[shard]

I recently had the opportunity to listen to a friend's custom made tube amp.

I noticed something, when the volume was turned way up and the source is not playing, I heard hissing. When I asked him about the hissing, he said that it was noise from the tubes (depending on the tubes) and is normal because his amp was made a little too powerful.

Having said that, the volume has to go way up for the hissing to be noticeable. Way past the max my ears can take if the source was on. So under normal listening conditions, the hissing will never be noticed.

I have isolated it to the the amp for sure, I tried both a HD590 and HD600 as well as connecting different sources in case the original source was causing the hiss even when it was not playing.

Is what he said about tube noise true?

Edit.

To clarify, his volume knob rotates from 5 O'clock to 4 O'clock clockwise (estimated). At 12 O'clock, I will pretty much go deaf if I listened to anything at that volume for any amount of time. At 2 O'clock the hissing becomes noticeable.

 

[gpalmer]

Most tube amps I have heard tend to have a bit of background hiss/noise, it sounds like what you were hearing is normal.

 

[markl]

I think it depends on the tube amp (and the tubes), but yes "tube roar" (I think it's called) is one *potential* drawback of some tube gear.

 

[Hirsch]

Turn the volume high enough, and you'll notice hissing in most solid state equipment as well. Good design can pretty much eliminate the hissing in solid state equipment...and can also do so in tube equipment, as long as the tubes are good.

 

[Hirsch]

Quote:

Originally posted by markl I think it depends on the tube amp (and the tubes), but yes "tube roar" (I think it's called) is one *potential* drawback of some tube gear.

The "tube roar" would likely be due to microphonics. The cure is a non-microphonic tube...easier to find with some types than with others.

 

[shard]

Thanks for the information.