[xecluded]

Greetings,

I am new to OB and hoping someone can educate me on the OB type of speakers.  For the OB to work at their best, is it necessary to use a full/wide range speaker for the main and augment the low/high frequency with a helper woofer or tweeter.  Or OB would well with traditional woofer/tweeter combo - if this is the case, all I have to do is using some old speakers that I already have (spica tc50, or boston acoustics A100) and mount the drivers/crossovers on the baffle and augment the low frequency with a 15" woofer - saving lot of time for design or trying to find what work best with OB.  What do you think. Thanks.

[Saurav]

There are certain characteristics of speaker drivers that make them better suited for OB. You 'could' put any old driver on an OB, and you'll get some sound out of it, but it probably won't be very good.

I suggest reading these (though they can get pretty technical):

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

http://www.musicanddesign.com/

[Brad]

Welcome to AC (and the OB Circle)

To make usable bass in OB, your woofer (or full ranger) is going to need a higher Q (among many of the other variables)than might be desirable for a box speaker.
You might be surprised how good most mid/tweets will sound in ob
(take 'em out of the box  )

[xecluded]

Thanks for your replied and the warm welcome.  I have read lot of topics relating to OB and the more I read, the more confuse I get. 

I am well aware of the lacking bass situation of OB hence trying to supplement the low end with a 15" augmented woofer.  I guess the only way to find out what work best is trial and errors.  I will experiment with what I have when time is permit.  Thanks again.

[ttan98]

I was new to the OB experiment, after did some research and reading on the net then I decided on a configuration(I have experimented with a few), my is TWW, with woofer connected in parallel. This config is similar to CS2 from Emerald physics, essentially a 2-way system.

My speaker is designed from ground up, if you want to approach that way they you need a few tools to help you otherwise you should build a predesign speakers eg. a design from MK.

The tools you need if you decide to design yourself includes:

1. An active, digital x-over, DBX,Behringer etc. hence avoid lots of soldering and resoldering, very time consuming.
2. Microphone for measuring the freq response, microphone and preamp combo is quite cheap. you can get free s/w from the the net eg.ARTA. I was able to use Soundeasy(SE) s/w from a friend.
3. s/w that will allow you to design passive x-over as well. There are free s/w available as well, SE can do that too. SE is not cheap, but very powerful.

One drawback there is a learning curve for using all the above tools.

If you want to use your existing componets without the above tools you will conduct design with some trial and error chew up lots of components, cap, resistors and inductor. It will work however it will take up lots of your time.

cheers happy developing.

[Dmason]

what I found works best for me for experimentation was to build an OB system from the ground up, with bass augmentation and its separate power and control, and roll through drivers to see what sounded best to-my-ear, and how it gelled and blended with the bass drivers, extant. They are all very different.

I agree with Graham, that after trying H, W, Ripol, I prefer the simple dipole sound. For me, the most basic sounds the best, again to my ears, my place, etc. As someone above stated, cut a 20X30+ baffle, offset a mains driver(s) and go from there. You can get free plywood clinkers from about any jobsite.

Lately there has been some outstanding work done in measurement, furthering the observations made by Martin; the state of the dark art is advancing apace! I really like where all this is going.

I personally have found a preference for smaller diameter wideband cones, preferably the Japanese ones, which would include everything from the outrageously high value Fostex FE126/7, to some of the more obscure stuff. I think the Tone Tubby Alnico 10 is the best widerange larger diameter cone i have ever heard, and by no small measure. The B&C compression drivers show that things have come a very long way with that technology, with these nice, short-throw, NON-metallic diaphragm inexpensive units.

 Caution: OB sonics are known to be addictive.

[xecluded]

Hi all,  Thank you for your inputs.  I've been expereimenting with some vintage full range alnico on OB and most of them sound quite nice.  Though they leave a lot to be desired as I really can not crank them up to a realistic listening level.  I think I will try a 15" with some compression drivers/wave guide and see. Thanks again.

[DanH]

I heartily recommend the Martin J King design at http://www.quarter-wave.com/OBs/OB_Theory.html. I built a pair and I just love them. They have plenty of bass and a wonderful musical sound.

[DanH]

My finished MJ King OB speakers.

[xecluded]

Nicely built DanH.  I have a pair of Fostex 126 myself. While they are nice, I really can not crank them up, that's a big downfall for me....

[DanH]

In this design the FE103 have a second order xover around 400 hz. I play mine pretty loud at times and I have never felt they sounded stressed in any way. I have played a couple of my Maynard Ferguson albums as loud as I was comfortable with and I detected no problems.

[xecluded]

Here is what I just put together - a 15" vintage rca with jbl 2416 driver/$10 waveguide crossing at 1700hz 1st order. 

[iON]

Xecluded,

Wonderful! A pair of trestles with attached baffles. Very Zen.

That's one thing I really like with OB, you can just throw together a working prototype in notime! With some black cloth draped over the backsides they would even be able to pass the spouse acceptence test!

Cheers!

[xecluded]

Thanks Ion for the kind word.  With the trestles, i can play / experiment with all kind of settings til i find what i like.  Quite convenience indeed.

[gitarretyp]

Is there a reason you have the horns in that orientation?

[xecluded]

I mount them that way just to fill up the space.  They sound the same either horizontal or vertical....

[gitarretyp]

I mount them that way just to fill up the space.  They sound the same either horizontal or vertical....

On axis it may sound the same, but the off-axis response will be a little strange. As you have them, you have more energy radiating in the vertical rather than the horizontal.

[xecluded]

On axis it may sound the same, but the off-axis response will be a little strange. As you have them, you have more energy radiating in the vertical rather than the horizontal.

Yes, but for my tiny listening room, it seems to fill up the room with sound better...