[drphoto]

I love Danny's stuff. I have sung the praises of his OB servo subs for months here. I would love to hear the V1 or Super V or whatever it's called. But I would urge you to consider an entirely different path and consider the designs of  Dr. Geddes at Gedlee or Duke at AudioKinesis, also using 'pro' drivers, but in a different way. I have not heard them myself, but several people here, who's opinion I value and respect, speak highly of them. I'm hoping to make a road trip this spring to check them out.  The theory seems sound. I know for a fact his idea of multiple subs works.

It may seem crazy, but the ideal situation might be OB subs and controlled directivity monitors, rather than all OB.

I hope I'm not opening up a flame war here. I'm honestly not trying to do that. Just trying to give the OP another option.

[Danny Richie]

It may seem crazy, but the ideal situation might be OB subs and controlled directivity monitors, rather than all OB.

The coaxial drivers also have the same controlled directivity as a horn. Then opening up the back of the compression driver to give it both open baffle and some controlled directivity took it to another level. It makes it sound more relaxed in in the room rather than through a horn. And once you get rid of the sound of a box, then it is really hard to go back.

[ebag4]

And once you get rid of the sound of a box, then it is really hard to go back.

My sentiments exactly!

[jdbrian]

I love Danny's stuff. I have sung the praises of his OB servo subs for months here. I would love to hear the V1 or Super V or whatever it's called. But I would urge you to consider an entirely different path and consider the designs of  Dr. Geddes at Gedlee or Duke at AudioKinesis, also using 'pro' drivers, but in a different way. I have not heard them myself, but several people here, who's opinion I value and respect, speak highly of them. I'm hoping to make a road trip this spring to check them out.  The theory seems sound. I know for a fact his idea of multiple subs works.
It may seem crazy, but the ideal situation might be OB subs and controlled directivity monitors, rather than all OB.
I

  Thanks for the input.

 I have looked at Dr. Geddes designs and see the merit in what he is doing. I will check out the other site you mentioned. Like you, I am unable to hear any of these designs and am unlikely to get the chance, as I live in Nova Scotia Canada and don't travel much. IMO speaker choice is the most difficult part of putting together a sound system. I have come to the conclusion that there is no one solution for everyone and personal preferences vary wildly. I am continuing to learn about these various speaker systems and design philosophies and the input I get on this forum from designers and listeners is greatly appreciated.

Brian

   

[drphoto]

I never really thought about how in the coaxial design, the larger driver would in effect, act as a waveguide for the the HF unit. As I said, I'm open (no pun intended) to both concepts and hope to hear each. As I will soon be assembling the lower half of the V1, it would be relatively simple for me to buy the coax units and crossover and have the complete speaker down the road.

[cujobob]

I didn't want to hijack the thread to mention it, but since it was brought up I will say that I own Gedlee Abbeys and, for me, they are a near perfect speaker.  For value and overall quality, the Gedlee and GR offerings are some of the best around.  Demo-ing Dr. Geddes' work is indeed quite difficult ATM but it would be well worth it.

[mcgsxr]

I don't think your suggestion is unwelcome cujobob, although I would say that the OP is looking for insights around OB speakers.

Glad that you have landed on a solution that makes you happy, and thanks for sharing.   

[drphoto]

Well, maybe the problem with either of us mentioning the Gedlee or Audiokinesis here, is that neither are OB designs. But both of these and OB's  are trying to address the room interaction issues issues that arise from conventional wide dispersion monopole speakers. (two sides of a coin perhaps?)

Plus the use of prosound based drivers, which is also being done in some OB designs such as the Super V is addressing the problem of effortless dynamics, required for realistic music reproduction, heretofore available only from large megaexpensive speakers.

Again, I am not trying to offend anyone, I'm just trying to offer up some ideas. There are various ways to attack the problem, but it has come to my attention that room interaction and dynamics are the key issues to realistic sound reproduction (along w/ low distortion, of course)

[mcgsxr]

Agree that there are many ways to skin the audio cat (examples of non OB speakers can even be found in my home - shhhhh  ), and appreciate the delicacy shown by all posters, respecting the circle it is in, and the OP's query.

Keep it coming guys, always good to have respectful open dialogue about helping a fellow music addict!

[Rudolf]

I know for a fact his idea of multiple subs works.
It may seem crazy, but the ideal situation might be OB subs and controlled directivity monitors, rather than all OB.

You could even argue the other way round: The ideal situation might be multiple closed subs and OB monitors with controlled directivity (which is a built-in feature of dipoles, if done right).
What remains is the common strong emphasis on in-room-behaviour, which is sadly ignored in too many discussions focussing solely on pure speaker design.

[jdbrian]

Hi Folks
   I spent yesterday creating an OB hybrid speaker from what I had on hand. I had a pair of Fostex 206's and I mounted them on a mdf baffle 12"w X16H. I added a bottom to the baffle and side braces and set this on top of the woofer box of my Newform 645's. I had to turn the box sideways to avoid the ribbon mounting bracket.
  So I had the Fostex OB sitting on a 40l sealed box with 2 Scan Speak 8545's facing sideways.
    Next I took a Marchand Electronic crossover and set it up for 180hz 24db/oct. and added a dipole compensation circuit to the output stage to boost the low end of the Fostex. To help compensate for the drooping low end of the low Q driver I added a 10ohm 10w resistor in series with the amp output. I disconnected the 8545's from the passive Xover and connected them to the amp.
   Using the gain controls on the Marchand and a Behringer Deq2496 I adjusted the output for a response that was within a 6db window and sloped downwards a few Db from bass to 10khz.
   I must say, I was surprised at how good this crude OB sounded. I am familiar with the Fostex and it sounded much better OB  then in a box. The dynamics were excellent. There was a big improvement in lower midrange clarity over the boxed 8545's which normally cross to the ribbon at 1200hz. The extra ambience from the rear and the lack of sidewall reflections added up to improved clarity and resolution and a pleasent overall tonal balance was easy to achieve with the EQ. The fostex never seems to move at all. Even at loud levels there is no observable excursion so I think I will try going to 150hz for a crossover.
   This answers the question "do I in fact like the OB sound in general". The answer is yes! Please keep in mind that I did this as quickly as possible and using what I had on hand so it is not an attempt at a serious speaker design. I have to go listen and tweek it some more. I'll see if I can post pictures later

Brian

 

[Rick Craig]

I've heard one of John K's designs and he's a very intelligent guy who knows what he's doing. The 8545 is capable of very good performance with the right crossover. With the 645's I've tested them and the integration of the ribbon and woofers isn't that great; in fact, if you convert the ribbon to a line array the sound will be much better.

[johnk...]

Thanks Rick. You have produced some nice speakeres youself. FYI, I have something new in the works. http://www.musicanddesign.com/NaO_Note_Previews.html