Sonic effects of tubes

[Rodango]

I was wondering if anyone had read any technical papers on the source of various tube-based sonic effects.

Let's take into consideration the imaging effect most commonly referred to as 'air'. It it caused by transparency on the part if the tube or is it caused be an interplay of odd-order harmonics within the tube? Or perhaps something else?

[SY]

Can you define "air" in this context and provide an example or two so I know what aspect you're asking about?

[Miles Prower]

There are lots of various "theories" (mostly audiophool old wives' tales) but very little that's in any way definitive. You don't see anything concerning this in something like the Radiotron Designers Handbook. A big part of the problem lies with the terminology and limitations of language. WTH does "air" mean anyway? It's as difficult to describe a sound as it is to tell a man born blind what "blue" looks like.

You can measure distortion spectra and draw some general conclusions, but that's about the best you can do. You don't see the subject even mentioned in EE classes at all. Which is probably why a good deal of your Big Box equipment sounds as horrible as it does.

This was a big problem during the development of my latest project: virtually nothing concerning the sonic qualities of a cascoded LTP. All that was left was to actually put one together and hope for the best. Forch, it worked out just great. Different VTs will have different sonic "personalities" depending on whether they produce mainly the sonically benign h2 and h3, or whether they produce lots of dissonant high order harmonics. About all you can do is design and listen. Then, and only then, can you decide what needs to be done so far as NFB correction is concerned. Keep in mind that what sounds good to you may not sound so good to some other listener.

[Ty_Bower]

Well, tubes are made of glass, and glass is transparent so obviously the sound they make is transparent too. Solid state amplifiers are made out of silicon, which is sand. Sand is gritty, so that's why all solid state amplifiers have a gritty sound. But air? Everyone knows that vacuum tubes don't have any air in them. That's why they're called vacuum tubes. I can't imagine how they could sound "airy".

[/sarcasm]

Just kidding.

[TubeHead Johnny]

Vacuum tubes have little to do with "sonic effects" and "air", when you compare them to the circuit they are in, quality of the OPT's, power supply design, even the source material.

[Rodango]

Come to think of it, you're right. The tubes which sound gritty to me often have thick glass and it's the presence of all that sand that does it... interesting...

So what we need is tubes made from thin lead crystal or zircon to sound good. There goes my dream of making tubes from beer bottles!!! lol

set BS/off

I'm going with the transparency theory...

This all started with me getting some '52 Soviet 6C2C tubes for my handmade amp. The things are incredible! It would be great if Russia was still producing tubes of that quality..

[kstagger]

Lynn Olson wrote the following on THD -
http://www.nutshellhifi.com/library/FindingCG.html

worth a further discussion?

[Salas]

Great impulse response, wide bandwidth, very low noise, tend to give a sound that it has good dimensionality, well defined space among HF harmonics of various instruments, and faithful reverberation feel up high. That last one they mean with 'air'.

[Psychobiker]

Slew factor, even order level THD....

[Rodango]

Originally posted by SY
Can you define "air" in this context and provide an example or two so I know what aspect you're asking about?

The best example of 'air' that I can come up with is 6:05 into 'Andalu' by Chris Spheeris. It's the effect where the sound stage becomes huge and even the most subtle of sounds are caught in echos. Of course the example I cite is more than just 'air'. It's brilliant!!

Originally posted by TubeHead Johnny
Vacuum tubes have little to do with "sonic effects" and "air", when you compare them to the circuit they are in, quality of the OPT's, power supply design, even the source material.

Various 6J5s in the amp I am using sound quite different...