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Little Dot Tube Amps: Vacuum Tube Rolling Guide - Page 77

post #1141 of 7355
Quote:
Originally Posted by Audiofanboy View Post

Yes, it is really is pleasant to know that you can trust people's opinions here and happily make your tube shopping list based on the consensus of -always polite and respectful- opinions. That kind of pleasantness, that allows for broader opinions and creativity, doesn't just happen magically though, it's obviously because of everyone effort to keep things productive and nice (besides, a troll would be quickly disarmed by the lack of response he'd get here lol, and probably go back to more feisty thread to troll). Many similar threads are much less amusing to browse through lol...

 

Great, heptodes! I'd had a few written down in my notes for a while, just waiting for investigation, and I believe that Alain person (the guy who had mysteriously tried many new tubes types by himself a year ago, and never gotten ant responses) had tried one or two of them. Funny thing is that at the socket level, all those extra grids are pre-strapped together, so it makes no functional difference compared to a pentode. There are a few more compatible ones out there though, I'll look through what I'd written down.

 

At any rate, so 6AU6 level apparently? That would already put these at the top or second top tier, which is pretty amazing for random tubes (I don't think we've bumped in to a bad or really mediocre tube for a while now, so we must be doing something right). Look forward to your review after 15-20 burn-in! Btw, any other common brands for these (GE, TS...)?

 

Edit: There other 7-pin heptodes: 6CS6 and 6BY6. All three tubes families have a ton of special types too, it's always worth getting those.

 

This is my very first post in this forum,  just to concur with Audiofanboy when he says that you can trust people's opinions here, which have been very useful to me.  I am not new to high def audio,  (in fact, I have a long experience)  but have to confess that headphones were not exactly my priority (kind of heresy said here).  I do have an excellent pair of  vintage Stax electrostatics and some mid range Sennheisers, but I simply was not into it, until I saw  some highly positive comments in this forum about the LD MKIII, so I decided to give it a try.  Paired in stock form with my relatively modest but splendid-sounding  Audio Technica ATH-M50 LE (Anniversary Edition), the result was really astounding.

 

 Since this is a tube rolling thread,  I do not want to go off-topic, so let me say that I followed the excellent guide from Dept of Alchemy  and replaced the stock GE 5654  tubes with a pair of Voshkod 6J1P-EV gold/platinum grid,  NOS military tube ("OTK" rhombus seal) made in the 1980´s in the Voshkod plant,  Kaluga city, sent to me from an Ebay seller directly from Moscow at a cost of around $ 18 the pair (including postage).  Authentic military stuff, these Russian tubes are clearly extremely  well made, solid and sturdy, a little bigger than the stock ones.  I wonder what its military use was in the Cold War, I suspect they were made by the thousands so there is still a big stock of NOS tubes you can get at around $ 3 each.  Very interesting historical piece, it was obviously not made for commercial purposes but for reliability and ruggedness, so its original cost must have been much higher, no problem for the mighty URSS military budget.  

 

Before I give my humble sonic impressions as a newcomer in this forum of  headphone experts,  I must say that I am fully aware that a closed back headphone is not the ideal tool to evaluate  the LD MKIII.  It really needs a good open back HP to be appreciated.  I am thinking seriously in the HD 650 or Beyer 800 series. (My wife will kill me if she ever find out the price of these) I do favor a dynamic but natural sound, with precise, not overextended bass and very good soundstage.  Any suggestions ?    

 

