Output Capacitor Upgrading Questions

[EniGmA1987]

I am going to be upgrading my output capacitors and doing a smaller bypass cap. However, I had bought a 0.1uF Mundorf Silver|Gold+Oil for the bypass cap use and I am seeing a lot of people on this site are going with values closer to 1uF. I also happen to have some 2.7uF Mundorf Aluminum+Oil here, would it be better to use the 2.7's or the higher quality 0.1 capacitors for the bypass? Or should I hold off and get some 1uF capacitors to use?
The larger output cap will be staying stock for a little while longer until I do a couple other mods, and once I know how much space I have left I will be replacing them with either some 100uF F&T electrolytic's or some 85uF Clarity film caps if I have enough room.

One more question for output capacitors that will probably be really crazy, but just wanted to ask about before I give it a try. I know that capacitors in series block DC, but can pass AC if the frequency is high enough. Smaller values of a capacitor can "bleed through" more frequencies. So my crazy idea is, what if I used a silver mica capacitors in series on each channel right before the headphone out, in the range of something like 0.0001uF so that pretty much all the frequencies could get through (probably cutoff at 10Hz or lower) but would help to block out any remaining DC voltage that is still around? Would that idea even work at all? Do you think it would sound absolutely horrible? Is every little bit of DC filtered out by that point anyway so it is useless? I am thinking of trying it out just to satisfy my curiosity, and the experiment can always be undone afterwards anyway. I just wanted to ask about my idea first in case it would make the amp explode or something (lol) if I were to ever try it.

 

[Grainger49]

Capacitors in parallel add.  You bypass by putting the capacitors in parallel so you are passing lower frequencies, one or two Hz, using a larger capacitance.

As for bleeding, this happens at startup.  As the capacitor(s) charge a small amount of the DC voltage bleeds through.  That is the function of the resistors on the output jack.  There is also a sticky in the Crack folder that describes a way to make that voltage even lower.

You don't want to put anything in series with the output capacitors.  It will block a lot more frequencies.

 

[2wo]

I think you have the wrong idea about caps in series and blocking DC. The main purpose of the output cap is to block the DC and allow the music (AC) thru. Any decent cap will do an effective job blocking the DC but has to be sized to allow the low notes to pass. your idea of inserting a very small cap in series will block all but the most extreme high frequencies...John       

 

[ZacharyP]

Has anyone here attempted to replace the two coupling caps with two Solen 100uf 400v mkp?  Also any reccomandations on a film cap to replace the last electrolytic in the power supply?

 

[ZacharyP]

Forgot to mention I'll be replacing the last resistor in the power supply with a triad c7x choke.  If I understand correctly this means I can use a lower uf capacitor, but it shouldn't be any lower than my coupling caps, so I'd be looking for 100uf ideally.  I'm still kind of new to this and I've done hours of reading at this point still trying to fine tune my understand.

 

[Grainger49]

Zachary,

A number of Bottleheads have used the C7X in the Crack.  Not everybody availed themselves of the opportunity to upgrade the last cap with film.  Do a quick search and you will find several different values for that final cap. 

IMHO, going to film is a good step up.  Going to a designer film, high $, isn't necessary.

 

[ZacharyP]

Grainger,

Thanks for the reply.  I think I'll stick with my Solens and fit them in as my coupling caps.  I agree, it seems that capacitor prices are here to remind us just how diminishing the returns can become

 

[Grainger49]

There is no "Like" so:

 

[EniGmA1987]

So as part of my massive no holds barred upgrade to the Crack I am upgrading the output coupling caps and one or two of the filtering caps to film. I am wondering if anyone knows the sound difference or an opinion on which is better between the Mundorf MKP and aluminum EVO capacitors? They are the exact same price for 150uf capacitors. The MKP description talks about things like low loss factor, but then there is a ZN series (that doesnt go high enough uF) that in their description talks about having a loss factor 10x lower than the MKP's! So are they really very good? Maybe the EVO's are better? I dont really know because I cant find much info and descriptions for the EVO series. Another thought would be to use Clarity Cap 175uF TC600 capacitors, that specifically list an ESR of 1mOhm and low ESL. I was planning on using these Clarity caps for the PSU filtering but maybe I should just use them for both tasks? Model numbers are:

MUNDORF-71347 <- MKP series
MUNDORF-76417 <- EVO aluminum series
CLARITY-77666 <- TC600 series


Also when I move from 100 to 150Uf, should I leave the output jack resistors at 2.5k or drop down to a bit lower?

