0,01 uF cap on 4430 Xover?

[robertG]

Looking at the schematic of the 4430 Xover, I noticed that all caps were parralleled with another 0,01 uF cap. Why is that?
Thanks!

[spwal]

dont some people like those for "extra air". im no techie and in no position to talk. I did ask paul if i should put some low value bypass caps in my "new crossovers" and he said not to.

maybe someone else can clarify.

[Earl K]

- Here's Giskards' (Techbots' ) basic overview about Bypassing & Charge Coupling ™ capacitors .

- In my own experience, the audible benefits from employing both of these topologies far outweigh ( all ) the additional costs ( both, in physical area occupied and the additional purchase price ) . ( My "home use" horn drivers are Altec 288-8Ks ) .

-Yes ; ( I find that ) bypassing with Polystyrenes ( Film & Foil ) does add a bit of "air" into my perception of the UHF content / while I find that bypassing with Polypropylenes ( F & F ) typically enhances the "definition" of HF signals occuring an octave lower.

- Bypassing with both ;( I find that ) by playing around with the ratio ( formed by the 2 caps' values ) is a fun ( & very time consuming ) way to alter the sonic signature ( or presentation ) of the "base" cap .

- To effect some basic bypassing, I'd suggest starting with JBLs' recommended values ( .01 uF for polypropylene bypass caps ) and ( .005 uF for the polystyrene bypass caps ) . These stated values were empirically derived for use with JBLs' Mylar base caps . That's why I wouldn't be too dogmatic about their inclusion or usage ( & / or the values employed ) when a Polypropylene type cap is used as the base cap .

[spwal]

This is what was written to me. Please forgive me if i have taken it out of context and i will gladly erase it. It did however dissuade me from incorporating them into my setup..

"People will add a bypass cap and hear a change, which is there... they have added capacitance, changed the crossover freq slightly... there is a change. But is it better? Have they introduced a peak that should not be there?

And all of this is dependent on your room. You can increase or decrease response with your L-pads in certain ranges, certainly changing the sound.

I can hype the range by a few db from 4000-6000 hz and you will hear increased "clarity" or "stage presence" or "better imaging". I can hype 70 hz - 200 hz and many will hear this as more bass... but it is not true LOW bass. I can reduce the range of 500 hz - 1000 hz slightly and the male voice will sound a little hollow, perhaps "distant".

All of this can be demonstrated in freq response in different ranges. And swapping around caps will do that.

The things I look for in a good cap is accurate values, good voltage rating, and very important, long term retention of specs. An electrolytic from the 60's is likely to be dried out and way off value. Paper in oil can change, too. Poly films are the best as far as durability, and they all sound about the same. The Dayton (Bennic) and Solen are used in plenty of good speakers, Pro Audio, where price is no object. Hey, when you spend $400 on a woofer or horn driver, do you think they care if a cap cost $3 or $7?"

[spkrman57]

.01 ufd and .005 ufd will add very little to the overall capacitance in the the crossover.


"People will add a bypass cap and hear a change, which is there... they have added capacitance, changed the crossover freq slightly... there is a change. But is it better? Have they introduced a peak that should not be there? "

Ron

[grumpy]

"People will add a bypass cap and hear a change, which is there... they have added capacitance, changed the crossover freq slightly... there is a change. But is it better? Have they introduced a peak that should not be there?

Sorry. I don't buy it. Changing a value in the range of a very few percent (or much less) of a capacitor
in a crossover, in and of itself is not going to change a crossover frequency audibly.
The tolerances of the parts themselves are -much- worse than that.

That there can be an audible difference anyway (mild change in frequency response, etc...)
means that there is more going on than just a change in nominal capacitance value (or
other electrical characteristics) of the part...likely vs. frequency or level or ...

Any introduced "peak" due to cap bypassing I would consider the byproduct of an improperly used component
(faulty or poorly selected).

-grumpy

[robertG]

Thanks for the info. This is fascinating stuff. In the past 30 years I never saw networks using bypass caps to get better transients. Where's my solder kit?

[Robh3606]

There is no "peak" added from using bypass caps. The added value is insignificant compared to tolerance issues. Well under 1%.

Hey, when you spend $400 on a woofer or horn driver, do you think they care if a cap cost $3 or $7?"

Well yeah! business is business. Can you imagine how many caps a manufacturer uses in a year??? They would have to be total morons not too.

Rob

[doodlebug]

Now, there's a guy who's been to that mountain and came back to tell us something - thanks Giskard.

As for the bypassing, I do it when I install new caps but will not stray from the original values of the caps. I don't dwell on it but just redo them and sit back to enjoy.

Who am I to worry about details that far smarter engineers dealt with decades ago? Same logic applies to old tube amps, too.

Cheers,

David

[soundboy]

Not to beat a dead horse, but if you can't hear the difference between solens and others, then bypassing is a waste of time....it works, but sometimes makes things worse. Bypassing solens, for instance makes for a intolerable forward, overly bright sound. I ended up with SA series clarity caps in three different systems (dynaudio's, JBL 4406, JBL 4301B) and bypassing threw the image forward and made things way less musical than with just the claritycaps alone (which were a HUGE improvement in every way over the stock mylars). The origonal mylars sounded much better with bypasses. Much cleaner and extended than without....JBL wouldn't have wasted the money if it didn't matter....the values used are far more outweighed by the 5% tolerance of the larger caps...would never affect the networks....polystyrene is a tough one for me... .005 is the max....I tried .01 polystyrene, and it threw everything forward and changed the timbre too much. It's all a balancing act, for sure. Solens are only worthwhile in a top flight system for large low end networks....they are just to forward and bright for anything JBL IMHO...good mylar with quality bypasses actually sound better IMO in this case...and I have used a TON of solens over the years...FWIW

[spwal]

thats great. my new networks are on the way back to me and all solen

[spwal]

for what its worth, the sonicaps that i put in my Klipsh E networks in my heresys did a world of good over the tired old aluminum cans that were in there.

i think the solens will be fine. upgrading to anything over a solen at those values would have cost almost as much as the speaker itself. now that simply doenst make sense.

[soundboy]

I should have mentioned using the solens biased is a different ballgame. Without it, they are what they are. I didn't realize how much they "added" to the sound until I replaced them over the last year...mostly becoming aware of it because of this forum....and Giskard, amongst others....thought it was electronics, digital processor, preamp....at the time the solens were installed (90's) there wasn't a reasonably price alternative...now there are a few...I have used the PX series claritycaps, which are similar in price to solens, and they are night and day more neutral and transparent. The top SA's are even better, but somewhat more expensive (and HUGE)!...The sonicaps are more expensive yet...haven't tried them.

[spwal]

sorry... but in my stock model 19 altec crossovers, are the caps biased?

you guys have me all hot and bothered...

i had Jensen PIO copper caps in my cornwalls... talk about smooth.. but they would cost many many 100s of $ in this configuration.

remember, with the 19s i can adjust hf and lf, but would prefer to keep them "optimal"

please advise.
thanks!

edit: clarity caps dont seem to support the values i need anyway...

[Music Lover]

If I can add my thoughts on this subject ...... You will also find .01uF and sometimes 0.1uF parallel caps in some high end professional audio electronics as well, the reason for this I was always led to believe was to improve the Transient Response of the generally large inductive wound type of coupling capacitors, even if they are high grade they still exhibit inductance due to the foil winding, this inductance with the capacitance will naturally kill transients. These bypass caps are generally non inductive ceramic type or similar and generally included in circuit design as "good engineering practise". There will be absolutely NO change in crossover frequency that the ear could detect I'll stake my life on it.