Jordan JX92s in sealed box

fatmarley · 3rd December 2007, 08:57 PM

Hi Guys,

What would be the ideal box size for this driver in a sealed box. It would be used with a Rel strata 5 active subwoofer, so no need for maximum bass extension. Speed/accuracy would be more important.

Thanks in advance
Matt

Scottmoose · 3rd December 2007, 09:59 PM

Something roughly like a 0.1765 cubic foot box (5 litres), 10in tall, driver in the middle, with a CSA of 30.5in & stuffed 0.4lbs ft^3 of hollow fibre material should do the job passably (dimensions internal BTW).

fatmarley · 4th December 2007, 05:14 AM

Thanks for the reply Scott. I was thinking about adding the G2si ribbon tweater + crossover as in Jim Griffins design. From what i understand, as long as i keep the front panel to his dimensions, everything (The crossover values) should be ok in a 5 litre box.

Does anyone know what type of resistors and inductors i would need?

Any recommendations for the capacitors?

Cheers

Colin · 4th December 2007, 10:53 AM

Increasing it to 7.2 litres gives a Qtc of 0.707 and drops the F3 from 90 to 80Hz. It won't harm to increase it to 7.5L, giving you the option of using the enclosure either sealed or ported, as in Jim's 92/ribbon design, and a bit more flexibility with placement and/or high-pass rolloff on the REL.

Don't forget to allow for the cubic volume of the driver itself, which is around 0.4 litre. (I have an old, damaged driver and one day I will get round to dunking it in a measuring bowl to double check that figure.)

soongsc · 4th December 2007, 12:31 PM

Somehow I recall 9L.

Colin · 4th December 2007, 01:46 PM

Bit big for a max flat response. Maybe thinking of the 8L reflex on Ted's site?

Anywhere between 5 and 8 litres will probably do fine. More info on the Jordan site.

fatmarley · 4th December 2007, 08:53 PM

Colin, Have you got any recommendations for inductors/resistors for this project? I know bugger all about building speakers.

Or any hints/tips in general would be great!

Cheers

Jim Griffin · 5th December 2007, 02:19 AM

Matt,

You might start by reading about my Jordan with a Ribbon project at:

http://www.esnips.com/doc/0cd36443-0...SG2siDesignPak

Note the measurements with the port tube stuff to create essentially a sealed box. This is a 9 liters volume but the performance is very close to what would be achieved in a 7 liters box.

Six years ago I built my original JX92S mini-monitor in roughly the a 7 liters box and used a baffle step network of a paralleled 1.5 mH coil and 6 ohms resistor circuit which was then placed in series with the positive lead of the JX92S driver. You can change the resistor between 4 to 8 ohms to yield between 3 to 6 dB of baffle step. By the way you will need a baffle step circuit with the JX92S unless you mount the box flush against the wall behind it.

If you ever think you might build the version with the ribbon tweeter design, I would suggest that you build your box with the same front baffle dimensions as my design. Of course you would not initially cut out the tweeter hole and port tube in your box. Use the baffle step circuit as I suggested earlier until you get ready to cutout the tweeter hole. Then add the crossover and rewire the drivers (don't need the baffle step network as the crossover has inherent baffle correction) and you will be in business with the tweeter.

Another option is to build my version (sealed box without the port tube) with a tweeter from the start and you'll really be in heaven.

Jim

Colin · 5th December 2007, 11:13 AM

Yep, follow Jim's advice and you should be there. You could also cut the tweeter hole and mount a blanking plate if you're sure you'll go this route.

Inductors etc can be obtained from Wilmslow Audio or Williams-Hart and they can advise on type.

I recently tried my 92 MLTLs with baffle step correction and it made a big difference, balancing out a too-forward mid-range.

BTW, my partner now thinks I am mad but fifteen minutes with a water jug, bowl and a destroyed JX92S revealed that the driver's cubic volume (up to the back of the mounting flange) is 0.5 litre (+/- about 20ml).

fatmarley · 6th December 2007, 10:11 PM

Quote:

Originally posted by Jim Griffin

Another option is to build my version (sealed box without the port tube) with a tweeter from the start and you'll really be in heaven.

Jim

This is what i plan to do. It will be interesting to see how these compare to my Mk2 Linn Kans.

