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6SN7 Tube Addicts - Page 258

post #3856 of 4283
Those numbers don't mean anything without knowing what tube tester they are from and what that testers target numbers are for a 6SN7.

But regardless, if the tube is quiet and sounds good otherwise, I don't think what you describe as a lack of bass weight is anything more than the way that tube sounds in the amp you are using it in.
post #3857 of 4283
Thread Starter 
Quote:
Originally Posted by lojay View Post

Thanks! The 6SN7W is really quite magical, I can see why it is highly sought after. Luckily I got mine at a bargain price biggrin.gif Can't wait to see if it has synergy with the 300B and 5U4Gs I'm going to buy.

Skylab, you are quite right my pair is absolutely quiet with the WA5. No microphonics or hum at all. However, it may be that my pair is past its prime. The readings on the label say "6.3/1.65, 5.5/1,80" on one and "6.8/1.95, 7.1/2.05" on the other, any idea how I could gauge whether my pair is good?

Neo, I hope you are right, my Ken-rad is arriving on Monday..

 

 

These values my guess is are from an AVO tester.

 

For a new 6SN7 the values are:

Ia (mA) 9

mA/V    2.6

 

So your weakest section is 61% of a new tube.

 

This is low, but still useable of course.

The test results never tell how a tube will sound. 

post #3858 of 4283

Have to agree here.  You kind of shot for the top with a metal base W as your first roll.  If you want more bass try  some Ken Rad, the black glass look cool but aren't sonically better than their clear glass brothers.  Some swear by the military designated versions, but they all excel with bass extension and emphasis. I like the Ws midranginess and treble and am using one now in my headphone amp (Extreme).

post #3859 of 4283
Quote:
Originally Posted by rosgr63 View Post
 

 

 

These values my guess is are from an AVO tester.

 

For a new 6SN7 the values are:

Ia (mA) 9

mA/V    2.6

 

So your weakest section is 61% of a new tube.

 

This is low, but still useable of course.

The test results never tell how a tube will sound. 

Thanks, this is very helpful. The seller was quite honest when he said that the 6SN7W are used and are not strong. That's why I "shot for the top" with this one, it was selling at a discount. I guess the question is how much this affects the sound. I guess I will never know until I get my hands on a true NOS 6SN7W. 

post #3860 of 4283
Thread Starter 

Any ideas what year are these Sylvania date codes?

 

2ZR

T3R

post #3861 of 4283

Somebody should explain the various Sylvania date codes! It's about time.

post #3862 of 4283
Thread Starter 

Agreed, does the Tube Lore have any info?

 

I left my copy home and I can't check.

post #3863 of 4283

Actually it might if those tubes are from about 1939 to 1946! I must go now but it's on pp. 176 & 177.

post #3864 of 4283
Thread Starter 

Thanks Oskari, I was told they are 40's vintage.

 

Have a nice day

post #3865 of 4283
Quote:
Originally Posted by Oskari View Post
 

Somebody should explain the various Sylvania date codes! It's about time.

Sylvania codes are as follows:

If you see six numbers (either in a row or in two pairs of three):  First three numbers will read 312, which is Sylvania's manufacturer code.  The next three numbers tell you the year and month.  The first digit of the three numbers is the last digit of the year.  The next two digits in this grouping represents the week of production.  A tube that reads "312 235" means it is manufactured by Sylvania in the 35th week of a year ending in 2 (1942, 1952, 1962, etc.).  Since Sylvania designs rarely lasted more than a decade, it's pretty easy to figure out what decade the tube was made.

 

If you see only one letter and one digit, than the letter represents the month (A = Jan, B = Feb, etc.) and the digit represents the last digit of the year.  This was only done in the 1940s.  For example, a Sylvania 6SN7W with a top acid-etching code of A5 means it was made in January  of 1945.

 

Sometimes you'll see a four digit code.  These are very simple to read.  A code that reads 5612 means 1956, 12th week.

 

The last set of codes you might see is below the 6SN7 hexagonal acid etching.  It'll read as a letter, number, then letter (e.g. E2M).  The first letter is for the month and the following number is for the year.  The third letter is the manufacturing plant.

 

Last note: A lot of Sylvanias will have two sets of codes, and oddly enough sometimes they don't match.  I tend to trust the acid codes because base silk-screening is sometimes put on later.


Edited by Len - 1/7/14 at 11:58am
post #3866 of 4283
Quote:
Originally Posted by rosgr63 View Post
 

Any ideas what year are these Sylvania date codes?

 

2ZR

T3R

 

edit: From what I've read, the R stands for "replacement" (not OEM issue).  The other letters/numbers represents year, quarter, and production but I don't know how to read it.  My 6SN7 and tube interests kinda stop in the 1950s :)


Edited by Len - 1/7/14 at 12:16pm
post #3867 of 4283
Thread Starter 

Thanks Len.

 

Bendix use a similar system with the codes etched on the dome of the 6080WBs for example.

 

The numeric part is easy but numbers like 235 for example are post 50's and start from 1952 not 1942 I think.

post #3868 of 4283
Quote:
Originally Posted by Len View Post

 

edit: From what I've read, the R stands for "replacement" (not OEM issue).  The other letters/numbers represents year, quarter, and production but I don't know how to read it.

 

Yep.

 

According to Tube Lore:

 

N = Feb–Apr, Z = May–Jul, V = Aug–Oct, T = Nov–Jan.

 

T3R = Nov 1942–Jan 1943, replacement.

 

This type of code was used 1939–1946.

post #3869 of 4283
Quote:
Originally Posted by Len View Post
 

Sylvania codes are as follows:

 

Thanks! Later on they had date codes with letters only, too. 

post #3870 of 4283
Thread Starter 

That's even more fun............

 

Nice work Oskari, thanks.

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