New production 12AX7

[Audiotexan]

I apologize for my Eurocentric post.

LOL! No harm, no foul!

It's just a vintage vs modern thing. *grins*

[überfuzz]

LOL! No harm, no foul!

It's just a vintage vs modern thing. *grins*

You mean modern as in, you've got houses, Churches, bridges and stuff confidently pushing 100 in North America. :-P

[Audiotexan]

You mean modern as in, you've got houses, Churches, bridges and stuff confidently pushing 100 in North America. :-P

I'm confused.

Are you saying we DON'T still have currently/actively used outhouses in Kentucky and Tennessee? LMAO ;P

[km6xz]

Yes, the envy of everyone in West Virginia....

Most of the infrastructure was built in the period from the mid 30s to late 60s and not much since, so all those shiny new bridges in 1937 will collapse at about the same time, and the 1950s highways and overpasses are approaching End of Life. At least we have 1990 internet.....unfortunately, the rest of the world has 2010 internet. But hey, no one builds more Wal-Marts or Payday Loan offices. That is what is meant when foreigners always here chants "we are number 1" from Americans who never traveled out of their state.
We used to make good tubes with actual quality control but that was when we actually made things.

The early post about frequency response was wider with older tubes must have been a joke, surely no one actually believes that. I have never seen a functioning 12AX7 which did not have flat response from DC to 20Mhz and one in good condition would have a -3db point of over 60Mhz. I have read similar nonsense on the internet before but apparently those repeating it never measured it themselves. That is how dangerous the internet can be, because a lot of people repeat something there must be truth to it. Try it yourself, set up a lab type test rig, and plot the frequency response of a grounded cathode tube. All the power tubes can exceed 30Mhz and some types can hit 100Mhz. The 6L6 was used often for 25 watt transmitters finals up to 50Mhz, since it was a descendent of the 807 that was a 5 pin + place cap transmitter tube from the 30s.
Think about it. Why would an amp sound like it had a wider response when the notes from a guitar are from a very narrow range? If it is brighter sounding(which many confuse with better HF response) it is because more harmonics are being generated: more distortion. If it was coming from a tube, that would be a bad thing, not a good thing with better frequency response, because it means even when you do not want distortion, you have it regardless. It might be a defective tube or defective tube and design combination, but it is not because of wider frequency response of the tube.

[J M Fahey]

Try it yourself, set up a lab type test rig, and plot the frequency response of a grounded cathode tube. All the power tubes can exceed 30Mhz and some types can hit 100Mhz. The 6L6 was used often for 25 watt transmitters finals up to 50Mhz, since it was a descendent of the 807 that was a 5 pin + place cap transmitter tube from the 30s.

This is what Stan means, straight from Popular Mechanics 1946 , when USA did run the World (well, half of it) ; by the way what Stan probably built when he was 9:

[km6xz]

I never saw that one since I was not born yet but my first transmitter used a 807 that were $0.25 new at the time, because of the great amount of war surplus available. The 807 was a durable tube, it had to be for tolerating a little kid not old enough for Little League baseball trying to get 75 watts out of it. 850volts B+ helped. 1956-57, I can't remember the year but sure can remember the details of the schematic. I quickly graduated to 6146A's for 180 watts out of a pair then big tubes after that like 450TL and 750TL. The 750TL needed 7.5 volt heater supply at 20 amps and could handle 6,000 volts on the Anode. It is almost 2 feet tall. They became surplus because they were used in some military point to point short wave transmitters. I snagged a partly disassembled Wilcox transmitter and conned my neighbor's dad to go pick it up with his truck if I repaired his RCA TV(I had never repaired a TV before). The transmitter was in excellent condition but had been used for parts in an emergency and no one ever reassembled it. It probably cost $10,000 in the 1955 but I got it for $8. I always loved surplus, great engineering for hobbyist prices and prided myself in being able to identify just about every module and sub assembly from every piece of military or test instrument electronics by the time I was 12. I did not lust after a new bike or mitt, I saved every penny to go to surplus actions or sales yards at the nearby air base.

