to pay this price. As much as I love music, I am willing to sacrifice a little bit of that sound quality in order to make this project happen.

I am looking to make two towers, each with respectively 1 12" woofers, 1 8" mid-range, and 1 4" tweeter. This are all used Technics components from my current stereo. Since I am on a tight budget (but am definitely willing to spend the time; and some money) I will use what I have in stock!

Another reason why I am going with dipole speakers is that I wouldn't have to worry about the enclosure volume, and would really like to use these speakers as a piece of art of my own (this sounds cheesy but this is something big for me as I want to make these prefect!).

I am also planning on incorporating 1 subwoofer unit made of two 16" speakers.

Now, this being said, I have a few questions, and any comments or ideas are more than welcome!

- Fiberglass thickness: I was thinking 3/4" or 1". Thoughts on that? I am leaning toward the 1" because of vibrations issues and overall look.
- Subwoofer: I am undecided between making one unit with the two 16", or two separate units. Or incorporate the subwoofers to the towers?

Well, I guess that's all I had to ask, please feel free to comment or advice me on issues I might encounter!

Thanks a lot.
Enzo

 

[90gstman]

Plexi glass sounds like a fun idea. Things I would be concerned about would be:

Melting: Plexi glass tends to melt during cutting so you need to use sharp bits, blades, etc. A router will turn it into soup if you're not carfull.

Every mistake will show: There is no hidding any irregular cuts scratches, chips after they have been made.

I wont go into the benifits and pitfalls of open baffle's just yet. Just that it will be a tricky first project.

 

[annunaki]

Open baffles require very specific driver choices and tend to work best as active designs as the crossovers can be complex.

From what I have seen and heard these are some of the best designed open baffle speakers: http://www.linkwitzlab.com/DIY products.htm

 

[GranteedEV]

I second the idea of using an existing dipole design given how complex they apparneltly are. Another, more affordable option to the Linkwitz is the NaO

http://www.musicanddesign.com/naomain.html

 

[TLS Guy]

I second Annunaki's advice.

We have this problem again and again, a novice starting by trying to build the most complex difficult speaker system possible.

Saul Linkwitz is the only guy who has really pulled this off. The others are a mess and even his design has limitations.

These types of designs absolutely need active crossovers and complex equalization because of the summing peaks and canceling nulls inherent in the design. You also have to come with the 6db roll off inherent on open baffle design.

Incidentally your proposed design is not an infinite baffle but an open baffle, and these systems are totally different in concept.

An infinite baffle consists of large drivers in a wall. The rear of the speakers face into a very large space not connected to the listening room. This space is usually an unused room or garage.

You need to read everything on the Linkwitz lab site about open baffle dipole cone speakers. There really is no other resource that can compare with the informati0on there.

If you don't understand the science behind this, or the resources to accomplish it, then you can't build it.

Unless significant time and cash are thrown at this problem, it will sound a lot worse than a TV speaker. I can be certain your speakers are not suitable for open baffle.

 

[GranteedEV]

S(igfried) Linkwitz is the only guy who has really pulled this off. The others are a mess and even his design has limitations.

Do you mind to elaborate? This is the first I've read of the NaO II being a mess. All I've heard prior is that between the the two each does some things well and some things not so well but each is a quality loudspeaker.

 

[TLS Guy]

Do you mind to elaborate? This is the first I've read of the NaO II being a mess. All I've heard prior is that between the the two each does some things well and some things not so well but each is a quality loudspeaker.

I was not aware of that speaker. Its design makes sense. It has active Eq which any speaker of that type would have to have, as a passive solution is not possible. Although there are speakers around that are of that type and passive, and that was the mess I was referring to.

 

[MJK]

Two Way OB Designs

Open baffle speakers do not need to be complicated, expensive, or difficult to build. Below is a link to a simple passive two way OB design.

http://www.quarter-wave.com/OBs/OB_Theory.html

I have built this simple OB and have been running it with different 3" - 4" full range drivers bi-amped using an active crossover for the past six months. I am listening to the system as I type this post (Mark Audio CHR-70 full range drivers and Eminence Alpha 15A woofers) and it sounds very good.

Another option can be found at this link.

http://www.quarter-wave.com/Project08/Project08.html

Other examples can be found in my gallery.

I know that the in-crowd uses narrow baffles, three or four way designs, and complicated active multi amped systems. I am sure they sound great. But it does not have to be that complicated or expensive. Simple and elegant designs using reasonably costing drivers also works very well in a two way OB system.

It is easy to design your own OB system with minimal experience and have it work well first time, just follow the recipe I have provided.

Martin

 

[belt drive]

Open Back Plexiglass Speakers

Anybody heard of the Entec (Element) C100 speaker?

Imagine an Infinity IRS. Same size. In plexiglass.

7' ribbon midrange array.

7' ribbon tweeter array.

8 cone mid-woofers.

6' + subwoofer columns-(4) 12" drivers per side.

(All drivers are off-the-shelf components and still available.)

Pristine flawless 1+ " thick plexi (Lexan? Macrolon? Acrylite? ).

It's a scaled up version of the ($50,000) C50.

The C100 (MSRP $100,000) was shown at an audio show or 2 but never bought into production, so only one pair exists! And I've got them! Really.

They need most drivers to be put back into service. The ones previously installed were used for C50's of which a few pairs were sold commercially.

Anyway, if you'd like some pictures please email me. I don't have enough posts yet to put links in. Or, you can go to photobucket user lennyzack and look for the Entec-Element E100 album.

Right now I don't have the $ to complete them so they'll either have to wait till I can put together funds or find someone that wants to take the project over.

So, whaddayathink about these babies? Do they perhaps qualify as the most extreme open back plexi speakers you've ever seen or heard of?

And if you've got a gal that wants them in the living room, you're a luckier guy than me (or anybody else I know). And does this gal have a llike-minded sister?

Happy listening!