On the other hand,  a good studio monitoring HP like the ATH-M50 LE is like a microscope.  Maybe not much soundstage or spatial clues, but It will reveal a lot of detail in the music and has superior bass rendition.   My feeling was that the stock GE 5654 tubes are not that bad,  as stated in the "rolling guide",  in the sense that these tubes are rough and have bad midrange or highs. Perhaps not so delicate and yes, an "upfront" presentation,  but overall a nice, balanced, dynamic sound with more than adequate bass, and they improve a lot  after about 50 hs, of use.  The Voshkods, however, are a different story.  With no burn in at all these tubes inmediately revealed themselves as high definition ones.  Suddenly,  there was more music and more information:  powerful and tight bass, extended highs,  great midrange and a superior spatial rendition of the performance, very  dynamic and revealing.  However, after my initial positive impressions, and after listening to a lot of different music ( jazz, rock, classical, latin, etc.)  with some VERY demanding HD recordings in both 24/96 and 24/192,  going to the limit, the Voshkods showed a kind of "over the edge" quality with some HD music at perhaps the 2k to 4k range resulting in  some  mild "hardness" in the midrange. The highs were surely very extended, but not as sweet as I would like.  I have no doubt that a good burn in will solve some of this problems.  It is kind of funny that I am talking about one or two tubes here when the people in this forum have experience with hundreds of them. Well, this is the good thing, as Audiofanboy said, I will trust your advice...                           

post #1142 of 7355
Yesterday, a pair of 6AT6 arrived. I thought it was about time I put some genuine GM parts in my LD! :)
 

 

 

 

Actually, these are made by Sylvania, tube code 312-139, perhaps 1961? I figured since these were selected for use in automobiles, they should be pretty durable. However, as I am still working with the the 6AV6 and 6AQ6, I haven't had a chance to see if they even light up. 
 
For those of you who are sitting on the fence, trying to decide between the Sylvania 6J4/8532W and these 6AQ6/6AT6/6AV6, I believe that the 6AQ6/6AT6/6AV6 are just a bit better. (To the best of my knowledge, these three are all variations of the same tube.) I was able to spend some time last night comparing the 8532 and 6AV6. They are actually very similar, but the 6AV6 is bit more forward. Vocals and horns are front and center and crystal clear, and wetter, I think. Moreover, the sound stage is very spacious, wide and deep, with great detail, clarity and separation. At times simply breathtaking. Of course, this shouldn't be a complete surprise as these are essentially one-half a 12AX7...
 
I think it is unfortunate that the guy with the worst ears and the cheapest gear got these first. I simply don't have the vocabulary or the experience to put into words what I am hearing. However, I do believe these are very good tubes. We will have to wait until those with better ears and gear have a chance to check these out to see if they are as good as I think they are. 
post #1143 of 7355
Quote:
Originally Posted by mojorisin35 View Post

I still enjoy the tubes from the other families but now it is like matching wine with your meal instead of one wine for everything. Am I the only one who does this, has the drive to discover the ultimate do it all tube relinquished all your previously loved tubes to the dust bin?

 

While I intellectually understand where you are coming from, like wine, selecting a particular tube to suite the current mood or genre of music, I guess I seem to be programmed to want just one tube, a superlative "all rounder." And yes, I am afraid that all my previously loved tubes have been relegated to the bottom of the pile...

 

But even if you are the "only one", there is room here for everyone, the more the merrier!  So when your TS 6485s finally arrive, please give us your impressions. :)

post #1144 of 7355
Quote:
Originally Posted by Johnnysound View Post

 

This is my very first post in this forum....

 

However, after my initial positive impressions, and after listening to a lot of different music ( jazz, rock, classical, latin, etc.)  with some VERY demanding HD recordings in both 24/96 and 24/192,  going to the limit, the Voshkods showed a kind of "over the edge" quality with some HD music at perhaps the 2k to 4k range resulting in  some  mild "hardness" in the midrange. The highs were surely very extended, but not as sweet as I would like.  I have no doubt that a good burn in will solve some of this problems.                    

 

Welcome! :)
 
You might want to search this thread for "TESLA 6F32V".  These tubes seem to be similar to the Voshkods but with better highs.
 
On the other hand, if you are willing to get two little pieces of wire and connect pins 2 and 7 in the socket, I would encourage you to order a pair of Tung Sol 6485 with round getters. These are head and shoulders above your Voshkods.
post #1145 of 7355

Im exited today saw my tube guy at flea market and got a pair of 6ew6 and 6cb6a for $4 .00 would of gotten more of the new tubes but didnt remember the numbers so ill go back tomorrow and hopefully he has the 6au6a tubes or 6ah6, 6at6 i think if i left out a couple feel free to refresh my memory .

post #1146 of 7355
Quote:
Originally Posted by MIKELAP View Post

Im exited today saw my tube guy at flea market and got a pair of 6ew6 and 6cb6a for $4 .00 would of gotten more of the new tubes but didnt remember the numbers so ill go back tomorrow and hopefully he has the 6au6a tubes or 6ah6, 6at6 i think if i left out a couple feel free to refresh my memory .

