[jhljhl]

How about eml mesh plate - can those survive the woo wa5/le?

 

[2359glenn]

  How about eml mesh plate - can those survive the woo wa5/le?

It should but I don't know what the plate current is in the woo.
Tony has manual bias so he can turn it down for mesh plate tubes that can't handle as much current as solid plate.

 

[2359glenn]

  HEXFRED (For some reason I want to say Hexifreddie! lol) arrived today. Thanks Glenn!
 

 

 
From the outside, it is appears to be an octal socket filled full of epoxy (with a rather artistic arrangement of bubbles on top I should add) and it is very solid. Put it in and, of course, it works! But until I have had some time to compare it to my favorites, GEC U18/20 and Cossor 53KU, can't really say how it sounds....

I am not really proud of that Epoxy job tried to tap the bubbles out but more came up from the bottom

 

[JazzVinyl]

I am not really proud of that Epoxy job tried to tap the bubbles out but more came up from the bottom

Black Fingernail Polish...

 

[musicman59]

  How about eml mesh plate - can those survive the woo wa5/le?

Yes they can I have been running them for 5 years in mine.

 

[jhljhl]

  Yes they can I have been running them for 5 years in mine.

How they compare?

 

[TonyNewman]

I have been reading the official history of UK war production in WW2 (yes, very nerdy, I know) and just came across the section dealing with valves. Interesting reading. The usual suspects all get a mention - Mullard, Cossor, GEC etc.
 
Some fun facts:

1. Pre-war UK valve production was around 16 million per annum, with the military taking around 500,000 of that total.
2. With the widespread usage of radio and radar equipment the demand for valves jumped enormously during WW2, until in 1944 the demand was a staggering 60 million units. Many of these were specialist valves for use in centimetric radar sets. Despite a massive effort, the UK could not meet this number and had to import 15 million valves from the USA in 1944 under Lend Lease.
3. The UK War Office worked on the assumption of "7 valves per socket" - meaning that over the life of a piece of equipment every valve could be expected to be replaced 6 times.

 
A little OT, but it makes me look at my 1944/1945 NOS TS RP and NU 6F8G/6C8Gs with a new respect. These valves were vital to the allied cause and were a high priority production item.
 
I don't have figures for valve production in the USA for 1943 or 1944, but I would guess a figure well in excess of 100 million for both years. No wonder a few survived to be snapped up by OCD audio nuts

 
For anyone interested in such things, the volume is available for Kindle download for around $4. LINK

 

[Xcalibur255]

I'm convinced that a large chunk of the surviving round plate Tung Sol 6SN7s are B stock pieces that went onto a military surplus shelf to be used in times of major shortage.  They were parts that tested low off the factory line or had some other issue.  The A stock tubes that passed all tests went out into the field and powered equipment that was used during the war.
 
Of course some of these supplies will have remained after the fighting ended, but I think a lot of it was actually used up for its intended purpose.  It's those rare caches of tubes you find over in Europe that are the really good scores for US made tubes, because they were A stock sent over there for the war effort that never actually got used.  The stuff that stayed in the states was the backup supply.

 

[TonyNewman]

  ...
 
Of course some of these supplies will have remained after the fighting ended, but I think a lot of it was actually used up for its intended purpose.  It's those rare caches of tubes you find over in Europe that are the really good scores for US made tubes, because they were A stock sent over there for the war effort that never actually got used.  The stuff that stayed in the states was the backup supply.

 
Interesting. My TS RPs came from a supplier in Italy who got them cheap from a NATO base. My NUs came mostly from India - also a military surplus buy.

 

[TonyNewman]

Deleted - just read the reply of someone that has run them (EML mesh) for 5 years with no drama.

 

[2359glenn]

  Deleted - just read the reply of someone that has run them (EML mesh) for 5 years with no drama.

Good tubes you can tell by the bias staying rock steady no drifting.
I use KR globe 300Bs with no issues what so ever had them for a year now and used every day.  TV sound played through the
amp for good sound so on at least 6 to 8 hrs a day every day.

 

[TonyNewman]

 
Good tubes you can tell by the bias staying rock steady no drifting.
...

 
Yep - Taks/EML have all been very stable. I like that.
 
I am contemplating hacking off a pinky finger joint - Yakuza style - to remind myself to never, ever put craptastic tubes from you-know-where in my amp again.

 

[musicman59]

 
How they compare?

I have used the EAT, Elrog and AVVT.
I personally like them better than the EAT and Elrog (the Elrog failed). IMO they are much more musical.
The AVVT 32SL are just a little behind them in musicality but they have a higher output. They are equivalent to the EML 300B XLS and since I have the original version of the WA5-LE my HE-1000 benefit form the extra power.
 
I am in the list and hopefully close the the top (Glenn?) for ones of Glenn's 300B amps.

 

[gibosi]

HEXFRED
 
I haven't yet had a chance to directly compare the HEXFRED to any 5 volt tube rectifiers, but I did plug it in and spend some time with it last night. My initial impression is that the HEXFRED is a very fast and transparent rectifier. But upon further reflection, given that the voltage drop is very near zero, it might be more accurate to say that the HEXFRED has no affect on the sound. Nothing is added or subtracted, and therefore, with the HEXFRED installed, it is all about the sound of driver and output tubes. And it occurs to me that perhaps the HEXFRED gives me a sound similar to an OTL with the updated transformer and 42EC4/PY500 rectifiers? (An interesting side note, the HEXFRED never seems to get hot. After several hours of listening last night, it was cool to the touch.)
 
And speaking of drivers and output tubes, I am currently running a quad of 1953 GE 6BX7 and a Tung-Sol RPBG 12AH7. I have tried both Sylvania and GE 6BX7 as output tubes, and find that I prefer the GE. That said, my ears are somewhat sensitive to treble and I find that with some drivers, the Sylvania has too much treble energy for my comfort. But of course, my ears and gear... YMMV.
 
Here on Head-Fi, both Xcalibur and Jamato have compared the 6AH7 and its loctal counterpart, the 7AF7, to the 6SN7 and found them to be wanting. But it seems to me that in the case of these tubes it is not always easy to find a suitable 6SN7 counterpart for comparison purposes. So when I saw this RPBG 12AH7, I felt that this was the comparison to make. The 12AH7 is still not burned in, but my impression is that this tube is every bit as good at imaging and front-to-back layering as the TS 6SN7. But will be able to say more after I have had a chance to compare it directly, rather than going by memory.
 

 

[rosgr63]

  I'm convinced that a large chunk of the surviving round plate Tung Sol 6SN7s are B stock pieces that went onto a military surplus shelf to be used in times of major shortage.  They were parts that tested low off the factory line or had some other issue.  The A stock tubes that passed all tests went out into the field and powered equipment that was used during the war.
 
Of course some of these supplies will have remained after the fighting ended, but I think a lot of it was actually used up for its intended purpose.  It's those rare caches of tubes you find over in Europe that are the really good scores for US made tubes, because they were A stock sent over there for the war effort that never actually got used.  The stuff that stayed in the states was the backup supply.

If that's the case I'm lucky as most of my US tubes are of European stock.
 
The AVVT 300BSL-C37 Ennemoser design are also great tubes and the the Mesh plates even better.
The AVVT PX4M considered by some as the holly grail of PX4.
 
Alesha like Glenn is a genius, their designs often copied and used by others.
 
I see some traitors here going SS...........