Dang these Jordans!

[soongsc]

Two pairs of drivers in series and both in parallel with each other would average out the power, thus the effeciency of the array would be the same as a single driver.

I would really recommend Jordan's MJ sub, otherwise if you can get a hold of some JX150, those would drive more air for larger rooms, and might be a better choice dynamic range wise.

Use foil inductors with Jordan drivers to get the best results. Make sure you got good sized wires in your inductor.

 

[Jim Griffin]

Two pairs of drivers in series and both in parallel with each other would average out the power, thus the effeciency of the array would be the same as a single driver.

I would really recommend Jordan's MJ sub, otherwise if you can get a hold of some JX150, those would drive more air for larger rooms, and might be a better choice dynamic range wise.

Use foil inductors with Jordan drivers to get the best results. Make sure you got good sized wires in your inductor.

On the 4 drivers in the Jordan linear array (2 strings in parallel of 2 drivers) you will attain an increase in acoustical efficiency of 3 dB because of the paralleled drivers. Hence, the efficiency of the array is NOT the same as for a single driver but 3 dB greater.

 

[soongsc]

Two parallel lines of two in series make the impedance the same. Since there are two parallel lines, then each get half the current. Since there are two drivers in series for each line, the voltage drop across each driver is half. This results in 1/4 watt going to each driver. How does the additional 3db come about?

 

[Jim Griffin]

Two parallel lines of two in series make the impedance the same. Since there are two parallel lines, then each get half the current. Since there are two drivers in series for each line, the voltage drop across each driver is half. This results in 1/4 watt going to each driver. How does the additional 3db come about?

I agree that the array impedance is the same as for one of the individual drivers. Actually, my original statement was incorrect. With more cones and overlapping sound fields you'll have acoustical or efficiency gain. It goes by 10*log (Number of Drivers Driven). Thus 10 log (4) = 6 dB. See my line array white paper for details.

Jim

http://www.audiodiycentral.com/resource/pdf/nflawp.pdf

 

[Colin]

Presumably the overlapping sound fields also means that the increase in efrficiency won't occur across the whole bandwidth of the drivers but will come in below the point where the separation distance is half a wavelength?

 

[Colin]

Meanwhile ... back to Dave's posts. That's valuable information about crossing over from the JX92, to reduce the amount of bass it receives. One or two people have recommended leaving the 92s to do their own thing. Your approach makes much more sense.

 

[Jim Griffin]

Collin,

Your concern about spacing is correct. The 6 dB is not acrosso the entire frequency band. In my line array white paper I detail that you will not have the array gain beyond the frequency wherein the center to center spacing between the drivers is less than one wavelength. Beyond one WL, and especially at 2 WLs and above spacing, you will have comb lining in the vertical axis. The array sensitivity will also start to decline.

Jim

 

[planet10]

That's valuable information about crossing over from the JX92, to reduce the amount of bass it receives. One or two people have recommended leaving the 92s to do their own thing

I have been saying for 30 years that the biggest improvement with adding an active woofer -- and a high pass on the sats -- is improved midrange. The caveat being that in a system with good revealing power, the active crossover electronics can sometimes negate the improvement... my Marchand XM9 went for that reason -- the veil it added was just too much.

dave

 

[JVA]

Dave I hope you don't mind me staying on this thread, seeing there is a lot of Jordan people here. Thanks Colin ; Jim ,others for some insight on the array. Colin I love to get info. on the 33 L, BR enclosure. This would probably assist in bringing up the 125's efficiency to match the array. Im using one 125 per side,but would want to cross over at a higher frequency, as indicated on the Jordan website.This would involve using a 2 MH inductor to cross over at 500 HZ.Colin if you get a chance , ask Ted what parameters to use. The drift I got is that running the 53;s in parallel,series,would be the same as one,except, higher efficiency.To end I think I have some of the last 125 's Jordan has made,thanks to Bob from C.S.S.
Joe

 

[JVA]

This is the speaker that I'm planning on building.

Joe

 

[JVA]

This is the sub and my future rear surrounds.

Joe

 

[Dave Jones]

Meanwhile ... back to Dave's posts.

Thanks for the try, but once a thread gets hijacked, it stays hijacked.

 

[Dave Jones]

I have been saying for 30 years that the biggest improvement with adding an active woofer -- and a high pass on the sats -- is improved midrange. dave

Say it a little longer.

 

[JVA]

I got the hint Dave ,thanks for using your thread,i'm still a little new at forum protocall ,but thanks for all your input.
Joe

 

[soongsc]

I agree that the array impedance is the same as for one of the individual drivers. Actually, my original statement was incorrect. With more cones and overlapping sound fields you'll have acoustical or efficiency gain. It goes by 10*log (Number of Drivers Driven). Thus 10 log (4) = 6 dB. See my line array white paper for details.

http://www.audiodiycentral.com/resource/pdf/nflawp.pdf

The calculation is correct if you have the same amount of power going through each driver. But in the array configuration, the power to each driver is only 1/4 of the power if driven alone. Wouldn't that get you back to the same effeciency?

 

[planet10]

To end I think I have some of the last 125 's Jordan has made,thanks to Bob from C.S.S.

Here is another JX125 option (i have the plans with dimensions too)

dave

 

[Colin]

Im using one 125 per side,but would want to cross over at a higher frequency, as indicated on the Jordan website.This would involve using a 2 MH inductor to cross over at 500 HZ.

Hi Joe

The 500Hz crossover is for a single JX53 and it isn't necessary to go this high with the array. I've heard Ted's and he let's it run to 100Hz using the recommended frequency compensation on the site. I've used this design (1x JX53 and 1 x JX125) and IMO, you can detect the 500Hz x/over point as the slope is so gentle.

The BR port dimentions were 2 ins diamter by 11 inches long, for 1 JX125 in the 33L BR.

GM has also designed a MLTL for the JX125 - is this the one you posted, Planet10? I'm not sure how a MLTL.

Colin

PS Jim - thanks for info on the spacing of the array. I have your paper and it's fascinating reading.

PPS A complete hijack, but I played around with the Augsperger tables for an offset TL and the alignment seemed to work out for a JX53 array. F3 was about 130Hz, if I remember right, with a line length of around 36 inches.

 

[Colin]

Always finish your sentences:

I'm not sure how a MLTL would compare with a BR operating purely as a bass enclosure.

 

[soongsc]

Jim,

The array spacing white paper was good information. This does make me wonder why the Jordan JX53's were designed to make the drivers as clos together as possible. It seems this would be necessary for real closeup listening.

George

 

[JVA]

Thank you very much Colin for info. I will probably go with the 33BR or the transmission line. Planet 10, any chance for those dimensions? I will start my one thread on these speakers and inform on how they do once thay are built.
P.S. Thanks to Dave Jones and sorry for the hyjack. Good Luck.

Joe