 

The 6AT6, 6AV6 and 6AQ6 are very similar, so if you can't find a pair of 6AT6, maybe you can find one of the others. Also, see if he has a pair of 6485 (6AH6) or 8425 (6AU6). Good luck! :)

post #1147 of 7355
Quote:
Originally Posted by gibosi View Post

 

The 6AT6, 6AV6 and 6AQ6 are very similar, so if you can't find a pair of 6AT6, maybe you can find one of the others. Also, see if he has a pair of 6485 (6AH6) or 8425 (6AU6). Good luck! :)

Thanks for the imput will send him an email  to make sure that he brings some along if he has any .

post #1148 of 7355
Quote:
Originally Posted by gibosi View Post

 

Welcome! :)
 
You might want to search this thread for "TESLA 6F32V".  These tubes seem to be similar to the Voshkods but with better highs.
 
On the other hand, if you are willing to get two little pieces of wire and connect pins 2 and 7 in the socket, I would encourage you to order a pair of Tung Sol 6485 with round getters. These are head and shoulders above your Voshkods.

Many thanks for your welcome.   As I said, I never did "tube rolling" before, but now I think it is very interesting to experiment with tubes, specially with  headphone amplifiers.  No speakers, no room to fill, no pre or power amp, no cables to worry about.  The sound of a particular tube is inmediately apparent in this very high definition environment, something that do not happens so easily with speakers ¡  In fact, the Voshkods have some particular characteristics in musical terms which you may or may not like,   but are extremely revealing, so I discovered that you can use them as a kind of laboratory tool to fine tune your system, particularly computer audio/DAC settings.  Differences in sampling frequencies (for example) can be subtle, and with the stock tubes It took a little effort to perceive, but with the Voshkods the differences jumped out instantly.  However, I am not interested in spectrum analyzers but in music, so I will search the Tesla tubes you suggest.  Thanks for the advice.  Regarding the Tung Sols, you really scared me with that wires in the tube sockets ¡¡             

post #1149 of 7355

Dear Gibosi,

 

I don't think that you have to be so bashful. My hearing isn't the greatest but I still feel confident that I can identify and differentiate good tubes from bad. The description that you give of the 6AV6 tube is perfectly adequate and informative. (The only thing I didn't understand is what you mean with "wetter".)

 

 

" I think it is unfortunate that the guy with the worst ears and the cheapest gear got these first. I simply don't have the vocabulary or the experience to put into words what I am hearing. "

 

"For those of you who are sitting on the fence, trying to decide between the Sylvania 6J4/8532W and these 6AQ6/6AT6/6AV6, I believe that the 6AQ6/6AT6/6AV6 are just a bit better. (To the best of my knowledge, these three are all variations of the same tube.) I was able to spend some time last night comparing the 8532 and 6AV6. They are actually very similar, but the 6AV6 is bit more forward. Vocals and horns are front and center and crystal clear, and wetter, I think. Moreover, the sound stage is very spacious, wide and deep, with great detail, clarity and separation. At times simply breathtaking. Of course, this shouldn't be a complete surprise as these are essentially one-half a 12AX7..."

 

Now about your gear. The following little story is appropriate:

 

A couple had invited another couple for dinner. After the meal the husband of the guest couple showed beautiful pictures from a recent trip. The hostess kept on saying over and over again: Wow, such pretty pictures - you must have a very good camera! Finally, the guest had enough, and said to the hostess as they were leaving: Thank you for such a nice and delicious dinner - You must have very good pots!

