Drivers for sale

[John Warren]

Need to clear some room for new test gear.

 

http://northreadingeng.com/For_Sale/For_Sale.html

 

[toolz]

John, you have a PM.

[John Warren]

The 2404H units are sold.

 

The 2123Js are still available.

 

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[Dr Morbius]

What time period are those University speakers from?

[John Warren]

They're out of the White Plains, NY facility.  I'd say early 60s.  The model was available without the co-axial mounted tweeter as early as 1957.  

Edited March 6, 2015 by John Warren

[Marvel]

Are the 2123Js what you used on the mids for the Khorn project? Those in the cabinets with the 2404s would blow away most folks mid horn systems.

 

Beautiful drivers.

 

Bruce

[John Warren]

_{Hi Bruce-}

 

_{Thank you Sir!, I hope things are well with you.}

 

_{I used the 2123Js in the mid-horn project but the ones being shown in the boxes were not the ones used.  These are from a stash of JBL units I have that I'd like to move.  Other than a few sine-sweeps and impedance measurements they have no real use time.} 

 

_{The Klipschorn 2123J+2404H tops were sold.  When I made those, I used good birch ply but wasn't interested in making them "pretty".  The buyer was, and had them finished in white gloss to match the folded bass units he finished in the same way.  I thought they looked interesting.}      

 

_{The 2404H is (was) a good, high output tweeter but there are better units available today.  The 'MTM" configuration shown in the photos was driven by a dedicated "mid+HF" amp (a Hafler) with a passive net.  The output clarity was the first thing (I) noticed and good to about 300Hz.   I'd bet that the setup using the 2123Js, if heard by anyone accustom to listening to horn mids will make them think long and hard about using mid-range horns for critical listening.  You realize that there's a lot more to hear from the source material, especially if it has lots of dynamic range.}

Edited March 7, 2015 by John Warren

[toolz]

The 2404H is (was) a good, high output tweeter but there are better units available today.

   John, what tweeters would you consider better?  

[John Warren]

A customer sent me a pair of Faital Pro HF108 compression tweeter units with STH102 horns attached.  He wanted to replace the stock K77s with them.  He sent his K401 mids too. 

 

Since the Faital has much wider bandwidth than the K77, it allows to put the K401 on a diet by cutting it's high end output with the net (first plot).  I tried 4.0, 3.8, 3.4, 2.8 and 2.2kHz.  With the grille cloth in place, 2.8kHz seemed to provide the "smoothest" crossover response (not terrible phase response) so I went with that (second and third plot).

 

The harshness, spit, etc. heard from the stock K401 is gone.  It's easier to listen at higher volumes.  New baffles for the stock top-end sections are required which requires some work to fab but it's straightforward.  Nothing fancy on the network, L-pads, run-of-the-mill polypropylene caps and a few air chokes.

 

He says his wife listens to the rig on her own, something she did not do before he made the mod.   

 

That said, I would consider the Faital units somewhat smoother than the 2404H.

Edited March 14, 2015 by John Warren

[John Warren]

The 2404Hs have better dispersion.

 

Edited March 14, 2015 by John Warren

[John Warren]

^{Price drops on 2123Js and the McCauley!}

 

^{http://northreadingeng.com/For_Sale/For_Sale.html}

Edited March 22, 2015 by John Warren