Gonna "bust a cap" in my LM3875.. What size cap? - Page 2 - diyAudio
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Old 8th May 2014, 02:57 PM   #11
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Two tiers here, each with 91 4700uF/25V caps, total is around 800,000uF.

Lots of small caps in parallel beats fewer big ones for ESR.
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Old 8th May 2014, 03:11 PM   #12
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blimming heck, that is impressive.. It reminds of this..

Click the image to open in full size.

May I ask what are the advantages of so many caps?
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Old 8th May 2014, 03:16 PM   #13
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Well I don't know yet in regards to my chipamps. For my DAC it really makes a difference to the low frequency ambience retrieval. I hear further into a recording's acoustic space. As my DAC runs from a lower voltage I've been using more caps than I've shown here - I'm currently between 1 and 2F, using 6.3V caps.
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Old 8th May 2014, 05:18 PM   #14
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Impedance to anything other than DC is very high with so much capacitance.
Other possibilities include:
PSU > K-Multiplier > Regulator > DAC
or
PSU > Tracking Pre-Regulator (simple "nested regs") > Amplifier
The "tracking pre-regulator" is the secret on how to get the high current regs to sound good.
These active alternatives aren't nearly as bulky as giant cap banks; however, there is some heat output from the regulators.
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Old 9th May 2014, 09:50 AM   #15
AndrewT is offline AndrewT  Scotland
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The cap bank gives out heat as well.
You are pumping in lots of hum energy and almost none comes out as electrical energy.
The caps emit it as heat.
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Old 14th May 2014, 07:48 PM   #16
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Well, the regs are easier than an incredibly bulky cap bank.

Here's some information on regulated power for the amplifier:
Building an LM3886 Gainclone chip amp with a regulated power supply (PSU).
and
Pedja Rogic Audio Pages - Chip Based Power Amp i.e. Gainclone - Regulated Supplies

Note that the above maybe could be more entertaining if using twice the number of regulators, a pair of regulators for left and a pair of regulators for right (dual mono with only one transformer).
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Old 14th May 2014, 08:10 PM   #17
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There's a simpler unregulated option in the attachment below.

Here are some notes for Audiosector.com and Chipamp.com amplifiers when used with the power supply attached.
Amp hookup: The power supply 0v hooks to amplifier board common ground, "CG" via (the PG vias are Not used at all).
Speaker negative hookup: From speaker jack, the speaker negative attaches to the power supply 0v, not the amplifier board (amplifier board speaker negative is not used).
Power supply cap options: The pair of 6800u can be swapped for either a pair of 10000u or 5x3300u (per rail).
Board options: This can be fabricated easily with 14ga solid copper wire for the rails and some copperless phenolic perfboard.
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Old 16th May 2014, 11:08 PM   #18
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The schematic does not indicate board layout.
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Old 17th May 2014, 11:04 PM   #19
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Quote:
Originally Posted by abraxalito View Post
The great audio capacitor myth : 'There's such a thing as too many PSU caps'.
No, but there IS the law of "Diminishing returns".

Frank.
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Old 18th May 2014, 05:00 AM   #20
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It actually takes that many caps to approach the performance of "tracking pre regulator" (aka nested regs). The task is a lot more difficult with just a lotta caps, but yet doable, costs more and really bulky.
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