Clipping? why not build amp with twice rms needed and only use half volume?

John Biles · 26th August 2005, 04:55 AM

Hello Everyone,
I always read about amplifiers and the damage done to speakers by clipping when the volume is turned up to high.
It seems to me that all you have to do is build an amplifier with twice the rms wattages you need and set up the volume pot with an additional resistor to only make 1/2 that wattage avaliable to the user. Hopefully never allowing the Amplifier to clip?
What do you think and is there any amplifier being made that does this? Or have someone on the forum done this

peranders · 26th August 2005, 05:03 AM

I think you have a good idea but if you really think: Make an amplifier and half of the power isn't possible to get out but in the same time you the power in order not to clip the signal. I'm sorry but I can't figure out the logic.

John Biles · 26th August 2005, 05:18 AM

Hello Peranders,
My family is used to over engineering everything we build from sheds to electronics, So using components rated at half the load they would normally be used at can't be a bad thing as a side effect to setting up an amplifier to only give half its rms watts and prevent clipping. That's the logic behind the idea.

richie00boy · 26th August 2005, 10:40 AM

Firstly, you will be paying for capacity that can't be used, both financially and in size and weight. Secondly, you can't actually stoip people running the amp into clipping because input sensitivity is not really a standard, there will always be some source or pre-amp that can put out more voltage and drive the amp into clipping.

If you buy a decent pro amp it will have a 'soft' clipping limiter in anyway

janneman · 26th August 2005, 10:48 AM

Quote:

Originally posted by John Biles
Hello Everyone,
I always read about amplifiers and the damage done to speakers by clipping when the volume is turned up to high.
It seems to me that all you have to do is build an amplifier with twice the rms wattages you need and set up the volume pot with an additional resistor to only make 1/2 that wattage avaliable to the user. Hopefully never allowing the Amplifier to clip?
What do you think and is there any amplifier being made that does this? Or have someone on the forum done this

I don't think there is anything to built. Just figure out the absolute max output level and buy/built an amp that can do that.

Jan Didden

peranders · 26th August 2005, 11:00 AM

If the clipping problem is big:

1 Get a more powerful amp

2 Turn down the volume

3 Get more efficient speakers

John Biles · 26th August 2005, 11:05 AM

I don't run my amp into clipping as i only use half the volume. this post was just a thought i had.

janneman · 26th August 2005, 11:22 AM

Quote:

Originally posted by John Biles
I don't run my amp into clipping as i only use half the volume. this post was just a thought i had.

Well John, you got us to think. That's an achievent in itself!

Jan Didden

Mr Evil · 26th August 2005, 11:43 AM

Aside from the increased cost, there will also be an efficiency hit. Wasting electricity is bad!

A limiting circuit is probably a better idea. Also using active crossovers will prevent bass energy from being redirected to the tweeter during clipping, reducing the risk of damage.

quasi · 26th August 2005, 11:53 AM

Well your thought is very valid, in fact it is used by professional amp manufacturers already for something they call "dynamic headrooom".

You could build an amp that can say deliver 200 watts of music power (real music power) and only say be capable of 100 watts RMS.

Lets imagine a stereo amp with the following

A ransformer with the following ratings; 40v 0 40v and 200va
100,000 uF of capacitors for each power supply.
This will provide DC rails of around +/- 55 volts DC.

In theory this amp could deliver 150 watts per channel of music power into 8 ohms but only say 80 watts per channel of RMS power as the transformers voltage would collapse under sustained power conditions.

But music is nothing like RMS and the average power delivered by the amp (and transformer) over a few minutes may only be 50 watts.

Indeed this amp coud provide music power of almost 300 watts per channel into 4 ohms and do this quite comfortably without any strain on the transformer at all. (Except if you listened to organ music or severe classical tracks, but for pop, rock disco, etc ...no problem).

But most DIY's (like me too) go for a big transformer because, like hot cars etc... we gotta have it.

