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Little Dot Tube Amps: Vacuum Tube Rolling Guide - Page 135

post #2011 of 6980

Updated the table on page 77 with two new pentode families:

 

6BJ6: pin-out as normal 6AK5 but not everything connected on the base if understand this right. 0.15 mA heater current. Hence you should be able to operate even EF91/92 setting as well as 2/7 strap. I haven't tested those. "The 6BJ6 is a variable μ RF pentode designed for broadcast radio receiver applications. A key feature is the modest heater power making it attractive for mobile applications" (National Valve Museum).

 

 

6BA6: I got a Shuguang 6K4 in my hands, which is basically a 6BA6 derivative. 0.3 mA heater current. The pin-out is that of 6AU6. The cut off is remote though. Funny enough, it even works with EF95 but obviously the recommended setting is 2/7 strap. Just very coarsely, the tube sounds fine.

 

 

Quote:
Originally Posted by gibosi View Post

It was everything I could do just to do what I did! And now you want more? lol

 

Sorry, I didn't want to sound greedy but this spatial perception was what I particularly didn't like about the Mullard 6AQ4. It would be a straight rule out criteria for me. Thank you for your impressions and also AFB's, which described the triodes further.

post #2012 of 6980
Quote:
Originally Posted by Acapella11 View Post

6BA6: I got a Shuguang 6K4 in my hands, which is basically a 6BA6 derivative. 0.3 mA heater current. The pin-out is that of 6AU6. The cut off is remote though. Funny enough, it even works with EF95 but obviously the recommended setting is 2/7 strap. Just very coarsely, the tube sounds fine.

 

And I have a little experience with this tube. As it is a remote cut-off pentode, I wasn't sure how well it would work with LD II, III and IV amps. Tubes provide no gain in the 1+, so a nonlinear grid seems to present no real problems, but I have wondered how these might sound in amps where these tubes are configured as amplifiers to provide gain.

 

If you are interested, see posts 966 and 989 on pages 65 and 66.

post #2013 of 6980
Quote:
Originally Posted by gibosi View Post

I have been looking for some tracks to help me evaluate bass, especially sub-bass, and I have been told that this is a good test. What do you think?

 

Regarding sub bass i have a tune for this its by Yanni and its called Vertigo but you can only ear the full  effect  of that sub bass from cd only with headphones you can ear it on utube partly as well but your missing half the wow factor i would say first time i heard that with the Denons it was like omg went to my friends house and did not ear that sub bass on his speakers they didnt go low enough.

post #2014 of 6980
Quote:
Originally Posted by hypnos1 View Post

BTW. Above the B****s are the letters GE1 - which I first thought stood for 'Germany'. Silly me. Any ideas folks?

 

GE = the Philips code for EH90

 

1 = change code. Over time, as Philips implemented various changes and modifications to their tubes, the change code was incremented. I would guess that most of the time, these changes were small and perhaps undetectable to the naked eye.

 

A good example is the Philips E91H/6687 manufactured in Heerlen, Holland, as I am somewhat familiar with four different pairs:

 

3L = E91H

 

Date 1957 = 3L3 (D-getter and pinched glass envelope)

Date 1960 = 3L6 (D-getter and straight glass and ????)

Date 1962 = 3L7 (O-getter and straight glass and ????)

Date 1968 = 3L8 (?????)

post #2015 of 6980

  Does anybody have an opinion as to which of these tubes should be best on paper because right now i am trying the ELECTRONOR...... 62AP the dime a dozen tubes strapped 1-7 and they sound as good to me and maybe better than the Siemens eh90 i had on just before  or maybe it was just John Williams Close Encounters of the third kind Conductor Zubin Mehta i think i maid a good deal unless they change for the worse. if you have an opinion i would like to ear it  because i contacted seller about it just to ear is side of the story. 

 

 

                                                                                                                                                                                                  