The cool thing about the 450 and 750TL or H was they glowed a little in the dark. The glass seals were uranium glass. That was harmless but sure was cool anyway....By 1959, the sun spots were so strong that short wave was open night and day for talking all over the world even with low power. My location seemed like a pipeline into the southern Pacific where I made friends with other kids on small islands all over, in into Northern Europe and Russia every afternoon when I got home from school. Talked to 100 countries in that one year alone. That was probably the source of my interest in travel and cultural anthropology later on.

[Chuck H]

I snagged a partly disassembled Wilcox transmitter and conned my neighbor's dad to go pick it up with his truck if I repaired his RCA TV(I had never repaired a TV before). The transmitter was in excellent condition but had been used for parts in an emergency and no one ever reassembled it. It probably cost $10,000 in the 1955 but I got it for $8.

Cool!

If it weren't for the Stans of the world there'd be no one to want to be like

I've often kicked around the idea of a 50W Champ using an 807 tube! I'm not really into the Champ sound but the idea seems too cool NOT to consider.

[Audiotexan]

I was playing in jest with uberfuzz' last reply, since he was doing the same.

Yes, the envy of everyone in West Virginia....

Now if you'd have left it here... that would have been a funny addition! However

<snipped irrelevant 1950s highway info> At least we have 1990 internet.....unfortunately, the rest of the world has 2010 internet. But hey, no one builds more Wal-Marts or Payday Loan offices. That is what is meant when foreigners always here <sic> chants "we are number 1" from Americans who never traveled out of their state.

If you could pass a chance to get a good dig in at "those nasty Americans", you might have realized that I was enjoying a light go at those same backwoods types.

We used to make good tubes with actual quality control but that was when we actually made things.

Now you speak as though you're a proud American?

The early post about frequency response was wider with older tubes must have been a joke, surely no one actually believes that. I have never seen a functioning 12AX7 which did not have flat response from DC to 20Mhz and one in good condition would have a -3db point of over 60Mhz. I have read similar nonsense on the internet before but apparently those repeating it never measured it themselves. That is how dangerous the internet can be, because a lot of people repeat something there must be truth to it.

Yeah, and we know you claim there are no sonic differences in tubes either. We've been down this road Stan. So why would you intentionally try to stir it up, and confuse the subject matter?

Not sure if you're referring to:

Take a set of tubes from the golden age, the frequency response is flatter, the breakup is smoother over the frequency range etc...

or my comments on his comment above (which were based on sound characteristics/qualities):

" there was still quite a bit of variance back then (if not more so, because of more manufacturers) in the frequency response/breakup points than what there is now.

IF tolerances/QC was tighter nowadays, you wouldn't have nearly the wide range of "freq. response" that we due, thanks largely in part due to manufacturing inconsistencies.

Where the "wide range" came in was rather obvious. If you get two of the same brand, batch, mu-rating, and they sound different...but it's nothing to do with the direction you've twisted the topic towards. It's manufacturing inconsistencies.

Think about it. Why would an amp sound like it had a wider response when the notes from a guitar are from a very narrow range? If it is brighter sounding(which many confuse with better HF response) it is because more harmonics are being generated: more distortion. If it was coming from a tube, that would be a bad thing, not a good thing with better frequency response, because it means even when you do not want distortion, you have it regardless. It might be a defective tube or defective tube and design combination, but it is not because of wider frequency response of the tube.

I'll buy/believe (as you point out) that it might be a defective tube. Because certain current tubes aren't manufactured to the same standard, as even the other ones rolling off the same line using the same materials/process/people....

And I agree that circuit design definitely affects (enhances either positively or negatively) already intrinsic properties of any given tube.

But thinking all 12AX7 tubes sound the same (if made to the same standard) would be a joke right? Surely no one actually believes that. As different materials, different structures...I digress. Again.

[überfuzz]

with the last couple of posts youre using an analogy in an attempt to try and examplify how some tubes got mojo and some just wont grove with the rest of the hardware, right?

[Leo_Gnardo]

IBut thinking all 12AX7 tubes sound the same (if made to the same standard) would be a joke right? Surely no one actually believes that. As different materials, different structures...I digress. Again.

The subject's been kicked around so much it's just rags n bones. Of course all 12AX7, ECC83, 7025 etc have flat response from DC to the moon. When tested in a physically stable jig. When being shaken by a speaker a couple inches away, might find resonances that enhance some audio frequencies and make others sound awful, but that's a test AFAIK never been done. Sometimes you don't even need a speaker shaking it.

