Quietest amp.

jerryo · 25th September 2010, 02:21 PM

What amplifier is absolutely the quietest of them all? Which amp has the highest s/n ratio?
If I remember correctly Susan Parkers "Zeus" amplifier has a s/n of 130db
can this be beaten?
Which power supply, input stage, and output stage lends itself to low noise ability?

AndrewT · 25th September 2010, 03:30 PM

Quote:

Originally Posted by jerryo

Susan Parkers "Zeus" amplifier has a s/n of 130dB

what is the value of the signal reference?

lineup · 25th September 2010, 04:32 PM

From my lateast power amplifier I can hear nothing.
I designed it yesterday.
And when I run sinuswaves in spice simulation at more than 1Vrms into it
I still can not hear a thing!
Must be the quietest

jerryo · 25th September 2010, 05:25 PM

No idea AndrewT

I only ask as I am in the middle of a Line Array project that will be very efficient which will exacerbate any amp noise present. (NAD 2100 at the moment but not for too long I hope)

Lineup; are you using very efficient speakers for this test? Is it totally quiet at full power?
If so, could you share your new design; it must be the quietest.

john curl · 25th September 2010, 05:27 PM

Jerry, this is more a problem with construction, than design. In theory, a power amp can have the input noise of a very high quality phono stage, which when REFERRED to its rated power output, can give a HUGE S/N. However, it is not really that important, unless you are using HORN loudspeakers, which amplify noise of the power amp, because they may be as much as 20dB more efficient than planar drivers or most direct radiators.
The KEY is the S/N of the preamp, because it has an extra 10-20 dB of gain in front of the power amp. This is where things fall apart, because of the VOLUME CONTROL which adds up to 1/4 the effective loading resistance of the volume control, 50K/4 is typical, that usually limits the S/N.

Leon08 · 25th September 2010, 08:13 PM

And it depends on transistors wich you use in the input stage.There are special low noise transistors.

jerryo · 25th September 2010, 10:50 PM

Hi john curl,
I don't use a pre amp; I just have a cd player feeding my amp directly and therefore rely on the cd players volume control which will I know, not be ideal.
Which form of volume control will introduce the least amount of noise?
Do amp's gradually generate more noise with time due to component degradation?

Leon08; such as Toshiba ?

john curl · 25th September 2010, 11:05 PM

You worry perhaps too much. The need for low self noise is dependent on WHERE the signal is. For amps, UNLESS you use horns, noise is a 2'nd level consideration. However, SOME amps are extra noisy, so it COULD be important, but usually it is not.

Leon08 · 26th September 2010, 12:58 PM

Toshiba is good, but they make many transistors and not all are low noise.You must look in the datasheet for noise specs.

jerryo · 26th September 2010, 02:48 PM

Every amp that I have ever owned has put out some sort of noise; mainly low level hiss which with a lot of material cannot be heard. However it is an issue with acoustic music like certain minimalist jazz recordings.
Any form of noise detracts from the listening experience with this sort of music. I recently bought a Behringer 32 band eq (1024) to mess around with and that does add quite alot of noise (hiss) You get what you pay for I guess.

So is there a general rule, principle, or best practice that one should follow in order to have a totally silent background coming from your speakers?

25th September 2010, 02:21 PM	#1
jerryo diyAudio Member Join Date: Jun 2007	Quietest amp. What amplifier is absolutely the quietest of them all? Which amp has the highest s/n ratio? If I remember correctly Susan Parkers "Zeus" amplifier has a s/n of 130db can this be beaten? Which power supply, input stage, and output stage lends itself to low noise ability?

25th September 2010, 04:32 PM	#3
lineup diyAudio Member Join Date: Dec 2005 Location: the north	From my lateast power amplifier I can hear nothing. I designed it yesterday. And when I run sinuswaves in spice simulation at more than 1Vrms into it I still can not hear a thing! Must be the quietest __________________ lineup

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25th September 2010, 05:25 PM	#4
jerryo diyAudio Member Join Date: Jun 2007	No idea AndrewT I only ask as I am in the middle of a Line Array project that will be very efficient which will exacerbate any amp noise present. (NAD 2100 at the moment but not for too long I hope) Lineup; are you using very efficient speakers for this test? Is it totally quiet at full power? If so, could you share your new design; it must be the quietest.

25th September 2010, 05:27 PM	#5
john curl diyAudio Member Join Date: Jul 2003 Location: berkeley ca	Jerry, this is more a problem with construction, than design. In theory, a power amp can have the input noise of a very high quality phono stage, which when REFERRED to its rated power output, can give a HUGE S/N. However, it is not really that important, unless you are using HORN loudspeakers, which amplify noise of the power amp, because they may be as much as 20dB more efficient than planar drivers or most direct radiators. The KEY is the S/N of the preamp, because it has an extra 10-20 dB of gain in front of the power amp. This is where things fall apart, because of the VOLUME CONTROL which adds up to 1/4 the effective loading resistance of the volume control, 50K/4 is typical, that usually limits the S/N.

25th September 2010, 08:13 PM	#6
Leon08 Banned Join Date: Sep 2010 Location: at Home	And it depends on transistors wich you use in the input stage.There are special low noise transistors.

25th September 2010, 10:50 PM	#7
jerryo diyAudio Member Join Date: Jun 2007	Hi john curl, I don't use a pre amp; I just have a cd player feeding my amp directly and therefore rely on the cd players volume control which will I know, not be ideal. Which form of volume control will introduce the least amount of noise? Do amp's gradually generate more noise with time due to component degradation? Leon08; such as Toshiba ?

25th September 2010, 11:05 PM	#8
john curl diyAudio Member Join Date: Jul 2003 Location: berkeley ca	You worry perhaps too much. The need for low self noise is dependent on WHERE the signal is. For amps, UNLESS you use horns, noise is a 2'nd level consideration. However, SOME amps are extra noisy, so it COULD be important, but usually it is not.

26th September 2010, 12:58 PM	#9
Leon08 Banned Join Date: Sep 2010 Location: at Home	Toshiba is good, but they make many transistors and not all are low noise.You must look in the datasheet for noise specs.

26th September 2010, 02:48 PM	#10
jerryo diyAudio Member Join Date: Jun 2007	Every amp that I have ever owned has put out some sort of noise; mainly low level hiss which with a lot of material cannot be heard. However it is an issue with acoustic music like certain minimalist jazz recordings. Any form of noise detracts from the listening experience with this sort of music. I recently bought a Behringer 32 band eq (1024) to mess around with and that does add quite alot of noise (hiss) You get what you pay for I guess. So is there a general rule, principle, or best practice that one should follow in order to have a totally silent background coming from your speakers?