For direct experience (after years of job).
I built years ago a p-p of 300B; each one run at 45 mA bias / 420 Vdc (180 mA total only on bias)
One 5842 and 6463 / channel for driving.
With a nos (one for stereo) GZ34/37 these amps ( I built some for friends) runs for years at 95 % of its max current.
The stability of bias current was fantastic; after months it stay fix!
I tested some chinese, russian and JJ; very short life!!!!
If possible buy real nos/nib GZ34/37 or 5AR4; the price is high but also the life!!!
Walter
I built years ago a p-p of 300B; each one run at 45 mA bias / 420 Vdc (180 mA total only on bias)
One 5842 and 6463 / channel for driving.
With a nos (one for stereo) GZ34/37 these amps ( I built some for friends) runs for years at 95 % of its max current.
The stability of bias current was fantastic; after months it stay fix!
I tested some chinese, russian and JJ; very short life!!!!
If possible buy real nos/nib GZ34/37 or 5AR4; the price is high but also the life!!!
Walter
I think I can settle this as an unbiased observer.
I've got a Monarch ST400 that was missing the tube rectifier (GZ34/5AR4) when I got it. I need to finish refurbishing it, and have a JJ GZ34 to try in it.
Y'all send me your NOS 5AR4/GZ34s and I'll perform a zero blind test (I'll know which one is installed) to see if they make a difference.
I've got a Monarch ST400 that was missing the tube rectifier (GZ34/5AR4) when I got it. I need to finish refurbishing it, and have a JJ GZ34 to try in it.
Y'all send me your NOS 5AR4/GZ34s and I'll perform a zero blind test (I'll know which one is installed) to see if they make a difference.
This is all very interesting..
On the measurement front:
Describe a colour with numbers..describe a sound with numbers..
Then describe either as perceived in someones head with numbers and then say that this measurement is the same for everyone..
__________________________
Now if this is the case (or not the case) lets look at mono blocks because theoretically they can never match, and only be very very close to specification...If this be right or wrong..(a car built on a friday) two mono blocks made in different factories to the same spec put in a box as a pair..would you be happy with this or would you want them made in the same factory..maybe by the same person..would you be happy with one built on shift 1 and the other as the shift changes and built by another person...would you be happy with two OP Tx's made in different factories to the same spec? or in the same factory by different machines or people?
Are we paranoid..or superstitious..when holding two OP tx's one in each hand knowing they come from different factories (to the same spec) are you happy?
If you stood in a shop with another person with the same matching pair of Tx's would you swap one with them and still be happy you had a "set of two" Tx's for your high end amp?
Regards
M. Gregg
On the measurement front:
Describe a colour with numbers..describe a sound with numbers..
Then describe either as perceived in someones head with numbers and then say that this measurement is the same for everyone..
__________________________
Now if this is the case (or not the case) lets look at mono blocks because theoretically they can never match, and only be very very close to specification...If this be right or wrong..(a car built on a friday) two mono blocks made in different factories to the same spec put in a box as a pair..would you be happy with this or would you want them made in the same factory..maybe by the same person..would you be happy with one built on shift 1 and the other as the shift changes and built by another person...would you be happy with two OP Tx's made in different factories to the same spec? or in the same factory by different machines or people?
Are we paranoid..or superstitious..when holding two OP tx's one in each hand knowing they come from different factories (to the same spec) are you happy?
If you stood in a shop with another person with the same matching pair of Tx's would you swap one with them and still be happy you had a "set of two" Tx's for your high end amp?
Regards
M. Gregg
Last edited:
No, that's not looking at it correctly. The point is that if there be a perceived change in sound texture, quality call it what you like, then there can only be an electrical reason for this assuming identical listening conditions etc.
So if someone says so-and-so's 12AX7 sounds better than one from the XYZ factory, there must be an electrical reason, indeed there can only be an electrical reason.
All else is imagination.
Paul
I think you need to think again..what sounds good to one person many sound different to another..beauty is in the "ear of the beholder" We know that all tubes have different characteristics..thats why they match them even then they are close not exact..Yes their would have to be a difference in characteristics..and yes it would probabably be measurable..But how close is the part to spec? How measurable is cost effective for anything?
I agree their is a mystical element in it<<<I'm not saying that its all real.
Even you must admit if you have a choice and hold two identical parts in your hand you will choose one over the other that maynot be based on anything measurable that you can say for sure is logical choice. It might be you don't like the weld on some metal but it is not out of spec..
