JX92S monitors

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I bought a pair of boxes from Parts Express. http://www.partsexpress.com/pe/pshowdetl.cfm?&PartNumber=302-704&DID=7 They are billed as .25ft^3, but the small prints says they are really .3ft^3. No matter. I used the recommended BSC circuit comprising a 3.9 Ohm resistor and a 1.5mH coil. At first I thought it was a bit much, but after moving the sub about a bit, it's fine. I glued the coil to the bottom of the cabinet in the front section using Goop (tm) goop. It's not going anywhere. I put open-cell acoustic foam on the back wall, and filled the boxes loosely with poly fiber from the crafts store.

I had to enlarge the holes in the back of the cabinet to accommodate the binding posts I used. Here's something I learned about drilling holes through veneer: Scribe a circle where the perimeter of the new hole will be with an exacto knife, then put tape around it. The idea is to try to prevent the veneer from chipping. I did okay.

A friend who owns a high-tech machine shop cut the speaker openings for me. I forgot to tell him where to position the bolt holes, and he put them on the top, bottom, and sides. The bolts interfere with the decorative grills. The bolt holes should be rotated 45 degrees.

I don't think I'll use the grills anyway. In order to put the grills on so they'll hold, you have to push some press fit sleeves into the attachment holes on the front baffle. It doesn't look like they would be easy to remove if, for some reason, I wanted to remove the baffle.

For cosmetic reasons, or maybe because I couldn't think of anything else, the center of the driver is positioned at the golden ratio on the front.

The mains are crossed over to a sub at 80Hz. It's made with a Peerless 10" XLS driver and passive radiator in a box that's slightly under 1ft^3. I also have it running through a Richter Scale which provides some EQ for room modes and a steeper rolloff on the lowpass filter than the plate amp on the sub provides. It's the same sub that was described in the thread about the Locust I.

Obligatory gushing:

I can't believe how good this setup sounds. There are duet parts that I've listened to dozens of times that just sounded "duet." Now they sound like two individuals singing a duet. There are other recordings that I thought had "shout" in some places. Nope. With these units the shout is gone, although there is plenty of treble. Sibilants are perfectly defined but not zingy. Orchestral music never has the "blob with spikes coming out of it" sound in the louder passages that most speaker systems produce. The bass is solid and punchy. I can't find a thing to complain about.
 

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Hi Dave,
nice work...
I've seen on your last picture that you used those plugs
that are used in car electrics to connect the Jordans.
I recommend that you solder the wire to the jordans,
those plugs will get loose with time and sound quality
will decrease....
I often refurbish speakers, the first thing I look after
is if all connections are soldered. It makes a big
difference...
 
knorke said:
Hi Dave,
nice work...
I've seen on your last picture that you used those plugs
that are used in car electrics to connect the Jordans.
I recommend that you solder the wire to the jordans,
those plugs will get loose with time and sound quality
will decrease....
I often refurbish speakers, the first thing I look after
is if all connections are soldered. It makes a big
difference...

I thought about that. I tried to solder the connectors, but the solder wouldn't flow. I need some flux, I guess. Maybe I'll buy some gold plated connectors.
 
Colin said:
Hi Dave

They look a really neat job.

As for the gushing ... I've had my MLTLs up and running for a week using these drivers. I can confirm that the imaging is just incredible.

Colin

What strikes me is the clarity, particularly when voices sing in harmony. These little guys rival my Lynn Olsen Ariels in musicality, but because of the sub, the bass goes close to an octave lower.
 
Colin said:
Hi Dave

They look a really neat job.

As for the gushing ... I've had my MLTLs up and running for a week using these drivers. I can confirm that the imaging is just incredible.

Colin

What did you do about BSC? I've got these pretty close to the back wall. I think I could use a little lower ohmage resistor with the 1.5mH inductor. I'm using a 3.9 ohm resistor. I tried bypassing the BSC entirely, but that was not good.
 
Hi Dave

No BSC, just wire straight to the amp. I'm using the taller MLTLs (the 48" versions) and they don't seem to need any frequency compensation, even out in the room. Have you tried them without? I'd have thought that used with a sub you could get away without it.

BTW, regarding soldering the terminals, I'm a fan of Wondersolder, not because of any claimed sonic benefit but because I've always found it easier to use (soldering is not my favourite activity). I guess any lead-free solder would have similar benefits.

(I have to admit that the MLTLs are currently connected via 5amp mains cable. I was planning to sort out that sort of thing once I tried them to make sure they worked - I've been enjoying them so much I haven't got round to it yet.)

Colin
 
Colin said:
Hi Dave

BTW, regarding soldering the terminals, I'm a fan of Wondersolder, not because of any claimed sonic benefit but because I've always found it easier to use (soldering is not my favourite activity). I guess any lead-free solder would have similar benefits.

Colin

I thought Wondersolder was just relabelled Ersin multicore....


It's a Wonder that they can charge so much for it.

:)
 
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