Tube Rolling: Does it Make a Difference?

[Keith_W]

I did not read through the 29 page thread. But if someone hasn't mentioned it yet - the tolerances for tube manufacturing are not the same as any other electronic component. This is because they are by nature more difficult to manufacture, and it is more expensive to discard the tube if it is out of tolerance. So tube amps are designed to compensate for a the inconsistent performance of tubes.

A friend of mine who repairs valve amps and has a tube tester once told me that he has never found a pair of so-called "matched tubes" to be exactly matched. Tubes that come out of one manufacturer might have different tolerances to another manufacturer, and they might have different interpretations of the standard. All that matters is electrical performance of the tube and how closely it matches the standard which the amplifier was designed to meet.

His conclusion: hearing differences with tube rolling is real. Even changing tubes from the same manufacturer can result in measurable and potentially audible differences. However, spending money to buy expensive tubes is not worth it, unless the extra money buys you tighter tolerances and better build quality and not better mystique and better marketing.

 

[SIY]

I did not read through the 29 page thread. But if someone hasn't mentioned it yet - the tolerances for tube manufacturing are not the same as any other electronic component. This is because they are by nature more difficult to manufacture, and it is more expensive to discard the tube if it is out of tolerance. So tube amps are designed to compensate for a the inconsistent performance of tubes.

A friend of mine who repairs valve amps and has a tube tester once told me that he has never found a pair of so-called "matched tubes" to be exactly matched. Tubes that come out of one manufacturer might have different tolerances to another manufacturer, and they might have different interpretations of the standard. All that matters is electrical performance of the tube and how closely it matches the standard which the amplifier was designed to meet.

His conclusion: hearing differences with tube rolling is real. Even changing tubes from the same manufacturer can result in measurable and potentially audible differences. However, spending money to buy expensive tubes is not worth it, unless the extra money buys you tighter tolerances and better build quality and not better mystique and better marketing.

Tolerances for tubes are actually tighter. For example, FET transconductance and Idss can have. 5:1 spread.

 

[mhardy6647]

The thing about commercial designs is the cheapest components are selected to maximize profit. Maybe consider replacing electrolytic caps in crossovers with cost effective polypropylene caps... Just don't get carried away with the expensive parts that only provide "buzzword bragging" rights.

No argument, there -- and I do agree vis-a-vis NP electrolytics, FWIW.
My point was directed at the lunatic fringe.

 

[fpitas]

No argument, there -- and I do agree vis-a-vis NP electrolytics, FWIW.
My point was directed at the lunatic fringe.

But they usually have the most enthusiasm.

 

[MattHooper]

This says a bit more than you likely intended.

I assure you nothing unpredictable escaped that post.

I've been around a long time and I'm quite aware of the context of such a post on this forum, including that it will be seen as red meat to some.
In particular, your response was predictable down to the granularity of a precision micrometer.

And that's fine of course. I understand, and all the appropriate caveats are there as usual. For anyone who misses the caveats and becomes triggered by my subjective flourishes: see my tag line.

 

[mhardy6647]

But they usually have the most enthusiasm.

that they do...

 

[fpitas]

No argument, there -- and I do agree vis-a-vis NP electrolytics, FWIW.
My point was directed at the lunatic fringe.

And keep in mind Beranek's Law. Which admittedly has to be stretched somewhat to include "re-designed" speakers:

"It has been remarked that if one selects his own components, builds his own enclosure, and is convinced that he has made a wise choice of design, then his own loudspeaker sounds better to him than does anyone else's loudspeaker. In this case, the frequency response of the loudspeaker seems to play only a minor part in forming a person's opinion."

—L. L. Beranek, Acoustics (McGraw-Hill, New York, 1954), p.208.

 

[MattHooper]

And keep in mind Beranek's Law. Which admittedly has to be stretched somewhat to include "re-designed" speakers:

"It has been remarked that if one selects his own components, builds his own enclosure, and is convinced that he has made a wise choice of design, then his own loudspeaker sounds better to him than does anyone else's loudspeaker. In this case, the frequency response of the loudspeaker seems to play only a minor part in forming a person's opinion."

