[califmike33]

Well thank you that too many pages to read through I'll take a look at some of those tubes.

 

[MIKELAP]

A few power tubes that were tested on page 201 post 3007 https://www.head-fi.org/threads/little-dot-tube-amps-vacuum-tube-rolling-guide.563884/page-201

 

[califmike33]

Thanks I will check it out.

 

[Cognomen]

Recently bought 717A to 6AK5 adapters to roll queued up various brands of metal 6SH7 and metal 6SG7 (generic photo of that) and their GT glass variants with solid metal and mesh "shields" (photo) as well as 717A's, "the little doorknob," quite a "Little Miss Mufett Tuffet" of a tube. For the last few days I've been auditioning eBay 6N6P-T's and feel they have very clear/accurate treble, mids and bass without being analytical/dry. The bass sometimes reminds me of the precision, depth and accuracy of solid state and the mids have some of that tube euphony - very promising - time and more listening required to decide how I rank them versus a half dozen or so alternatives/upgrades from stock 6N6P power tubes. As for the T suffix, we're not sure what it means with perhaps the best evidence that it was designed for tropical hot and humid weather. The USSR datasheet on the 6N6P, however, advertises it was designed for up to 95% humidity and 40C (104F). Perhaps it didn't perform as well as the datasheet advertised or there was a military or industrial or dacha/Crimean spa need for sauna conditions. I have ruled out T for Thorium because the tubes glow regular color. And T for transmission carrier was another possibility. The 717A's glass is not symmetrical and mine have fairly heavy getter flashing. While the 6N6P-T's produce some light the other species do not produce much or none at all. Perhaps the Little Tuffets would if viewed from a different angle where the glass is less silvered. There are versions with less silver. (A vendor on eBay is currently in the process of selling dozens of them by undercutting high prices.) With the lights off a few pinpricks of light show up through the 6GT7GT mesh. I have very briefly listened to the queued up driver tubes and feel some show promise. I regard Yugo 6HM5 and Siemens C3G (adaptor needed) as setting a high bar for drivers and regard the 6n6P-ir as a solid improvement. ALL VERY MUCH THANKS TO PEOPLE WHO HAVE SHARED SO MUCH HERE!!! In the meantime I very much enjoy the 6volt car audio RCA 6AR5 smooth shield made in Japan (EF 95 plug and play) drivers which may not have enough power for those who like it loud and/or have low-z cans.

 

[triod750]

And I listen to a pair of 'modern' Siemens EL41 with a pair of Melz 6N12S in my LDMKIVSE. External PSU used, @Deyan made. Adapters from same source.

 

[barbazz]

Recently bought 717A to 6AK5 adapters to roll queued up various brands of metal 6SH7 and metal 6SG7 (generic photo of that) and their GT glass variants with solid metal and mesh "shields" (photo) as well as 717A's, "the little doorknob," quite a "Little Miss Mufett Tuffet" of a tube. For the last few days I've been auditioning eBay 6N6P-T's and feel they have very clear/accurate treble, mids and bass without being analytical/dry. The bass sometimes reminds me of the precision, depth and accuracy of solid state and the mids have some of that tube euphony - very promising - time and more listening required to decide how I rank them versus a half dozen or so alternatives/upgrades from stock 6N6P power tubes. As for the T suffix, we're not sure what it means with perhaps the best evidence that it was designed for tropical hot and humid weather. The USSR datasheet on the 6N6P, however, advertises it was designed for up to 95% humidity and 40C (104F). Perhaps it didn't perform as well as the datasheet advertised or there was a military or industrial or dacha/Crimean spa need for sauna conditions. I have ruled out T for Thorium because the tubes glow regular color. And T for transmission carrier was another possibility. The 717A's glass is not symmetrical and mine have fairly heavy getter flashing. While the 6N6P-T's produce some light the other species do not produce much or none at all. Perhaps the Little Tuffets would if viewed from a different angle where the glass is less silvered. There are versions with less silver. (A vendor on eBay is currently in the process of selling dozens of them by undercutting high prices.) With the lights off a few pinpricks of light show up through the 6GT7GT mesh. I have very briefly listened to the queued up driver tubes and feel some show promise. I regard Yugo 6HM5 and Siemens C3G (adaptor needed) as setting a high bar for drivers and regard the 6n6P-ir as a solid improvement. ALL VERY MUCH THANKS TO PEOPLE WHO HAVE SHARED SO MUCH HERE!!! In the meantime I very much enjoy the 6volt car audio RCA 6AR5 smooth shield made in Japan (EF 95 plug and play) drivers which may not have enough power for those who like it loud and/or have low-z cans.

Great experiments. Thanks for sharing.

Interesting that you mention 6SH7/6SG7. Yesterday I was wondering how 6SJ7/6SK7 octals would sound (slightly different pinout: pins 3 and 5 are not connected). Need to source some more adapters...

By the way, 6AR5 also has an octal version: 6K6G(T). One more to test?

 

[Cognomen]

Great experiments. Thanks for sharing.

Interesting that you mention 6SH7/6SG7. Yesterday I was wondering how 6SJ7/6SK7 octals would sound (slightly different pinout: pins 3 and 5 are not connected). Need to source some more adapters...

By the way, 6AR5 also has an octal version: 6K6G(T). One more to test?

6sj7

And I listen to a pair of 'modern' Siemens EL41 with a pair of Melz 6N12S in my LDMKIVSE. External PSU used, @Deyan made. Adapters from same sourc

 

[Cognomen]

I've wondered about Chinese 6N12P? Any info here on that? I can't find a datasheet and can't figure out datasheets in Chinese. $18Australian.

https://diyhifisupply.com/product/6n12p-vacuum-tube/

 

[Cognomen]

Great experiments. Thanks for sharing.

