[fz1jmp]

Being a relative new person to the wonderful world of tubes, well let me re-phrase that; I don't think my older systems were good enough to actually hear much difference in changing tubes, I heard a fairly significant difference between 2 sets of tubes. I have the Hogan 6sn7/76/300b amp and changed my NOS RCA's (I think) to a pair of the Shuguang Treasures and like I said, I heard a not subtle difference. Now, if its better or worse, that's another topic, but my question is really, why? What changes between the tubes? If the specs are relativity the same, why so different? I generally don't hear such a difference unless its a significant component changed out, you change an amp out, its a change, bam. Are the components in the tube that different?

Thanks!

[R_burke]

Usually quality of build - did the manufacturer of the tubes adhere to the specs and if so +/- how much, what was the quality of the materials used, etc.  Of course some times it's just blind luck and you get the right synergy between your machine and the tubes, or the reverse, the wrong synergy

[FullRangeMan]

There is a lot of responses to this question. Some are easy, the type of materials used in construction of the tube, as DHT Thorium or Oxide cathodes, direct or indirect heating, type and form of grid, single or double Triode, material and plate shape, the list is huge.

The small Triodes 12AU7, 12AT7 and 12AX7 are gemini brothers of the same family, but its gain are 20x, 60-70x and 100 times respectively.

This is about the construction only, however when similar tubes start working its behavior and sound may vary greatly.
A fascinanting subject.

[fz1jmp]

Usually quality of build - did the manufacturer of the tubes adhere to the specs and if so +/- how much, what was the quality of the materials used, etc.  Of course some times it's just blind luck and you get the right synergy between your machine and the tubes, or the reverse, the wrong synergy

Thanks for that feedback, so this is where I think that build quality kind of goes for anything. Is 1 pre-amp build (same company, model, etc.) better or worse then the next one off the line? I've worked in manufacturing most of my life, I'm a software development manager, and between sampling, quality control, etc., pretty much each lot has extremely narrow variance, barring issues of course. I wonder if that's like that one web site that listens to say 100 LP's then picks the best one and charges a boat load of cash for it.

So, I wonder if each manufacturer has a distinct sound, then between lots of that tube, there is a smaller variance that may or may not be  heard.

[fz1jmp]

A fascinanting subject.

Yes! Very interesting. Would different transistors have a signature sound also?

Hey, I think I just stumbled on a new audiophile business; we get 1000's of transistors and carefully 'listen' to each one, then we take the "A" grade, charge a bunch, and sell em! Who's in??

[FullRangeMan]

I listen and read about FET or JFET, MOSFETs and IGBT transistors had many sound differences.

[Quiet Earth]

Hi fz1jmp,

All parts that meet the same spec. are not created equally, nor are they made in the same factory by the same people, or from the same materials.  Would you believe there is a difference in the sound of the same value of resistors and capacitors too? Well, there is, if they are made out of different materials and by different factories. Chassis material, wire, transformers,,,,  they can all have a unique character in the final recipe of your amplifier soufflé.

Does a hamburger taste like a hamburger no matter where you get it? Maybe if you only eat at McDonald's.

Just out of curiosity, which tubes did you swap, the 6SN7 or 300B?

[medium jim]

The idea or notion that older or vintage amps weren't built well enough to tell a difference in tubes is absurd, at least to me.  Now factor in the fact that the OP is saying he can't disquinguish between tubes as the basis for that statement? Then is stating the tubes are NOS RCA's vs new Chinese?  Several questions come to mind, the first is are the tubes even burnt in....then there is the fact that some just cannot hear the difference even when it is present.

Jim

[medium jim]

Yes! Very interesting. Would different transistors have a signature sound also?

Hey, I think I just stumbled on a new audiophile business; we get 1000's of transistors and carefully 'listen' to each one, then we take the "A" grade, charge a bunch, and sell em! Who's in??

Already being done, but not for tone, for value matching and tolerances....

Jim

[Ericus Rex]

The idea or notion that older or vintage amps weren't built well enough to tell a difference in tubes is absurd, at least to me.  Now factor in the fact that the OP is saying he can't disquinguish between tubes as the basis for that statement? Then is stating the tubes are NOS RCA's vs new Chinese?  Several questions come to mind, the first is are the tubes even burnt in....then there is the fact that some just cannot hear the difference even when it is present.

Jim

Re-read the OP.

[medium jim]

Re-read the OP.

Oh I get it....what I don't get is comparing vintage NOS RCA 6SN7's to modern Chinese tubes....if he didn't hear a difference we would have a real problem.   

It doesn't matter when something was made, if fact, most quality tube amps from the day had superior Iron than what is being made today.  Marantz, McIntosh and HK tube amps are legendary and timeless.   I tube roll and there is a difference in my old gear!


To address the OP's real question, hell yes there is a huge difference in the quality of NOS from the 40's thru 60's and tubes made after that.   The quality of the metalurgy, gases and QC were vastly superior in the day....not to mention the construction.


Jim

[Ericus Rex]

The Treasures and the Pavane tubes are pretty well received and have a good record of reliability.  To dismiss them as 'Chinese' and bad-sounding, as your post implies, is folly in my opinion.

