Bypass capacitor questions


I have built new crossovers for my Thiels using mostly Clarity CSA caps. On the coax board, the two feeds and subfeed are bypassed with Multicap RTX (~1%). I am super happy with the SQ improvement. Well-recorded music sounds fantastic, just sublime. Really hard to fault, especially at this price point. Excellent transients with resolution and transparency for days; adding the RTX added a bit to the transients and resolution. But poorly recorded music is now more evident than ever and can sound relatively "cool", even thin, most notably on vocals. I’m wondering if a double bypass or different bypass cap might add a bit more flesh or hint of warmth. The Jupiter copper foil at 0.01 uF caught my interest but I’ve read reports that this small of capacitance can be inaudible, as well as reports that it can make a big difference (eg, humblehomemadehifi review of Dueland bypass).

Two questions:

a) do you think a different bypass or double bypass would result in the sound I seek?
b) if yes, more likely to get a good result with Jupiter double bypass at 0.01 uF or, say, Audyn True Copper Max at ~1%.

Budget: something more affordable than Duelands!


beetlemania
The rtx is bypassing a 'clarity cap'?

If so try and go to a single cap of one type.

We don’t know what cap is being bypassed, is the deal.

Your language is a bit imprecise, regarding clarity.
Sorry, I'll try again.
Nearly all of my caps are Clarity CSAs.This includes two caps directly in the coax feed and one subfeed.
These three caps - and no others - include RTX bypass.
I compared, in mono, with and without the RTX to discern their impact on SQ. Then added RTX to both channels.
Without knowing the crossover topology it’s very hard to give you advice.   In general bypassing a dull cap adds sparkle at the expense of phase issues (sibilant sounds move forward) and squeakiness (if bypass caps are too high a value).  Your post is IMO better answered on diyaudio rather than here. 
Btw I wonder how your Thiels have a “coax “board. Are you referring to the PCB that houses the crossover for the mid highs vs the woofer?  
I have repaired botched crossover jobs by people who just swapped in boutique caps into crossovers and blindly followed the 1/100 bypass rule.  The Zobel and the LCR filters do NOT need boutique caps.  The bypass rule normally applies to high voltage regulation and not speaker crossovers. Also size and vibration and cold solder joints are key concerns for diy speaker mods.  Be careful and think twice.  
My suggestion is about 0.1uF.
Try Audyn True Coppers. They are very good, and relatively inexpensive. If you can't hear a difference with those, you likely won't with others.

I don't like to get complicated in bypassing. I would not suggest multiple different types of bypass caps being used at the same time.
I would not suggest multiple different types of bypass caps being used at the same time.
Interesting. Thanks for the comment.
The thing about bypassing is that if you try it in an RF circuit you get: fire.

What this tells you is that you might gain some clarity due to speed increase in pass through, but there is still a problem of trapped energies in the temporal domain, ie phase issues, in the paring of the caps.

Which also means that some of the energy is being trapped and released, out of phase, for a bit of ’temporal smear’.

The ear hears this and can sometimes relate to it as increased detail. But due to smear, it can also be obscuring signal clarity. Both happen hand-in-hand.

This is why bypass caps should be no more than 1/10th the value of the main film cap it is bypassing, and more like 100th the size.

This, to try and avoid resonant can modes in the pairing under high slewing high current.

Which is especially possible in audio circuit use, due to very complex and exceedingly wide bandwidth considerations, which no RF circuit would ever encounter. Not just likely (I was being polite), but that it will be there, in some way or another, in a given audio circuit application.

It’s a trade off game, with all that in mind and being listened for. It can be half increase in quality and half increase in smear for the impression of greater clarity but really, the exact opposite.

Bypass caps are most efficient when the impedance differential is the greatest, as in in conjunction with an electrolytic cap. The large impedance differential between the two caps...helps avoid high level can resonances in the paring. the can resonance will still occur ...but the benefit outweighs the detraction, in most cases of properly done film bypass of an electrolytic.

