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Little Dot Tube Amps: Vacuum Tube Rolling Guide - Page 229

post #3421 of 10504
Quote:
Originally Posted by Audiofanboy View Post
 

I haven't even dared to go delve in the Schiit thread yet, as it seems like an other pool of varying opinions that would just drain my wallet quicker than buying DR tubes lol... But I gather that there aren't that many 6DJ8 tubes considered top tier, so the choice isn't that hard considering how much feedback there is on the internet. Philips, Siemens, Mullard, some German manufacturers and an occasional US tube, but you quickly go into second tier. I'm not buying a pair of Siemens CCa for $300 shipped from some crazy country quite yet!

 

As you might guess, the super premium European versions are generally considered the very best of the 6DJ8, but fortunately, for those of us who have to live on a budget, the standard Amperex Orange Globes are often rated in the top tier as well. And with patience, these can often be found for as little as $25 a pair. In the end, for someone in my circumstances, with old ears, mid-fi cans and a $100 amp, purchasing a $300 pair of Siemens CCa is pretty hard to justify....

 

But for now, listening to a pair of $25 Orange Globes through my cheap little LD1+ is pretty amazing. While probably not as good as a Schitt Lyr, I believe it might be pretty close. :)

post #3422 of 10504

I love used tubes, they don't require any burn-in and let you have fun right away without having to wait 4 days to enjoy your new toy... And of course, they're cheap! (somewhat)

 

Just got my two no-silk-writing EI ECC83 (12AX7) tubes in the mail, so I killed two birds with one stone and took pictures of both the adapter and the new tube.

 

 

No doubt about the source on this one: EI, Nish factory, Yugoslavia, ECC83, as per the codes on the bottom of the tube. I'd say 1980 for production date, could be 1970 or 1990, but that seems unlikely. And you can definitely see the recognizable "long smooth plates" that Telefunken is famous for on this tube type. The other tube I got barely has any legible factory codes and, while it has the exact same plates, is built a little differently. I could still kind of read the same factory code (little doubt on this one: Tele plates in Philips glass, not a gazillion solutions...), and a 7 for year code, so I'd say 1977 or 1987. The whole structure on this tube is 90° off compared to this picture, and the glass is different (not the "nub" and getter though, still Philips looking), so I can't know for sure which is one is "better" or older.

 

 

Anyway, as you can see, I mounted it on my "new & improved" adapter to give it a spin. And, yeah, it's an awesome tube, seriously. I don't know what gibosi thinks about these double triodes, but it might be hard for me to go back to our previous pentodes and heptodes lol. Yes, these tubes are more expensive, but they're also money better spent!

 

So, awesome tube, basically. Natural, musical, airy, detailed, realistic, holographic... I could go on with the adjectives but the rest of the world using this tube would describe it better. Now, I finally understand what people mean by the "Telefunken sound". And these EI Yugoslavia tubes are only supposed to be ~85% of the original Tele quality. I would love to hear those last 15% now! Guess I should start hunting down genuine -used- Tele tubes huh?

 

Quick reminder here: this is a ECC83/12AX7 tube with very high mu (voltage gain of 100), and low gm (between 1 and 2), whereas a -totally unrelated- ECC88/6DJ8 tube has medium mu (gain of 33) and very high gm (over 13, which is huge for driver tubes). So, these tubes would normally not be used in the same circuits or situations at all, even though they're well suited for voltage gain.

 

For the moment, and though I very much like my EI -made on Philips gear- ECC88/6DJ8, I definitely find more listening pleasure (both critically and toe-tappingly) in these EI -with Tele plates- ECC83/12AX7. It may have to do with the inherent quality of each tube, but I actually think that the 12Ax7 types may be more suited to my use. I'm always trying to squeeze the last drop of sound quality and power out of my LD, and high gain driver tubes help me do that with my low impedance headphones.

 

So, basically, if you're going to investigate either double triode tube family, choose the one that's better suited to your needs. A MK III user with HD650 phones may prefer the ultra-detailed and medium gain sound of the ECC88/6DJ8 for example. Just food for thoughts, and pure speculation...