Cheers

26th August 2005, 04:55 AM	#1
John Biles diyAudio Member Join Date: May 2005 Location: Victoria Australia	Clipping? why not build amp with twice rms needed and only use half volume? Hello Everyone, I always read about amplifiers and the damage done to speakers by clipping when the volume is turned up to high. It seems to me that all you have to do is build an amplifier with twice the rms wattages you need and set up the volume pot with an additional resistor to only make 1/2 that wattage avaliable to the user. Hopefully never allowing the Amplifier to clip? What do you think and is there any amplifier being made that does this? Or have someone on the forum done this

26th August 2005, 05:03 AM	#2
peranders Electrons are yellow and more is better! diyAudio Member Join Date: Apr 2002 Location: Göteborg, Sweden Blog Entries: 4	I think you have a good idea but if you really think: Make an amplifier and half of the power isn't possible to get out but in the same time you the power in order not to clip the signal. I'm sorry but I can't figure out the logic. __________________ /Per-Anders (my first name) or P-A as my friends call me

26th August 2005, 10:40 AM	#4
richie00boy Did it Himself diyAudio Member Join Date: Nov 2003 Location: Gloucestershire, England, UK	Firstly, you will be paying for capacity that can't be used, both financially and in size and weight. Secondly, you can't actually stoip people running the amp into clipping because input sensitivity is not really a standard, there will always be some source or pre-amp that can put out more voltage and drive the amp into clipping. If you buy a decent pro amp it will have a 'soft' clipping limiter in anyway __________________ www.readresearch.co.uk my website for UK diy audio people - designs, PCBs, kits and more

26th August 2005, 11:00 AM	#6
peranders Electrons are yellow and more is better! diyAudio Member Join Date: Apr 2002 Location: Göteborg, Sweden Blog Entries: 4	If the clipping problem is big: 1 Get a more powerful amp 2 Turn down the volume 3 Get more efficient speakers __________________ /Per-Anders (my first name) or P-A as my friends call me

26th August 2005, 11:43 AM	#9
Mr Evil diyAudio Member Join Date: Aug 2004 Location: Behind you	Aside from the increased cost, there will also be an efficiency hit. Wasting electricity is bad! A limiting circuit is probably a better idea. Also using active crossovers will prevent bass energy from being redirected to the tweeter during clipping, reducing the risk of damage. __________________ https://mrevil.asvachin.eu/


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26th August 2005, 05:18 AM	#3
John Biles diyAudio Member Join Date: May 2005 Location: Victoria Australia	Hello Peranders, My family is used to over engineering everything we build from sheds to electronics, So using components rated at half the load they would normally be used at can't be a bad thing as a side effect to setting up an amplifier to only give half its rms watts and prevent clipping. That's the logic behind the idea.

26th August 2005, 11:05 AM	#7
John Biles diyAudio Member Join Date: May 2005 Location: Victoria Australia	I don't run my amp into clipping as i only use half the volume. this post was just a thought i had.

26th August 2005, 11:53 AM	#10
quasi diyAudio Member Join Date: Sep 2004 Location: Adelaide, Australia	Well your thought is very valid, in fact it is used by professional amp manufacturers already for something they call "dynamic headrooom". You could build an amp that can say deliver 200 watts of music power (real music power) and only say be capable of 100 watts RMS. Lets imagine a stereo amp with the following A ransformer with the following ratings; 40v 0 40v and 200va 100,000 uF of capacitors for each power supply. This will provide DC rails of around +/- 55 volts DC. In theory this amp could deliver 150 watts per channel of music power into 8 ohms but only say 80 watts per channel of RMS power as the transformers voltage would collapse under sustained power conditions. But music is nothing like RMS and the average power delivered by the amp (and transformer) over a few minutes may only be 50 watts. Indeed this amp coud provide music power of almost 300 watts per channel into 4 ohms and do this quite comfortably without any strain on the transformer at all. (Except if you listened to organ music or severe classical tracks, but for pop, rock disco, etc ...no problem). But most DIY's (like me too) go for a big transformer because, like hot cars etc... we gotta have it. Cheers __________________ http://sites.google.com/site/quasisdiyaudiosite/

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