Describing that "ON" noise in old SS equipment

6f6 · 19th December 2009, 06:18 PM

How would one describe the "ON" noise that one usually gets in 1970's era solid state equipment electronics? I just put my McIntosh C-28 preamp up for sale at Ebay; I described the sound as "white noise"- kind of like air draining out the hose from an air compressor. This is not hum or squeal- I know what causes those. Would this be more accurately described as "transistor noise"? Do you guys use other words to describe it?

dhaen · 19th December 2009, 06:21 PM

Faulty?

Rafael L · 19th December 2009, 06:33 PM

White-noise and Pink-noise is used to make measurements on loudspeaker, in equipment electronics is used to SNR for measure noise

6f6 · 19th December 2009, 06:37 PM

Not faulty, just old. All the old SS equipment make this sound, its not a bad part, I'm guessing that it is an issue stemming from the interelectrode capacitances of older BJT transistors- they charge and discharge and create a very low noise floor

Glowbug · 19th December 2009, 06:47 PM

Has it been re-capped?

dhaen · 19th December 2009, 06:51 PM

Sorry 6F6 that was just my odd sense of humour...
However, I'm still not sure what you mean. I do remember when this "ilk" of kit was new, but don't remember any strange noises, except in the occasional badly designed one. I doubt there's anything iffy about the McIntosh's design.

Rafael L · 19th December 2009, 06:53 PM

Quote:

Originally Posted by 6f6

Not faulty, just old. All the old SS equipment make this sound, its not a bad part, I'm guessing that it is an issue stemming from the interelectrode capacitances of older BJT transistors- they charge and discharge and create a very low noise floor

Electrolytic capacitors should be aged, filtering the power supply is not good as when the equipment was new...

6f6 · 19th December 2009, 07:18 PM

No, I did not recap it. I know that leaky electrolytics usually cause hum.

Rafael L · 19th December 2009, 07:35 PM

Yes is hum, not is this noise that you have?

6f6 · 19th December 2009, 08:11 PM

Not hum. If there was hum, I would have replaced the electrolytic caps. My guess here is that it is transistor or resistor noise. This noise may have very well been present 30 years ago- it is very common to classic 1970's solid state equipment. I guess that I'm a bit picky; I DIYed a tube-based preamp and tweaked it until nothing could be heard with the volume all the way up.

19th December 2009, 06:18 PM	#1
6f6 diyAudio Member Join Date: Oct 2006	Describing that "ON" noise in old SS equipment How would one describe the "ON" noise that one usually gets in 1970's era solid state equipment electronics? I just put my McIntosh C-28 preamp up for sale at Ebay; I described the sound as "white noise"- kind of like air draining out the hose from an air compressor. This is not hum or squeal- I know what causes those. Would this be more accurately described as "transistor noise"? Do you guys use other words to describe it?

19th December 2009, 06:47 PM	#5
Glowbug diyAudio Member Join Date: Feb 2006 Location: Hillsborough, NC/McLean, VA	Has it been re-capped? __________________ Jim J.

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19th December 2009, 06:21 PM	#2
dhaen diyAudio Moderator Emeritus Join Date: Jun 2002 Location: U.K.	Faulty?

19th December 2009, 06:33 PM	#3
Rafael L diyAudio Member Join Date: Nov 2008 Location: Brazil	White-noise and Pink-noise is used to make measurements on loudspeaker, in equipment electronics is used to SNR for measure noise

19th December 2009, 06:37 PM	#4
6f6 diyAudio Member Join Date: Oct 2006	Not faulty, just old. All the old SS equipment make this sound, its not a bad part, I'm guessing that it is an issue stemming from the interelectrode capacitances of older BJT transistors- they charge and discharge and create a very low noise floor

19th December 2009, 06:51 PM	#6
dhaen diyAudio Moderator Emeritus Join Date: Jun 2002 Location: U.K.	Sorry 6F6 that was just my odd sense of humour... However, I'm still not sure what you mean. I do remember when this "ilk" of kit was new, but don't remember any strange noises, except in the occasional badly designed one. I doubt there's anything iffy about the McIntosh's design.

19th December 2009, 07:18 PM	#8
6f6 diyAudio Member Join Date: Oct 2006	No, I did not recap it. I know that leaky electrolytics usually cause hum.

19th December 2009, 07:35 PM	#9
Rafael L diyAudio Member Join Date: Nov 2008 Location: Brazil	Yes is hum, not is this noise that you have?

19th December 2009, 08:11 PM	#10
6f6 diyAudio Member Join Date: Oct 2006	Not hum. If there was hum, I would have replaced the electrolytic caps. My guess here is that it is transistor or resistor noise. This noise may have very well been present 30 years ago- it is very common to classic 1970's solid state equipment. I guess that I'm a bit picky; I DIYed a tube-based preamp and tweaked it until nothing could be heard with the volume all the way up.

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