Regards
M. Gregg
Not at all. Of course it is entirely probable that no two persons will hear in the same way - or even hear exactly the same things; but this is not the basis of my argument.
The point at issue is the fact that individuals will say (for example) that an ECC82 with a diamond on the bottom sounds better than an ECC82 from some unknown factory in the central Europe or the far east. The fact that an ECC82 is a horrible valve has nothing to do with this kind of thing; the fact is that people will insist that Valve A sounds better than Valve B. Once again, if someone perhaps with "golden ears" can hear a difference then I insist that there must be an electrical or electronic reason; if there be no electrical or electronic change then the sound must be the same all else being equal.
Paul
There was a statement somewhere in this thread about being able to hear the differences between resistors......Well, I must state that I have heard obvious differences between different types of resistors that were operated within their ratings......and I could measure them! This was years ago when I had crappy equipment too (I used an old 331A and a 204C). How? Rig up a common cathode amp using a high Mu triode (I used a 5842) buffer its output with a cathode follower of mosfet follower so it sees a very light load, and swap in different plate load resistors. Use a large value resistor and a high supply voltage to maximize gain. Measure a bunch with a digital meter and select them for exact value match. The THD can vary by almost 1% with carbon comp being the worse. The cheap Xicon metal film are among the best when operated within their ratings, a bit schizophrenic above their VOLTAGE rating.
Back to rectifier tubes. I, and my customers have all had brand new production 5AR4's spark out on initial start up. Sometimes 2 or 3 will blow on power up, but once a good one is found they will usually live for a few years. Autopsy on failed tubes reveals sloppy construction, either an uneven cathode coating or sometimes poor plate / cathode alignment. Either of these conditions causes all of the cathode current to flow through a small area exceeding the current density causing an arc. This has been seen in all of the current production tubes and seems to be batch related. I do have an old RCA (made by Sylvania) 5AR4 that I have been using for about 10 years and it has no problem starting up into a 100uF input cap.
Lets assume we want to test the rectifier tubes before use to find defects. A conventional tube tester is virtually worthless for finding anything but a stone dead rectifier tube. I have rigged up testers for many different tubes, but I have yet to find a method for finding rectifiers that will explode, except for an actual power supply.
There is however a simple test that can be done to find the tubes that pass a tube tester, but can cause hum or IMD in an amp (yes you can hear it if it is real bad). A full wave rectifier tube like the 5AR4, 5U4, or 5Y3 can have a mismatch between the two plates. It is usually worse with indirect heated tubes like the 5AR4. To test for this, light the heater, ground the cathode, and apply a fixed current to each plate (use a CCS or current limited power supply) of a magnitude equal to the maximum tube spec, aor the amount that will be seen in the actual circuit. Measure the plate voltage for each plate. It should be considerably below the value given in the tube manual, and each plate should match within a few volts. A mismatch will cause 60 Hz (or 50 Hz) ripple that can cause hum, or low level 60 Hz IMD.
I use this method to select a handful of good tubes to keep from a large box full of used tubes. If you are going to make a bridge with damper tubes, use this method to find 4 that match for lowest B+ ripple.
So I find a big box full of 6AX4's, grade out some with the lowest voltage drop, writing the number on each tube, select 4 with matching numbers that are all made by the same manufacturer. I stick them all in an amp, flip the switch and zap the line fuse blows. In my usual style I stick in a bigger fuse and repeat. This time one of the rectifiers sparks out, glows blue, and then the fuse blows. New tube, amp works. The tube that tested good, but sparked out has a hole through the plate! It has obviously seen some hard use. End of story????? Is my name Tubelab????? Do rectifiers glow????
I decided to repeat my matching setup, but this time I set the power supply current limit on 1 amp instead of 200 mA. It would see 4 amps before I was done.
Back to rectifier tubes. I, and my customers have all had brand new production 5AR4's spark out on initial start up. Sometimes 2 or 3 will blow on power up, but once a good one is found they will usually live for a few years. Autopsy on failed tubes reveals sloppy construction, either an uneven cathode coating or sometimes poor plate / cathode alignment. Either of these conditions causes all of the cathode current to flow through a small area exceeding the current density causing an arc. This has been seen in all of the current production tubes and seems to be batch related. I do have an old RCA (made by Sylvania) 5AR4 that I have been using for about 10 years and it has no problem starting up into a 100uF input cap.
Lets assume we want to test the rectifier tubes before use to find defects. A conventional tube tester is virtually worthless for finding anything but a stone dead rectifier tube. I have rigged up testers for many different tubes, but I have yet to find a method for finding rectifiers that will explode, except for an actual power supply.
