Has anyone measured the effect (if any) of tube rolling?

[paulraphael]

Yeah, the error bars for that kind of measurement swamp any tube variations. And tube variations won’t usually show up in frequency response anyway- the main differences are distortion and noise.

[My emphasis added]

This is the question that I'm interested in from this thread. Are there tube circuits (or tubes) that could be expected to create significant differences in frequency response?

 

[SIY]

[My emphasis added]

This is the question that I'm interested in from this thread. Are there tube circuits (or tubes) that could be expected to create significant differences in frequency response?

Circuits, yes. Tubes, not to any significant degree.

 

[paulraphael]

Circuits, yes. Tubes, not to any significant degree.

That's interesting. This may be the first time I've caught myself in an audiophile delusion. I had a hybrid integrated amp, and tried rolling tubes to dial down some of the brightness of the system (please be nice to me ...)

I swore I heard frequency response differences with some of the tubes, but interestingly, in one case I heard very much the opposite of what I expected. A pair of Mullard 12au7s (with a reputation for warmth) sounded bright and thin, to the degree that I didn't listen through a whole song with them.

Is there a possibility I was hearing something real, or is this guaranteed to be random perceptual who-knows-what?

 

[SIY]

Is there a possibility I was hearing something real, or is this guaranteed to be random perceptual who-knows-what?

Guaranteed, no, there's always edge pathological possibilities. The latter is far and away the most probable, though.

 

[egellings]

I suspect that a circuit designed to use a particular tube type would likely suffer degradation of performance if another type were substituted. It might, however, sound more euphonic, and with tubes, that's what matters, I 'spoze.

 

[Ron Texas]

One should be very careful when rolling tubes or you will have to clean up broken glass. LOL

 

[SIY]

I suspect that a circuit designed to use a particular tube type would likely suffer degradation of performance if another type were substituted. It might, however, sound more euphonic, and with tubes, that's what matters, I 'spoze.

Type, yes. Brand, less likely.

 

[egellings]

Brand rolling likely poses no threat of damage at all. Type rolling can cause problems.

 

[Wes]

What about Tube Trolling?

 

[egellings]

Tubes are fun. They ight up. They can sound good. What's not to like? Lab standard precision and noise performance? Perhaps not so much.

 

[Katji]

Valve amplifier builders are concerned with electrical characteristics of valves and topologies, and with signal/noise/distortion and output, not much with euphonics per se.

 

[AmadeusMozart]

What about Tube Rolling?

Tubes having the same designation are supposedly the same. Unfrortunately this is not the case as different manufacturers, and even the same manufacturer, may construct the tube totally different. This results in different optimum operating points. And if you use a tube outside its optimum operating point then it will behave less optimum. Sometimes this is audible, sometimes it is not audible but this also depends on the way the tube is operated: if it is inside a feedback loop then it does not make one iota difference. If it has no feedback what so ever then it may be audible.

 

[dfuller]

So... I think when tubes are run in their linear regions, this ultimately doesn't matter. It's when they're overloaded that they start to sound different, because different makes of the same tube type will have somewhat different grid clipping characteristics (read: hi-fi it doesn't matter, guitar amps it does).

I've been meaning to try to measure that, but haven't quite yet figured how to do so without a ton of statistical noise.

 

[egellings]

Some go at tubes for the euphonics, particularly the single ended crowd, while others go for low distortion designs using feedback to fix things up a bit. They like tubes for the appearance, largely, and demand reasonably accurate sound reproduction. It's in the ears & eyes & expectations of the beholders.

 

[Wes]

on tubed gear, I like to let the manf. select and match (or 'match') replacement tubes

if people want to play around with different tubes that's fine with me - it keeps them off the streets and out of trouble