Where with a pair of film caps, the can resonance problem is virtually guaranteed to happen in some notable way. The counter argument is that the smear is really fast, and of less importance due to the very high speed aspect. You decide, with all that in mind and being listened for.

Thus, for audio and pure film caps in the given application, the best direction is generally the highest quality single cap you can get in there, and like the sound of. It might be darker to the quick analysis... but in the final analysis, more correctly scaled detail will emerge, in my experience. To get this part right is important so that mistakes in changes are not made elsewhere to compensate for mistakes made here. Then it’s just an insane correction circus with no end (as the mistake was missed and thought to be a real and correct backdrop).

Importantly, you can’t have this discussion I just brought up at DIY audio. To many opinions raging on at the red cape of the thing I just said. There would be no discussion, just attacks, for suggesting that the ear is as important as the biblical dogmatic math. Math which came from human minds (and math exists no where else- math is conceptual, it is not a reality) which were considering realities. But never mind that fundamental contradiction in engineering dogma.....


Beatle
i guess my inclination would be to turn to Tomthiel and others who focus on first Order filters for guidance....
i know RV is a fan of WIMA properly bypassed and with zobel  network as required and DBS as well ( sharing a patent w Low of Audioquest )
i agree that it is both a listen / measure thing - one reason why every Vandersteen above the model 3 goes into the anechoic chamber for fine tuning. As for phase and timing impacts, few more passionate about the science, math and listening for that than JT, RV and of course Dunlavey.
have fun !!!!
" increase in smear for the impression of greater clarity "
teo_audio is a wise sage.
Remove the bypass caps.  Only bypass in power supplies not in speaker crossovers as the results are oftentimes all over the board and impossible to predict.  Bypassing in crossovers makes the sound phasey and not quite right. 

Also look to the resistors.  Remove sandcast and replace with Mills MRA. 
Bypassing in crossovers makes the sound phasey and not quite right.
That was *not* my experience. I heard sharper transients and a tad more resolution with the RTX.

The first change I made was replacing the sandcasts with Mills MRAs. That was a really nice improvement in SQ for short money. So much so that I'm curious to try a Path Audio resistor in a key position.

Thanks for the responses everyone. I think I will stand pat for now. I mean, I'm *very* happy with the sound I'm hearing. Easily the best ever in my room. Just with the downside of TMI on poorly recorded music, a problem Michael Fremer and others have complained about with some speakers. But, honest reproduction of the recording is a "problem" I'm happy to have.

@teo_audio, very interesting information!   I'm going to apply it in my next high-end audio crossover build. 

Suppose you have a situation where you must use multiple capacitors to arrive at the desired value.   Based on your comments, I presume that using multiple identical-value capacitors, where possible, would be the best approach? 

Duke

Sharper transients is your phasiness rightbthere. I think several of us are willing to bet $ you will pull it out eventually esp if you listen to classical music.  
willing to bet $ you will pull it out eventually esp if you listen to classical music
Interesting. From my listening notes in mono, a couple of concerto selections were among those where I most greatly preferred the sound of the RTX bypasses (there were a few songs in other genres where I was hard pressed to identify any differences). The RTX channel sounded richer and fuller than the channel sans bypasses. Yet another example of no "one size fits all".
Path Audio resistors are the best.   Very neutral and so smooth.  I love them. Dislike bypass caps unless the combo is a known homerun. Still think that combo is causing issues.  Just my opinion. 
I heard nothing deleterious with the bypasses, only positive changes. YMMV.


If it’s a mid-range coupler and you are bypassing say 47uF with a 0.47 to 1uF it makes sense. Further bypassing with 0.01 ventures into the realm of astrological psychics (not astrophysics). Bear in mind there is something called a RC time constant which I think is second only to Ohm’s law when it comes to audio. The 0.01uF bypass will assume your midrange plays radio frequencies if it’s a 4-8ohm driver.