Do bypass capacitors work on passive crossovers and what about shunt caps. . .

[erickalan77]

I post this as I was once searching this very question months ago and did not find the answer....

First let me tell, there is some one with a famous Capacitor test that states bypass caps don't really work in passive speakers, yet elsewhere states they did make a difference once with some Vishays. I also remind you Madisound (love you guys) is wrong to recommend that shunt caps don't make a difference.

I had some B&W DM5 I was trying to rebuild and tweek. A great design with a very high flux density, exponential (good midrange) cone. In an acoustic suspension so I would not hear midrange leakage or out of phase bass when I mix or master recordings. I wanted to make these buggers work.

I bypassed the polyester in line caps and shunt caps with high voltage Polystyrene. It cleared up a sizzle in the tweeter and opened up the depth in the tweeter and woofer (I bypassed the shunt remember). Now the tweeter still don't sound as good as a straight S.C.R. cap, but it sure did improve everything over the stock the polyesters in the crossover ( 3 in the high pass and 2 in the low pass). (subject was an XT-Vifa tweeter & B&W 7" driver)

I had made the mistake of trying the Bennic made Dayon precision caps.
These turds sucked the life out of my d27tg-45-06. Not the best but a damn good and flat tweeter, especially when you put wool in the pole and use high end caps. ( It has wool in the chamber). This was a fourth order crossover....To say I was dissapointed is an understatement. I was out right ticked off at the horrible muddy sound and loss of depth... Well after some time working on other stuff.
I revisted that system. I bypassed the the Dayton/Bennic caps with .1uF Vishay... the famous ones I won't name ( gotta keep prices reasonable).
Well some resolution and depth returned to the tweeter. It is not as clean as my XT tweeter, but I doubt anything under $400 and named JBL would (maybe) or it's sisters badge scanspeak. The bypass made a real difference.

Now this is no substitute for good caps in the first place. But if you can't get them, don't know what to buy, or can't make them fit...I high end cap used to bypass a passive crossover will make a difference.....

Warning : I use to be skeptical of bypass caps as I used dayton/bennic film/foils to bypass electrolytics in a Jensen Four...I heard no difference,
and only modded on speaker to compare them. Bypass can not save a really horrible cap, design or driver. But they can help mediocre caps. . . .

have a nice day.. . .
~erick~

[AllenB]

In my opinion, bypassing can bring mixed results. In theory it has benefits, but after much playing around with this in the past I tend to shy away as I think it sometimes makes things worse. I don't feel there are benefits as great as the failures can be, if that makes sense. I will use single caps where possible, even though the idea of sprinkling a handful of top notch bypass caps around is an attractive one.

[fatmarley]

It gave me sibilance when I tried bypassing a series tweeter cap (polypropylene) with 0.1uF polyprop. I read somewhere that two films in parallel isn't a good idea (can't remember the exact details though), but an electrolytic with a polyprop is fine.

[erickalan77]

I agree I would prefer to and will use single and parallel quality caps in the first place.
There is no substitute for a good cap and good design...I was fearful of adding capacitance to my tuned circuits...but I ran a simulator / designer that showed 5% tolerance curves due to 5% product or not getting absolute values....it showed vary little, rather insignificant drift off the objective slope.....now what happens to transient response I do not know.....with the topic brought up butterworth and linkwitz filters are blown away by bessel (?) for transient response so a system from scratch with low DA factor caps is likely to be quick, sharp and clean with great resolution of the mixed reverb. . . .
later,
e

[jcx]

capacitor bypassing/cascading......