 

 

Now, the adapter. No, we won't talk about my soldering skills lol... I did what I could with very very limited resources (if you saw my soldering iron, you'd actually think I did an OK job here).

 

I used a 9 pin ceramic socket (PCB soldering type) and soldered three 22awg gauge blue wires on the three active components of the first triode, three transparent 22awg wires on the second triode, and two + one smaller 26awg wires on the heater pins and center tap. Each wire I then painfully got to squeeze into the appropriate hole on each side -each socket saver. It was horrible and took me hours to complete, so I won't take it apart or play with it to show anyone how it's made lol, sorry...

 

Tube actually sits right between the sockets, in the middle; I know it doesn't look straight but it can be, it just takes an effort to get it there with all those wires pulling in different directions and metal memory doing its thing. I think it doesn't even look that bad, frankly, and I could live with that, considering the sound quality! Again, making a prettier adapter from scratch (no socket savers) wouldn't be that hard...

 

 

Bird's eye view to show how it looks and how tight -too tight- the wires are. You can see where the cabling for both triodes goes, but the wires for the heaters and center tap are hidden. For anyone that's interested, I'm sure I'll get around to posting the pin-to-pin details, if I haven't already, or if someone with more time and motivation than me does it before I do (gibosi, I know you're reading this lol)!

post #3423 of 10504

I've been listening many hours with those new arrived tubes and made some initial observations. Westinghouse 6AG5 -45 tubes have beautiful glow, sad that their sound is not as good. Powertubes look little pale behind these.

700

 

I got Brimar 6AT6 and they got box on top. These sound very good, but i still think not better than russian 6J5P. I'm going to use 6EW6 lifetime's little longer, sound is very promising. Others that got my attention were telefunken 6AM6S, fivre 6CB6, sylvania 6DK6 and GE 6DT6A.

post #3424 of 10504
Quote:
Originally Posted by Audiofanboy View Post
 

Anyway, as you can see, I mounted it on my "new & improved" adapter to give it a spin. And, yeah, it's an awesome tube, seriously. I don't know what gibosi thinks about these double triodes, but it might be hard for me to go back to our previous pentodes and heptodes lol. Yes, these tubes are more expensive, but they're also money better spent!

 

 

I feel the same way. I have about 400 of these tubes - single triodes, pentodes and heptodes - and I seriously doubt that I will be listening to any of these in the future... I guess I ought to see if I can sell them....

 

And so far, I have been able to stay below $15/tube, and I feel that this is a bargain for the level of quality I am getting from these 6DJ8. Perhaps my stock $30/pair Siemens are giving me 80% to 90% of a $300/pair Siemens CCa? And perhaps my old ears would not even be able to distinguish between them? lol

 

Quote:
Originally Posted by Audiofanboy View Post
 

Bird's eye view to show how it looks and how tight -too tight- the wires are. You can see where the cabling for both triodes goes, but the wires for the heaters and center tap are hidden. For anyone that's interested, I'm sure I'll get around to posting the pin-to-pin details, if I haven't already, or if someone with more time and motivation than me does it before I do (gibosi, I know you're reading this lol)!

 

Yes, I am reading this! lol And I will definitely try these 12 volt double triodes. But for now, I have yet to receive all the 6FJ8 I have ordered... and my wallet is begging me to take a pause!  Soon... :)

post #3425 of 10504

 

