How much power can a Sanui 300watt max amp really give? ;) - diyAudio
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Old 31st May 2004, 05:24 PM   #1
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Default How much power can a Sanui 300watt max amp really give? ;)

I have acquired a 300watt max, sansui amp, mosfets in the powersupply were blown, so, I replaced them, the ones I used are higher power... hmmm this could be good.... I am now in the process of thickening up any PCB tracks that have to carry high current... after this, I will make a new transformer to get higher voltage rails, and add more output transistors... and add heatsinks to the smaller transistors (its 2:45am, can't think what they are called) anything else I need to change? currently, the amp multiplies the input voltage by 2... so, for 12volts in, you get +-24volt rails... I was thinking more along the lines of 4 X the input voltage.. the mosfets I used have twice the current handling of the originals, so that should be fine... will I have to adjust the bias because of the higher voltage rails??

THANX!!! MWAHAHAHA!!!
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Old 31st May 2004, 05:27 PM   #2
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....so you really want to design a new amp from the ground (sic) up, right?

Jan Didden
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Old 31st May 2004, 05:30 PM   #3
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Quote:
Originally posted by janneman
....so you really want to design a new amp from the ground (sic) up, right?

Jan Didden

ohh, sorry... I forgot to mention its a car amp
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Old 31st May 2004, 05:55 PM   #4
sreten is offline sreten  United Kingdom
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Doubling rail voltages for the power amplifier is not a good idea.

You should concentrate on making the thing more reliable, not
next to certain to shortly expire after you've finished your mods.

However regarding the bias it depends on the stability of the
section that sets bias to changes of rail voltages, but you
should not have to change anything.

Note that doubling voltage doubles current, so dissapation
in the power amplifier will quadruple, which is why iI'm sure
it will expire sooner rather than later.

sreten.
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Old 31st May 2004, 05:57 PM   #5
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Quote:
Originally posted by sreten
Doubling rail voltages for the power amplifier is not a good idea.

You should concentrate on making the thing more reliable, not
next to certain to shortly expire after you've finished your mods.

However regarding the bias it depends on the stability of the
section that sets bias to changes of rail voltages, but you
should not have to change anything.

Note that doubling voltage doubles current, so dissapation in
the amplifier devices will quadruple, which is why is why I'm
sure it will expire sooner rather than later.

sreten.

that was the whole idea... kill it... see how much power it ca do... I've used this amp quite abit, its got very good heatsinking, ran it hard with 2 ohms per channel, and its barely warm... so... I'm willing to take the risk.. lol
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Old 31st May 2004, 05:59 PM   #6
sreten is offline sreten  United Kingdom
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Fair enough, sreten.
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Old 1st June 2004, 01:39 PM   #7
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Default M tech your Amp

Its sounds like you have donegood with your amp,
I would add a cooling fan along the heat sinks on both sides just to drink off some extra heat, you wont kill your amp unless your running it at a very low load or playing it very load lets say, so forget everybody else fears and just do it! lets ee what you can get away with!
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Old 1st June 2004, 03:00 PM   #8
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anyone wanna wind me a new transformer? I'm also going to have to mess around with the switchmode controller IC's feedback line.. hmm...
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Old 2nd June 2004, 12:33 PM   #9
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ok.... I made the tracks thicker, and wound a new secondary on the existing core, and keeping the original primary (I'm lazy, and I've never made a transformer before, it was practice, ok?)

anyway, I chose not to double the voltage I now have +-33volt rails... about... I think I have one too many turns on one of the secondaries lol ohh well...

+-24 volt rails results in an output of 144watts per channel, into 2 ohms... MAX!! (which is why its a 300watt max amp)

ofcourse, it doesn't do that well.... hmmm.... I have a feeling I needed to make a totally new transformer... lol

well... now the amp is 500watts max lol

I WAS going to measure it, but I think me cro went ohh noo... lol and died... so, that didn't happen... lol

SEEYA!
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