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Its all about that big 10 incher!
One of the magical things about the 4340/41, 4343 and 4345 Monitors is the 10 inch Midbass driver. This driver helps the big woofer (15 or 18") handle just the really low notes, and keeps the horn/compression driver from having to go below its optimal range.
Here's a thread showing how Infredible redid the surrounds on a pair of those ultra-rare 2121s - http://audioheritage.org/vbulletin/showthread.php?t=3527
In an older thread, Giskard said
The 4343 uses the alnico 2121 and the 4343B uses the SFG ferrite 2121H. Both have the 4" inverted paper dust cover.
The 4344 and 4345 use the newer 2122H which has a harder 3" dust cap. It is less susceptible to break-up.
All of them use a 3-inch edgewound copper ribbon voice coil.
*****
"Isn't this inconsistent with what we would normally use above 300Hz? I would assume aluminum would be desired due to the lightness and quick response at the higher frequencies."
Sure, it just wasn't in the cards way back then. The newer 2123H uses an aluminum voice coil.
Thanks for that info, G!
One thing thats a problem for modern fans is that the original model 2121 driver is unavailable. It was replaced by the model 2122 - which is rapidly getting near impossible to find as well. You can occasionally find a replacement cone (as of May 2007) for a rebuild, but even they are in quite short supply.
Some folks have substituted the model 2123 driver - but its not equivalent, its more efficient (higher output levels), and has a different response curve that the earlier 2 drivers. You'd need to re-design the crossover and, frankly, its just not the same driver.
But some folks do like it.
For those who can read the design specs - here's a chart Giskard has posted numerous time showing the different parameters.
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Improvements to the 4343 Monitors
One of the first recommendations to improve the sound of the 4343 (or any of the big 4-way pro monitors) is to biamp the system. This means to use an external crossover circuit to separate the audio from your preamp into low frequency and high frequency ranges and feed those signals to a dedicated pair of amplifiers. The low split output feeds just the woofers, and is will be a much higher powered amp (200-300w/ch) than the high split side - the high split should be very low noise as the 2405 slot tweeters will tend to accentuate any hiss in the circuits.
Porschepm posted this link to a generic article on the basics of biamping: http://sound.westhost.com/bi-amp.htm#elect_xovers
Biamp image below courtesy of Ian
How to pull the drivers from a 4343 Monitor
Quote:
Originally Posted by
georgebrooke
Hi Fangio,
... At the moment the new foam is setting on the mid range units and the next step will be to strip the speakers down. The trouble is that I am not sure whether the back removes. Also, if I take off the front panel do I have to remove the speakers first, and what stops the units falling in if I do. Any ideas on this ?
:applaud:
George
Recommend you have some masking tape and a pen handy so you can label the various wires as you disconnect them from the drivers.
Lay a 2x4 or chunk of styrofoam or something on the floor (a book at the two top corners?) so once you lay the speaker on its back there is room around the edge to get your hands in and lift the cabinet back up later.
Put a towel on the baffleboard (so you can rest the woofer magnet there in a bit and not scratch anything up. If you have a lens on the horn remove that and put it aside. I have found the plastic snap on cap from a 1 lb can of Yuban (coffee) will slip on the open end of the horn and prevent the risk of something falling into the horn. (If you have to, masking tape will cover the opening just as well).
Lay the cabinet on its back. Remove the screws holding the woofer in place and gently slip a putty knife under the edge to give you room to lift it. If it doesn't come free recheck all the screws and then careful run the putty knife under the edge of the woofer frame to be sure its not stuck to the face (careful - don't want to nick the cone or anything). set the speaker on the towel and label the wires (LF red and LF blk - for the red and Black clips on the woofer) remove the two wires from the spring clips and move the woofer to somewhere safe.
Now, remove the screws holding the 10" midBass driver and lift it up, put it on the towel. Label the wires MB red and MB blk (as needed), unclip the wires and put the 10" somewhere safe.
Update - the following ONLY APPLIES to the 4343
To access the horn and slot tweeter in a 4343, you'll need to remove the upper baffleboard.
Fangio says there are two different -length screws screws used to hold that upper front panel on -
so I'd recommend making a drawing of the panel and noting which screws go into each hole.
Update - the following ONLY APPLIES to the 4341 -
To access the horn and slot tweeter in a 4341, stand the cabinet back up and you can remove the access plate on the upper back. I use a piece of styrofoam or similar to wedge it under the horn against the "dogbox" (the 10"s internal box) and support the compression driver. Now is as good a time as any to label the wires for the horn (HF red & HF blk), and for the slot tweeter (UH red & UH blk).
Go around to the front and you can remove the 4 big screws that hold the horn and compression driver in place. Do them in opposing pairs and reach your hand into the cabinet to support the driver as you undo the screws.
Lower the compression driver and attached horn into the cabinet, release the wires, and lift the whole assembly out through the access hole. You can do the same for the slot tweeter (2405)
Thanks to George and Florian for the info to update this procedure,
