Jean Hiraga Superclass A 30Watts why does one need 1.2F caps? - diyAudio
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Old 17th September 2012, 05:17 AM   #1
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Default Jean Hiraga Superclass A 30Watts why does one need 1.2F caps?

Jean Hiraga's Super Class-A Amplifier

Is it really required to pump in such a huge value of capacitance like 1.2F per channel? Thats the max I have ever seen in any amp monoblock..

Can I use Jean Hiraga in 4 ohms as I require 50Watts into 4 ohms.. Is the amp stable or becomes super hot? I can use bigger heatsinks if required..
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Old 17th September 2012, 05:23 AM   #2
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http://diyaudioprojects.com/Solid/Je...ic-and-PCB.jpg

Thinking to use Bipolar for the decoupling caps does it makes sense...
will take two 100uf polar caps and connect the negative pins of that and use them as decoupling? does it work? i read on audionote site regarding using the bipolar for decoupling made big difference I dont understand how one find the difference using Bipolars in decoupling...
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Old 17th September 2012, 09:58 AM   #3
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Quote:
Originally Posted by rhythmsandy View Post
Jean Hiraga's Super Class-A Amplifier

Is it really required to pump in such a huge value of capacitance like 1.2F per channel? Thats the max I have ever seen in any amp monoblock..

Can I use Jean Hiraga in 4 ohms as I require 50Watts into 4 ohms.. Is the amp stable or becomes super hot? I can use bigger heatsinks if required..
no, you don't need 1.2F
no, you will not get anywhere close to 50W class A at 4ohm. 15W class A at 4ohm with normal bias.
class A amps is at there hottest on idle.
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Old 17th September 2012, 10:14 AM   #4
AndrewT is offline AndrewT  Scotland
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He still does not understand what ClassA means, despite all the advice, explanation and links to useful sites.
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Old 17th September 2012, 10:21 AM   #5
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i know
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Old 17th September 2012, 12:32 PM   #6
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Default You will need a huge bank of capacitors or you will listen some low frequency noise

from the mains.

But you can use an electronic filter...or a capacitance multiplier...this type of circuit can increase the filtering...because the base to ground capacitor "appear" in the output multiplied by the transistor gain...so.... if you have a gain of 50 in that current..then you will have 5 thousand microfarads multiplied by 50 as a result.

You can use these two diodes shown (35V - 5W zener) per rail or you can use the resistor in the place of these two diodes (per rail) that should be removed if you decide to use the resistors...but you can also keep them in place i you want....use resistor distant from the pcboard (clearance) to avoid the heat to burn the fiberglass board.

Power transistor should be mounted in heatsinks...at least 20 watts heatsinks or use a 150 square centimeters area aluminum blade.

As you see, the input voltage should be higher than the output voltage....your supply should be 32 plus 32 VAC - 120W or 120VA to each channel or a 250W or 250VA if your supply willl be feeding both channels.

Use fuses in the rails... 2.5A fuses to protect your series pass transistors not to be destroyed by a short circuit.

This works fine...some call this circuit a capacitance multiplier.... it is an electronic filter, or a step down regulator.

Be happy,

regards,

Carlos
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Old 17th September 2012, 01:22 PM   #7
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lets say 250VA pr ch. at least.
dissipation is around 90-100 watt pr ch. plus the losses in the supply.
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Old 17th September 2012, 01:55 PM   #8
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Default Correct...it is fine this way...two time the stand by current is perfect

This way, 250 watts each channel is perfect.

I have made a mistake inverting resistor values...if someone decide to assemble, then please, correct these resistor's values indicated inside green circle... swap 100 to 150 ohms resistors

regards,

Carlos
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File Type: jpg Correction.jpg (50.7 KB, 544 views)
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Old 17th September 2012, 02:32 PM   #9
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Default A much better adjusted option

This one was simulated under load conditions...works better this way.

regards,

Carlos
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Old 17th September 2012, 04:01 PM   #10
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andrew i understood how much cap is needed but it looked strange to see such a big figure so I just posted.. if its .2F i would have said might be an overkill but when I saw 1.2F its super big figure... so just posted man...

I know that we cant expect more than 15W in Class A but the site says it can go to 50w before clipping...

why are they rating that high? when it cant deliver?
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