question for expert

anton · 24th February 2006, 07:45 AM

I have a question about a PPI amps. since 1990 i have a 2075M
(very nice amp) 75x2 4 ohm, 150x2 2ohm 300x1, manual says to put a 20A fuse. last week i saw a PPI art serie, model was A300, 75x2 150x2 300x1, fuse 40A. My question is why a so big difference of fuses between 2 amps of same power.
I look inside the 2 amps and they are almost the same, I mean mosfet for power supply, BJT for amp stage etc... How is possible that fuse difference?

anton · 24th February 2006, 10:41 AM

up

AndrewT · 24th February 2006, 11:20 AM

Hi,
is this the mains supply fuse?
or the secondary fuses in the DC power rails?
or the output fuse on the loudspeaker line?

It seems mighty large for any of them!

clem_o · 24th February 2006, 01:55 PM

Car amplifier perhaps?? Power-in fuse...

anatech · 24th February 2006, 06:34 PM

Yup, it's a car amp.

-Chris

K-amps · 24th February 2006, 08:01 PM

If the latter amp has more OP devices then it can handle more current thus ok with 40amp fuse. Do not assume your's can run with the 40A fuse unless you have compared the schematics of both and they are identical.

DigitalJunkie · 25th February 2006, 07:12 AM

Quote:

Do not assume your's can run with the 40A fuse unless you have compared the schematics of both and they are identical.

Even if they were identical,why double the rating of the fuse for no reason? If it works with a 20A fuse without blowing it,I'd just leave it at that.
You might lower the resistance of the power supply with a larger fuse,but you also defeat any protection the fuse offered in the first place.
Then again,We all know the silicon will die first to protect the fuse,So what's it matter?!

The magic smoke would get out one way or another!

24th February 2006, 07:45 AM	#1
anton diyAudio Member Join Date: Jul 2005 Location: rome	question for expert I have a question about a PPI amps. since 1990 i have a 2075M (very nice amp) 75x2 4 ohm, 150x2 2ohm 300x1, manual says to put a 20A fuse. last week i saw a PPI art serie, model was A300, 75x2 150x2 300x1, fuse 40A. My question is why a so big difference of fuses between 2 amps of same power. I look inside the 2 amps and they are almost the same, I mean mosfet for power supply, BJT for amp stage etc... How is possible that fuse difference?

24th February 2006, 11:20 AM	#3
AndrewT diyAudio Member Join Date: Jul 2004 Location: Scottish Borders	Hi, is this the mains supply fuse? or the secondary fuses in the DC power rails? or the output fuse on the loudspeaker line? It seems mighty large for any of them! __________________ regards Andrew T.

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24th February 2006, 10:41 AM	#2
anton diyAudio Member Join Date: Jul 2005 Location: rome	up

24th February 2006, 01:55 PM	#4
clem_o diyAudio Member Join Date: Jun 2005 Location: Manila	Car amplifier perhaps?? Power-in fuse...

24th February 2006, 06:34 PM	#5
anatech diyAudio Moderator Join Date: Jun 2004 Location: Georgetown, On	Yup, it's a car amp. -Chris

24th February 2006, 08:01 PM	#6
K-amps diyAudio Member Join Date: Nov 2003 Location: Indiana	If the latter amp has more OP devices then it can handle more current thus ok with 40amp fuse. Do not assume your's can run with the 40A fuse unless you have compared the schematics of both and they are identical.

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