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Little Dot Tube Amps: Vacuum Tube Rolling Guide - Page 141

post #2101 of 8062
Quote:
Originally Posted by mordy View Post

Mikelap,

 

 

Pardon, è Mordicci, non Mordy
 

scusa mi signor Mordicci

post #2102 of 8062

Received my TS 6AH6WA!!!! numbers 6745 and 6734 not sure what they mean. 2 different sets of numbers on 1 tube.

post #2103 of 8062
Quote:
Originally Posted by siles1991 View Post

Received my TS 6AH6WA!!!! numbers 6745 and 6734 not sure what they mean. 2 different sets of numbers on 1 tube.

 

It is hard to say... My best guess is these are dates: 1967, week 45 (November 6-12, 1967) and 1967, week 34 (August 21-27, 1967). To add to the mystery, "A 9/67" is printed on the box (It appears that I have the same tubes).

 

While I think it is safe to say that your tubes were manufactured in 1967, I do not know what events these various dates correspond to....

post #2104 of 8062

Most likely the dates on the tubes are the manufacturing dates; 9/67 is the intended packing/shipping date. Sometimes there could be more than a year's difference between the manufacturing date and the shipping date on the box forward or backwards in time!

 

Reading your post again I now realize that both numbers appear on the same tube. I have the same situation with my TS 6AH6WA tubes. One tube reads    6

                                                                                   301

                                                                                U.S.A. 7

                                                                            JTL-6AH6WA

                                                                            6316

 

IMHO this means manufactured 1st week of 1963 in the US factory #7.

JTL is the military designation for Tung Sol. 6AH6 is the tube type, the W means ruggedized, and A means revision A of the tube (usually revisions were minor changes such as the time needed to heat up etc). [I don't have the original box].

6316 is the packing date - week 16 1963.


Edited by mordy - 7/31/13 at 8:15am
post #2105 of 8062

tomorrow some new tubes i ordered should be here,

when i've had tube amps before in my hi-fi rig, i'd keep reading about mullard tubes, so when i saw these, i bit

http://www.ebay.com/itm/221258929156?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1439.l2649
 

post #2106 of 8062

HI jaywillin,

 

When you burn in these tubes, be prepared that the amp will run very hot. Nothing to worry about, but the EF91/92 tubes run hotter than any of the tubes.
 

post #2107 of 8062
Quote:
Originally Posted by mordy View Post

HI jaywillin,

 

When you burn in these tubes, be prepared that the amp will run very hot. Nothing to worry about, but the EF91/92 tubes run hotter than any of the tubes.
 


i'll keep that in mind, thanks !!

post #2108 of 8062

i've been meaning to ask, and maybe i should search first, now that i'm getting more tubes, new, and not burned in

is there a the proper procedure, or limits i should be aware of, not that i'd be leaving an amp, or anything powered up and running

all day, , but i don't want to blow or burn anything up ! lol

  edit:

 

just did a quick search, there does seem to be plenty of info on the subject , and if "burn in" even really is needed, beneficial

i do realize tubes need to warm up, that they often make noises until the temp stabilizes


Edited by jaywillin - 7/31/13 at 9:49am
post #2109 of 8062
Quote:
Originally Posted by jaywillin View Post

i've been meaning to ask, and maybe i should search first, now that i'm getting more tubes, new, and not burned in

is there a the proper procedure, or limits i should be aware of, not that i'd be leaving an amp, or anything powered up and running

all day, , but i don't want to blow or burn anything up ! lol

  edit:

 

just did a quick search, there does seem to be plenty of info on the subject , and if "burn in" even really is needed, beneficial

i do realize tubes need to warm up, that they often make noises until the temp stabilizes

 

LittleDot recommends no more than 8 hours at a time.

 

Usually people will play pink noise during the duration of the burn in, I personally just play music.

post #2110 of 8062

I was wondering how do you guys clean the pins for the NOS tubes you get?

post #2111 of 8062
Quote:
Originally Posted by siles1991 View Post

I was wondering how do you guys clean the pins for the NOS tubes you get?

I'm a nutcase about this. I prefer to clean all of my tubes pins with the backside of an xacto blade. Scraping that many pins with that method is a serious pain.
I recently read about using 99% alcohol. I ordered and tried it with no luck. Maybe I just need to soak the pins for a few hours...
I'm considering just ordering something like this though.
post #2112 of 8062

I currently am using a dremel tool with wire brush tip but need to find a better quality tip, this one flings stray wire at me...

post #2113 of 8062
Quote:
Originally Posted by siles1991 View Post

I currently am using a dremel tool with wire brush tip but need to find a better quality tip, this one flings stray wire at me...

Previous experience with those stupid tips confirms your report.
post #2114 of 8062

LittleDot recommends no more than 8 hours at a time.

 

In the interest of furthering the knowledge of the various tubes it is necessary to burn them in for extended periods before evaluating them, or using them to their full potential. IMHO heptodes require about 50 hours, others more (120 hrs) or less (30hrs).

 

The reason why there is an 8hr recommendation of use is because of heat build up. If the tubes run cool, your amp is well ventilated on cones or whatever, and under EF92 conditions with a little computer fan blowing hot air away from the amp, IMHO the amp can stay on for very long periods. I mean, 48 hours is two full days, and then the next set of tubes to burn in for another 48 hours....

 

I use my iTunes program with continuous play with all kinds of music for burning in.

 

During long runs, as long as the amp feels slightly warm to the touch am not worried. If it gets quite hot I turn the fan on but usually I don't need to do it.

post #2115 of 8062
Siemens EK90 and EH90
 
With all the different versions of Siemens EK90 and EH90 we have seen recently, no one really knows which are "real" and which are simply rebranded. While I am not sure I am any closer to answering this question, I think I have made a little progress in clearing away some of the haze.
 
I have Siemens and Siemens-Haltron EK90 with ribbed plates that might be "real". However, since there are no tube codes or any other markings which can be used to trace them directly to the Halske factory, I can't be sure. Even though I am not sure that either of these are real Siemens, all of us who have these tubes find them to be top tier tubes. In the end, what's good is good, and it really doesn't matter who made them. And so I got to thinking that if I could find a pair of Siemens EH90 from the same factory, where ever this factory might have been, they too might be similarly excellent.
 
I have four different Siemens EH90 tubes, all singles. Comparing them under a magnifying glass with my Siemens EK90, I have come to the conclusion that the Siemens EH90 with ribbed plates, "EH90" etched into the glass and "foreign" printed on the glass, very likely came out of the same factory as my Siemens EK90.
 
The Siemens EK90 is to the left and the "Foreign" Siemens EH90 is to the right:
 

 

 

 

So those of you who have these "foreign" Siemens EH90s... What say you? How do these tubes sound?
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