Sound of new production tubes

[ruffrecords]

..and you're quite sure that what you see is not because someone sold you previously de-selected goods?

I had experiences like that until I started buying wholw sealed boxes of JAN tubes: Yes, some of them are off, but nothing like what I was getting used to in buying "N"OS stashes.

I suspect very much that someone is skimming the market for good ones and letting the junk back into rotation...

Jakob E.

I am sure there are plenty of shady people selling dodgy NOS tubes. I have purchased well over 100 NOS tubes from eBay and from reputable suppliers and I am unable to dtect any significant improvement in ones from legit suppliers. I have not tried sealed boxes of JAN NOS tubes - didn't know they were available. If you have some 12AX7 tubes from this source I would love to borrow a few to test and compare with current production

Cheers

Ian

 

[tommypiper]

How does a rectifier tube affect the sound of an amp other than changing the operating voltage? 

How does any tube change the sound?  How do capacitors change the sound?  They all do.

This point was amazingly illustrated to me when I participated in a tube rolling session in a class I took years ago when we all built single-ended class A hi-fi line stages in the class.  Towards the end of the semester, twenty or so of us gathered in the instructor's garage and we tried different tubes, including the rectifier.  It was a very controlled listening session. 

There were no right or wrong answers.  Sometimes we heard things a little differently.  But most of the time the differences were obvious, plain and clear and everyone in the room agreed.  The rectifiers changed the tone.  Just like your choice of caps do.  The power supply becomes the audio signal, remember.  One member brought in a Mullard GZ34 he had, and we all agreed it sounded amazing.  When he told us the cost of those now, it made sense -- other people hear the difference too and are willing to pay for it. 

I was a skeptic before these experiences.  You really need to try it yourself.  I would guess some circuits will reflect these tones better than others, and being a musician helped me tremendously in the class -- there were two students who couldn't hear any differences because they were inexperienced listening to music and were unfamiliar with subtle shifts in tone, character timbre. The instructor was not a musician, and he heard everything that I heard, and that was one reason he found the tube rolling session so interesting -- it illustrated how different tubes change tones and he wanted less experienced students to be exposed to it.  To my ears, as a musician, the results were night and day.  It's one of the main reasons I'm interested in DIY, because I'm able to shape the sound of my own gear and recordings.

...or at least I have fun learning and trying... 

 

[Heikki]

there were two students who couldn't hear any differences because they were inexperienced listening to music and were unfamiliar with subtle shifts in tone, character timbre.

They probably hadn't been corrupted by bad influences yet.

I would stay away from "NOS" tubes, unless you need some tubes that aren't manufactured anymore. I think it was couple years back when a guitar player on one Finnish forum was complaining how his new boutique guitar amp sounded like crap. He had changed the all the tubes to "tested NOS" tubes he had bought from another member on the forum and never even tried the amp with the tubes it came with. If I remember correctly he sold the amp and of course took the expensive "NOS" tubes out and sold it with the original tubes. It was later found out there was nothing wrong with the amp and the bad sound was entirely caused by the expensive "NOS" tubes.

For some reason most "NOS" tube bases and pins look like tubes that I have used for a decade. Maybe the pins and bases get darkened too when stored in cardboard box for long periods of time.

In most cases if there are any significant changes in tone when changing tubes I would blame the designer of the circuit and not the tubes. Excluding cases like mentioned earlier where bad tubes were sold as good tubes.

Using rectifier tubes in studio equipment is just asking for trouble. Rectifier tubes fail too often even when used within specs. I like them in some guitar amps but it's annoying because every year or so I need to replace a 5AR4 on my Tweed Bassman like amp. Next time the rectifier fails I might just put silicon diodes and a resistor there.

 

[emrr]

OTOH, I've had NOS tube rectifiers in at least a dozen studio pieces for more than 10 years, no failures.

 

[Heikki]

OTOH, I've had NOS tube rectifiers in at least a dozen studio pieces for more than 10 years, no failures.

Broadcast gear from tube era has much more conservatively designed power supplies than guitar amps so my experiences with rectifier tubes probably isn't comparable. Still I wouldn't use them in any new designs or even clones of old gear and maybe NOS tube rectifiers are really better than new ones, but they are way too expensive.

 

[ruffrecords]

How does any tube change the sound?  How do capacitors change the sound?  They all do.

This point was amazingly illustrated to me when I participated in a tube rolling session in a class I took years ago when we all built single-ended class A hi-fi line stages in the class.  Towards the end of the semester, twenty or so of us gathered in the instructor's garage and we tried different tubes, including the rectifier.  It was a very controlled listening session. 

There were no right or wrong answers.

Snip

I was a skeptic before these experiences.  You really need to try it yourself.  I would guess some circuits will reflect these tones better than others,

And that is exactly the point. What you are hearing is the effect of a poor design.

