[D OB G]

Hi cboy168,

What Jordan do you have in mind?

I tried the new 2", and the sound of the rear radiation was quite unacceptable.

I'd be interested to know if the 4" is any better in this respect, since I haven't seen it used in any OB configurations (no doubt it has been).

David

[D OB G]

Sorry Martin re Jordan.

I should have read your website first

[cboy168]

I am very interested in this OB based on Jordan and 18inch woofer. I think the approach is very creative and could be the answer to many OB's woes in the past. One question, can this design be used with a passive crossover???

I have a passive crossover design built, measured, and running. I finished the first pass write up last night and added it to my site this morning. I got tired of looking at it so let me know about any typos. The passive crossover works very well.

This should be really interesting. But I somehow cannot find it in your website.

Pls pm me how to make contributions. I know you are such a gentleman and not asking for it. But your work is genius and people ought to support great minds like you.

 

[MJK]

This should be really interesting. But I somehow cannot find it in your website.

Pls pm me how to make contributions. I know you are such a gentleman and not asking for it. But your work is genius and people ought to support great minds like you.

You can find the write-ups under the "Projects" link on the opening page, it is the last project listed. There are now three entries.

1) Active Jordan OB and Goldwood H Frame
2) Passive Jordan OB and Goldwood H Frame
3) Passive Fostex OB and Goldwood H Frame

No contirbutions are necessary, I do this because I enjoy the challenge. If you build one of my designs a picture for the gallery would be appreciated.

[MJK]

I'd be interested to know if the 4" is any better in this respect, since I haven't seen it used in any OB configurations (no doubt it has been).

I have listened to the rear of the Jordan OB and it seems to be OK, not sure what you are looking for in the SPL response. I did not do any critical listening but the sound from the rear sounded a lot like the front.

There are a number of copies of my Jordan OB and Goldwood H frame design built and running. People seem to be happy with the design. Now that there is a passive version I think it will become more popular.

[D OB G]

Hi Martin,

With the 2" Jordan, the problem might be that the magnet almost completely shadows the cone (unlike the 4"). It is really only open at the corners.

So the forward sound was excellent, and the rear was peaky, screechy.  It sounded that way from the back and measured that way.

I only found out that the forward sound was good when I stuffed the rear openings with fairly dense dacron!!! Not exactly OB!

David

[panomaniac]

There is a new little FR driver out from Audience.
http://www.audience-av.com/loudspeakers/A3.php

I have ONE of these, but have heard them in the line array.  Very nice driver, very detailed and refined, good resolution.
As the back is so open, I'd love to use it in OB in a rig similar to Martin's Jordan rig.

I'm trying to get my hands on a few more for testing.

[Russell Dawkins]

I couldn't find the price per unit on the site, also their figures did not to add up in some ways. They claim a line array with 8 per side will play at 123 dB continuously, but this does not fit well with other stated specs - it seems optimistic, unless the specs are conservative...

Still, I can imagine how these would sound very nice. It must really be something to see a 60mm diameter cone moving through a peak-to-peak range of 12mm!
An OB line array would be interesting but, I suspect, expensive!

[cboy168]

This should be really interesting. But I somehow cannot find it in your website.

You can find the write-ups under the "Projects" link on the opening page, it is the last project listed. There are now three entries.

1) Active Jordan OB and Goldwood H Frame
2) Passive Jordan OB and Goldwood H Frame
3) Passive Fostex OB and Goldwood H Frame

No contirbutions are necessary, I do this because I enjoy the challenge. If you build one of my designs a picture for the gallery would be appreciated.

Martin this is awesome. Will order the parts this week and maybe build a prototype first using 3/4inch plyboard. Later I can build a really nice hardwood for the OB and H-frame if it beats my tannoy gold in corner enclosure. Will report back soon

More power to you!!!

[panomaniac]

I suspect, expensive!

You suspect correctly, sir!  Jordan style prices.  Still, a very nice driver.
If I ever get my hands on more than one, I'll let you know.

(the one I have is 16 ohm)

[Shenzi]

Adding to the comment above about the 2" Jordan. This needs to be used in a box as it has no conventional suspension. A better route would be to use two, one forward and one rear-firing. Wired in series, they would about match the JX92 for sensitivity but would be 8Ω rather than 6Ω, so the passive x/over would need adjusting.

[D OB G]

You're right about the 2" Jordan.

No rear spider at all. Relies on front roll surround for centering.

Recommended 1 liter to 4 liter sealed enclosure.  Specifically not recommended for OB!!!!

However... the response is published as going "flat" to at least 20kHz, and I've measured it too.  But it doesn't sound like it does.  Jordan claims "electrostatic" speed and clarity.  I found it sounds good, but not as a full-ranger (well above 120-150 Hz anyway).  It is really a mid-range driver.  It doesn't have any air at the top end. 

In any case, I think we have established that it doesn't belong in a dipole system.

David
 

[jkelly]

I got the passive version going and I like it.
Initially I thought the bass was lighter, but actually
it is cleaner sounding.  I think I had raised the bass
level up a little too much on the active crossover.
After a few position adjustments, they are sounding fine++.

I am noticing improvements in dynamics.

Need to play some more with cables and amps.

So far so good!

Jeff

[dublin78]

I was always lead to believe that these iron core (low dcr) inductors were fine for LF but should be avoided for XOs affecting mid and high frequencies, where air cores and ribbons should be employed.

Comments?

[MJK]

Initially I thought the bass was lighter, but actually
it is cleaner sounding.  I think I had raised the bass
level up a little too much on the active crossover

Jeff,

That is exactly what I experieced. It is so easy to raise the bass up too high with boost and an active crossover, powerful bass becomes addicting. But the more I listen to the passive version the more I think it is balanced right. The same thing could be done with the active version by just scaling back on the boost.

I was always lead to believe that these iron core (low dcr) inductors were fine for LF but should be avoided for XOs affecting mid and high frequencies, where air cores and ribbons should be employed.

dublin78,

If you look at the role of the inductor in the high pass crossover I really don't see it playing a big part in the mid to high frequency response. The inductor is placed across the positive and negative leads, at low frequency it shorts the cap and driver while bass is coming from the H frame. At high frequencies, it acts as an open circuit (very high impedance) so very little current flows through the inductor. To me it seems like a non player for the mids and highs. It sounds fine to me.

Martin

[jkelly]

Glad to see we are having similar sonic experiences.

I also like having the speakers on spikes, raised about an inch from the floor.
I am using the Dayton ones from PE

http://www.parts-express.com/pe/showdetl.cfm?Partnumber=240-715

These cleaned up the boominess and livens up the sound, (in my room).

Jeff

[ecir38]

Congrats Jeff, I think you are one of the first to use the passive network. Sounds like it is working great. One of these is on my list in the future but am enjoying every bit of Martin's design with the FE87E and the Alpha 15a right now.

Brad

[panomaniac]

Nicely built!  I like the terminals, especially. 

[Russell Dawkins]

that looks like a great value in spikes, jkelly, about the nicest I've seen.

[cboy168]

I got the passive version going and I like it.
Initially I thought the bass was lighter, but actually
it is cleaner sounding.  I think I had raised the bass
level up a little too much on the active crossover.
After a few position adjustments, they are sounding fine++.

I am noticing improvements in dynamics.

Need to play some more with cables and amps.

So far so good!

Jeff

Nicely done sir.

what kind of efficiency do you get when using passive x-over on this OB??? TIA