Little Dot Tube Amps: Vacuum Tube Rolling Guide
Dec 27, 2013 at 10:49 AM Post #4,486 of 13,438

 
Got tired of ugly wires...
 
Dec 27, 2013 at 1:04 PM Post #4,487 of 13,438
Received a few 8CG7 today. The one on the left appears to be an older RCA with a side D-getter, even though it has the "Micro" label. I think the one in the middle is Japanese, and the one on the right is dated 7022 Japan, so no doubt about that. None of these have a shield. That is, pin 9 is not connected to anything. Evidently, some of these *CG7 tubes have shields and some don't. Those with shields are often described as having "3 Plates" by vendors. My Raytheon 6CG7, which sounds extremely good by the way, does have a shield.
 
Anyway, I dialed in 8.4 volts, fired them up and they all light up and play. I only paid about $7.00 for these as I just wanted an excuse to adjust my DC heater voltage. lol  Will spend a little more time with them, but don't expect much. 
 

 
Dec 27, 2013 at 1:41 PM Post #4,488 of 13,438
Hi All,
 
At the present time I am exploring different 6SL7 tubes. However, first I want to say that I have been listening to a bunch of tubes from the 6DJ8 family, mainly different brands of 6BC8/6BZ8, 6BZ7 and 6N23P tubes. The amazing thing is that all of them are very good, with the trademark etched detailing of sound, wide sound stage and good bass and treble. The only con is that they are a little cold and analytical, but not in an irritating way; just the way they are, in a pleasant "intellectual" way. These variants probably offer almost all of the sound of the very expensive Amperex tubes at a fraction of the price.
 
Now back to the 6SL7 tubes: In contrast to the 6DJ8 family these tubes are warm and musical. Some of them lack in the detail but it is made up by the musicality and heft in the bass that can go very low with some of these tubes. My favorite right now is this 6SL7GT Tung Sol tube from July 1967:

 

 
This tube has a very sweet, warm sound, excellent imaging with great bass and mid range. What stands out is a fat mid bass. The treble is not sizzling, but still very good and satisfying. The slam and attack is lesser and slower than the 6BC8 tubes, but as said before, this tube makes it up with it's musicality.
 
The tube is shown in action mounted to a breadboard wired for a 12AX7 tube with an octal adapter. The multi colored wires come from a discarded computer power supply.
 
I realize that some people on this forum are intimidated by the thought of making up adapters to fit tubes that were not originally intended for the Little Dot amps. Personally, I was myself very hesitant to fiddle with the electronic stuff since I do not have any background in this. However, once you decide to try it is not that difficult, especially with the excellent wiring diagrams provided by the esteemed members of this thread.
 
If there is an interest, I would show in pictures how to put together an adapter using a 9 pin breadboard socket and Vector adapters for those who are new to tube rolling and want to use non native tubes in the Little Dot MKIII amp. As I learned through Gibosi, this can be done without the use of a soldering iron.
 
Happy tube rolling and listening!
 
Dec 27, 2013 at 2:24 PM Post #4,490 of 13,438
Well another milestone  weve just it page 300 time flies !
 
Dec 27, 2013 at 2:55 PM Post #4,491 of 13,438
I realize that some people on this forum are intimidated by the thought of making up adapters to fit tubes that were not originally intended for the Little Dot amps. Personally, I was myself very hesitant to fiddle with the electronic stuff since I do not have any background in this. However, once you decide to try it is not that difficult, especially with the excellent wiring diagrams provided by the esteemed members of this thread.  
If there is an interest, I would show in pictures how to put together an adapter using a 9 pin breadboard socket and Vector adapters for those who are new to tube rolling and want to use non native tubes in the Little Dot MKIII amp. As I learned through Gibosi, this can be done without the use of a soldering iron.

 
Indeed, it would just be too much of a shame for people not to try the 6DJ8 (and other) types just because they're afraid of making/crafting an adapter. It really isn't that hard once you get the diagrams down, and you've got metric tons of help here on this thread, so go for it and roll yourself some double triodes this Christmas, or whatever holiday you prefer!
beerchug.gif

 
Page 300 huh? Wow, it was like page 30 something the first time I posted here... Time flies when you having fun lol.
 
Dec 27, 2013 at 4:14 PM Post #4,492 of 13,438
  Hi All,
 
At the present time I am exploring different 6SL7 tubes. However, first I want to say that I have been listening to a bunch of tubes from the 6DJ8 family, mainly different brands of 6BC8/6BZ8, 6BZ7 and 6N23P tubes. The amazing thing is that all of them are very good, with the trademark etched detailing of sound, wide sound stage and good bass and treble. The only con is that they are a little cold and analytical, but not in an irritating way; just the way they are, in a pleasant "intellectual" way. These variants probably offer almost all of the sound of the very expensive Amperex tubes at a fraction of the price.
 
