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How important is this cap? and is it's value, or Quality help please

qboneus

qboneus

Senior Member
I have finished with my re-cap of the B2101 but in the process I managed to damage one of the bypass? I think caps.
How important is this cap, and how important is the quality and is there and variance in the values used or that I can use to replace the one damaged?

Thanks in advance,
Tal
 
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Its not very importent, Improrves stability and extends the max. peak-power .....use 4x 1µF/100-250V Wima/RIFA/ERO or what ever good quality poly-cap and regard it as a mod. ;)

Ps. Im also having a B2101 on my bench for the moment, a few details missing before its finished :yes:
 
PMik said:
extends the max. peak-power .....use 4x 1µF/100-250V
Click to expand...

Don't see how it would appreciably influence the peak power adding 1uF to a 10000uF cap... stability is another matter, even though you will get most of the improvement due to a simpler load seen by the rectifiers (keep in mind there is a fair amount of wire from there to the amp, presenting a series resistance and inductance from cap to amp).
 
First of all...You see...by messure....1-50mS burst ;)

I have former been a part of a firm which made "High End" amps....to mention a 100Watt/8Ohm amp.....peak current 96Amps/0.1 Ohm. (926W)

Yes its correct the cap should ideal be located close as possible of the collector(s) for the final stage...but real life do have its limitations. ;)


Ps. qboneus to close the gab betwin the 10.000µF and 1µF caps....add 220µF/100V- par. ;)
 
Thanks for the advice,

the original was a .474 @100v(I assume on the voltage as it isn't listed)

I have readily at hand:
not in polys but the same as the original,
A set of mallory .68/100v,
A set of NTE .47/100v,
Or, a set of NTE .47/250v

Which of these would you use to replace the fallen caps?
I am lost about what you said about closing the gap are you saying I should also be adding a 220uf/100v cap in with the replacement?
What type of cap are we talking about?
Thanks and sorry for my confusion.
Warmest regards,
Tal

BTW the original only utilized one cap per bank of caps rather than 4 caps, one at each 10k, is this more desirableto use 4 ?
 
Yes...you can with audible improvement as the result, add several caps in par. the PSU will get a wider range of filtering.

"is this more desirable to use 4 ?"
Yes....more filtering is better ;)
But for easy mount. you can use 1x 220µF/100V- + 1x mallory .68/100v par. with the each bank of 2x10.000µF/100V- el-caps ....
I use almost the same (220µ+1µ) in my B2101.

"BTW the original only utilized one cap per bank of caps rather than 4 caps" one at each 10k

Thats correct....i did wonder about the metode sansui use for electrical placement of the el-caps, when i first had a closer look inside my unit. :scratch2:
 
so we are talking about adding 220uf/100V El caps?

I just so happen to have some Nichicon 110v 220uf Low impedance electro caps handy,...... also a bag of Nichicon UVZ radial electros 220/100 if this is what you are saying..
is this correct?

Would I install plus to plus/minus to minus or would I hook one leg of the mallory to the pos/neg leg of the electrolytic?
so I guess I don't know if the 220/100 is stand alone or hooked to the .68's


How are they wired is my last question. I hope.

Thanks a lot!!!
tal
 
The incredible bad drawing (sry for that and lol) made in a hurry, shows you how to add the caps for your B2101 ;)
 
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The addition of more electrolytic caps in parallel at the terminals of the large electrolytic is, IMHO, a waste of time and effort. Any additional filtering by an electrolytic ought to take place much closer to the load to be any real use, and the circuit designer has already taken care of that in this amp, I can assure you.

Bottom line is that, if you use a very good large electrolytic (and that Panasonic 10,000µf 100V cap is indeed a very good one), all you need is a small film cap to assist in helping the DC power supply to look like an AC short at all frequencies. Every circuit has its AC equivelent, and the intent is to have DC supplies appear as an AC short at all frequencies. Due to the construction of electrolytic capacitors, they begin to appear as inductors at the highest audio frequencies. Providing a 'shorting' path for these frequencies with a small non-inductive film cap is the way to do this.

To that end, I have a bag of 2.2µf 250V Panasonic ECQ-E(B) metalized polyester capacitors that are used solely for bypassing large electrolytic caps.
 
so it looks like one bypass across each cap is fine?

so I would put one .68 across two of the caps and the other electro's (220/100)would go across the remaining two 10k caps matching polarity of electro to electro?

And am I correct that you are referring to electrolytics for the 220/100?

Would using the nichicon HE Low impedance be more desirable than using only the nichicon UVZ high temp standards?

Thanks a lot for spending your time to walk me through this.

Warmest wishes,
Tal
 
we are two B2101 owners making exchange of facts about our amps :yes:

Dr. Jung had a quite different pov. in par. of caps....he claimed the same as you did in the great terms...if you read betwin the lines of his results, it was the skill of engineering there where demanded to get the best result when par. caps ... in short there placement in the practical layout :scratch2:

When we talk about lenght of cables from the PSU to the final stage in a B2101 ...you will for sure get higher peak current by adding these caps. :thmbsp:
 
The low impedance cap is the best of them.
heat should not be a problem...dispite the placement of the rectifire.
 
You read Jung, I read Pass. The additional capacitance is wasted at the end of the leads to the caps...it should be as close to the load as possible.

There is nothing wrong and it would certainly do no harm to add them at the terminals, but in my book, neatness counts. I'm not sure it could be done neatly.

Do what you like. Your gear, your decision.
 
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