bypass capacitor
canadianicon25
Posts: 200
i was doing some reading about caps and came across a review that stated that a particular cap should be used as a bypass capacitor. what does this mean? if the cap is simply paralleled to another isn't it just slightly adjusting the effective capacitance value?
Post edited by canadianicon25 on
Comments
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So why use a bypass at all? There are actually components of very high frequencies in some audio waveforms. Some are high order harmonics. If you think of a square wave, the right angles at the top of the wave are extremely high in frequency. Sometimes there are high frequency components in very fast audio sounds, for example, the instantaneous tap of a drum stick on a cymbal. These are the sounds that should be "helped" by including a small-value bypass capacitor in a high pass crossover.
Well, I don't think so. If the 8 µF capacitor blocks frequencies below 5000 Hz and passes frequencies above 5000 Hz, why do we need what is actually another crossover for the same tweeter, but operating at frequencies already passed by the big cap? I am sure engineers have a very good reason, and a couple of them have tried to educate me on this subject. I respect the science and electrical theory on this subject, and my technical background helps me to understand it fairly well. But there is one small problem: the bypasses all sound bad! They add a quality that at first sounds like an increase in air and detail, but after a couple of hours becomes an intrusive harshness and discontinuity in the upper treble. Remove the bypass: all of the detail is present but without that grating and annoying sound. The high frequencies are cleaner, smoother, and much more enjoyable. It doesn't matter if the bypass cap is Teflon®, polystyrene, or common polypropylene, the results are very similar. And to be avoided.
I found the above to be true.Political Correctness'.........defined
"A doctrine fostered by a delusional, illogical minority and rabidly promoted by an unscrupulous mainstream media, which holds forth the proposition that it is entirely possible to pick up a t-u-r-d by the clean end."
President of Club Polk -
If you want better detail, just use a better cap."He who fights with monsters should look to it that he himself does not become a monster. And when you gaze long into an abyss the abyss also gazes into you." Friedrich Nietzsche
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You should use better caps, but I have not found what the article says to be true, nor have some very well regarded designers (speakers and components) who swear by bypass caps...HT: Ninja Master LSi9s, Ninja Master LSiC, Slightly Modded LSiFXs, Modded LSi7s, Outlaw LFM-1 EX and Polk PSW125
Outlaw 970 Preamp, Outlaw 7700 Amp, Velodyne SMS-1, Oppo BDP-83,
2 APC H-15s and a Panamax 5400 for good measure
Stereo: DIY Alix Music Server, DODD Audio Battery Tube Buffer, Modded DAC-60 and MF V-Link (for now), DIY Silver ICs, Battery Powered Class D SDS-254 Amp, and GR-Research N2X Speakers -
Looking at the ultra high end, $20,000-100,000 speakers, I haven't seen any bypasses in any of those crossovers. The first part of your post sums it up, if you feel you're missing detail, use better caps."He who fights with monsters should look to it that he himself does not become a monster. And when you gaze long into an abyss the abyss also gazes into you." Friedrich Nietzsche
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Looking at the ultra high end, $20,000-100,000 speakers, I haven't seen any bypasses in any of those crossovers.
Agreed. The only place I've seen bypass caps in crossover designs is in speakers where it looks like a few corners where cut to save money; a bypass on an electrolytic for example. If you don't like the sound of your caps, simply try a new one until you are satisfied. I've even seen a crossover builder who built his prototype crossovers with screw terminals instead of solder junctions so he could easily swap parts and fine tune his crossover until he got the sound he wanted.