Here are intructions on how to modify 6BQ7A or ECC/6DJ8 DOUBLE TRIODE tubes and the sockets they use.Its not pretty but it works. Pins 1-2-3-9 need to be bent or cut off on 6BQ7A tubes or if you are using ECC/6DJ8 and Littledot has to be on EF95 setting. you need to insert in a sequence tube pin 4-5-6-7-8 into pin holes 3-4-5-6-7 of the adapter and insert adapter in Littledot in regular position (remembering that there is 2 pins that were cut off on the adapter)                                                                                                                                                                                                                                                            Regarding socket mod ;using  wire solder pin 6 to pin 1 and pin 7 to pin 2 on adapter .Also you will need to cut  pins 6 and 7  those are the pins on the adapter that go in the Littledot. One last thing you can link pin 6 to 1 and 7 to 2 inside the adapter also for a cleaner look using 30 gauge wrapping wire .Wire used in picture is 22 gauge which is to big .                                                                                                                                                                                                                                                                                                                                                                                                                            Of course soldering the wires inside his not easy for a novice also you have to reinsert the pin assembly into socket holes which is loads of fun.ALSO ALWAYS REMEMBER THOSE WIRES HAVE ELECTRICITY PASSING THRU THEM SO BEWARE DO NOT TOUCH THE CONNECTIONS WHILE USING AMP.By the way a special thanks to Audiofanboy,gibosi, and Troll Dragon for there advice, instructions,and patience .Thanks guys.

                                                                                                                                                                                                                                                                                                                                                                              

 

 

                                                                                                                                              

 

 

                                                                                                                                              

 


Edited by MIKELAP - 10/14/13 at 7:47am
post #3426 of 10504

I just got my RCA 6DT6A's as recommended a few pages back.  All I can say is wow these sound amazing out of the box, I prefer them to my Mullard 8100, and I got two of them for $8 shipped.

post #3427 of 10504

I now have a Little Dot 1+ with an LME4990 op amp and Voshkod tubes.

 

My first impression of the product is underwhelming to be honest (it was paired with a Schiit Bi-Frost DAC). I tried the Voshkods, it had a black background with no distortion at all, I could hear MF DOOM whisper to his friends before he actually raps which kinda took me by surprise, I NEVER heard such micro details before. But overall, there was barely a difference in sound quality. I have heard Voshkods take a while to burn in (several days). So I installed the Tung-Sol 6AK5, if i'm not mistaken and then stuff started to change.

The Tung-Sols have a little distortion, but I can hear stuff that I've never really heard before. Voices sound a bit more realistic. Slightly larger soundstage with better imaging. It didn't wow me.

But of course, I have to let the tubes burn in for a couple of weeks before I even give my full opinion on this combo


Edited by Sony Slave - 10/11/13 at 4:23pm
post #3428 of 10504
You sir need to explore further then the 6AK5 tubes... They are very average vs the other tubes we are currently all rolling. The 6DT6, 6AV6 and 6HM5 would be good starters.. The 6HM5 runs in EF95 with no straps and sound very good. Plus its fairly cheap.
post #3429 of 10504
Quote:
Originally Posted by kvtaco17 View Post

You sir need to explore further then the 6AK5 tubes... They are very average vs the other tubes we are currently all rolling. The 6DT6, 6AV6 and 6HM5 would be good starters.. The 6HM5 runs in EF95 with no straps and sound very good. Plus its fairly cheap.

I bought those WAAAAAAAAAAAAAAAAAAY back, about a month and a half ago.

 

I just purchased these two tubes.

 

Vintage Electronic 6DT6 6DT6A RCA and 1680 IBM 6BE6.

 

Are these any good?

post #3430 of 10504
Quote:
Originally Posted by john57 View Post
 



Heat is one factor. Heat can dry out or breakdown the caps in time. When changing the caps one thing that can help is to use caps with a higher temperature ratings when possible. Also heat can effect the carbon resistors and the value can raise over long periods of time. Wireround resistors are more stable for long periods of time in the heat as compared to carbon resistors. Heat can also casue some sagging on parts in the tube. There is also contamination in the tube if left on for long periods of time with no signal.