There is however a simple test that can be done to find the tubes that pass a tube tester, but can cause hum or IMD in an amp (yes you can hear it if it is real bad). A full wave rectifier tube like the 5AR4, 5U4, or 5Y3 can have a mismatch between the two plates. It is usually worse with indirect heated tubes like the 5AR4. To test for this, light the heater, ground the cathode, and apply a fixed current to each plate (use a CCS or current limited power supply) of a magnitude equal to the maximum tube spec, aor the amount that will be seen in the actual circuit. Measure the plate voltage for each plate. It should be considerably below the value given in the tube manual, and each plate should match within a few volts. A mismatch will cause 60 Hz (or 50 Hz) ripple that can cause hum, or low level 60 Hz IMD.
I use this method to select a handful of good tubes to keep from a large box full of used tubes. If you are going to make a bridge with damper tubes, use this method to find 4 that match for lowest B+ ripple.
So I find a big box full of 6AX4's, grade out some with the lowest voltage drop, writing the number on each tube, select 4 with matching numbers that are all made by the same manufacturer. I stick them all in an amp, flip the switch and zap the line fuse blows. In my usual style I stick in a bigger fuse and repeat. This time one of the rectifiers sparks out, glows blue, and then the fuse blows. New tube, amp works. The tube that tested good, but sparked out has a hole through the plate! It has obviously seen some hard use. End of story????? Is my name Tubelab????? Do rectifiers glow????
I decided to repeat my matching setup, but this time I set the power supply current limit on 1 amp instead of 200 mA. It would see 4 amps before I was done.
Attachments
Nice post from Tubelab above - I always respect his contributions.
What I find utterly depressing about these kind of threads - and why I rarely want to contribute to them - is the glee that so many posters seem to derive from making dogmatic statements.
So where is curiosity? That essential element that has fuelled all advances in science? Where is the openness and tolerance of chaos that is the primary part of the creative process?
So we should be able to measure all differences electronically. Good arguments in favour - we have very sophisticated techniques. But all measurement evolves - it won't be as good today as it will be in 5 years. So measurement itself isn't a static factor. Hell - look at the genome project and how much more we can measure as a result of it. That's very recent. It confirmed a lot of what we already knew before by other means, but it also came up with wholly new stuff.
What are we measuring? Jean Hiraga showed with MC cartridges back awhile that we weren't then measuring the right things (harmonic spectrum) to verify the differences we were hearing. Some version of "measuring the right thing" will always be present, so that's not static either.
And then there's the interpretation of the results - As Pano said, the violin testers COULD hear differences, they just didn't all prefer the old violins - a point which several missed. I'm sure we haven't heard the last of those tests.
Tubelab made the point that the construction of parts is a factor - no two parts will be identical. So what effect does this have? He also made the point that parts change over time, sometimes very short periods of time.
I don't know the answer to a lot of the questions above, partly because I suspect that there is no definitive answer, simply an evolving scientific culture that requires curiosity and open-mindedness to sustain its continual development.
My brother and father are/were doctors. One day my brother pulled out one of my father's student textbooks and was rolling around the floor laughing his head off. Yet at the time a lot of eminent scientists contributed to what was then the state of the art.
andy
What I find utterly depressing about these kind of threads - and why I rarely want to contribute to them - is the glee that so many posters seem to derive from making dogmatic statements.
So where is curiosity? That essential element that has fuelled all advances in science? Where is the openness and tolerance of chaos that is the primary part of the creative process?
So we should be able to measure all differences electronically. Good arguments in favour - we have very sophisticated techniques. But all measurement evolves - it won't be as good today as it will be in 5 years. So measurement itself isn't a static factor. Hell - look at the genome project and how much more we can measure as a result of it. That's very recent. It confirmed a lot of what we already knew before by other means, but it also came up with wholly new stuff.
What are we measuring? Jean Hiraga showed with MC cartridges back awhile that we weren't then measuring the right things (harmonic spectrum) to verify the differences we were hearing. Some version of "measuring the right thing" will always be present, so that's not static either.
And then there's the interpretation of the results - As Pano said, the violin testers COULD hear differences, they just didn't all prefer the old violins - a point which several missed. I'm sure we haven't heard the last of those tests.
Tubelab made the point that the construction of parts is a factor - no two parts will be identical. So what effect does this have? He also made the point that parts change over time, sometimes very short periods of time.