Cheers

Ian

 

[mjrippe]

Broadcast gear from tube era has much more conservatively designed power supplies than guitar amps so my experiences with rectifier tubes probably isn't comparable. Still I wouldn't use them in any new designs or even clones of old gear and maybe NOS tube rectifiers are really better than new ones, but they are way too expensive.

Of the commonly used rectifier tubes, only the 5AR4/GZ34 seems to be expensive.  5Y3, 5U4, 6X4, etc. are all pretty cheap still.  I have replaced a few bad current production JJ 5AR4 but cannot remember the last time I saw a bad RCA/Mullard.

 

[ruffrecords]

Of the commonly used rectifier tubes, only the 5AR4/GZ34 seems to be expensive.  5Y3, 5U4, 6X4, etc. are all pretty cheap still.  I have replaced a few bad current production JJ 5AR4 but cannot remember the last time I saw a bad RCA/Mullard.

I wonder how this is because all the infant mortalities have been weeded out of the NOS many years ago.


Cheers

Ian

 

[mjrippe]

I wonder how this is because all the infant mortalities have been weeded out of the NOS many years ago.


Cheers

Ian

Not sure I understand that statement, Ian.  If the tubes are truly NOS, then they have not been used and any that had manufacturing defects would still fail when installed today.

 

[CJ]

here is a tip  for all you Champ owners>

 

[bibi]

here is a tip  for all you Champ owners>

That pretty much sums up what I suspected all along.  There isn't a "sound" of the rectifier per se-- it is the internal resistance which determines the operating voltage which in turn affects the tone.  The Champ, as well as any other Class A circuit, is not affected by rectifier "sag" so using a tube here is essentially pointless.

And that is exactly the point. What you are hearing is the effect of a poor design.

I wonder however why this is an example of poor design.  Surely any circuit will respond differently to the variance in operating voltages?  As I remember you aren't particularly a fan of regulated power supplies either?

 

[kambo]

And that is exactly the point. What you are hearing is the effect of a poor design.

Cheers

Ian

so, if my TLA or classic pre sounds bad, i come and bug u  ;D ;D ;D

 

[ruffrecords]

so, if my TLA or classic pre sounds bad, i come and bug u  ;D ;D ;D

Yeah, no problem. My classic pre is one which is likely to sound different with different tubes because it is based on very simple old RCA design with no negative feedback. In the instructions I show how to alter the circuit for extra tube sound.

Cheers

Ian

 

[DaveP]

Wouldn't inferior cathode coating just make tube loose emission sooner? Is there any data to backup claim of superior NOS cathode coating? I will look into RDH if they give such data.

If it's any help to this discussion, as a young chemist in 1970, I had the job of making a large batch of "Triple Carbonate" for valve heater coatings.  This formula had been developed from the original Barium Carbonate emissive coating and consisted of almost equal quantities of co-precipitated Barium, Strontium, Calcium Carbonate.  I believe this formula was unchanged from the 1950's and my batch was probably for the final lots of tubes made in the UK.  All the ingredients had to be very carefully purified and filtered before they were mixed and precipitated.

DaveP

 

[moamps]

That pretty much sums up what I suspected all along.  There isn't a "sound" of the rectifier per se-- it is the internal resistance which determines the operating voltage which in turn affects the tone.  The Champ, as well as any other Class A circuit, is not affected by rectifier "sag" so using a tube here is essentially pointless.

That's true only if an amp works only in clean (linear) mode. But, if it is in  overdrive,  the working point of the output tube is not in  class A anymore for the most of time and the current demand becomes very complex, IMO.

 

[bibi]

That's true only if an amp works only in clean (linear) mode. But, if it is in  overdrive,  the working point of the output tube is not in  class A anymore for the most of time and the current demand becomes very complex, IMO.

no, class A remains class A regardless of whether or not there is clipping involved. 

 

[PRR]

> class A remains class A regardless of

There's a point here. The idle V/I should be set similar to the expected load impedance. But when OVER-driven, to fully-clipped, the amplifier will suck the I required by the load. If load is greatly different from designed, current *will* change. In the specific case of Loudspeaker load, the load is almost never the design load, and often several times higher.

 

[CJ]

yes, and to see this overdrive the amp with a signal generator, look at AC and DC voltages and currents at the pwr stage, a scope adds to the fun,
maybe swap  tubes and build data table like a prof might make you do, 

 

[Gus]

Jakob E, posted some good links in this thread from 2005
https://groupdiy.com/index.php?topic=5829.msg69410#msg69410

some others links I found
http://www.effectrode.com/signal-tubes/mullard-ecc83-12ax7-reissue-original-physical-comparison/

http://transene.com/cathode/

 

[CJ]

Awesome!  Thank's Gus!