 

[Paul Birkeland]

Also when I move from 100 to 150Uf, should I leave the output jack resistors at 2.5k or drop down to a bit lower?

The -3dB point moves by 3 Hz going from 100uF to 150uF (not worth it), and the size difference between those caps will be huge (really not worth it), and the 2.49K resistors won't be a good value.


-PB

 

[Grainger49]

Funny, and it puts it in perspective.  Those 3 Hz might be one note, but I doubt it. 

 

[mcandmar]

I recently picked up some 100uf and 150uf JFX poly caps on eBay, curious thing is both are 50mm diameter but the 150uf is exactly twice the length of the 100uf.  My brain is having a hard time trying to rationalize that one..

 

[Grainger49]

I think the value of the capacitance is relative to the area.  They decided to make the plates taller rather than wider before rolling into a tube.

 

[grausch]

Well, received shipping notice for my Speedball this morning ;D

I now have quite a few upgrades coming, but was a little hesitant to order output caps. Firstly, I suspect the difference after the Speedball install will really be minimal, and secondly, I don't really know which caps I would prefer ("different spices" as per Grainger).

Was going to order the Mundorf M-Caps, but reread the capacitor review at http://www.humblehomemadehifi.com/Cap.html and did a quick ebay Germany search for the Jantzen Cross Cap. Found the Cross Cap for a third of the price of the M-Caps. Don't think the M-Caps will sound 3 times better, so I have 2 of the Jantzens incoming.

Once those are mounted, I think the only non-upgraded parts in my Crack will be the tubes, top-plate, transformer, and PSU caps...Literally everything else either has been or is in the process of being upgraded.

 

[Grainger49]

The Speedball should be one of the largest sonic improvements you will make.  It has been in everything I have put a C4S into.  Next will be improving the capacitor that the signal passes through at the output.  IMHO.

So, enjoy!

 

[grausch]

I still need to decide on the sequence of implementing the improvements. Currently the Crack is stripped down. I needed some new cloth wire (as it does not take kindly to being twisted with a drill) and USPS still hasn't updated the shipping status a month after the label was created. Once I receive that, the build can progress further.

Updates that will affect the sound that are all incoming are:
Schottky diodes (saw richmi's build and they were cheap)
Output caps (everyone needs big caps 8))
Speedball (since this will make the biggest difference, definitely interested)
Triad C-7X (after all of the above, I figured, why not?)

Buildwise, I am not sure yet which upgrades will go in first, but Speedball will go in before the output caps. Everything else is still up in the air. Any suggestions on a preferred order?

 

[lth1]

I have just rebuilt my Crack.  Here is a list of the things that I upgraded after the original Crack build.

-New 7 X 10 top plate so that all of these items can fit without being overly crowded", the main reason for the rebuild, and was able to reuse my burl top
-Speedball
-silver/gold input wire (could not believe the difference this made, only need 24")
-Goldpoint attenuator (IMHO the first thing that should be change in any bottlehead kit, usually install dual mono Khozmo  attenuators for the 48 steps and balance control)
-output caps 108uf (used paralleled 54uf aerovox caps)
-power supply cap 108uf (used what I had on hand, same paralleled caps as output caps) and CX-7 choke, started out with a 47uF solen, then 4 22uF solens, sound seemed to improve with each increase in uF, but could have been just wish full thinking
-Cree schottky diodes (do not believe that this is necessary, but usually install them in all of my builds anyway, just covering all angles)

Hope this helps, the stock Crack is a very good amp, but with these mods it is just amazing. 

 

[Grainger49]

Awesome!

 

[grausch]

Lee,

Are you telling me you rebuilt the "Custom Crack" of yours? That is a phenomenal build...can't wait to see how it looks now.

I am just thinking about an upgrade path that will make me notice differences of each individual upgrade. Generally I am sceptical of hearing differences, but I plan on upgrading a certain part, maybe listening for an hour or two, upgrading another part and so on.

Speedball will most likely make the biggest sonic difference. Installing the Schottky's early on will be much easier than installing them at a later stage. Thus, still need to plan the build out a little so that ease of installation is maintained and sonic upgrades are noticeable.

 

[EarWorm]

I just grabbed these two from Hifi Collective.  The price is very good at the moment.