It had to happen eventually... capacitor upgrade question for the Mainline

[Alonzo]

I went thru a number of comparisons from 10 to 30 and settled on 15uF Jupiters.  I found these to be the best bass without losing any sparkle for my setup (HD800's - Mainline -fed by BiFrost MB).  It took about 2 weeks of back and forth to settle on these or Mundorf Supremes.  But my experience is limited to Mundorf, Jupiter and Obligatto oilers, there may be better caps for bass and more affordable ones out there. 

[Doc B.]

I would caution folks that sometimes the perception of more bass is more about the overall tonal balance that the cap delivers than the effect of more capacitance. That is to say, with two different 10uF caps you might perceive different bass presentation just because one of them sounds softer in the highs.

If you really want to know what's going on with the bass, you need to run response curves of the amp with each type of cap installed into a load that best represents the headphones you will be using. The idea is that the cap is part of a resonant system. As the cap value changes the resonance frequency shifts - bigger uF = lower frequency. The ideal cap value positions the resonance just below the amp's "normal" rolloff, mostly determined by the plate load inductance. This gives the bass a little more extension by creating a sharper knee to the LF rolloff. If you go too big with the cap you might get a dip at the rolloff frequency and a resonance bump somewhere below the dip. Too small and you will probably hear the classic small box speaker type of midbass hump as the resonance dominates at some frequencies above the normal LF rolloff.

I know that objective measurement seems like too much work to a lot of people. It's worth learning how these parts work if you're going to mess with them in a useful manner.

[ALL212]

Thanks Doc! 

I think you've a point.  I shouldn't say the bass is lacking and the balance is excellent.  I'm probably just a bass junky and am looking for my fix.   

What I probably should do is expand my listening experience with headphones to see if I really need "more bass" or if the headphones I'm using are lacking a bit.  That, over chopping up my Mainline anyday...

[deserat]

So my Mundorf Supremes in the coupling position have settled in delightfully.  Now I'm wonder what to mess with next. Am thinking of replacing the Daytons on the c4s board or possibly doing a bypass on the coupling caps.  Anybody done this? Thoughts on effectiveness or values for doing a bypass?

[Paul Birkeland]

I haven't ever heard a coupling capacitor bypass that I thought did anything positive. 

The Mainline isn't one of those kits where there are really any parts to upgrade other than the coupling caps.

[deserat]

Thanks .  Wasn't sure there would be anything meaningful from other mods. What I hear now is so astounding. But then, I didn't think there could be anything meaningful before I put the "better" caps in in so I thought it would be worth checking.  On to the Crack-a-twoa

[JamieMcC]

Not been any posts here for a while

Been trying out a new secret sauce recipe in the Mainline 10uf RTI Teflons topped off with a dash of of Duelund Cast Copper the results have been pretty yummy...

[Mordicai]

I'm installing some auricap and would appreciate a check on the installation. The short lead is the black lead and goes to 20u and 30U ?  The leads are beautiful but very long. Should I trim them or just let them be?  Another question: is it possible to remove one spring and ball bearing from the Attenuator after it has been built?

[Paul Birkeland]

The black lead is the outer foil, and generally goes toward the source side, not the load.  The source side is the side that connects to the 9 pin socket, which is 20 and 30.  It's a very good idea to provide extra mounting support for heavy caps.  Even using something like blu-tack to stick each cap to the chassis plate will be really helpful.

Yes, you can pull out a spring and ball from each switch after they are built. 

[Mordicai]

Thanks Paul.

[AllanMarcus]

Any thoughts on these rike caps for the mainline?

https://www.partsconnexion.com/RIKES-84093.html

[Paul Birkeland]

Any thoughts on these rike caps for the mainline?

https://www.partsconnexion.com/RIKES-84093.html

They are about 3.5" in diameter and 4" long.  600V caps will be much larger than 250V ones, and I don't think you're going to get these to fit without some custom fabrication.

[AllanMarcus]

Thanks for the thoughts on size. Very good point.

Any recommendations on specific Mundorf's or teflon or copper? There's just so many out there to choose from.
 

[Paul Birkeland]

A 10uF teflon cap will be about as big as your head, and you'll need 2 of them.

These should fit nicely:
https://www.partsconnexion.com/MUNDORF-71341.html

[AllanMarcus]

A 10uF teflon cap will be about as big as your head, and you'll need 2 of them.

These should fit nicely:
https://www.partsconnexion.com/MUNDORF-71341.html

LOL! It wouldn't be the first time someone has put the caps external to a Bottlehead amp! :-)

Thanks for the pointer to the "Mundorf Capacitor 15.0uF 250Vdc MCap® Classic (MKP)"
I gotta ask, though, if this cap is significantly better, why not include it in the base build? It's only $10.82/ea. I assume they would be a little cheap in bulk or wholesale.

Is it "better" or just different than the included caps?
mcandmar mentioned on page one that a high quality mundorf cap ("supremes at a minimum") would be warranted.
The "Mundorf Capacitor 15.0uF 600Vdc MCap® Supreme" is 41mmW x 106mm L - would that fit?
The "Mundorf Capacitor 10.0uF 600Vdc MCap® Supreme" is 36mmW x 106mm L - better fit?
The 10uF are $57.40/ea at MadiSound. (+$6 to $9 shipping)
https://www.madisoundspeakerstore.com/supreme-caps/mundorf-10.0-mfd-supreme-caps/

What's the  sonic difference between using the 10uF vs the 15uF?
 

Also, just re-read Loquah's post (#74). Thanks