Then there's tubes that are obviously defective for audio use, like the fake "Mullard" Sovtek I yanked out of a 100W Marshall head last night. Just started whistling like crazy - that's a resonance gone out of control. If it had a stable resonance short of whistling, that would put about a 5K peak in the audio response. "Clear-toned, bright and chimey" as you'd read in the sales literature or reviews. But I'll bet you that tube would measure flat as a pancake in a test jig just like Stan says. Round and round we go, take your dramamine so you don't get dizzy.

Old advice: When the instruments tell you one thing and your ears tell you another, you're not measuring the right thing.

Are we here to satisfy meters or our ears? I'd lose a lot of customers if I installed crappy sounding, whistling howling hissing popping ticking clanking tubes and insisted "my test gear says they're perfectly all right, now stop complaining and pay up!"

[km6xz]

He made the comment that old tubes were flatter in response. I countered that. It is a false statement but no where did I say they sounded the same in a particular circuit so why twist it, just to debate a point that is not related to the comments?
If he is hearing a brightness difference it is not the frequency response of the tube. How could it be? Sure a defective tube can be defective because of loose elements and be highly microphonic but that is talking about a specific tube not meeting even the loose specs of today. A high mu triode that works will "sound" very similar to any other if used according to their specs. A triode has a predictable amount of Thd and few vary by much, there are other factors that contribute to sound difference that also reveal themselves by measurements. The difference is the measurements are more consistent between tests whereas listening tests are notoriously inaccurate and inconsistent because the listener is part of the stimulus/response loop and sound memory is demonstratively poor. If someone is hearing the difference in frequency response it is not the tube, but many things can cause a difference in perception and measurement, like mu in a circuit that has reactive elements such as tone controls. Normalize the stage gain and test again, you might be surprised how little difference there is.

[Chuck H]

All I can say about all preamp tubes sounding the same is: In a perfect world and only on paper.

It's been made abundantly clear that there's no theoretically technical possibility that different tubes sound different. Well... Maybe not. There's still interelectrode capacitance! And very small differences here CAN matter. I don't know if this is the only player in the game. I do know that you can't always believe the spec sheets for accuracy. A small difference in plate to grid capacitance in a typical guitar amp circuit (100k plate/1.5k cathode/22uf bypass/150 to 200Vp) can make a very audible difference that I've read (but can't explain because of my own technical shortcomings) is a variable difference with moving plate voltage. So now there's a dynamic element as well as a strictly EQ element. So, to all the ney sayers, try this:

Plug a Sovtek 12ax7wa into the first preamp position of any amp that has a voltage divider between the first and second amplification stages and listen. Take whatever measurements you feel necessary.

Now replace it with a NOS Telefunken 12ax7 of any type. Make adjustments for bias, etc. and be sure to adjust the voltage divider so the exact same amount of amplified signal is getting to the next amplification stage.

That's it. Now tell me there's no difference. No one needs to key in and say otherwise unless they have run the test.

If this is a phenomenon that's only applicable to guitar amps and their signature class A 100k plate preamp circuit, well, isn't that relevant? It wouldn't seem like a fair judgment to say "Tubes sound the same." only to follow with "except in something like a guitar amp circuit."

[g1]

I guess it can come down to how many db you consider relevant (or irrelevant).


That graph comes from the following article. Some of the contents are debatable, but I don't have a problem with that graph.
https://www.amplifiedparts.com/tech_...ent_made_tubes

[km6xz]

The graph shows that when gain is normalized, even in a reactive circuit there is essentially no difference in gain based on frequency alone.

[J M Fahey]

if I installed crappy sounding, whistling howling hissing popping ticking clanking tubes and insisted "my test gear says they're perfectly all right, now stop complaining and pay up!"

Crappy sounding is 100% subjective and everybody has his own standard, meaning there is no standard.

But :
* whistling
* howling
* hissing
* popping
* ticking
* clanking


are ALL measurable; easily and with precision (and repeatably, I might add).

And your test gear will clearly show the differences.

Don't compare pears to oranges.