White Noise

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Clave
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White Noise

Post by Clave » Thu Jun 19, 2014 8:32 am

So it seems that no matter what there is audible white noise, or hiss, coming through my speakers. It's not loud--I have to be right near the speaker to hear it. With just the amp on, I don't hear it, so I assume it's coming from the pre-amp (BC 3). Some tubes produce lower levels than others (Genalex have been better than EH in this regard), but none that I've tried have eliminated it altogether. Curiously, there is always a little more of the noise from the left speaker than the right, or so I perceive it. Adding a Sillycone Filter a few months ago did lower the noise floor, so perhaps powerline noise is a factor?

I don't think the sound interferes with the music significantly, but the neurotic audio perfectionist in me would prefer silence. Any thoughts? Thanks.

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Gilbert Y
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Post by Gilbert Y » Mon Jun 23, 2014 11:51 am

Tube hiss...... something you will never able to get rid of it no matter how quiet the rest of the amp and/or preamp was designed and built.

Someone also sent us a PM asking a similar question. He also mentioned when the preamp is off, there is almost not noise. He is using a BC24 power amp and BC3 preamp. Yes, you are hearing the tube noise from the preamp amplified by the gain of the power amp. Therefore if the power amp gain is lower, the over all system tube hiss will be less. It is why I always design power amp at around 18sb to 23db.. Anything with higher gain will amplify the noise from the preamp.

If there is more noise from one channel than the other, it is likely the tolerance of the tube and it noises. Some brand or even some lots of tube are better than other.

ac powerline filter in theory shouldn't make the tube less noisy. However, may be there is more noise than the tube itself?

Those hiss, unless it is getting louder or start to sound spilty or like a motor boat. There is not much to be concerned about in term of interfering the music. A constant hiss is a normal thing for tubes.

Freddy
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Post by Freddy » Tue Jun 24, 2014 4:37 pm

If you look around the web, some tube suppliers offer ultra low noise tubes.
Might be worth a try.

Fred

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bjh
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Post by bjh » Wed Jun 25, 2014 9:34 am

It all depends upon the degree of your audio perfectionist neurosis, if sufficiently bad you may have to live with a solid state pre-amp. Let's hope for your sake it doesn't come to that!

:P

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Clave
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Post by Clave » Wed Jun 25, 2014 11:06 am

Well, I've had the pre-amp for about five years and this is the first time I've asked the question, so apparently it doesn't bother me all that much. I like the idea of a totally silent pre-amp, but in terms of music, I don't think it matters much. I try not too spend a lot of time with my ear right next to the speaker.

masluck
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Post by masluck » Wed Jun 25, 2014 3:29 pm

bjh wrote:It all depends upon the degree of your audio perfectionist neurosis, if sufficiently bad you may have to live with a solid state pre-amp. Let's hope for your sake it doesn't come to that!

:P
Don't let Bob Neill see this, he might turn all crimson and write three paragraphs with keywords such as "soften", "cloud" and my all time favorite "slow" to describe the sound of our beloved glass based illusion engines. He may even do it in ALL CAPS to make an illustrative point!! :lol: :lol: :lol:

Mark

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