Jim McShane wrote:
Peter W wrote:
Audio tubes produced today would be laughed right into the trash if foisted on the public 50 years ago.
A good reason to pay the freight and purchase such tubes as that GZ37 where possible, practical, and available.
Excuse me - but your blanket statement is incorrect IMHO and is insulting to people who use and enjoy current production tubes.
There is no current production tube directly comparable to the GZ37. But that doesn't mean all current tubes are "trash". And a good number are widely perceived to be sonicaly every bit as good or better than the old stock. The Genalex KT series power tubes come to mind as a good example.
There are also new production tubes that can really take a pounding - the EL84M Sovtek is just one example. The 6922 EH is another.
I believe you are doing a disservice to consumers of what is written here by making those statements.
Yes, the GZ37 is a hell of a tube. No, modern tubes are not all trash.
I gave myself some time to answer this.
Given my genuine respect for you as one of the few entirely ethical and legitimate tube purveyors on the planet today, and as an expert on the species, please understand my position. I will illustrate by two anecdotes first.
a) I have a Dynaco ST70 date-stamped 1963 that I have owned and used since the late 1990s. I purchased it from a private individual who retired from the record (as in vinyl) business. He purchased it as a kit, built it, and ran it 6 days per week in his store until he closed. Then, it sat in a closet for about 10 years before I purchased it at a house-sale. He was moving to points south. He claims it had the original tubes then (see below), and it has the same now. They test at 30+% over minimum on my Hickok 539B. They are within 6% for plate current as well. I would SWAG that those tubes have well over 30,000 hours on them. And still lots of getter-flash. Tubes are Siemens thin-man EL34s. Which suggest that they are replacements as they are not Dynaco-branded. So, I am splitting the difference between the 80,000+ hours that the pure math would support, and my use, and being conservative.
b) I have a Scott LK150 with all-GE 6550s. I traded for this device in 2004 from a collector in Michigan who lusted after a radio I had and had two of the above. He built it from-new, also in 1963, and replaced the OEM tubes in 1970 with the incumbents. He suggested about 20,000 hours, I have added about 10,000 hours. Those tube test about 20% over-minimum on the same tester, and are within 4% for plate current.
Now, there have been a LOT of complaints on recent-production Tung-Sol branded tubes.
Various other brands are getting mixed reviews.
Many here are experiencing short-life/multiple failures of various brands.
Those three actualities simply did not exist 'back in the day'. There was little to choose between branded tubes sold in branded boxes. Sure, IRC and off-brand tubes selling culls and seconds were a mixed bag, but when a box was marked RCA or GE or Tung-Sol or Mullard, or Telefunken, there was a near-certainty that it contained a good tube, well made, and with good longevity.
Not so much today. What is produced today would, very likely, turn up as seconds or culls by the majors. I was once in a Sylvania factory (no longer active, but the building it was in), that contained over 100,000 square feet on three floors in the main building, ran 24/7 at its peak and put out quite specifically millions of tubes in any given year, of hundreds of different types. That sort of broad and deep production simply does not happen today, nor does the level of quality control exist that would support such an endeavor. So, we get the bad Tung-Sols, and spotty quality elsewhere and so forth.
It is not that there are NO good tubes. But it is no longer possible to go down to the corner drug-store and be dead-certain that the tube purchased there would be a good one. As it once was.