Jim Griffin's JX92S designs

[Colin]

Without pre-empting Jim, my guess is that 3k allows the tweeter to take over before the JX92 becomes too directional.

BTW, reference Jim's post a little earlier: I've been running a smaller JX92 system and sub combination. The sub is a Rega Vulcan, capable of reaching below 30Hz in my room (it has a claimed low of 17Hz). It crosses to the smaller system at 60Hz. Compared to the MLTL, there is very little in it. The MLTL can reach 35Hz and I prefer the MLTL bass overall as the stereo extension into LF gives it more depth. (This may be an illusion, I guess, caused by setting off two sets of room resonances rather than one.) However the sub makes a very tidy system.

[Jim Griffin]

Colin said: "Without pre-empting Jim, my guess is that 3k allows the tweeter to take over before the JX92 becomes too directional."

That is exactly the reason for the crossover at 3 kHz. The JX92S begins to be directional at that point so the crossover was set to assure that the in-room response was well balanced between it and the ribbon tweeter. The goal was to maintain wide dispersion across the frequency band with a good power response. Beyond 3000 Hz the vocal range is limited so you don't cause noticeable impact on vocals.

Also I agree with Colin on the subwoofer. For most music you should not need a sub with the MLTL version. Unless you favor bass heavy music, the sub will not add much.

[navin]

Originally posted by Jim Griffin
Colin said: "Without pre-empting Jim, my guess is that 3k allows the tweeter to take over before the JX92 becomes too directional."

forgot about that. but in that case why not use a good 5" midbass or is the JX92 really a good midbass with a HF response that allows it to be used as a fullrange?

Forgive me for playing devil's advocate here but I am just trying to debate the use of the JX92 as a midbass. I hope there are no hard feelings. I have great respect fro both Jim and Colin (as well as Ted Jordan).

[Jim Griffin]

Navin,

I doubt that you will find another 4" driver that can match what the Jordan JX92S will do for its size. The JX92S has a low Fs (45 Hz), good extension (Xmax is 4.5 mm), reasonable sensitivity, and for a metal cone driver it has few audible breakups. Plus it produces sound that doesn't fatigue. While you can likely match the performance of the JX92S with a 5" or 6" driver, the enclosure size increases and the sound quality may suffer in the process. Finally, a quality European made driver, for example, from the Seas Excel or Scan Speak lines will cost just as much as the JX92S. Bottom line is that the JX92S is a excellent mid-bass driver for a two-way system such as mini-monitor or MLTL.

Jim

PS - I have my Jordan JX92S/Aurum Cantus G2si MLTL configured so that I can switch between the two-way version or the full range JX92S. Hence, you can hear the spatial content that the ribbon tweeter adds vs. just the JX92S alone.

[navin]

Originally posted by Jim Griffin

I doubt that you will find another 4" driver that can match what the Jordan JX92S will do for its size... While you can likely match the performance of the JX92S with a 5" or 6" driver..a quality European made driver, for example, from the Seas Excel or Scan Speak lines will cost just as much as the JX92S.

PS - I have my Jordan JX92S/Aurum Cantus G2si MLTL configured so that I can switch between the two-way version or the full range JX92S.

Comparing the JX92 to a 5" driver (like Scan Speak's 15W8530 as used in th3 ZD5) may not be right. Most 5" drivers I know need far bigger boxes than the JX92 can work in. In fact I have realised that the JX92 is very flexible in the variety of boxes it can work in from a 3 liter sealed box (with limited F3) to a 25 liter TL. The 8530 for example needs atleast 10 liters.

If one had to compare the JX92 to another driver one would have to consider drivers like the Excel W12CY and maybe the FR125/WR 125. Of these the W12CY costs about as much as the JX92 BUT does not have the extended HF response of the JX92 but when the JX92 is mated to the tweeter we do not use the HF response anyway.