Processed By eBay with ImageMagick, R1.1.1.||B2||T0JKX0lEPTVjYTFhYjFlYTM1YTAyOTMwNGVjMTcyZjgzNzEwNzA0ZWQ3ZDZkNzUyZWI5fHxTRUxMRVJfTkFNRT1zdWNob3k0Nnx8T1JJR0lOQUxfRUJBWV9RVUFMSVRZX1NDT1JFPTR8fENSRUFUSU9OX0RBVEU9Ny8yMC8xMyA4OjI1IEFN

post #2016 of 6980

Been listening to the Elctronorgtecnika 6A2P they are barely 3hours into burnin they are not the most transparent sounding tube in my arsenal maybe they will clear up i tried the 1-7 strap ,ef95 only, ef95 with 2-7 with modded socket adaptor and so far i like the 1-7 strap seems to have a fuller sound imo                                  .Processed By eBay with ImageMagick, R1.1.1.||B2||T0JKX0lEPTVjYTFhYjFlYTM1YTAyOTMwNGVjMTcyZjgzNzEwNzA0ZWQ3ZDZkNzUyZWI5fHxTRUxMRVJfTkFNRT1zdWNob3k0Nnx8T1JJR0lOQUxfRUJBWV9RVUFMSVRZX1NDT1JFPTR8fENSRUFUSU9OX0RBVEU9Ny8yMC8xMyA4OjI1IEFN

post #2017 of 6980
Quote:
Originally Posted by gibosi View Post

GE = the Philips code for EH90

 

1 = change code. Over time, as Philips implemented various changes and modifications to their tubes, the change code was incremented. I would guess that most of the time, these changes were small and perhaps undetectable to the naked eye.

 

A good example is the Philips E91H/6687 manufactured in Heerlen, Holland, as I am somewhat familiar with four different pairs:

 

3L = E91H

 

Date 1957 = 3L3 (D-getter and pinched glass envelope)

Date 1960 = 3L6 (D-getter and straight glass and ????)

Date 1962 = 3L7 (O-getter and straight glass and ????)

Date 1968 = 3L8 (?????)


Indeed, it is. My Mazda pair has "GE2" above the factory codes, while all my Blackburn-made ones have "GE1" written. The number is quite irrelevant for our purposes right now, as it is only a Philips change code. For older tubes, the change code can help discern production year, but here, nah...

 

Regarding tube design: while this isn't true for a number of tube types, a lot of Philips Group tubes had the same "design" regardless of which factory/brand/label/country they were made in. Minute differences aside, the designs were often identical, explaining why, for example, Mullard 6AV6 and Philips 6AT6 -themselves identical to 6AV6 for all intents and purposes- sound the same.

 

I'm pretty sure, in this case, that my M.B.L.E. Mazda EH90 sound very similar to Blackburn EH90 -like Hypnos'- and hell, they look the same, basically.

 

The fact that Hypnos mentions the way his EH90 render bass -and seeing how my EH90 rumble sub-bass which most of my tubes don't- only makes me think the Philips Group EH90 will turn out to be similar.

post #2018 of 6980

At some point in time, American tube companies began etching "U.S.A." above the tube type. For example:

 

U.S.A.

6AV6

 

Does anyone know the year this began to happen?

post #2019 of 6980

Not sure when that started but I have some mid-50's 12AX7 made by CBS and it has a 'Made In USA" printed on it. I also have a pair of JW2C51 tubes made by Western Electric that has a 'Made In USA" printed on it. I also have some vintage GE 6550s with 'Made In USA" printed on its metal base.

post #2020 of 6980

I have JAN Raytheon 6AK5W tubes from February 1945 that have the print MADE IN USA on them. Silk screening - not etched.
 

post #2021 of 6980
Any benefits to pre amping my ld mkiii with another ld tube amp?
post #2022 of 6980
-double post-
post #2023 of 6980

Greetings to more experienced and knowledgeable Little Dot tube-rollers from a new owner of the LD Mk III,

 

Do you have any experience with the tubes offered by eBay seller "tubemazestore" in a package he modestly calls "THE ULTIMATE Little Dot NOS tube set"?

 

 

post #2024 of 6980

we have been veering far from the 6AK5 tube family.

 

also for some awesome power tubes get a pair of 6N6P-IR, very low noise and very clean.

 

also check page 77 for a list of compatible tubes and modification setting for them to make them work, not all alternate tubes require modifications.

post #2025 of 6980
Quote:
Originally Posted by guildenstern View Post

Greetings to more experienced and knowledgeable Little Dot tube-rollers from a new owner of the LD Mk III,

 

Do you have any experience with the tubes offered by eBay seller "tubemazestore" in a package he modestly calls "THE ULTIMATE Little Dot NOS tube set"?

 

 

 

IMO, neither of these are "Ultimate" tubes. That said, I think you have to figure out if you might be a "tube roller," or if you just want to buy some nice tubes and listen to your music. If the latter, then this set might be a pretty good deal. But if you think that you might enjoy rolling a few tubes in a quest to find the best sound, as Mab suggests, you can certainly do better than these.

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