 

 

So guess it is not safe to burn in without music.

post #3431 of 10504
Quote:
Originally Posted by MIKELAP View Post
 

i marked the jumper location in red for you if you magnify picture you will see better

                                                                                                                                                               

 

  you see the red rectangle right of the volume right below its marked EF92 AND THERES 2 PINS thats your EF92 jumper the other one IS NEXT TO THE RED SQUARE and the bottom to the left there to its marked EF92 THOSE ARE THE LEFT AND RIGHT CHANNEL JUMPERS. for the other jumpers i see 2 other jumpers but its marked J3 so those must be your EF95 JUMPERS i dont see any other unless you see an EF95 inscription somewhere i dont . so those jumpers are right in the middle of the board.to the left of the opamp so i would SAY that according to the picture the amp is set on EF95 setting because jumpers are on the 2 pins get it so in this case to have the EF92 SETTING you remove the jumpers from J3 or EF95 and put them on EF92 JUMPERS . I hope its clear .

 

 

                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                           

My circuit board looks quite a bit different.

There are no switches present.

I need help moving the K1/K2 switches to side marked as 6j1 text on the circuit (EF95). Pics will help a lot. I have a Little Dot 1+.

 

There are two blue resistors inside of the little dot 1+, are the jumpers supposed to be in the same  orientation as the resistors?

If we were to compare the older Little Dot to the newer one in the exact position as the one above. The resistors would be horizontal, just like the ones by the op amp.

So far my K1/K2 switches are horizontal as well, is this correct?

post #3432 of 10504
Quote:
Originally Posted by Sony Slave View Post
 

I bought those WAAAAAAAAAAAAAAAAAAY back, about a month and a half ago.

 

I just purchased these two tubes.

 

Vintage Electronic 6DT6 6DT6A RCA and 1680 IBM 6BE6.

 

Are these any good?

 

Which ones did you buy about a month and a half ago?  6AK5? 6HM5? 6AV6?

 

And of course, "good" is very subjective...  Personally, I thought the RCA 6DT6 and the IBM (RCA) 1680 were quite similar, rather warm and very enjoyable tubes.

post #3433 of 10504
Quote:
Originally Posted by gibosi View Post
 

 

Which ones did you buy about a month and a half ago?  6AK5? 6HM5? 6AV6?

 

And of course, "good" is very subjective...  Personally, I thought the RCA 6DT6 and the IBM (RCA) 1680 were quite similar, rather warm and very enjoyable tubes.

6AK5.

post #3434 of 10504
Quote:
Originally Posted by jaywillin View Post
 


ok, mine didn't have switches either, so the diagram is more accurate then really

look at your board, and identify the jumpers j1, j2, 3,4,5,6,

the jumpers are the black pieces of plastic with the 2, or 3 wire post coming out , use some needle nose pliers

tweezers and they'll slide up and off, or just slide down to reinsert , make sure when you are putting them back on

to keep them right side up, its marked

 

To use 6JI, 6AK5, 5654, WE403A/B, etc:
1.
K1 and K2 set to the side of the “6JI” text
2.
Make sure the jumper caps are
removed

from J1 and J2

k1, and k2 are jumpers, not switches, move the jumpers to the 6j1 side

The j1 and j2 jumpers are vertical, the j3/j4 jumpers are horizontal. Do I place the K1/k2 jumpers next to the 6j1 text vertically like the j1/j2 or horizontally, like the j3/j4? (I have a newer Little Dot 1+)

post #3435 of 10504
Quote:
Originally Posted by Sony Slave View Post
 

My circuit board looks quite a bit different.

There are no switches present.

I need help moving the K1/K2 switches to side marked as 6j1 text on the circuit (EF95). Pics will help a lot. I have a Little Dot 1+.

 

There are two blue resistors inside of the little dot 1+, are the jumpers supposed to be in the same  orientation as the resistors?

If we were to compare the older Little Dot to the newer one in the exact position as the one above. The resistors would be horizontal, just like the ones by the op amp.

So far my K1/K2 switches are horizontal as well, is this correct?

 

Jumpers K1 and K2 allow you to switch between 408A tubes, which have 20V heaters, and EF95 tubes, which have 6V heaters. As you have been using EF95 tubes without smoke, or worse, I would assume that these jumpers are already set correctly, that is, for 6J1/EF95. Unless you are intending to use 408A tubes, I would advise that you leave these jumpers alone for now.

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