drdna wrote:

I built this amplifier more than ten years ago, before these other tube companies were in business. I know the Vaic tubes, which the EL tubes are related to. However, I have not tried either tube. Maybe it is a good idea (and I can always use some spares). I will order some of these tubes tomorrow, so I can compare side by side with the KR tubes. I will post the results here if anyone is interested.

This is the subject that I did not see covered anywhere but I have a resizable concern about it. There were mention in my DHT thread the good new production of Chinese, Czech and US made 2A3 tubes. I am sure that they are fine but there is a slippery moment in all of it. I spoke recently within a person who knows how properly vacuum tubes were manufactured and he explained to me that tubes making was amazingly “loaded” ceremony where each element of the tube was made from very specific, specially treated and specially made material. I mean this conversation was for hours but the idea was that the contemporary production of tubes MIGHT OR MIGHT NOT go into extend and the expense of proper metallurgy. For instance the 2A3 has no tungsten cathodes and therefore its cathode might be “poisoned” in time if it was not properly pre-burned and some other methods were not taken care.  Those methods are expensive but they have no impact to the sound of the tube when it is new and begin to make difference only in time after the tubes worked for a while.

So, I wonder, in the today world, when people look to sell merchandizes and to move forward would it be possible that the new production of tubes juts is not doen from a perspective of longetivety? Well all know that some old tube work for many years and do fine. We do not have the stats about stable sonic performance of the new production tubes. The manufacturers it looks like say nothing about it. Furthermore, I did read a number of comments on line by the looks like experienced with DHT people who bought new production tubes and very favorable comment about them. Then they admitted that in 6 moths or a year they changed their minds and went for other tubes. I read it a few times and I wonder if there is a pattern in all of it? Is it possible that the new production of DHT tubes juts are made from “wrong” material and “wrong” techniques and the new tubes on the fields get sonically degraded much more rapidly they need to? I spoke with one audio person a year ago who suggested me a specific MC cartridge  that he traded and he said that his cartridge in contrast to any other cartridge will maintain the very same sonic signature when it was new and when I ready to be trashed. Honestly, I did not happen to try that cartridge but this comment opened for me a whole new perspective…

I do not knock in a door of any specific current tube manufacture I just would like to hear from other who has more experience with DHT then I do. I would like to know if the SONIC life-expectancy of the new production of DHT tubes might be a factor.

Romy the Cat wrote:

For instance the 2A3 has no tungsten cathodes and therefore its cathode might be “poisoned” in time if it was not properly pre-burned and some other methods were not taken care.  Those methods are expensive but they have no impact to the sound of the tube when it is new and begin to make difference only in time after the tubes worked for a while.

AFAIK, cathode poisoning only happens when a cathode is kept hot with plate voltage applied for very long periods without any current flowing through it. A classic example of this are the tubes used in the sync generators of old Tektronix oscilloscopes. Many fine oscilloscopes were gutted out to get the prized Mullard 12AU7s only to find they were totally poisoned. I can assume that they were sonically dead too.

Romy the Cat wrote:

So, I wonder, in the today world, when people look to sell merchandizes and to move forward would it be possible that the new production of tubes juts is not doen from a perspective of longetivety? Well all know that some old tube work for many years and do fine. We do not have the stats about stable sonic performance of the new production tubes. The manufacturers it looks like say nothing about it. Furthermore, I did read a number of comments on line by the looks like experienced with DHT people who bought new production tubes and very favorable comment about them. Then they admitted that in 6 moths or a year they changed their minds and went for other tubes. I read it a few times and I wonder if there is a pattern in all of it? Is it possible that the new production of DHT tubes juts are made from “wrong” material and “wrong” techniques and the new tubes on the fields get sonically degraded much more rapidly they need to? I spoke with one audio person a year ago who suggested me a specific MC cartridge  that he traded and he said that his cartridge in contrast to any other cartridge will maintain the very same sonic signature when it was new and when I ready to be trashed. Honestly, I did not happen to try that cartridge but this comment opened for me a whole new perspective… I do not knock in a door of any specific current tube manufacture I just would like to hear from other who has more experience with DHT then I do. I would like to know if the SONIC life-expectancy of the new production of DHT tubes might be a factor. Rgs, Romy the caT

drdna wrote:

KR Enterprises 2A3. Minimal mechanical resonance. Solidly built. Very good, even reproduction of music across the frequency range. There is minimal harmonic distortion. The HF, midrange, and LF are correct. The reproduction of the waveform is not as accurate, with some slight sluggishness in the attack and decay. This leads to a less delicate sound that can be "steely." This tube is engineered to compensate for the problems with the recording process and the artificial nature of stereo. This compensation leads to the audio sounding most like the original musical event in the recording studio. The sound in the mixing sessions is the same sound here now. Despite its defects, more than any tube, it opens the window to seeing into the musician's soul.

Back in the “Single-stage Melquiades vs. DHT amps” there Adrian made a number of very positive comments about very promising sound from the new production from KR Czech’s Enterprises tubes

http://www.GoodSoundClub.com/TreeItem.aspx?PostID=9466

http://www.romythecat.com/GetPost.aspx?PostID=9321

I have no doubts that they sound exactly how Adrian described. Furthermore Adrian’s feedback very highly correlated with assessments I got from other trusted sources. However, there is a catch this story and I was thinking for a while to post it or not as the “catch” is none of my business. Anyhow, for the same to be honest with facts I decided that it worth to post it, not the last reason is because it is very much in line with the subject of the thread. This information came to me from a number of trusted sources but it is not my own information, so I take it for whatever it worth.