—L. L. Beranek, Acoustics (McGraw-Hill, New York, 1954), p.208.

I think it's also worth remembering how limited personal experience is ingrained in our viewpoints, whether someone is a pure "subjectivist" or if they are seeking to be a very empirically rigorous engineer.

We live in a very big, complex world, using small imperfect brains and our abilities to rigorously test all our beliefs is going to be limited. So even engineers are left with what seem to be received best practices or information, some of which may suffer *some* level of dispute (as one finds in science) and then that engineer's personal experience working on a problem or idea is going to ultimately heavily sway their view. So in science you'll find various scientists defending their pet views, in engineering the same. Through personal experience the technically inclined will arrive at their preferred solution, which may not be shared by another who went down an different avenue. (Hence, in audio, different speaker designs, amp designs, etc).

That's not for a moment to suggest empirical reality and hard won knowledge is just a free for all or purely subjective. Nor that some positions are more justifiable than others. Very far from it. Just an observation that it's understandable why disputes remain even among engineers and scientists, and various technically knowledgeable people.

 

[fpitas]

I think it's also worth remembering how limited personal experience is ingrained in our viewpoints, whether someone is a pure "subjectivist" or if they are seeking to be a very empirically rigorous engineer.

We live in a very big, complex world, using small imperfect brains and our abilities to rigorously test all our beliefs is going to be limited. So even engineers are left with what seem to be received best practices or information, some of which may suffer *some* level of dispute (as one finds in science) and then that engineer's personal experience working on a problem or idea is going to ultimately heavily sway their view. So in science you'll find various scientists defending their pet views, in engineering the same. Through personal experience the technically inclined will arrive at their preferred solution, which may not be shared by another who went down an different avenue. (Hence, in audio, different speaker designs, amp designs, etc).

That's not for a moment to suggest empirical reality and hard won knowledge is just a free for all or purely subjective. Nor that some positions are more justifiable than others. Very far from it. Just an observation that it's understandable why disputes remain even among engineers and scientists, and various technically knowledgeable people.

I agree with all that. But like Dr. Hardy complained about, some people are more than willing to tear into things they have no knowledge of. But on the other hand, my opinion is they paid for it, so they can screw it up all they want. Dr. Hardy on the other hand, perhaps believes some lèse-majesté goes on.

 

[mhardy6647]

I agree with all that. But like Mr. Hardy complained about, some people are more than willing to tear into things they have no knowledge of. But on the other hand, my opinion is they paid for it, so they can screw it up all they want. Mr. Hardy on the other hand, perhaps believes some lèse-majesté goes on.

ahem.
Dr. Hardy.
Just sayin'.



On topic: actually, perhaps the best thing about tyros re-engineering electronics may be... natural selection.

 

[fpitas]

ahem.
Dr. Hardy.
Just sayin'.



On topic: actually, perhaps the best thing about tyros re-engineering electronics may be... natural selection.

He meant to do that!

And I doctored my last post. So to speak.

 

[MattHooper]

I'll be completely honest (even though the following goes without saying at a place like ASR): The simple and non-optimal (objectively speaking) design of my chosen power amplifier (single ended 2A3, zero added NFB) is the root cause of its sensitivity to the electrical properties of the active components (tubes) used in it -- maybe some of the passives, as well. So -- instead of little knobs to turn to adjust the tone or contour, one may swap tubes to accomplish the same thing! It's much more expensive, and less predictable! But it's fun. In fact -- it's fun to even know one may do it if one wishes to, whether one actually does "roll tubes" or not!

Yeah, I definitely admit to having a foot in old school audiophiledom in that regard. I get why people like to "tweak." It's involving, helps you feel like you've guided sound exactly to where you want it, put something of a personal stamp in there. A bit different from just wanting a system to do it's job reliably, accurately as it's supposed to do it, where you *don't* want your personal touch messing anything up.

Some audiophiles aren't technically proficient so keep this in the 'audiophile tweak' realm (including the voodoo stuff), while others more technically proficient and inclined take the desire to have personal input right to the DIY level. Which is cool.