[mab1376]

I really wish i could afford them, but the 6N6P-IR tubes are still amazing to me. I think they're an improvement over the new EH 6H30P-PI that came with the amp. Much cleaner sound, to me almost completely transparent which is exactly what you'd want from a power tube.

 

[mordy]

Could not find a reference for the alloy machines, but found an interesting article about Victor Khomenko - link below. However, I came across a startling item: apparently old worn out tubes can be resuscitated:
 
"I mentioned to Victor, because I knew of his background with tubes, that I had an old Fisher amplifier that had bad tubes in it, and I needed to replace them. He said, don't replace them, just bring them in. And so I did. Victor proceeded to hook them up to his equipment at the bench and resuscitated them.
Victor Khomenko: It's actually very simple. I spent my years at university studying electronic emission. We made our own cathodes, and part of it is a process of activation. As a tube wears out, you can go through the same process again, and reactivate the tube by applying particular voltages."
 
 
http://www.stereophile.com/interviews/767
 

 

[Nic Rhodes]

Thanks for the CV850 info, I have pulled the trigger and bought a few to try. It seemed the most sensible idea! Do any of you know a 6xxx to 8xxx tube PQ / SQ version on the EF95? [Fine with UK examples, primarily interested in US ones].
 

 

[gibosi]

Quote:

..........Do any of you know a 6xxx to 8xxx tube PQ / SQ version on the EF95? [Fine with UK examples, primarily interested in US ones].
 

 
I have no idea what "a 6xxx to 8xxx tube PQ / SQ version" is? Can you explain?

 

[Nic Rhodes]

Sorry, for say an EF94 / 6AU6  we have 6136, 7543 amd 8425. For 6J4 we have 8532, 6AH6 has 6485, 8136 is close to EF91 (actually 6DK6) etc etc. 6xxx to 8xxx tubes are often a special quality type (SQ) or some premium quality selected characteristic tube (PQ). So 8425 is a premium 6AU6 and 7543 is a low hum, low microphonic 6AU6. When I first looked at all these tubes 20 years ago I only identified premium UK numbered EF95s (M8100, CV4010) and the closest I got was 6069 which was basically just another number on the M8100, CV4010 types. I never found good options for EF92s, EF95s from US types (most of my tubes are UK types because that is where I live and have better access to these).
 

 

[Audiofanboy]

Quote:

Sorry, for say an EF94 / 6AU6  we have 6136, 7543 amd 8425. For 6J4 we have 8532, 6AH6 has 6485, 8136 is close to EF91 (actually 6DK6) etc etc. 6xxx to 8xxx tubes are often a special quality type (SQ) or some premium quality selected characteristic tube (PQ). So 8425 is a premium 6AU6 and 7543 is a low hum, low microphonic 6AU6. When I first looked at all these tubes 20 years ago I only identified premium UK numbered EF95s (M8100, CV4010) and the closest I got was 6069 which was basically just another number on the M8100, CV4010 types. I never found good options for EF92s, EF95s from US types (most of my tubes are UK types because that is where I live and have better access to these).
 

As far as EF95/6AK5 tubes go, the US 5654(W) is supposed to be the "special type". Though I've seen the number "6069" written on some 60's Mitcham-made CV4010, it seems to be more of a theoretical US equivalent numbering (like 6064 and 6065 for EF91 et EF92) that wasn't actually used in the US.
 
I'm sure you could find "premium" US EF95 in theory though, but I think a lot of the special 6AK5 just ended up getting another name (tube type) altogether because they would have been made for specific applications with slightly different -but different enough- characteristics; after all, the 6AK5 is about as basic as you can go in terms of pentodes, so anything extra added to it kind of changes that.
 
You do have the Western Electric 403A and 403B, but those aren't so much special types than they are WE versions of the 6AK5, again for specific applications.
 
You should be able to find -at least in theory- some Mullard "10M" EF95 tubes, rated for 10000 hours, though I'm never seen any and there would be no guarantee that Mullard actually made them -they could have been sourced anywhere in Europe or even Japan in later times.
 
Anyway, good luck looking; I'm done with 6AK5 types if just because they reach silly prices...

