and, external coincidentally avoids any 'microphoning' effects on the bigger caps induced by high woofer SPLs, I bet.
If thats Don Julio, I'll cover your back!
ok, ok, I'm *so* outgunned in these forums, all I'd be good for would be deflecting bad jokes like this...
If you are familiar with the sonic virtues of SE class A sound there certainly are analogous effects to Charge-Coupling capacitors in loudspeaker applications.
Of course the merits of this technique become fully apparent when you use SE biased amplifiers as I do ie Passlabs X250.5 (this amplifier uses a trickle of SE bais in addition to significant push-pull class A bias operation, the result is superior high frequency performance and imaging...the 2405/077 never sounded so good)
If anyone has any doubt about C-C, build one normal XO and a C-C XO for the same speaker. Then listen to them in near field.
The first set of LCRs (L212) I built, I built the normal XO using many JBL original parts(new). Two years later I built a pair of C-C XO for the L/R speakers. I then I replaced the XOs in the first pair of L212s I bought in '79 with the first set of XOs I built.
Well for a period of time I had those original L212 wall mounted in this room, they were a bit harsh in the mid-range. For surround duty they were quite good.
At this time I have the pair with the C-C XOs wall mounted in this room, and they are as smooth as silk.
Living in the Land of the Sun
so how come the biased cap designs I've seen haven't also had bypass caps?
[/me ducks and runs laughing maniacally..... is it Friday yet? ]
If all the caps in a C-C network are Polypropylene there's no point to adding bypass caps.
As the reason JBL started using poly bypass was the main caps were mylar caps. And adding the poly bypass makes the sound more dynamic.
One exception might be for using polystyrene bypass to make the highs more open.
Living in the Land of the Sun
I finally got around to trying charge coupling a few months ago and was immediately impressed with the results. I added my thoughts to a thread on the Audio Asylum:
http://db.audioasylum.com/cgi/m.mpl?...charge+coupled
A few words from a complete non-techie who just loves his speakers:
Fwiw, I love my CC network. It is external and wood mounted with adjustable knobs and all Solen caps.
It is made for the 4345 I believe, but I am having no issues at all running it with my 4341.
I don't feel the need to mess with the knobs 90+% of the time from the 12 o'clock position (neutral).
One question that I know has been answered before -- how often do you change the 9V batteries????
And how about another thank you to the forum -- I wouldnt have such a wonderful sounding stereo if it wasn't for everyones help and input! I don't come here enough these days... (off the audio upgrade merry go round).
I am reluctant to link hi res pics of the crossover and my setup in a public forum, but if you are curious to see pics, just send me a pm and I will shoot them over to you.
the obvious answer is, when they aren't outputting 9V anymore. I'd bet they are good for 3-4 years assuming the series resistor is on the order of several megohms as I've seen in most of the diagrams. I'd use a volt meter on them every so often to confirm they are still OK
Usually the shelf life of the battery is the same as with several million ohms of resistance in series.
I would check them once a quarter to verify the voltage to be sure.
Also, the capacitors when hooked up the 1st time will need some time to fully charge to their potential. Sometimes that may take up to 24 hrs to maximum performance. Also, removing the battery will take about the same time to notice the lack of bias.
I hope I'm right with this information.
Regards, Ron
JBL Pro for home use!
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