When Adrian reported about positive quality of KR tubes he was taking about the specific pair or pairs that he had and most likely that he bought some times in back. Unfortunately in the today’s standing of KR Enterprises tubes the situation is much grimmer. According to people who use a lot of KR Enterprises tubes they were out very fast, they have very high percentage of catastrophic failures and they do not sound as good as they use to sound a few years back. Reportedly a few years back the KR Enterprises tubes were phenomenal, even better in some aspects then the older tubes. A couple years back the gentlemen who found company and who was THE KR man passed away and the torch was taking by other person, presumably his wife. According to the people who had a lot of dealing with KR tubes the quality, both build and sound of the KR tubes, from that moment went way down  and according to some judgment today the KR Enterprises personnel is not able to furnish the quality hat older KR tubes had not has know how to do it.

I personally do not know how accurate it is but I know that KR Enterprises is constantly shrink the warranty coverage, from one year to 3 month and to 1 month - that is generally bad sigh. There are some other circumstantial evidences that indicate that what I was told about KR Enterprises might be very accurate. So, if somebody on a marker for the KR Enterprises remakes then pay attention to the tube vintage. It looks like the tube before 2004 might be OK and might be considered as from the KR’s golden time… Unfortunately, there are so many companies that follow the same path…

Romy the Cat wrote:

The contemporary productions DHT tubes (Russian of Chinese) are superbly firm and have no internal noise when they shacked or hit. The mintage 60 years old tubes what you make the “close to ears” test responses like as somebody threw a bicycle from a roof of Empire State Building to the ground. However, the vintage tubes are not necessary all that rattling project to sound? So, since you have a long experience to correlate the shakable and auditable then I hope you will explore it further.

drdna wrote:

It is NOT that better tubes have no vibration. Instead, the tubes that sound best to me seem to have a sort of springy sound, like the sound of a water drop or the sound of the tabla drum being struck.

Interesting. My few period DHT tube all have this springy sound but they also has a long decay of rattling. It is like string attached under the bottom of the drum and when the drum sound dies away them strings continues to vibrate. The today Russian and Chinese tube has so such an effect at all. My YO186 has as well very strong and very long “dropped bicycle sound” when tapped. I am not accustomed to correlate this mechanic stress response to auditable effect for signal that flow via tube but I was under impression that this is very negative effect.

The only experience I had with listening tubes vibration was during the time I used a Lamm phonostage with high-gain tubes. I had a bunch of WE 417A pentodes and I did see a correlation between the signal microphoniks of the tubes and their response for bear ears after the tapping. I even was trying spectroscope during that time. However, if I discard the tendencies to microphonics then I did not see any coloration between shakeabilety and sound, in fact I remember that some of “microphonic tubes” had better sound then non-microphonics tubes.

I admit that I never made that observation with power tubes. I use 6C33C since 1995-96 and if I saw a tine that has any minute shakeabilety or the “dropped bicycle sound” I just trashed the tube, it was perhaps 2 tubes among around 50-70 that I went through. The 6C33C is very “dead” and response with no residual vibration at all. So, when I recently got engaged with DHT tine they kind of scare me with their aftershock response.. One of my 2A3 from 1943 when I shake it, it response like somebody forgot a handful of changed in the balloon. However, it sound what I drive a signal through is absolutely perfect. When I was complaining to my DHT people they told me that it is normal. I am not accustomed to it and if my IDHT 6C33C would behave like this I would not even plug it in.

Romy the Cat wrote:

My few period DHT tube all have this springy sound but they also has a long decay of rattling. It is like string attached under the bottom of the drum and when the drum sound dies away them strings continues to vibrate. I am not accustomed to correlate this mechanic stress response to auditable effect for signal that flow via tube but I was under impression that this is very negative effect. However, if I discard the tendencies to microphonics then I did not see any coloration between shakeabilety and sound, in fact I remember that some of “microphonic tubes” had better sound then non-microphonics tubes.

This weekend I will be finishing the whole Milq modefication, putting it back to the full-time service and this Sunday the James Levine’s live-to-tape broadcast of “Simon Boccanegra” is was planning to listen via the reincarnated Macondo.

Doing the final testing of the Mlquiades and knowing the now it is a well packed amp I was exposing to violent physical stress, I mean really brutal shaking. The MF was shorting. It was not shoring but I had very loud pops from the speaker, and it took it even further then it burned the 100mA fuse on the DH B+.

I shell not say that I 33240 time check everything possible but it was not visible reasons what was shoring. Then I resized that it happen only with 2.5V tube, I did not treat my 4V tube as violent.  Then I narrowed down that it happens ONLY with contemporary Chinese and Sovteck tubes. I have very high quality Teflon socket that do not loose contact but what I stress the Chinese and Sovteck tubes in socket  then they short. The RCA, Sylvania and Tang-Sold have absolutely no reaction to streets in the same socket.