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Modifying amplifier for more output power?
Modifying amplifier for more output power?
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Old 9th February 2018, 04:51 PM   #1
diy1995 is offline diy1995
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Default Modifying amplifier for more output power?

Hello,
I would like to know if car amplifier can be modified to deliver more output wattage?

I`m aware of other methods to get more power, like using lower impedance driver, higher sensitivity driver,...

The first thing that should be done is to bridge two channels together... ok, this gives a lot more power, but after that you're done, this is the max power you will get... or is it?

I did a research on the internet and didn`t found any useful information about modifying amplifiers...

Changing output transistors by itself obviously wouldn`t change anything.

But upping the rails voltage surely would... Let`s say from 30-0-30 to 40-0-40. I think that 20v peek to peek would be a good value and theoretically about a 30% increase of output power.

First challenge is to up the voltage coming from SMPS.
1.) Should this be made by changing number of coil turns on the transformer or are usually there any other voltage limiting components that could be changed?
2.) I`m aware that capacitors would need to be changed for higher voltage ratings, are there any other components that would need to be looked after and changed?

Now to the actual amplifier part:
1.) Capacitors would need to be replaced with higher rating ones.
2.) Transistors would need to handle more power, but if amplifier is rated 2ohms stable and only 4ohm drivers would be connected to it there is no need to change them, except if amplifier would be wired in bridged configuration?

After the modifications temperature should be monitored and heatsink would need to be upgraded is needed.




When looking at datasheets of various ICs I can see that maximum operating voltages are always much higher than recommended ones are. Amplifiers using ICs are usually designed using recommended voltages rather than close to maximum ones. Would this be the same for car transistor type amplifiers? I guess so because manufacturers want to be safe, amplifiers can hold more abuse, etc...


What do you think of this? Any ideas, recommendations, any precautions to keep components safe from getting damaged?
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Old 9th February 2018, 06:41 PM   #2
diy1995 is offline diy1995
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After some digging I have found formula for calculating peek output power
P=v^2/R
P=v*I

Amplifier that I would like to modify uses D718 and B688 transistors. They can handle 120 peek to peek and 8A.

In perfect world without losses you could get 225w peak without current limit at 4ohm and 30v.

With 40v it would be able to produce 400w, but because transistors can only handle 8A it would be able to produce 320W peak.

Is this telling me that I should not increase voltage that much without changing transistors? And I should increase it only to 35v where amplifier would produce 306,25W peak (better to leave a little headroom to 320w peak)?

Last edited by diy1995; 9th February 2018 at 06:58 PM.
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Old 10th February 2018, 10:20 PM   #3
Old'n'Cranky is offline Old'n'Cranky  Australia
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if you use the search function.
you will see this has been done to death.
again and again and again and again.
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Old 10th February 2018, 10:48 PM   #4
Sonce is offline Sonce  Macedonia
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Quote:
Originally Posted by diy1995 View Post
I would like to know if car amplifier can be modified to deliver more output wattage?
No.
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Old 11th February 2018, 11:36 AM   #5
diy1995 is offline diy1995
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Quote:
Originally Posted by Old'n'Cranky View Post
if you use the search function.
you will see this has been done to death.
again and again and again and again.
Hello,
I have searched, but I don`t find anything... I tried "more power, increase power, output power, ..." but I can`t find anything. Can you please tell me for what to search for?
Thank you
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Old 11th February 2018, 11:40 AM   #6
diy1995 is offline diy1995
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Quote:
Originally Posted by Sonce View Post
No.
Hello, why not?

I`m thinking of modifying old quality amp (i have one Car Tehnics from 90s and one Pioneer from 1989), not new chinese production ones, that have overrated specifications from the start and are built from cheap components and pushed all the way to the max...
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Old 11th February 2018, 11:41 AM   #7
scottjoplin is offline scottjoplin  Wales
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As you have found yourself just by thinking about it in your first two posts, it is really not that simple and you're effectively building a new higher powered amplifier. Another option would be just to duplicate everything, that is, more amplifiers powering more speakers. It would be simpler, safer and probably cheaper in the long run
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Old 11th February 2018, 11:53 AM   #8
diy1995 is offline diy1995
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Quote:
Originally Posted by scottjoplin View Post
As you have found yourself just by thinking about it in your first two posts, it is really not that simple and you're effectively building a new higher powered amplifier. Another option would be just to duplicate everything, that is, more amplifiers powering more speakers. It would be simpler, safer and probably cheaper in the long run
Yes, you are right, but I don`t need more power, I have 2 x 550rms @4ohm in my car, 2 x 720w power amplifier at home and a few spare ones...
I wan`t to modify one just for fun and education.
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Old 11th February 2018, 05:15 PM   #9
Bertje is offline Bertje  Netherlands
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You have to rewind the power supply transformer, to get a higher rail voltage. For sure everything else in the power supply and amplifier stages must work within its power limits.
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Old 11th February 2018, 06:07 PM   #10
diy1995 is offline diy1995
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Originally Posted by Bertje View Post
You have to rewind the power supply transformer, to get a higher rail voltage. For sure everything else in the power supply and amplifier stages must work within its power limits.
Thats the anwser I was hopping for.
Do you know if voltage will rise linearly to number of coil turns or do I have to do all the complicated math to find out how much turns I must add for desired voltage?

Thank you
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