I am sure the G2Si adds a lot of air to the JX92. I also understand that the reason the crossover point chosen is so low is becuase of the beaming of the JX92 at above 3K. I have heard the JX92 in a 8 liter box and while it's LF and midrange is excellent I did not like it's HF so I appreciate the need for a tweeter. The electronics used were a Roksan CD player and amp.

I was just wondering (since we are now talking about 2 ways instead of fullranges) if there would be another woofer-tweeter combo (W12CY mated to the G2Si, OW4, Seas T25 Excel, or Scan Speaks 9500 / 9700) would offer a credible alternative with similar low freq extension, midrange smoothness and HF air in a small box. The W12CY used in the example above is about 3-4db less sensitive than the JX92.

For HT however I think the JX92 is a fantastic driver as it allows you to use it as a fullrange AND as a 2 way. I know of only the FR125 that allows this (albeit I have not heard the FR125/WR125).

[Colin]

I think if you compare the specs of the FR125, it doesn't compare as a replacement for the JX92. Higher fs, lower sensitivity. But it's lower cost so you makes yer choice. The 92's versatility is a bonus to a good-sounding driver and has stopped me bothering about trying the rest.

[Ray Collins]

Colin,
Are you still running yours without the ribbon?

Ray

[Colin]

Hi Ray

I like the 92 as is, so haven't pursued the ribbon route. I did try it with a rough and ready crossover to the JXR6, which did clean up the highs. The JXR6 has a particularly fine HF but even used on its own, down to 120Hz or so, I prefer the imaging on the JX92 and I'm convinced this is due to its directional characteristics.

I'd like to hear the ribbon variant sometime, though, to see what my more hairshirt approach is missing.

[albertshi]

Hi, Jim,

Thank you for your suggestion.

I believe the the MLTL is great plan for this driver. However, I like my current speaker very much! I didn't mean this speaker leak bass, actually I think it is very nice on everything compare to its compact size. I had owned ProAC Response 2.5, the mini-monitor still has lots of good feature can beat that expensive speaker! It doesn't need any upgrade for most music, including Jazz, My concern is synphony only. I don't want to abandon my current cabinet and rebuild a new one. I will consider to build or buy a sub-woofer to enhance the bass.

BTW, could you please send my your original mini-monitor KIT plan and tech information? If I build a sub, what approximate frequency cut-off I should set on the sub?

Thanks again!
Albert

Originally posted by Jim Griffin
albertshi,

I am assuming that you have my mini-monitor design with the JX92S in a 0.5 cu. ft. box. With a ported box this design goes to 55-60 Hz as the 3 dB rolloff point.

You have several possibilities to consider. The easy way to add a sub would be to retain your current speakers and then build the sub to blend with them. I haven't used the Seas L26 but it widely used in 3-way speakers and would be able to blend in with the Jordan drivers just fine. I would stuff a sock or a piece of acoustic foam into the port tube and crossover in the 80-90 Hz range. Thus the minimonitors would be acting as a sealed box which would relieve their low end cone movement versus the ported box.

If you are willing to consider a non-sub solution, take a look at using your JX92S drivers in a new enclosure. My Jordan with a ribbon MLTL design does the trick in this case. It is more full range--goes below 40 Hz on the low end and extends better on the upper end because of the ribbon tweeter. Likely, it would suit your type of music just fine.

There is a thread that talks to this design at:

Jordan with a Ribbon MLTL

This design is the best JX92S version that I have built and I highly recommend it. The boxes are easy to build and the ribbon tweeters are currently on sale for 30% off at Parts Express.

If you need help with the Jordan with ribbon MLTL design, please contact me.

Jim

[Jim Griffin]

Albertshi,

I don't have a link to the original mini-monitor design but the mini-monitor with a ribbon link below will summarize the enclosure construction. The original mini-monitor used a 1.5 mH coil and 4 ohms resistor in parallel and that circuit was then placed in series with the positive terminal of the speaker for baffle step correction. The mini-monitor with a ribbon write-up is at:

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

For subwoofer integration I suggest that you stuff the port on the mini-monitor (effectively makes the box a sealed enclosure) and crossover in the 80-90 Hz range.

Jim