Tube brightness, darkness, fullness, etc.

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You know, or are you just saying it to pacify the engineering types here? ;)

How can tubes not have sound when everything else does? Perhaps you should rather ask these questions about passive components which for the lack of transconductance are much simpler to examine.

Why does a short piece of silver wire sound different to copper or gold? Apart from handwaving i have never seen any sensible suggestion of why this may be. The engineering types jump straight into denialism as the easiest way out.

tubes have a sound when plugged into its socket and the amp powered up..
otherwise if you drop them on the floor and broke they make horrible sounds and get you to cringe....:D

do you know how designers come up with tube operating points? what plate current? what plate voltage? unless you know this, your knowledge of tubes is just limited rolling them and listen to how the sound changes...
 
I love how many here make fun of 'tube rollers'. tube rolling makes a bigger difference than finding the 'sweet spot'.

I could measure the THD difference with 6sn7 and there are serious studies on different brands THD.

Moreover, section matching is making a tremendous difference and those nos tubes had some sections matching that are splendid sounding, a true revelation...

Vacuum Tube Manual: RCA 1940 Vacuum Tube Design : Free Download, Borrow, and Streaming : Internet Archive

I am sure there is a more recent version of teh vacuum tube design, it address all the factors, from glass to soldering, to metal alloys, composition and melting.

No wonder NOS tubes are super good in a time of high competition for producing the nice sounding ones.
 
analog_sa said:
Why does a short piece of silver wire sound different to copper or gold?
Why does it sound the same when the listener does not know what colour the wire is?

samsdad said:
what is it between two different pairs of 6922s that makes such a difference?
In a non-feedback circuit:
transconductance
optimum bias point
anode impedance
amplification factor
internal capacitances
details of characteristic curves
cathode emission
shot noise
excess noise
flicker noise
popcorn noise
microphony
leakage paths
 
No wonder NOS tubes are super good in a time of high competition for producing the nice sounding ones.
There was no competition to produce "the nice sounding ones". There was competition to sell parts in quantity that meet the requirements of manufacturers of electronic gear. A RCA tube radio from 1963 is no different than a Dell soundbar from 2003 in that regard.

Let's have a look at the RCA receiving tube manual. The example circuits in there are simple and cheap to build and work without fuss. Take a 12AX7 tube: high gain, low current, low transconductance -> perfect to (mass produce) cheapish (for the time) appliances.

Sidenote: tubes have certain characteristics. If a tube's measured values are close enough to say an EL34 it qualifies to be labeled an EL34.
 
Thanks. I’m gonna guess, then, that different manufacturers/brands aim for a certain range within the acceptable parameters some of these and that’s why one brand consistently “sounds brighter”, etc. over another.

same tube type number, different manufacturer, different materials, different process, while manufacturers strive to meet the specs...

more consistency is achieve with sand, but even then, devices coming off the same wafers still needed to be graded to specs....

no two things are exactly alike......
 
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