[WilliamLeonhart]

   
Yes. Even though these Russian tubes were manufactured in 1966, they have never been used. Again, new tubes, tubes that have never been used, need to be burned-in. And it doesn't matter if they were manufactured in 1945 or 2015.
 
It is generally considered best practice to have a set of headpones plugged in when any amp is on, but not when turning it on or off. That is, it is best to turn an amp on, wait a minute or two, and then plugin the phones. And likewise, unplug the headphones first, and then turn the amp off. This protects your ears and your headphones in the event that the tube fails catastrophically. Further, I always use a very cheap pair of headphones when burning in new tubes.
 
I am not sure that it is absolutely necessary to run a signal through them, but I do.  I like to be able to listen every several hours or so, to see if they tubes are quieting down. I just run a CD player on repeat.

Thanks for the tips. So far you have helped me tremendously

 

[Gravit8]

Hey all! First off, I have a Little Dot MkII. With 6N6P-IRs power, and 6HM5s up front.  The problem I'm having is tube feedback? Not sure if that's the correct term.  If you were to flick one of your tubes, and get a pinging sound, that's what I'm getting but almost at random, near anything will set them off. For instance, I'll sneeze (literally) and the tubes will ring for 10+ seconds unless I put my finger on them (stops the vibrating?).  Also, when I shut off the amp, the tubes all click like crazy (cooling down?).  All these side affects are something I didn't have with the stock tubes that came with it. Is this all normal for these tubes?  I have multiple pairs of 6HM5, and they all do this. 

 

[buldogge]

Hey Guys...Quick question re: a pair of Tung Sol Mouse Ears 6SN7s I have...I ended up with (3) tubes...Two test strong, one just OK...One of the strong ones has a much brighter glow at the center wire which protrudes thru the top plate/mica.  Is this glow an indication of anything...one way or the other...positive or negative?  The other (2) have no noticeable glow there...
 
???
 
TIA
-Mark in St. Louis
 

 

[TrollDragon]

I have a few tubes with a bright filament glow at the top and they work fine. I think it is just a little too much filament at the top during the manufacturing process and the bottom seems to have the same glow as the other tube.
 
I like the standoff's soldered to the copper pipe sides for the socket mounting screws.

 

[buldogge]

Thanx TD...Just waiting on those Amphenol loktal sockets now, to make final adapters for the C3Gs...it's touch and go every time something is moved with those chinese sockets...
 
Also, need to replace the volume pot on the MK III I picked up...Anyone have soldering tips when working with a pot?  In and out quickly, I presume??
 
-Mark

 

[TrollDragon]

I have the ALPS Blue Velvet in the MK IV, I am not sure what is in the MK III.
A solder sucker or some dry wick will work good, the boards traces are fairly decent.

 

[TrollDragon]

  Hey all! First off, I have a Little Dot MkII. With 6N6P-IRs power, and 6HM5s up front.  The problem I'm having is tube feedback? Not sure if that's the correct term.  If you were to flick one of your tubes, and get a pinging sound, that's what I'm getting but almost at random, near anything will set them off. For instance, I'll sneeze (literally) and the tubes will ring for 10+ seconds unless I put my finger on them (stops the vibrating?).  Also, when I shut off the amp, the tubes all click like crazy (cooling down?).  All these side affects are something I didn't have with the stock tubes that came with it. Is this all normal for these tubes?  I have multiple pairs of 6HM5, and they all do this. 

The microphonics (pinging) you mention can happen in any tube but my 6HM5's do not have this. Are all the 6HM5's from the same seller? If so he or someone might have dropped the case of them at some point which would loosen up the tubes internals and make them very microphonic.
 
Have you swapped out the 6HM5's for the 5654 stock driver tubes to see if it is the output tubes making the noise?

 

[buldogge]

  I have the ALPS Blue Velvet in the MK IV, I am not sure what is in the MK III.
A solder sucker or some dry wick will work good, the boards traces are fairly decent.