Now back to the 6SL7 tubes: In contrast to the 6DJ8 family these tubes are warm and musical. Some of them lack in the detail but it is made up by the musicality and heft in the bass that can go very low with some of these tubes. My favorite right now is this 6SL7GT Tung Sol tube from July 1967:

 

 
This tube has a very sweet, warm sound, excellent imaging with great bass and mid range. What stands out is a fat mid bass. The treble is not sizzling, but still very good and satisfying. The slam and attack is lesser and slower than the 6BC8 tubes, but as said before, this tube makes it up with it's musicality.
 
The tube is shown in action mounted to a breadboard wired for a 12AX7 tube with an octal adapter. The multi colored wires come from a discarded computer power supply.
 
I realize that some people on this forum are intimidated by the thought of making up adapters to fit tubes that were not originally intended for the Little Dot amps. Personally, I was myself very hesitant to fiddle with the electronic stuff since I do not have any background in this. However, once you decide to try it is not that difficult, especially with the excellent wiring diagrams provided by the esteemed members of this thread.
 
If there is an interest, I would show in pictures how to put together an adapter using a 9 pin breadboard socket and Vector adapters for those who are new to tube rolling and want to use non native tubes in the Little Dot MKIII amp. As I learned through Gibosi, this can be done without the use of a soldering iron.
 
Happy tube rolling and listening!

Hi, i am interested in making the adaptor(for the tube in the picture) please let me know what are the materials  i need and if you can show the diagram i have the VECTOR 7 Pin adaptor. Thanks!
 
Dec 27, 2013 at 4:58 PM Post #4,493 of 13,438
Speaking of adapters i started to put together an adaptor for octal tubes since my chinese adapters are probably lost ,using  Troll Dragon's  design and Artsi's schematics here's the  12AX7 an 6DJ8 adapters i made heres a few pictures the 6SL7 octal adapter is more elaborate since theres cutting and soldering i would say just for the chassis i will probably put in a couple hours since i have to open up the diameter where the octal socket goes in the tube .as for the rest the parts used will be like the other adapters                                                                                                                                                                                                                                                                                                                 


 
 
 

 
Dec 27, 2013 at 5:42 PM Post #4,494 of 13,438
  Speaking of adapters i started to put together an adaptor for octal tubes since my chinese adapters are probably lost ,using  Troll Dragon's  design and Artsi's schematics here's the  12AX7 an 6DJ8 adapters i made heres a few pictures the 6SL7 octal adapter is more elaborate since theres cutting and soldering i would say just for the chassis i will probably put in a couple hours since i have to open up the diameter where the octal socket goes in the tube .as for the rest the parts used will be like the other adapters                                                                                                                                                                                                                                                                                                                 


 
 
 

 
  Speaking of adapters i started to put together an adaptor for octal tubes since my chinese adapters are probably lost ,using  Troll Dragon's  design and Artsi's schematics here's the  12AX7 an 6DJ8 adapters i made heres a few pictures the 6SL7 octal adapter is more elaborate since theres cutting and soldering i would say just for the chassis i will probably put in a couple hours since i have to open up the diameter where the octal socket goes in the tube .as for the rest the parts used will be like the other adapters                                                                                                                                                                                                                                                                                                                 


 
 
 

That is nice, what gauge is that wire you are using(solid and the stranded)?
 
Dec 27, 2013 at 6:00 PM Post #4,495 of 13,438
   
That is nice, what gauge is that wire you are using(solid and the stranded)?

22 gauge stranded copper wire for the connections and 1 m.m.(.039) copper wire for the pins
 
Dec 27, 2013 at 11:22 PM Post #4,497 of 13,438
  Speaking of adapters i started to put together an adaptor for octal tubes since my chinese adapters are probably lost ,using  Troll Dragon's  design and Artsi's schematics here's the  12AX7 an 6DJ8 adapters i made heres a few pictures the 6SL7 octal adapter is more elaborate since theres cutting and soldering i would say just for the chassis i will probably put in a couple hours since i have to open up the diameter where the octal socket goes in the tube .as for the rest the parts used will be like the other adapters.

 
Nice Job on those adapters!
 
Dec 28, 2013 at 12:15 PM Post #4,498 of 13,438
My late 1950 (or early 1960) US-made Raytheon 6CG7 with black plates is fast becoming one of my favorite tubes. It is slightly warmer than the Amperex and Voshkod 6DJ8-types, with excellent liquidity and flow, and a spacious 3D stage with very good depth and detail. But what really separates this tube from the 6DJ8 is the midrange. Vocals are slightly forward and crystal clear, but never stridant, and as a result, I am hearing more mid-range detail with this tube than with the 6DJ8. Highly recommended.
 
In the second photo, you can clearly see the shield in between the two triode plates. Some vendors describe such a 6CG7 as having three plates. Also, this tube is taller than a standard 6DJ8. 
 

 

 
Dec 28, 2013 at 7:00 PM Post #4,499 of 13,438
I got my DC regulator all wired up and tucked safely inside my enclosure, the little bit of hum I had is now 100% gone... makes these tubes seem more dynamic (Amperex A frames) probably due to having a completely black image on quieter passages... now I just have to figure out how to mount the DC regulator and cut holes so it is accessible/visible from the front.
 

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