PDA

View Full Version : Bookshelf 2-way crossovers..



austx
12-29-2011, 03:47 PM
I recently replaced the surrounds on the LF drivers in my L26A and my 4301B speakers and now I'm interested in replacing the capacitors and anything other crossover 'maintenance' needed..the problem is that I don't know anything about this except what I've read on the internet (mostly on this site, great site!).. I've read opinions regarding inexpensive vs. expensive capacitors, bypassing etc..I'm soliciting any and all help/suggestions/instruction.. one thing I have a specific question about is when I look at the schematics for the two speaker systems the 4301 has a 16.5 uF cap that I suppose is a high pass filter, but the L26 does not have a capacitor in that area of the crossover at all..why?.. thanks.. scott

austx
12-29-2011, 04:00 PM
learned how to do this thanks to folks here..
now I want to learn more!..

5426454265

grumpy
12-29-2011, 04:07 PM
Nice looking work!

L26A? HF has to pass through that 8uF cap ... Schematic
diagrams can be arranged in a number of ways... some are
more readable than others.

austx
12-29-2011, 04:23 PM
thanks..
I have an ailment now..I've found myself searching craigslist for more vintage JBLs with rotten surrounds..

let me ask this way..these are similar loudspeakers..2-way, JBL..
why does the 4301 have two caps (16.5uF and 7uF) while the L26A has only a single cap (8uF)?..

DavidF
12-29-2011, 09:34 PM
thanks..
I have an ailment now..I've found myself searching craigslist for more vintage JBLs with rotten surrounds..

let me ask this way..these are similar loudspeakers..2-way, JBL..
why does the 4301 have two caps (16.5uF and 7uF) while the L26A has only a single cap (8uF)?..

Probably the simplest answer is that JBL voiced their pro models differently than the consumer versions. "Voiced" means the crossover components are tweaked for desired effects in sound reproduction or intended applications. The 16.5 cap in series with the 5 ohm resistor is to smooth out the woofer impedance as frequency rises. Appears to be what is commonly referred to as a zobel circuit.

austx
01-02-2012, 10:38 PM
thanks for the reply..I was curious about the crossover design differences given the similarities between the two models..the L26s have a more 'open' sound than the 4301Bs..

I have been intending to do the Zilch crossover rebuild on the 4301Bs I read about here:

http://www.audioheritage.org/vbulletin/showthread.php?20249-4301B-Crossover-Rebuild&highlight=4301+crossover

do any of you have suggestions/comments?..this seems to be a relatively inexpensive maintenance/upgrade and possibly worth the small investment considering the modest value of these speakers..