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Old 4th December 2012, 02:13 PM   #12721
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Quote:
Originally Posted by jameshillj View Post
... the first cap after the diodes, ... that'll suffer quite severe current pulses without complaint -...

Hi all,

So we can espect a sorter useful livespan for first caps bank , then for second Bank after Resistor, If same time caps are used, due to work harder?

E.g. if we expect a useful lifespan of 8 years in second bank, can we expect about alf time for the first bank?

If so, Reducing the first bank will not worsen this problem?

Thanks

Last edited by carlomar; 4th December 2012 at 02:15 PM.
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Old 4th December 2012, 02:19 PM   #12722
6L6 is offline 6L6  United States
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Carlomar - The life of the capacitors is going to primarily depend on the operating temperature of those caps. Not the rating, but the ambient temperature inside the case. You will get more life out of all the caps, first and second bank if you have many vent holes on the bottom and top of the chassis to promote good airflow in the case. Also keep the amp exterior away from obstructions.

That will help more than capacitor selection.
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Old 4th December 2012, 03:05 PM   #12723
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Quote:
Originally Posted by 6L6 View Post
The life of the capacitors is going to primarily depend on the operating temperature of those caps. Not the rating, but the ambient temperature inside the case. ...
Thanks 6L6,

I know that, but my question goes in that diretion.
Due to warder work of first caps, it tendency to heat more tham second caps Bank. I am not refering to heat from chassis, but to heat from cap worK.

If we reduce the first caps bank, will it heat even more. I know it depens of the cap type and grade.

I think i remender read some think about caps heating due to poor capacity and hi corrent riple in one F5 tread.
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Old 4th December 2012, 03:27 PM   #12724
tinitus is offline tinitus  Europe
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Quote:
Originally Posted by carlomar View Post
I think i remender read some think about caps heating due to poor capacity and hi corrent riple in one F5 tread.
there was one member having this problem, yes

not all know that there are different cap types, also among the Pana
quite many actually
and not all have the experience needed to choose the right type in that cap jungle

even the similar looking snap in caps may vary from 2A to 6A
Im now looking at much smaller caps(different purpos)
some have up to 4A ripple current specs
and other of exact same size could have only 500mA

though, I do have 'small' Rifa 4700uf caps with 30A, at 40 degr temperature

but 6L6 is right
your box design and layout could make a difference
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Old 4th December 2012, 04:39 PM   #12725
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Quote:
Originally Posted by AndrewT View Post
Use your best capacitors after the R of the rCRC.
Ensure the caps before the R can take the ripple current that will be imposed on them.

Many smaller capacitors usually run cooler than a few big capacitors in this first C position.
Use cheap commercial caps for that first C. They are so far removed from the Audio Signal That comes later that they have virtually no effect on Audio Quality. But they MUST operate as capacitors for the first stage filtering rC to be effective. Fakes and undersized are no good here.

Back to the caps after the R:
These supply the LF current to the amplifier. They should be adequately sized to meet that LF current demand and they should be good for Audio. That does not mean they need to be exotic AudioPhool types, but they must be good capacitors that can release charge when demanded.
These 10 caps are original, not fakes are Vishay BC 15.000uF.

Both caps have left over the bank turned on in the 2nd, the F5 was connected any warms two hours, it was more to not stay 2 caps on the shelf.

They were connected as the schema in Red...
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Old 9th December 2012, 01:55 PM   #12726
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Hi there!

I want to start an F5.

Can I use instead of usual MBR's for the diode bridge, use IXYS High Current, Fast Recovery Epitaxial Diodes Freds, 2 x 30A 600V? And do I use than 2 of them? I have some of them from a damaged amp from the junkyard. Thanks for the answer. Teake
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Old 9th December 2012, 10:23 PM   #12727
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Hi intense-tavda,

in my std F5 i am using 2 briges IXYS VBE 17-06N07 27A 600v 35ns from Parts Conexion
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Old 9th December 2012, 10:27 PM   #12728
6L6 is offline 6L6  United States
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Those bridges should work well!
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Old 10th December 2012, 07:00 PM   #12729
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Thank you for the ansswer. So I will start. I'll let you hear how the building proces is going. Teake
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Old 11th December 2012, 03:45 AM   #12730
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If using the DIY-Store psu board with 8 x 22,0000uf 25v caps be to much for a F5 ? I had just found a really good deal on some....
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