Considering upgrading both electrolytic and film caps

[arsun]

Thank you for the comment. I thought also that it would be nice to hear one change at a time, but then I decided against it because of the burn-in times of the caps especially.

If the teflon wire is ok, then I will probably use it, cause I have some spare now. I am thinking of using some blu-tack to hold the caps in place.

 

[ssssly]

you can build a simple rig to burn in caps. That way you can burn in a bunch at once and then install them at your leisure. I forget where the link is but it is someplace in the community section. Came across it looking at Foreplay II stuff linked there.

I normally use velcro to hold large caps to the sides of the case until I decide if I like them or not then I if I am going to keep them in I'll make a simple bracket out of an old cotton T-Shirt. Kind of like a little cap sock and screw it to the inner wall of the case. Blue tack is great for vibration dampening but if you have a decent size cap it will only keep it in place for so long (in my experience). But I also shoehorn some huge PIOs into my gear. My Foreplay has about 2lbs of caps in it.

As a slight aside this post inspired me to get some resistors to test out in my gear. I let you know the results I get. Got a combination of Takman metal films and Shinkoh Tantalums for the signal paths and C4S in my paramours.

Be well.

 

[ssssly]

Found the link for that cap burn in rig, click on "jsn's foreplay page" on the community page.

 

[Grainger49]

 .  .  .   I thought also that it would be nice to hear one change at a time, but then I decided against it because of the burn-in times of the caps especially.   .  .  .  

You can burn in a pair of caps for a week then start on the next pair.  That way you listen to each improvement for a week while preparing the next tweak.  

I have used this successfully many times.  My fast burn in method doesn't do a whole string of caps at a time but it puts a higher voltage across them while burning in.  In addition to the higher voltage amplifier output, the more caps you parallel the lower the current becomes through each one.  That is why I do a pair at a time.

Click Here For My Post On A Fast Break In Method

I'm not saying JSN's method is bad.  I haven't tried it, I don't know.  

 

[arsun]

I know it's a bit late, but thank you very much for the information about burning in. I appreciate it...

Some recent news, due to budget constraints, I still did not order anything, but will do so in 2 weeks. I made up my mind about pretty much everything, however the size of TubeCaps are making me consider about them. I can shave a bit size and some money, if I switch from TubeCap to the MKP line of capacitors again from Mundorf. I can also pickup the correct value of 22uF with MKP. The problem is that they are rated 400V, not 450V as the manual recommends. How tight is the recommendation for these electrolytic capacitors? Also, does anyone here have any experience with that MKP line?

Before I forget, I got the top metal plate and the top part of power transformer powder coated by some local company to a very nice green. If you are in Chicago area, I recommend uvmetalarts for that. No affiliation, just a very satisfied customer. Their prices are also very fair. I will post some pictures in the gallery section as soon as I finish it. I also have a different headphone jack (which makes me think how to install the 120R resistors, but still ) and teflon tube sockets. I polished the top sections of MQ irons, they are nice and shiny. It is looking really good. I am looking forward to finishing this project... 

 

[Paul Joppa]

I recommend that you NOT use 400v rated capacitors in the SEX amp; stick with at least 450v rating for the electrolytic capacitors.

There are two ratings, the working voltage and the surge voltage. The surge rating is the maximum short term voltage, valid for only a few seconds. This should be compared to the peak voltage in the power supply, which occurs shortly after the amp is turned on, before the tubes start to conduct. In the SEX amp, with the design value of 120v from the line power, that is 470v. Allowing for up to 10% extra (132v line) which is within some specifications for power lines, the peak can be 515 volts. Surge voltage ratings for 400v capacitors are 450v; for 450v caps they are 500v.

In normal use the power supply produces a nominal 380v, which becomes 420v at +10% line voltage. However, capacitor lifetime depends on temperature, with the best lifetime occurring when operated at 50% to 80% of the rated voltage. So ideally I'd like to use 500v or 550v  capacitors - unfortunately those ratings are very rare.

Polypropylene capacitors have an expected lifetime that is dependent on temperature and voltage. At 85C and rated voltage, they are expected to last only 5000 hours, but at 90% of rated voltage they are expected to last a 80,000 hours. (This comes from some CDE data sheets; there's a wealth of information available there for those who are interested.)

I can't find the data right now, but mylar is more sensitive and I would not operate a mylar capacitor at more than 70% of its rated voltage.

 

[arsun]

Thank you for the information you provided. Seems like Tubecaps are the best option then, they are rated 600V anyway... Here is another question then, do you see any benefit of upgrading 220uF capacitors? The tubecaps only go to 200uF at 550V and MKP goes to 220uF at 250V. If there is a benefit of upgrading these, then I might add them to the order too, in that case, which option will be better specs wise? They are the same price with this value of cap... I really appreciate your valuable comments. Thanks again.