Thanks for the reply Jim.
Cheers
Matt

3rd December 2007, 08:57 PM	#1
fatmarley diyAudio Member Join Date: Aug 2003 Location: Cheltenham	Jordan JX92s in sealed box Hi Guys, What would be the ideal box size for this driver in a sealed box. It would be used with a Rel strata 5 active subwoofer, so no need for maximum bass extension. Speed/accuracy would be more important. Thanks in advance Matt

4th December 2007, 12:31 PM	#5
soongsc diyAudio Member Join Date: Mar 2005 Location: Taiwan	Somehow I recall 9L. __________________ Hear the real thing!

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4th December 2007, 05:14 AM	#3
fatmarley diyAudio Member Join Date: Aug 2003 Location: Cheltenham	Thanks for the reply Scott. I was thinking about adding the G2si ribbon tweater + crossover as in Jim Griffins design. From what i understand, as long as i keep the front panel to his dimensions, everything (The crossover values) should be ok in a 5 litre box. Does anyone know what type of resistors and inductors i would need? Any recommendations for the capacitors? Cheers

4th December 2007, 10:53 AM	#4
Colin diyAudio Member Join Date: Aug 2003	Increasing it to 7.2 litres gives a Qtc of 0.707 and drops the F3 from 90 to 80Hz. It won't harm to increase it to 7.5L, giving you the option of using the enclosure either sealed or ported, as in Jim's 92/ribbon design, and a bit more flexibility with placement and/or high-pass rolloff on the REL. Don't forget to allow for the cubic volume of the driver itself, which is around 0.4 litre. (I have an old, damaged driver and one day I will get round to dunking it in a measuring bowl to double check that figure.)

4th December 2007, 01:46 PM	#6
Colin diyAudio Member Join Date: Aug 2003	Bit big for a max flat response. Maybe thinking of the 8L reflex on Ted's site? Anywhere between 5 and 8 litres will probably do fine. More info on the Jordan site.

4th December 2007, 08:53 PM	#7
fatmarley diyAudio Member Join Date: Aug 2003 Location: Cheltenham	Colin, Have you got any recommendations for inductors/resistors for this project? I know bugger all about building speakers. Or any hints/tips in general would be great! Cheers

5th December 2007, 02:19 AM	#8
Jim Griffin diyAudio Member Join Date: Jun 2003 Location: Tennessee	Matt, You might start by reading about my Jordan with a Ribbon project at: http://www.esnips.com/doc/0cd36443-0...SG2siDesignPak Note the measurements with the port tube stuff to create essentially a sealed box. This is a 9 liters volume but the performance is very close to what would be achieved in a 7 liters box. Six years ago I built my original JX92S mini-monitor in roughly the a 7 liters box and used a baffle step network of a paralleled 1.5 mH coil and 6 ohms resistor circuit which was then placed in series with the positive lead of the JX92S driver. You can change the resistor between 4 to 8 ohms to yield between 3 to 6 dB of baffle step. By the way you will need a baffle step circuit with the JX92S unless you mount the box flush against the wall behind it. If you ever think you might build the version with the ribbon tweeter design, I would suggest that you build your box with the same front baffle dimensions as my design. Of course you would not initially cut out the tweeter hole and port tube in your box. Use the baffle step circuit as I suggested earlier until you get ready to cutout the tweeter hole. Then add the crossover and rewire the drivers (don't need the baffle step network as the crossover has inherent baffle correction) and you will be in business with the tweeter. Another option is to build my version (sealed box without the port tube) with a tweeter from the start and you'll really be in heaven. Jim

5th December 2007, 11:13 AM	#9
Colin diyAudio Member Join Date: Aug 2003	Yep, follow Jim's advice and you should be there. You could also cut the tweeter hole and mount a blanking plate if you're sure you'll go this route. Inductors etc can be obtained from Wilmslow Audio or Williams-Hart and they can advise on type. I recently tried my 92 MLTLs with baffle step correction and it made a big difference, balancing out a too-forward mid-range. BTW, my partner now thinks I am mad but fifteen minutes with a water jug, bowl and a destroyed JX92S revealed that the driver's cubic volume (up to the back of the mounting flange) is 0.5 litre (+/- about 20ml).

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