Help on Jordan JX-150, JX-92s, G2si three way design

[Padel]

Hello all,

I have a pair of Jordan JX-150, a pair JX-92s and a pair of the Aurum Cantus G2si ribbon tweeters that i want to use in an active speaker system.

The bass box for the Jordan JX-150 is a sealed box, 40lt net volume, construction material is 25mm MDF heavily braced (matrix?) and the inside of the enclosure is covered with some pyramid shaped wood blocks against standing waves.

On top of the bass box rests the JX-92s (separate box, time align, on spikes) enclosure, net volume is 3lt and on top of it rests the G2si tweeter (separate box, time align, on spikes)

I will ''feed'' the sytem with three Gainclones/channel (tri-amp) driven by an active three way 24db/oct Linkwitz-Riley crossover which also have transform circuit (EQ) set for + 13db at 20Hz.

What i'm not sure about is the selected crossover frequencies for the system. I was thinking about 100Hz and 6000Hz.

Opinions?

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P

[jonk]

I personally wouldn’t try to get 20 HZ out of a jx-150 (I have a pair). At 20 Hz the woofer will run out of excursion at ~85db. IMHO you’d be better off using a bigger box (say 60-70L) and mounting the woofer close to the floor for added room gain and use very modest eq if any. I’d be temped to use something like a behringer dsp1124 (just over $100) for the woofer only to smooth out your bass response and pre-set various eq curves. For low volume listening you could go for a more aggressive eq. I also would use a xover of about 250hz to get rid of the floor bounce suckout that happens around 150hz (Allison). Of course that just my $0.02. Take it for what its worth.
Sould be a nice sounding three way.

[chris ma]

JX150 is an excellent woofer but it is not a sub woofer. I have found that once they were released from duty from 60Hz down it can play really realy well! But it just me I guess. Show us some pictures please!!

The Butcher

[Padel]

Hi, thanks for your replies,

So, you think it is better not to use the Transform circuit (EQ) on the JX -150? How about the crossover points? 250Hz is better than 110Hz for the low-mid?

How about the mid-high crossover point, around 6KHz?

Regards
P

[ScottG]

The JX92S is what you'll base your crossover on.

(looking at the graphs on the website..)

First the treble region:

Off-axis response starts droping around 2.3kHz. This (or slightly lower in freq.) would be the ideal location for your crossover. However I suspect that its to low for the G2si. Looking at the graph a bit further you'll see that the off-axis response isn't to bad at the 30 degree mark up to 3.8kHz. Considering the slope and the ribbon I'd say that 3.5kHz is just about right. Be aware though that padding down a ribbon resistivly is usually a bad idea (the alternative for a flat response is using a transformer).

Lower Midrange region:

Presumably the baffles for the JX92S will be narrow. This will cause baffle-loss starting around 400Hz. Additionally the box for the JX150 will also be narrow. Futhermore the JX150 doesn't appear to be any more eff. than the JX92S. Calculate what the lower freq. response of the JX92S response will be with the 3 lt volume. IF you are not using a highpass feature on the JX92S, AND you have enough response down to 100 Hz with the JX92S then you should be able to sum the drivers to "virtually" eliminate this problem by overlapping the response. As a guess I'd estimate that 320Hz would be about right for the JX150 with no highpasss on the JX92S. Jonk's meathod of floor-loading by placing the JX150's very close to the floor could offer enough gain for the JX92S's low freq. response to be un-neaded (i.e. you could have a high-pass crossover with it).

As for "eq.ing" the JX150, the problem with all the Jordan drivers is distortion with increasing excursion. Based on this I'd say the others were right about NOT eq.ing this driver. A good normal T-Line could extend the response (and the driver spec.s are excellent for this meathod). Of course to keep the visual signiture down on the speaker would require that the depth of the speaker would be increased greatly.

[GM]

FYI, Jim Griffin used 3kHz/3rd order to good effect:
http://maxhawk.bravepages.com/diyatl/

GM

[Padel]

Considering the slope and the ribbon I'd say that 3.5kHz is just about right. Be aware though that padding down a ribbon resistivly is usually a bad idea (the alternative for a flat response is using a transformer).

I think this is fair. But how about the idea of having a driver (JX-92s) covering a much as possible of the spectrum? What i'm saying is that the JX-92s is a hell of a driver BUT can not play loud when it must cover 9 octaves due to limited excursion and some cone breakup above 6KHz.

So the idea of the project is....i will dare to say it.....a three way speaker but as close as it can get to the single driver, that's why i was looking at extreme(?) crossover points.

Opinions?

Thank you all.

P

[GM]

Originally posted by Padel
But how about the idea of having a driver (JX-92s) covering a much as possible of the spectrum? What i'm saying is that the JX-92s is a hell of a driver BUT can not play loud when it must cover 9 octaves due to limited excursion and some cone breakup above 6KHz.

First off, the JX92S is not going to play any louder with a tweeter or super tweeter. Its practical limits will be dictated by where/how you XO it in the lower octaves, and as SG implied, how big the baffle is. Second, as he noted, there's the issue of its rising on axis response, which makes blending a tweeter problematic so IMO either use the Jordan as is, or go with JG's or a similar design.

That said, if you are one of those rare adults that have bat-like hearing, then I suggest you try a super tweeter XO'd really high, like start with a cap at 35-40kHz and work your way down until you can just perceive some added 'air' around the cymbals and violin strings, etc.. This should still be high enough that a poorly measuring polar plot will not be obvious due to our virtually non-existant spatial hearing acuity beyond ~9 kHz.

GM

[Norris Wilson]

Hi everyone, GM,

The bandor 150 model looks to be very close to the Jordan JX150. Has anyone compared these two drivers, could the Bandor 150 drivers be substituted for the Jordan JX150?

Norris Wilson

www.bandor.com

[Padel]

First off, the JX92S is not going to play any louder with a tweeter or super tweeter. Its practical limits will be dictated by where/how you XO it in the lower octaves, and as SG implied, how big the baffle is. Second, as he noted, there's the issue of its rising on axis response, which makes blending a tweeter problematic so IMO either use the Jordan as is, or go with JG's or a similar design.

I did not said that with an add-on tweeter the JX-92s it's going to go louder. I do understand that and that's why i'm using a the JX-150 to handle the lower octaves. Sorry for my english, must be the language barrier.

This thread is about how wide a JX-92s can go to get good results when placed between a JX-150 and a G2si.
The idea is to let the JX-92s to cover as much as possible of the audio spectrum. By placing the crossover points at 315Hz and 3KHz we are heading for a convencional three way system, not exactly what i have in mind.

P

That said, if you are one of those rare adults that have bat-like hearing, then I suggest you try a super tweeter XO'd really high, like start with a cap at 35-40kHz and work your way down until you can just perceive some added 'air' around the cymbals and violin strings, etc.. This should still be high enough that a poorly measuring polar plot will not be obvious due to our virtually non-existant spatial hearing acuity beyond ~9 kHz.

No, no, i'm not ........... Batman, i just feel that the top end of the JX-92s have some ugly cone resonanse, that's why the use of the G2si and with the addition of the JX-150 to handle the lower octaves the JX-92s can go much louder than all alone and for sure it's going to feel much more comfortable.


Regards
P