I don't know the answer to a lot of the questions above, partly because I suspect that there is no definitive answer, simply an evolving scientific culture that requires curiosity and open-mindedness to sustain its continual development.
My brother and father are/were doctors. One day my brother pulled out one of my father's student textbooks and was rolling around the floor laughing his head off. Yet at the time a lot of eminent scientists contributed to what was then the state of the art.
andy
Last edited:
reading tube books of old i failed to find todays' many claims about "this tube or "that tube"....
the emphasis then was about how to make those tubes work....
the emphasis then was about how to make those tubes work....
Hi Andy,
I think there is curiosity and open mindedness as well as the opposite in both camps of this discussion.
Whenever I see such claim about this or that brand of a rectifier or other miniscule detail allegedly making a 'huge' difference in sound, I point out that this rather is a sign of a poor amplifier circuit which apparently is so sensitive.
It takes curiosity and open mindedness to accept that this holy amp which is able to reveal differences in rectifiers might not be that good after all. Why not try to understand why it is such and what can be done to remove that sensitivity?
I have yet to hear an amp which allegedly is showing such difference between rectifiers that actually sounds good to me. As mentioned, last time I listend to such an amp which was claimed to need a very specific rectifier, I didn't like it at all.
I think there is so much focus in audio on rather unimportant detail. I have seen many people loose the big view. One can easily fall into a trap and zoom into miniscule sound details. But what is the point in optimizing on a small scale when there is so much room to optimize an a large scale.
It remains yet to be proven to me that rectifier brands, power cords and similar snake oil stuff actually does produce clearly audible differences. So far the owners of such components could not even demonstrate to me that they are reliably able to hear such differences themselves. What's the point if an improvement is only audible when you concentrate real hard? I rather optimize things which you can easily hear from the next room. Tube rolling so far never gave such differences to me (if all tubes are actually ok).
Best regards
Thomas
I think there is curiosity and open mindedness as well as the opposite in both camps of this discussion.
Whenever I see such claim about this or that brand of a rectifier or other miniscule detail allegedly making a 'huge' difference in sound, I point out that this rather is a sign of a poor amplifier circuit which apparently is so sensitive.
It takes curiosity and open mindedness to accept that this holy amp which is able to reveal differences in rectifiers might not be that good after all. Why not try to understand why it is such and what can be done to remove that sensitivity?
I have yet to hear an amp which allegedly is showing such difference between rectifiers that actually sounds good to me. As mentioned, last time I listend to such an amp which was claimed to need a very specific rectifier, I didn't like it at all.
I think there is so much focus in audio on rather unimportant detail. I have seen many people loose the big view. One can easily fall into a trap and zoom into miniscule sound details. But what is the point in optimizing on a small scale when there is so much room to optimize an a large scale.
It remains yet to be proven to me that rectifier brands, power cords and similar snake oil stuff actually does produce clearly audible differences. So far the owners of such components could not even demonstrate to me that they are reliably able to hear such differences themselves. What's the point if an improvement is only audible when you concentrate real hard? I rather optimize things which you can easily hear from the next room. Tube rolling so far never gave such differences to me (if all tubes are actually ok).
Best regards
Thomas
Hi Thomas,
Agree with a lot of what you say - especially the big picture. Oak feet.... yuk.
I think one of the big problems with what we hear, though, is that human hearing is extremely sensitive. But the human brain has to INTERPRET what our perception provides to the brain, and this is where all sorts of errors creep in. The brain, in order to function at all, has to selectively attend to stimuli, and does this on a constantly changing basis. We can physically hear all kinds of things but we don't have the processing power to interpret more than a fraction of it.
andy
Agree with a lot of what you say - especially the big picture. Oak feet.... yuk.
I think one of the big problems with what we hear, though, is that human hearing is extremely sensitive. But the human brain has to INTERPRET what our perception provides to the brain, and this is where all sorts of errors creep in. The brain, in order to function at all, has to selectively attend to stimuli, and does this on a constantly changing basis. We can physically hear all kinds of things but we don't have the processing power to interpret more than a fraction of it.
andy
Hi Andy,
Yes agree, the human hearing is an incredible sensitive thing. Far more advanced than our measurement technology. At the same time our brain can also fool us.
I have attended so many listening tests and shootouts, I have seen it all. People who are so burried in their self dillusion that they hear what they want to hear. I have attended listening sessions in which some guys got totally excited about alleged differences where I could barely hear anything.
At the same time I have seen big question marks in the same people's faces when confronted with the sound difference between two amps which I found extremely different and they couldn't really tell which was better.