Hey TD...The MKIII pot mounts to the faceplate and runs a JST 4S (5 pin) extension lead to a socket on the PCB.  I'm going to replace it with this pot:
 
http://www.ebay.com/itm/201239685917?_trksid=p2059210.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT
 


My concern is simply heat/damage at the pot interface...???
 
TA
-Mark

 

[TrollDragon]

I wouldn't see any problem soldering to that at all. I would tin the via's first then solder your wires to them.
 
Unless your using one of the old board chewers...

Then it would be time for an upgrade to a nice Hakko FX-888D or similar.

 
 
I still use my Weller WCPL that I was given for a birthday present back in the 70's...

Many, Many miles on the old girl and many thousands of solder connections.

 

[buldogge]

Thanx TD...My OE MKIII Alps pot was wonky when I got it (bought it cheapish, as broken)...tried to repair it...seems the connections/connectors/vias? loosened while de-soldering and re-soldering.  
 
I'm just using a run-of-the-mill Weller 25w....but I also have a simple Weller 80w (need to get a non-chisel tip)...
 
-Mark

 

[MIKELAP]

  I have the ALPS Blue Velvet in the MK IV, I am not sure what is in the MK III.
A solder sucker or some dry wick will work good, the boards traces are fairly decent.

 

[gibosi]

This looks very interesting... A way to improve our LDs that is a bit less drastic than replacing capacitors....   Could this "DACT Type 21 Stepped Attenuator Potentiometer 100K" referenced above by Buldogge be used in an LD 1+?
 
 

 

[gibosi]

A National Union 6F8G arrived here the other day:
 
The NU with round plates is ranked as one of the best 6F8G by a number of folks, so was pleased to find this Philco rebrand for a good price. The Philips date-code is "3S" which suggests that it was labeled and packaged by Philco in the last quarter of 1943. Next to it is a grey-glass National Union VT231/6SN7GT probably manufactured in the mid 1940s. (Is anyone out there able to translate National Union date codes?  "GU"?)
 
I personally prefer the sound of the grey-glass NU 6SN7 over the black-glass version and am interested to see how the 6F8G compares.
 

 

[MIKELAP]

  A National Union 6F8G arrived here the other day:
 
The NU with round plates is ranked as one of the best 6F8G by a number of folks, so was pleased to find this Philco rebrand for a good price. The Philips date-code is "3S" which suggests that it was labeled and packaged by Philco in the last quarter of 1943. Next to it is a grey-glass National Union VT231/6SN7GT probably manufactured in the mid 1940s. (Is anyone out there able to translate National Union date codes?  "GU"?)
 
I personally prefer the sound of the grey-glass NU 6SN7 over the black-glass version and am interested to see how the 6F8G compares.
 

Received several 6f8g waiting for adapters  Glenn made for my tubes. was asking guys in WooAudio thread about branding and its a real mess looks like you really have to see the tube regarding the structure .So far what i found was that Westinghouse ,Philco, Tung Sol, can be similar or not ,RCA ,SYLVANIA ,G.E,RAYTHEON , also G.E. and Kenrad can be similar or not theres seems to be more than one structure type for the same brand like i said a mess .Like my Westinghouse plates looks similar to your Philco                                                                                                                                                                                                                                                                                    

 

[buldogge]

  A National Union 6F8G arrived here the other day:
 
The NU with round plates is ranked as one of the best 6F8G by a number of folks, so was pleased to find this Philco rebrand for a good price. The Philips date-code is "3S" which suggests that it was labeled and packaged by Philco in the last quarter of 1943. Next to it is a grey-glass National Union VT231/6SN7GT probably manufactured in the mid 1940s. (Is anyone out there able to translate National Union date codes?  "GU"?)
 
I personally prefer the sound of the grey-glass NU 6SN7 over the black-glass version and am interested to see how the 6F8G compares.
 

Are the grey glass NUs made by NU...any other brands they were sold as to look for?  The black and grey glass tubes seem to go for silly (to me) money...
 
TIA
-Mark