 

It's not just the equipment; it's what you do with it. Thanks for all your research and new exploits!

post #1150 of 7355
Quote:
Originally Posted by Johnnysound View Post

Regarding the Tung Sols, you really scared me with that wires in the tube sockets ¡¡             

 

When you have some time, check out post #876 on page 59.  A number of us are successfully using tubes requiring this little mod and no one has reported any problems. :)

post #1151 of 7355
Quote:
Originally Posted by mordy View Post

It's not just the equipment; it's what you do with it. Thanks for all your research and new exploits!

 

Thank you. I do the best I can. :)

 

Oh, "wetter" in my mind means "more liquid".

post #1152 of 7355

Hi folks. This is my first post, having near brain burn-out after checking out nearly all the entries for LD tube info - mine being  the MKiv se...what a fabulous piece of kit for not too much money.

 

The Senn HD650s are really singing now, even after the Heed CanAmp -  which I thought  was brilliant!

 

Have tried various driver tubes, and thought the Voskhods were about the best, until the Telefunken 6AK5Ws opened things up even more (to my ears anyway). Then I tried the Teslas... had a bit of a weird sound at first, but after a decent burn-in became quite exciting. Similar to the Telefunken in detail and soundstage, but with a bit more weight to the bass.

There is just one caveat however - unfortunately 4 out of the 5 I acquired from 2 different sources are exhibiting microphonic "ringing", and the 5th gave such a bright flash from the lower inner wires each time on power-up that I have discarded it already.

It would appear Czech quality control may not be on a par with the Germans or Russians...Perhaps I was just extremely unlucky - shame...

 

Anyway, am awaiting the new discoveries of wonderful people like AudioFanboy, viz TS 6485s, which hopefully will remove the quandary.

 

Ah well, must get some dinner, so will have to sign off for now - but will be back before too long methinks. Have caught the bug (LD that is)!!

 

 

.

post #1153 of 7355
Quote:
Originally Posted by hypnos1 View Post

Hi folks. This is my first post, having near brain burn-out after checking out nearly all the entries for LD tube info - mine being  the MKiv se...what a fabulous piece of kit for not too much money.

 

The Senn HD650s are really singing now, even after the Heed CanAmp -  which I thought  was brilliant!

 

Have tried various driver tubes, and thought the Voskhods were about the best, until the Telefunken 6AK5Ws opened things up even more (to my ears anyway). Then I tried the Teslas... had a bit of a weird sound at first, but after a decent burn-in became quite exciting. Similar to the Telefunken in detail and soundstage, but with a bit more weight to the bass.

There is just one caveat however - unfortunately 4 out of the 5 I acquired from 2 different sources are exhibiting microphonic "ringing", and the 5th gave such a bright flash from the lower inner wires each time on power-up that I have discarded it already.

It would appear Czech quality control may not be on a par with the Germans or Russians...Perhaps I was just extremely unlucky - shame...

 

Anyway, am awaiting the new discoveries of wonderful people like AudioFanboy, viz TS 6485s, which hopefully will remove the quandary.

 

Ah well, must get some dinner, so will have to sign off for now - but will be back before too long methinks. Have caught the bug (LD that is)!!

 

 

.

 

+1 for the MK IV SE. Fabulous piece of equipment for the price really, and pretty nice looking imo. Equipped with the best Russian missiles power tubes and some American 6485 driver tubes, it shows performance that I think puts it close to the $1K price point for a head amp, imho of course. Never heard the MK III, but I'm sure 80% of what I said if also true.

 

If you've never tried anything outside of the 6AK5 family, the 6AU6 and 6AH6 types might come as a bit shock at first, it may be difficult to go back lol...

post #1154 of 7355

Hey,

 

Firstly, Gibosi, you are a great part of the team and thanks for your contributions, appreciated.

With respect to Hi-Fi vocabulary, check this glossary:

 

http://www.head-fi.org/t/220770/describing-sound-a-glossary

 

Wet is mostly used as "a reverberant sound, something with decay. Opposite of Dry." Think a tiled large room as wet, a dampened small room as dry.

Of course, you can define what you mean, then that is also fine.

 

Secondly, I am following the burn in of the Sylvania JAN 5750 (6BE6).

