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madotec
02-28-2010, 05:36 AM
hi,

i have been asked for duplicating the passive crossover of the japanese jbl 4348 speakers. i managed to get the crossover schematic and have a couple of questions about it.

the charge coupling circuits are using resistors stated as "2.2 mohm" in series with the +9V. Does it mean 2.2 milliohm or 2.2 megohm ? i suppose it means 2.2 milliohm but i can't explain why a so little value :blink:

also are the capacitors rated at 100VDC right after the +9V are polarized capacitors or non polarized ones ?

thank you so much for your help :)

dominique

Chas
02-28-2010, 06:10 AM
Megohms, for sure. Regarding the capacitors, can you post a copy? I suspect they are non-polarised, but can't say for sure without a schematic.

madotec
02-28-2010, 10:01 AM
hi chas,

here we are ;)

Chas
03-03-2010, 06:43 AM
Re. the capacitors, I would be guessing at what JBL used. It may be polarised electrolytics in the woofer (low pass) network and non for the rest. It's hard to say looking at the diagram.

If I were trying to reproduce the network, I would use Solens (fabrique en France!), I and some folks around here have had excellent results using them charge coupled.

pos
03-03-2010, 08:37 AM
I would use Solens (fabrique en France!)
Solen fast caps are made by SCR:
http://www.toutlehautparleur.com/mkp-serie-pa-250v-c-203_164_529_394.html

these are exactly the same :)

Zilch
03-03-2010, 11:34 AM
Re. the capacitors, I would be guessing at what JBL used. It may be polarised electrolytics in the woofer (low pass) network and non for the rest. It's hard to say looking at the diagram.No polarity being shown on the schematic, if they are electrolytics, they are non-polar.

Audio is AC. Polarized electrolytics don't work here.... ;)

Chas
03-03-2010, 12:20 PM
Of course....I am suffering from mental fatigue today....