The best systems I have heard so far had been assembled by people who do not care about tube rolling, who use standard power cords, cheap power distribution boxes and who only care little about wire and cable. The worst systems I heard usually had cables and cords thicker than garden hoses, power distribution boxes made of expensive materials, placed on vibration damping elements and more such silly stuff.
I was in that camp a long time ago in my dark audio past, hunting for the best cable, suspending wires from the floor, vibration damping, the whole crap. I only really advanced when I let all that stupid stuff go and tried to understand what is really going on.
Best regards
Thomas
Yes agree, the human hearing is an incredible sensitive thing. Far more advanced than our measurement technology. At the same time our brain can also fool us.
I have attended so many listening tests and shootouts, I have seen it all. People who are so burried in their self dillusion that they hear what they want to hear. I have attended listening sessions in which some guys got totally excited about alleged differences where I could barely hear anything.
At the same time I have seen big question marks in the same people's faces when confronted with the sound difference between two amps which I found extremely different and they couldn't really tell which was better.
The best systems I have heard so far had been assembled by people who do not care about tube rolling, who use standard power cords, cheap power distribution boxes and who only care little about wire and cable. The worst systems I heard usually had cables and cords thicker than garden hoses, power distribution boxes made of expensive materials, placed on vibration damping elements and more such silly stuff.
I was in that camp a long time ago in my dark audio past, hunting for the best cable, suspending wires from the floor, vibration damping, the whole crap. I only really advanced when I let all that stupid stuff go and tried to understand what is really going on.
Best regards
Thomas
True that! I am at a point in my audio life that if I have to focus so hard to hear the sonic difference then I am not listening to the music and it's not worth my time. Notice in audio get together when everyone is closing their eyes on trying to hear the details and forced to tell if there's any difference when there's none. My experience is if the sound is not represented to me effortlessly and if it only sounds good on audiophile recordings then the gear is not doing its job. The question is not if you can hear the difference but if you can hear it effortlessly. Of course this "effortlessness" in sound requires a lot of hard work to achieve in an audio system. And to this date, I'm still working on it.
Life is short. Seriously, enjoy the music and not focus so much on the sound.
Is anyone aware of a tube with similar characteristics to the GX34/5AR4 with different pin out, but similar height (2-7/8")?
I could rewire the socket for a different tube if the JJ does not hold up. The tubes I've found that are short enough (5W4, 5AX4GT, 5AR4) are direct heated and spec lower input capacitance 8-10uF) than the amp runs (40uF). Transformer specs look like the 2X 260V at 230mA on the schematic.
I could rewire the socket for a different tube if the JJ does not hold up. The tubes I've found that are short enough (5W4, 5AX4GT, 5AR4) are direct heated and spec lower input capacitance 8-10uF) than the amp runs (40uF). Transformer specs look like the 2X 260V at 230mA on the schematic.
I'm with directdriver on this one. Since getting involved in hifi in the early 1970s, I bought into all the crap of hugely expensive interconnects, speaker cables, spikes etc. i was forever searching for "tweaks" that invariably cost a lot of money and yielded nothing audibly different.
Yet when we all got together, we ummed and ahed and cooed as if this justified the latest purchase. Now older and poorer, I still enjoy hifi but it's really about the music and I only wish I'd spent the money on music rather than the gadget. Snake oil selling is apt for this bollocks and is primed by sales teams using hifi magazines. I enjoy following the technical posts on this excellent site and am learning for the first time about valves, circuits etc. my kt88 pp amp with Tannoy Revolution speakers playing CDs on an East Sound player sound perfectly good to me and I shan't be spending money on expensive valves just because someone says they are the dogs bollocks. Different maybe but "better"? I've got ears not an oscilloscope and the coloration that may exist is subjectively fine.
Yet when we all got together, we ummed and ahed and cooed as if this justified the latest purchase. Now older and poorer, I still enjoy hifi but it's really about the music and I only wish I'd spent the money on music rather than the gadget. Snake oil selling is apt for this bollocks and is primed by sales teams using hifi magazines. I enjoy following the technical posts on this excellent site and am learning for the first time about valves, circuits etc. my kt88 pp amp with Tannoy Revolution speakers playing CDs on an East Sound player sound perfectly good to me and I shan't be spending money on expensive valves just because someone says they are the dogs bollocks. Different maybe but "better"? I've got ears not an oscilloscope and the coloration that may exist is subjectively fine.
- Status
- Not open for further replies.