Tube rolling can be as significant, and thankfully much cheaper, as a component change.  When I got my current pair of speakers a few years ago they weren't working well with any of my three amps.  Some tube rolling got the sound exactly where I wanted it.  Sure beat having to sell my amps and starting the audition process for a new one.

[Quiet Earth]

I can relate to the O.P. if I am reading it correctly.

I remember changing output tubes in my old Quicksilver amp and not really hearing much of a character change other than the difference between new tubes and worn out tubes.  I also remember changing all of the tubes in my Counterpoint preamp and not really being blown away by a major character difference. I think I bought cheap tubes when I did that (or whatever was available), but I should have heard a significant change if it really mattered, right?  Back then, my whole system was not really very good in terms of resolving shades and showing any contrast.  I don't think I wanted to acknowledge that sort of thing anyway, since I had a more spec oriented, absolute-sound mentality when I was younger.

I never really "got it" until I let my belief system relax a little, and I purchased a nice SET amp because it sounded better than what I had. Not because of the science behind it.  So, I can totally understand where he is coming from (I think). Suddenly he notices real differences that make no scientific, spec oriented sense. At least that's the way I read it.

Q. "These parts all meet the same spec. Why do they sound different?"
A.  Because now you are listening.

[fz1jmp]

Just out of curiosity, which tubes did you swap, the 6SN7 or 300B?

and

I remember changing output tubes in my old Quicksilver amp and not really hearing much of a character change other than the difference between new tubes and worn out tubes.  I also remember changing all of the tubes in my Counterpoint preamp and not really being blown away by a major character difference. I think I bought cheap tubes when I did that (or whatever was available), but I should have heard a significant change if it really mattered, right?  Back then, my whole system was not really very good in terms of resolving shades and showing any contrast.  I don't think I wanted to acknowledge that sort of thing anyway, since I had a more spec oriented, absolute-sound mentality when I was younger.

I never really "got it" until I let my belief system relax a little, and I purchased a nice SET amp because it sounded better than what I had. Not because of the science behind it.  So, I can totally understand where he is coming from (I think). Suddenly he notices real differences that make no scientific, spec oriented sense. At least that's the way I read it.

Q. "These parts all meet the same spec. Why do they sound different?"
A.  Because now you are listening.

I swapped the 6SN7. I had a pair of GE/Admiral (which did sound good) and put in the Treasures. I have to say as of my last few hours of listening, they are excellent. Jazz, Pop, everything I have thrown so far have been so good. I'm absolutely loving this sound, buying this amp was the best audio move I think I have ever made. Now I see on the old tubes they are marked 86/88 and 92/96, not sure if that matters. Also, I ordered a pair of 6SN7GT Sylvania Bad Boy's (the 3 rivet ones) before the Treasures came to be, I heard they were excellent also. So I will also listen to them.

I do like the hamburger analogy. Well said. Quiet Earth, what you said about your experience with the Quicksilver amps, thats similar to my experience also. But, say with a computer. I've found when I buy say 15 for a project, if they all have the same rough build dates, they are identical. It's not like 1 is faster then the other, or the colors are better. Thats why I question it.

Thanks for all other comments. I can certainly hear a difference, my question was why.

[medium jim]

The numbers most likely represent their mutual conductance per side.

Jim

[ltr317]

The numbers are too low for mutual transconductance.  Those are emissions numbers from an emissions tester, probably Sencore or Heathkit/Knight/Eico/NRI same circuit models.   

[medium jim]

The numbers are too low for mutual transconductance.  Those are emissions numbers from an emissions tester, probably Sencore or Heathkit/Knight/Eico/NRI same circuit models.

Wrong....I have an Eico that tests for both, but emissions is merely a pass/fail, mutual conductance is tested under simulated power to the grid and will yield numbers similar to what the op's tubes have.

Granted the preferred mc measurements are stated in MU which yields numbers like 5500


Jim

[ltr317]

Wrong....I have an Eico that tests for both, but emissions is merely a pass/fail, mutual conductance is tested under simulated power to the grid and will yield numbers similar to what the op's tubes have.

Granted the preferred mc measurements are stated in MU which yields numbers like 5500


Jim

You're right, if you have either the Eico 666 "Satan's choice" or 667 models.  Those are exceptions though, as almost all MC testers read MU in the thousands, whereas almost all emissions testers read emissions in the hundred and under range.  The probability of the OP test numbers being emissions are far greater than they are MU. 

[medium jim]

You're right, if you have either the Eico 666 "Satan's choice" or 667 models.  Those are exceptions though, as almost all MC testers read MU in the thousands, whereas almost all emissions testers read emissions in the hundred and under range.  The probability of the OP test numbers being emissions are far greater than they are MU.

Actually there are many "Dynamic Mutual Conductance" type testers that don't read out in GM, or Microhmos.  They do have transformers to apply plate voltages, some are made by B&K, Sencore, Eico, Jackson.  Hickok pretty much owned the rights and theirs do read in GM, as do the Military grade testers, the TV-2 thru TV-7 and the newest TV-10.

Most people that buy/sell tubes will have a Dynamic MC tester or better.

I suppose it is possible the numbers could be the emission numbers, but more likely Dynamic Mutual Conductance. 

The sad thing is that without knowing what the tubes were tested on, they don't tell much other than they're not a tight match for expected life.  The best reading would be their ma per side.

Jim