Interesting that you mention 6SH7/6SG7. Yesterday I was wondering how 6SJ7/6SK7 octals would sound (slightly different pinout: pins 3 and 5 are not connected). Need to source some more adapters...

By the way, 6AR5 also has an octal version: 6K6G(T). One more to test?

I considered the 6sj7 path also! As of 10 days ago or so there were adapters from China on eBay that were not so easy to find. It seems to me based on my very limited electrical know-how that the 6K6G(T) might require a different adapter than the 6SH7. The pinout for 6SH7 is m (metalising internal and or external) / h / k+g / g / k / g / h / anode while the 6K6G is metalising internal and or external / h / anode / g / g / not connected (i.e. clip the pin and cover it) / h / kathode. As far as I know the only species I can roll in my LDIII in my driver adaptor without external power are 717A, 713A (which may be almost a clone of the former), 6SH7( GT)(L), 6SG7(GT), and a Russian 6SH7. Tubes I know of for the 6SJ7 adapter (double check before using!) include ~, 6SK7, 6SS7, 6Zh8 (Russian, probably equivalent of one already mentioned) with some GT variants. If one is willing to run drivers with .45 mA in the dot III (which would be a test of the the transformer's ability to survive that (or not)) or provide external power, one can also roll 6AC7, 6AB7, and 6Zh4. There may be more above .45 mA for both adapters. The 6SH7 has more gain than the 6SJ7 but makes some amps hum, not the case for my LDIII so far. While probably only tangentially of interest for the LD's in this forum, there are 300B fans of the 6SH7 and 6SJ7 who feel they sound excellent and virtually the same except for the gain and any current price differences.

 

[barbazz]

6N12P seems to not have any direct correspondence with a western counterpart, only with the Soviet 6N12S (6Н12С).

I've found a datasheet in Chinese and translated it with Google Lens:

 

[Cognomen]

6N12P seems to not have any direct correspondence with a western counterpart, only with the Soviet 6N12S (6Н12С).

I've found a datasheet in Chinese and translated it with Google Lens:

Thank you for finding that, confirms should work as power tubes in LDIII with my 6SN7 adapter.

 

[gibosi]

6N12P seems to not have any direct correspondence with a western counterpart, only with the Soviet 6N12S (6Н12С).

I've found a datasheet in Chinese and translated it with Google Lens:

The Russian 6N12S is often compared to the 6BX7 and 6BL7. They are not perfect replacements, but they are similar. I use 6 of them, 3 per side, as power tubes in my OTL and they work great.

 

[JScott03]

Wanted to add this to the guide incase a newbie (like myself) comes along... As a new owner of the LDMK2 I noticed it loves to pick up wireless signals. My router sits right next to my desk where the amp is located. When I disable the 2.4ghz band on my router I can hear the static/noise completely stop on my amp. 5ghz doesn't seem to bother it. Hope this helps someone!

 

[MIKELAP]

Wanted to add this to the guide incase a newbie (like myself) comes along... As a new owner of the LDMK2 I noticed it loves to pick up wireless signals. My router sits right next to my desk where the amp is located. When I disable the 2.4ghz band on my router I can hear the static/noise completely stop on my amp. 5ghz doesn't seem to bother it. Hope this helps someone!

Some also had this issue way back when .Like some had issues (hum)when using 6DJ8 with adapter Thanks for sharing .

 

[Cognomen]

I have continued auditioning plug and play car radio tubes. The Philips SQ E90F Miniwatt (EF91/92 setting) is better than typical EF95 and EF91/92 LDIII tubes, with perhaps a skosh higher treble and more detail, perhaps why it was merciless on a poor recording but very good on other recordings. It's a high gain tube. As a pentode: 4.6 transconductance and 1.4 M ohms plate resistance. The E90F is a longer life mesh tube promoted as a higher quality and longer life than the abundant functionally equivalent 6BH6, perhaps worth exploring. While the 6BH6 is a car audio tube, Marantz deployed it in its highly collectible 8B tube amp but as far as I can tell, not as a triode. Also auditioned a IEC/Mullard 6ES6 (EF91/92 setting) whose stats were questionable before I rolled it: less than 1 transconductance and 200k ohms plate resistance and variable mu. I had to pull out all the stops: flicked the gain switches on the LDIII to max and turned up the input gain on my cap-coupled power amp for speakers. While the midrange was good, sometimes the rest of the spectrum seemed somewhat muddy and not euphonic. I suppose it was an adventure. With the LDIII volume set at over 12:00, the headphone volume on somewhat low volume music was medium on my 250 ohm corded Beyer Amirons. Initially one tube was producing fuzz sound and then nothing but looked ok. I flicked it with my finger and it caught on and worked. I tend to rate my tubes good, better and best in terms of the LDIII sound they produce. The 6ES6 is not good! While the car RCA 6AR5 smooth shield sacrifices a bit of detail and is also lo amplification (too low probably for low ohm headphones and/or people who like high volume), I continue to feel the 6AR5 may be the most euphonic tube species I have heard in the LDIII. I also re-auditioned the M8161 (EF91 setting). While it has a nice warm midrange, I felt it was lacking elsewhere so I continue to rank it good. Thereafter I re-auditioned the Siemens C3g (adapter needed) and Yugo 6HM5 (plug and play EF95 and excellent price to sound quality ratio) and felt they qualify as some of the best driver tubes in my collection for the LDIII. While the 6AR5 is not a best tube, I still find it better than run of the mill EF95 and EF91/92 and euphonic, in a word, fun.