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Audio amplifier limiting output power

 
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Betty19



Joined: 21 Oct 2016
Posts: 1

PostPosted: Fri Oct 21, 2016 8:55 am    Post subject: Audio amplifier limiting output power Reply with quote

What I have:
• A transformer rated at 150VA / 30V (center tapped) / 5A
• Speaker rated at 30W / 8 ohms (measured 6.3 ohms with my multimeter)
Will use class AB amplifier:
• LM4780 http://www.kynix.com/Detail/1143170/LM4780TA%2FNOPB.html
• Question:
If I send +30V & -30V to this chip, I will get 45W at 1%THD+N:

Is it possible to keep +30V & -30V but limit the maximum power to 30W? Is it by playing with the gain (feedback resistor value)?
I read somewhere "...power amps at lower gains requires more input voltage to get the same power output, with the same speaker impedance".
How to adjust/calculate the gain so that I get a maximum of 30W output with +30V / -30V power supply? I own the transformer already so I plan to use it as the power supply (+30V / -30V). It is center tapped. It is 30V-0V-30V.

I know that sending +40V/-40V is almost at the maximum (recommended) value of 84V. Is it possible to use more diode to drop the voltage or any other method (I didn't found any regulator that fit my needs)? Maybe I can send 40-0-40 but then my output power will be around 82W and my speaker is rated 30W. In this case, I can lower the gain to 20db to help (minimum value) and add a resistor before the speaker (ie: 4 ohms, but very high watt)? I guess I could add a potentiometer at the input (A-B) to limit the power sent to my speaker right?

from the title of the chip, I think I cannot go higher than 60W in stereo: "Overture Audio Power Amplifier Series Stereo 60W". What will happen if sending 40-0-40?!
if sending 40-0-40 to the amp then the output power per channel will be around 82W. What will happen (an implosion or a black hole)?

I am connecting a line out having 16ohms impedance and 1V RMS signal level. What if I add a potentiometer / volume control at the input of the power amp, thus limiting the amount of signal level going in the amp. Would the power amp consume the 80V even if the signal level is only 500mV RMS (ie)?
Any advice would be much appreciated.
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mahanoor



Joined: 29 Nov 2020
Posts: 2

PostPosted: Sun Nov 29, 2020 1:45 pm    Post subject: Reply with quote

I am building 2x15W amplifier based on TA2024. I am also building small Munny speakers based on 1" full-range Tang Band drivers to go with the amp. The drivers are only 4W RMS and 8W max so the amp is way too powerful for them.

Is there an easy way to limit the output power of the amplifier so it does not exceed the speaker specs? This setup is going to my kids room so I am afraid that they may crank the volume all the way up destroying the speakers.

Thanks.
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PostPosted: Thu Dec 24, 2020 8:50 am    Post subject: Reply with quote

What can be read in this manual? Are there other more detailed data sheets?
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PostPosted: Sat Jan 09, 2021 3:24 am    Post subject: Reply with quote

Is there a standard for the size of the circuit diagram?
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PostPosted: Tue Aug 03, 2021 2:28 am    Post subject: Reply with quote

Thank you for your sharing,That's pretty cool.
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Larry_Dunbar



Joined: 02 Feb 2021
Posts: 1
Location: Minneapolis, MN, USA

PostPosted: Sat Aug 07, 2021 12:32 am    Post subject: Reply with quote

I am building 2x15W amplifier based on TA2024. I am also building small Munny speakers based on 1" full-range Tang Band drivers to go with the amp. The drivers are only 4W RMS and 8W max so the amp is way too powerful for them.
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Stellalucy0092



Joined: 15 Jul 2021
Posts: 1

PostPosted: Sat Sep 04, 2021 12:51 pm    Post subject: Electronic equipment repair and service manual search discu Reply with quote

You can get L-pad attenuators for 100W. Google "100w lpad" and the first few results should come up that are what you need.

Problem with using L-pads is that they load the device at full load constantly, and thus reduce part life - but if you're using a solid state amplifier this shouldn't be too much of a worry.

Simply get two (one for each channel) and put it a bit less than halfway, adjust to taste. That should kill about 60W from the output.
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Identifiedcall



Joined: 08 Sep 2021
Posts: 1

PostPosted: Wed Sep 08, 2021 10:20 am    Post subject: Identified Call Reply with quote

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parkerrichardson



Joined: 21 Sep 2021
Posts: 2

PostPosted: Tue Sep 21, 2021 9:47 am    Post subject: Reply with quote

Thank you for this post! Now I think I can do it
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parkerrichardson



Joined: 21 Sep 2021
Posts: 2

PostPosted: Tue Sep 21, 2021 9:49 am    Post subject: Reply with quote

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