 

[duncan1]

Just out of interest I have a large collection of tubes/valves with many unusual ones as this is mainly a US site maybe you will know more about this one=tube type 6J6-DA-30-069-ORD-1   /  MIL-P-75 / DATE PKD NOV. 1954 /MFRS-PT # 807835-1. Sperry gyroscope company division of the  Sperry corporation. This tube unusually for a small B7G tube is rated for use in a transmitter[low wattage output] as well as other uses. Packed in plain brown cardboard the glass extrusion at the top is painted a reddish color.

 

[Audiofanboy]

Quote:

Just out of interest I have a large collection of tubes/valves with many unusual ones as this is mainly a US site maybe you will know more about this one=tube type 6J6-DA-30-069-ORD-1   /  MIL-P-75 / DATE PKD NOV. 1954 /MFRS-PT # 807835-1. Sperry gyroscope company division of the  Sperry corporation. This tube unusually for a small B7G tube is rated for use in a transmitter[low wattage output] as well as other uses. Packed in plain brown cardboard the glass extrusion at the top is painted a reddish color.

 
In theory, a 6J6 could be used in our amps. It's a 7-pin base double triode with a common cathode, which means that both triodes could be wired to work together (parallel?), therefore forming a single triode.
 
I'd actually spotted that tube type a while back since its seemed interesting, but its pinout turns out to be too different from a 6AK5 or 6AU6 type to be easily used without a thoroughly different adapter...

 

[gibosi]

Recently, I received a couple small packages in the mail and thought they might be of interest:
 
Mullard EF94 manufactured in the Blackburn factory in 1962.
 

 
I usually do not post pictures of boxes, but thought these were pretty neat:
 

 
Dow Radio was one of southern California's leading electronics stores back in the day, and these could be had for $1.26 each!
 
(A Dow Radio advertisement from around that time: http://www.vintageadstock.com/products/1966-dow-radio-sony-solid-state-sonymatic-stereo-vintage-advertisement)
 
And in another package, a pair of premium Amperex 6687/E91H (6BY6). These were made in the Philips Heerlen/Holland factory in 1962 or 1972... Can't figure out which.....
 

 
These tubes are taller than the standard 6AU6. Also of interest is some printing on top of the tube: 05M. However, I have no idea what this sequence means....
 

 
Hope to get to these soon. However, now that the growing season is upon us, I find myself spending an inordinate amount of time in my garden doing battle with the weeds! lol

 

[mab1376]

Got my TS 6BE6 today, compared directly to the TS 6AH6WA and they are just a hair brighter, but without sacrificing the low end. Soundstage seems more spacious as well. This is only after about 45 min of burn in, so hopefully time with be good to them.
 
I was using the 2-7 strap on the 6AH6WA and no strap on the 6BE6.
 
I'm still waiting on Telefunken EH900S with gold pins and also Telefunken 6BE6. I also still have GE 6AU6WA on hand untested still, I hope to get to them soon.
 
I was trying to find the TFK 6BE6W to no avail, has anyone tried any 6BE6W variants?
 
This has been my defacto test track so far, the FLAC version obviously:
 

 

[gibosi]

Quote:

I was trying to find the TFK 6BE6W to no avail, has anyone tried any 6BE6W variants?
 

 
I have the GE 6BE6W. Unfortunately, I haven't had a chance to compare these directly with the TS 6485 or the GE 8425A. However, you can find my initial impressions in post #1291, page 87. Keep in mind that I was using the EF92 setting, as at that time, it was the recommended setting for heptodes.

 

[Acapella11]

Quote:

Got my TS 6BE6 today, compared directly to the TS 6AH6WA and they are just a hair brighter, but without sacrificing the low end. Soundstage seems more spacious as well. This is only after about 45 min of burn in, so hopefully time with be good to them.
 
I was using the 2-7 strap on the 6AH6WA and no strap on the 6BE6.

 
Hi mab1376, the treble should be reduced and become "round" during burn in. Agree, soundstage and bass are plus points for the 6BE6.

 

[gibosi]

After reading Mordy's strong favorable impressions of the Westinghouse matched Tektronix 8425/6AU6, I decided to purchase a pair. However, the "pair" I received were ill-matched. One was old-tech with dark-gray plates, a D-getter and the other was new-tech with light-gray plates and an O-getter. Further, the older tube was not labeled as 8425. Although the eBay vendor called these a"matched" pair, they didn't seem so to me and I put them aside while I explored the world of triodes.
 

 
Upon returning to the world of pentodes, I decided to to try to find a suitable mate for each of these and I now have two pair, one old-tech and one new-tech.

