Charge-Coupled JBL 4435 Networks
- Thread starter Zonker92
- Start date
randallflagg
New Member
Good Day
Maybe somebody could help. Got an JBL 4435 speaker pair. Wanted first to change the terminals, cables, capacitors and resistors and get rid of the selector. Wanted to use mundorf caps - could align the components like i saw on other forum (see photo)
Now i wondering maybe its a good point to make a charged coupled crossover.? Do You have a schematic?
Maybe somebody could help. Got an JBL 4435 speaker pair. Wanted first to change the terminals, cables, capacitors and resistors and get rid of the selector. Wanted to use mundorf caps - could align the components like i saw on other forum (see photo)
Now i wondering maybe its a good point to make a charged coupled crossover.? Do You have a schematic?
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Zonker92
All shiny and chrome
Congrats, Randall! To charge-couple, simply replace each cap with a pair of caps in series, and inject some voltage between the two new caps:
Double the capacitance value of the original cap and run it in series with a second cap of the same doubled value. To the connection between the two replacement caps, run a wire carrying some DC voltage.
You can draw that voltage from a battery or from the amplifier input (rectify it from the AC signal). Here is a sample showing the battery approach; you can see all the caps in series, with the battery input running through a 3 megohm resistor into their junctions:
So if your original cap was 1uF, you'd run two 2uF (approx.) caps in series, take a lead from the positive terminal of a 9-volt battery, run it through a 3-megohm resistor (use a separate one for each pair of caps) and into the connection between the two new caps. The battery's negative terminal would run directly to the negative amplifier input. You need only one battery but there MUST be a separate resistor for each pair of caps.
Alternatively, you can get AC voltage from the amp's positive input, run it through a 10K resistor and a 1N4935 diode (converting it to DC) and connect that to the junction between the two caps. Again, there must be a separate set of resistors and diodes for each pair of caps.
Some people say this diode approach could add noise so they prefer the battery approach. I've tried both and noticed no difference.
As you can see from my photos above, the two caps will be much larger than the single one they replace, so it can be necessary to mount them separately or differently from the original setup.
Double the capacitance value of the original cap and run it in series with a second cap of the same doubled value. To the connection between the two replacement caps, run a wire carrying some DC voltage.
You can draw that voltage from a battery or from the amplifier input (rectify it from the AC signal). Here is a sample showing the battery approach; you can see all the caps in series, with the battery input running through a 3 megohm resistor into their junctions:
So if your original cap was 1uF, you'd run two 2uF (approx.) caps in series, take a lead from the positive terminal of a 9-volt battery, run it through a 3-megohm resistor (use a separate one for each pair of caps) and into the connection between the two new caps. The battery's negative terminal would run directly to the negative amplifier input. You need only one battery but there MUST be a separate resistor for each pair of caps.
Alternatively, you can get AC voltage from the amp's positive input, run it through a 10K resistor and a 1N4935 diode (converting it to DC) and connect that to the junction between the two caps. Again, there must be a separate set of resistors and diodes for each pair of caps.
Some people say this diode approach could add noise so they prefer the battery approach. I've tried both and noticed no difference.
As you can see from my photos above, the two caps will be much larger than the single one they replace, so it can be necessary to mount them separately or differently from the original setup.
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