To me the, the formerly reported sonic differences hold, so I advise to test the EF91/92 setting first, so you get an idea, what I consider as the better setting. You lose some bass weight, but you win openness, presence and dynamics. IMO it is the best option.

 

Here is a list of differences comparing Sylvania JAN 5750 (6BE6) and Tung Sol 6485 (6AH6) tubes:

- The 5750 volume level is relatively low for a 'new' tube. I would say a bit below CV4015 (EF92). That makes a quite a bit lower volume than the 6AH6 or 6AU6 tubes, I have heard.

- The 5750 has a pitch dark  background. Also, the signature is somewhat darker but very enjoyable.

- Bass quality is good. Not as lose as 6EW6, not exactly as tight as CV4015, TS 6485.

- Treble is extended and sounds not rolled off, only not exactly airy because of the signature.

- Laid back sound compared to CV4015, TS 6485.

- Imaging would be a draw, possibly slight advantage for the TS because of the more trebly presence.

- The sound is nicely detailed, pretty much on par with TS 6485.

- Stage is slightly larger for the 5750 compared to TS 6485

 

In summary, I would describe the tube as dark in comparison and rather laid back with a great stage and very good detail. Now, the dark part is not taken as negative, the signature still sounds balanced, a bit warmer than CV4015, not too mellow, useful for long listening sessions.

 

Grade, ...difficult. As the tube changes, some of the treble I have quite enjoyed melts down, taking some openness. I think, I will wait for the final grade, but it surely is an enjoyable tube.

 

Table of Compatible Tubes

 

Find an example from Audiofanboy for the strapping wire below the table. I have also made a figure for the EF91/92 strap whilst in EF95 mode of operation, thanks Audiofanboy for the finding.

 

Compatible LD amps: I+, MKII+, MKIII, MKIV (SE)

 

Tubes     Jumper Settings / Mods
Families                        Alternative Names Remark EF95     

EF91/92

= EF95 + 6/7-wire mod (1)

EF95

+

2/7-Socket Wire Mod

 

EF95

+

1/7-Socket Wire Mod

EF91/92 (1)

+

Cut off and tape

Pins 5 & 6
 
6AG5, 6BC5, 6CE5 EF96, 6J3P(-E), 6186   yes no yes (2) no no
6AH6 6J5P, 6485   no no yes no no
6AU6 EF94, 6136, 8425, 7543 = mil spec 6AU6   no no yes no no
6BA6 (7) 5749, EF93, CV454, Shuguang 6K4   no (8) no yes no no
6BJ6 (9) CV3909, 6662, 7694, E99F   no (3) yes yes no yes
6CB6, 6CJ6 6676   no (3) yes yes no no
6DK6 8136   no (3) yes yes no no
6EW6     no (3) yes yes no yes
6GM6, 6AM6 6AM6 =  CV4014, EF91, CV138   no (3) yes yes no no
6GY6/6GX6     no (3) yes yes no yes
6J4, 6AQ4 6J4 = 8532, 6J4WA = M8248, CV5311 / 6AQ4 = CV4070, CV417, EC91 Triode no no no yes no
6AQ6, 6AT6, 6AV6   Diode / Triode no no no yes no
6BE6, 6CS6, 6BY6 6BE6 = EK90, CV4012, 5750, 6A2P, 1217 , 1680, 6H31; 6BY6 = EH900, 6687, EH900S, EH960, E91H, 5915; 6CS6 = EH90 Heptode yes (4) yes yes (5) no yes (6)
6HZ6, 6DT6 (10)     yes yes yes no yes
6AN5 (11)     yes no no no no
6HA5, 6HM5, 6HQ5 (12) 6HA5 = EC900 Triode yes no no no no
6BD6     no no yes no no

 

Recommended modes of operation are highlighted in green.

 

     

(1) EF91/92 = EF95 + 6/7-wire mod. See figure below.

 

 

(2): Mod doesn't add a function. Tubes are already internally strapped between pins 2 and 7. Use at higher risk only.

 

(3): Operation with "floating" grid 3 is strongly not recommended.

(4): Offers a great standard setting. Floating grid 3 but different grid architecture to (1).