 

 

Both old-tech tubes were both manufactured in 1962, so a pretty good match, I think. But again, these are just ordinary Westinghouse 6AU6. They are not 8425 and there is nothing special about them.
 

 

Unfortunately, there are no visible date codes on the new-tech tubes, but they appear to be identical and both have 6AU6 8425 etched into the glass, so again, a pretty good match, I think. And these are 8425, so considered special quality.
 
First, comparing the two Westinghouse pairs, they are virtually indistinguishable to my ears. The older pair might be just a tad bit brighter, but I am not sure... Otherwise, the same wide sound stage, detail, clarity and full, punchy bass.
 
The W 8425 are very good tubes and my conclusions are similar to those of Mordy. Compared to the GE 8425, the W 8425 seem to be a little brighter, with a wider sound stage and a full, punchy bass. Perhaps because of the added brightness and bass, they also seem to be a little louder than the GE 8425. And like Mordy, I would rank the W 8425 above the GE 8425.
 
Compared to the TS 6485, again, my conclusions are similar to those of Mordy. I find the W 8425 to be a bit warmer and brighter. The bass seems to have more punch and power, plus it is fuller and rounder.  However in the end, the W 8425 lack the incredible clarity, detail and balance that keep the TS 6485 on top of the heap for me.
 
But in the end, each of these three are very good tubes, and sound much more similar than different. I don't think anyone can go wrong with any of these.
 

 

[Acapella11]

Quote:

First, comparing the two Westinghouse pairs, they are virtually indistinguishable to my ears. The older pair might be just a tad bit brighter, but I am not sure... Otherwise, the same wide sound stage, detail, clarity and full, punchy bass.  
The W 8425 are very good tubes and my conclusions are similar to those of Mordy. Compared to the GE 8425, the W 8425 seem to be a little brighter, with a wider sound stage and a full, punchy bass. Perhaps because of the added brightness and bass, they also seem to be a little louder than the GE 8425. And like Mordy, I would rank the W 8425 above the GE 8425.
 
Compared to the TS 6485, again, my conclusions are similar to those of Mordy. I find the W 8425 to be a bit warmer and brighter. The bass seems to have more punch and power, plus it is fuller and rounder.  However in the end, the W 8425 lack the incredible clarity, detail and balance that keep the TS 6485 on top of the heap for me.
 
But in the end, each of these three are very good tubes, and sound much more similar than different. I don't think anyone can go wrong with any of these.
 

 
Hi Gibosi, If the stage for the Westinghouse tube is large, then you may find that the instruments or singers are not as close to you. This often gives the impression of lesser detail because you cannot "grip" them as well. But in fact because of the large stage, everything in the room just appears further away and a bit smaller. It is a natural side effect of a deeper stage. I experienced this effect with the wide and deep stage of the 6BE6. The exact opposite of this would be the triode, I guess. Being very clear but without a depth (at least my 6AQ4s are like this). Do you think, this is the case? This may put the Westinghouse tube a bit higher on my list.

 

[mordy]

Hi G,
 
I think that you will find that as you put more hours on these sets of tubes (TS vs W) the differences will be smaller with the TS having a punchier bass with more slam than the Westinghouse. Otherwise they are very similar. (My Tung Sol observations are based on 1960s 6AH6WA tubes.)
 
However, at least for me, after listening to these wonderful tubes for a while the "wow factor" diminishes and they become the "New Normal."
Some people say that "normal" means that you don't notice anything; everything just feels right.
 
So how do you bring back the "wow"? Well, you could just pop in one of the other types of tubes again such as the EF95s and so on. Suddenly something is missing, something bothers you when you are listening. Not enough bass, too much sibilance or muddiness. Or you realize when you get startled playing a recording with a vocal that there really isn't anybody else in the room. These tubes are really that realistic on some recordings! Sometimes it feels like the musician is right in front of you! Or you could listen critically to old well known recordings and discover new nuances in the music, especially in the background.
 
My hunch is that with all the excellent work of so many dedicated people on this forum we have perhaps found the best choices in driver tubes. What is left?
 
The next frontier is to find excellent inexpensive power tubes made in USA. I am hopeful that somebody will come up with a conversion or modification allowing different kinds of power tubes to be used that will better or equal the Russian DR tubes!
 
Suggestions?