(5): works flawless, preference dependent, bass heavy with rolled off treble for some 6BE6, for other 6BE6 and generally heptodes, this setting sounds brighter and more foreward than unstrapped.

(6): "Grid-to-grid strap", possibly, favourite option for 6BY6 heptodes, generally a good setting to try.

 

(7): Tested with Shuguang 6K4.

 

(8): Not recommended but works with Shuguang 6K4.

 

(9): Tubes of this family have not been tested yet (29/07/2013)

 

(10) 6HZ6 uses 0.45 A heater current, 6DT6 0.3 A. Similar to heptodes, these pentodes are FM-detectors. Thanks Gibosi.

 

(11) 6AN5 tubes follow the EF95 pinout and grid design but utilize a higher heater current (0.45 A). Thanks

Siles1991.

 

(12) ~ 0.19 A heater current triodes with µ ~ 72 that internally strap pins 2 and 7 to the cathode. Thanks Kvtaco17 and Gibosi.

 

 
- Tubes with A, W, WA, WB, WC specification share the same settings as the ones without.  
- CV versions usually indicate (improved) mil spec versions, specifically when used with four letters (thanks AFB).    
Gibosi and Audiofanboy started using triodes with the LD I+ and MKIV.      

 

Here is an addendum to clarify the pin numbering of the LD driver tubes and their socket:

 

(1) This figure below is to give you an alternative way for switching to EF91/92 compatibility whilst running in Little Dot EF95 mode. Just create a shorter jumper than for the Pin 2/7 strap and connect positions 6 and 7. =)

 

Updated 21/04/2013: Included 6J4WA information, thanks gibosi.

Updated 22/04/2013: Operation with floating grid g3 is strongly not recommended.

Updated 28/04/2013: Included Diode/Triodes and Heptodes, added EF91/92 compatibility socket jumper while running in Little Dot EF95 mode, thanks Audiofanboy.

Updated 14/05/2013: Altered EF95 setting entry for 6BE6, 6CS6, 6BY6 since this setting provides a different sonic experience.

Updated 16/05/2013: Included 7543 (mil spec 6AU6, thx Nic Rhodes) tubes, 6AQ4 alternative names and mil spec (thanks gibosi & AFB), added MKII+ compatibility, thanks vic2vic. Added 6AM6.

Updated 22/05/2013: Heptode setting for EF95 put into green colours.

Updated 27/05/2013: Added alternative names for heptodes.

Updated 24/06/2013: Updated heptode nomenclature, floating grid comment and 1/7-strap.

Updated 25/06/2013: Added 1/7-strap to 6EW6 and 6GY6/6GX6.

Updated 04/07/2013: Updated some info to the experience of 1/7- and 2/7-strapping of heptodes, alternative 6BE6 designations and most - importantly -  the colour for no :).

Updated 19/07/2013: Table reformatted and slightly updated.

Updated 20/07/2013: Added two new families: 6BJ6 and 6BA6. Modes of operation are not tested for 6BJ6. Included EF91/92 alternative mode of operation in header. Re-organized footnotes.

Updated 06/08/2013: Added 6HZ6 and 6DT6 pentodes.

Updated 21/08/2013: Added 6AN5 pentode.

Updated 25/08/2013: Added 6HA5, 6HM5, 6HQ5 triodes.

Updated 01/09/2013: Added 6BD6 remote-cutoff pentode (thanks Mordy).

Updated 03/09/2013: Corrected the headline of the last column of the table from pins 5&7 to 5&6. Thanks Gibosi.


Edited by Acapella11 - 9/3/13 at 11:39am
post #1155 of 7355
Quote:
Originally Posted by Acapella11 View Post

With respect to Hi-Fi vocabulary, check this glossary:

 

http://www.head-fi.org/t/220770/describing-sound-a-glossary

 

Thanks! This is very helpful and I will definitely consult it the next time I try to report on how tubes sound. :)

 

In today's mail, more tubes. First a pair of RCA JRC-5915/6BY6, dated 1964:

 

 

And a pair of GE JG-5750/6BE6W dated 1959:

 

 

I hope to get to these soon....

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