Head-Fi.org › Forums › Equipment Forums › Headphone Amps (full-size) › Little Dot Tube Amps: Vacuum Tube Rolling Guide
New Posts  All Forums:Forum Nav:

Little Dot Tube Amps: Vacuum Tube Rolling Guide - Page 375

post #5611 of 6944
Quote:
Originally Posted by gibosi View Post
 

 

As you are going to use an external heater PS to provide power to the 6AS7, pins 7 and 8, you should definitely leave pins 4, 5 and 9 disconnected in the socket.

 

Cheers :)

Thank You!

post #5612 of 6944

Hi I luvmusic 2,

 

Wishing you good luck in making the adapters. If possible, could you please take some pictures when you make them so that I can better understand how to wire in the power supply?

 

I wonder if I could run the the LD MKIII with 6080 tubes as power tubes if I wired in an external power supply to supply each tube with 2.5A.

 

Don't know what the amplification factor of 2 means in regard to using these tubes as power tubes.

post #5613 of 6944
Quote:
Originally Posted by mordy View Post
 

Wishing you good luck in making the adapters. If possible, could you please take some pictures when you make them so that I can better understand how to wire in the power supply?

 

I wonder if I could run the the LD MKIII with 6080 tubes as power tubes if I wired in an external power supply to supply each tube with 2.5A.

 

Don't know what the amplification factor of 2 means in regard to using these tubes as power tubes.

 

Pardon me for butting in here, but given Artsi's posting a few days ago, I would be very leery to try to use 6AS7s as power tube in your LD:

 

http://www.head-fi.org/t/563884/little-dot-tube-amps-vacuum-tube-rolling-guide/5565#post_10389835

post #5614 of 6944

What about as a driver tube?

post #5615 of 6944
Quote:
Originally Posted by mordy View Post
 

What about as a driver tube?

 

Given it's power requirements, I would be very leery. But I just don't know...... Perhaps Artsi can weigh in on this.

post #5616 of 6944

If the tube draws 2.5A, and my voltage regulator is rated 5A and the PS can put out more than 5A, why shouldn't it work? I have used the 6BX7 tube which draws 1.5A with very good results.

post #5617 of 6944

Yes, you can easily meet the requirements for the heaters. But as Artsi mentioned several pages ago, there might be other factors to consider:

 

"Now this is another real problem to use 6AS7's as powertube with LD. With 150ohm cathode resistors 6AS7 could hog 4-5 times the current what 6N6P uses! I think LD does not have enough anode current. And LD resistors can't stand the heat. Cathode resistors should be 10W."

 

And so my hesitation is based on the possibility that these same concerns regarding the current draw of the cathode and anode could also be an issue in using this tube as a driver. I just don't know...  and so I remain leery....

post #5618 of 6944

Received my 6HM5 sylvania tubes in the mail today. Put them into my Little Dot + and they are Sibilant with a capital Sssssssssssssss. I had to snatch that 4562 out very quick. Put my darker more smooth BB 2107 in and it calmed the treble down a great deal. These tubes are very Solid State sounding. Great bass authority and Excellent precision. I just need to know if the Sibilance or treble will smooth out over time. Is there another setting that can work. Gain is at the lowest setting. With my Denon D-7000 headphones.

post #5619 of 6944
Quote:
Originally Posted by CollectoR13 View Post


Here is my wiring diagram I used for my adapters, full tutorial coming soon!

 

Hi CR13.

 

Better late than never!...Something I did notice, which I presume doesn't make any difference? - ANYBODY? - the triode numbering looks different on the 6SN7 to most other tubes, ie pins 1, 2,3,4 are labelled triode 2 on the former, as opposed to triode 1. Just a quirk, I suppose...

 

And I believe the 'S' on pin 9 is for 'shield' - also sometimes combined with grids as 'suppressor'...

post #5620 of 6944
Quote:
Originally Posted by hypnos1 View Post

 

Better late than never!...Something I did notice, which I presume doesn't make any difference? - ANYBODY? - the triode numbering looks different on the 6SN7 to most other tubes, ie pins 1, 2,3,4 are labelled triode 2 on the former, as opposed to triode 1. Just a quirk, I suppose...

 

And I believe the 'S' on pin 9 is for 'shield' - also sometimes combined with grids as 'suppressor'...

 

Yes, the pin-out of 6SN7-type Octal tubes is completely different than the 9-pin 6DJ8s and 12AU7-type tubes. And it gets more complicated. The 7N7, the 8-pin Loctal version of the 6SN7GT, has a pin-out completely different from the Octal form. And the ECC40, the European 8-pin Rimlock version of the 6SN7GT, has a pin-out completely different from both the Octal and the Loctal forms.

 

In the 9 pin socket, if you are running 6DJ8-type tubes, pin 9 is the electrostatic shield and should be tied to pin 8. If you are running 12AU7-type tubes, pin 9 is part of the heater circuit when running these tubes in the 6 volt mode.

post #5621 of 6944
Quote:
Originally Posted by henree View Post
 

Received my 6HM5 sylvania tubes in the mail today. Put them into my Little Dot + and they are Sibilant with a capital Sssssssssssssss. I had to snatch that 4562 out very quick. Put my darker more smooth BB 2107 in and it calmed the treble down a great deal. These tubes are very Solid State sounding. Great bass authority and Excellent precision. I just need to know if the Sibilance or treble will smooth out over time. Is there another setting that can work. Gain is at the lowest setting. With my Denon D-7000 headphones.

Mine were far from sibilant... I assume the tubes you have are the tall bottles?

post #5622 of 6944

before, or after run-in period?

post #5623 of 6944
Quote:
Originally Posted by henree View Post
 

Received my 6HM5 sylvania tubes in the mail today. Put them into my Little Dot + and they are Sibilant with a capital Sssssssssssssss. I had to snatch that 4562 out very quick. Put my darker more smooth BB 2107 in and it calmed the treble down a great deal. These tubes are very Solid State sounding. Great bass authority and Excellent precision. I just need to know if the Sibilance or treble will smooth out over time. Is there another setting that can work. Gain is at the lowest setting. With my Denon D-7000 headphones.

i have a pair of Lawton modded Denon D-5000 and  sometimes there was  sibilance, but depending on the tune played do yours always sound like that with those tubes or just on certain tracks .

post #5624 of 6944

Hi,

 

Continuing my exploit of possible octal driver tubes for the the LD MKIII. Found a 12SN7GT Westinghouse tube and bought it mainly because it was inexpensive - less than $4 shipped. This tube has a side getter and the code 5R13, (maybe April 1955?).

 

Was just going to see if it lights up and makes sound and check out other tubes in this lot, but I can't get myself to pull it out of the socket; it is that good. Being fed a steady diet of 12.6V what is striking is the punchy, tuneful and detailed midrange bass as well as the quickness and liveliness of the tube.

 

For power tubes I am using two RCA 6SN7GT tubes. The 12SN7 draws 0.3A and has an amplification factor of 20 so we all can breathe easy - no worries about compatibility.

 

So far the only cons are a midrange that is very good but not sweet and a slight sibilance in the treble; however, these characteristics may very well change after burn in.

 

It is amazing - it is hard to find a mediocre 6SN7 family tube.....

post #5625 of 6944
Quote:
Originally Posted by MIKELAP View Post
 

i have a pair of Lawton modded Denon D-5000 and  sometimes there was  sibilance, but depending on the tune played do yours always sound like that with those tubes or just on certain tracks .

This is my first pair of these types of tubes. I would not have the d7000 if they always sounded this crisp. There was no info on ebay about these tubes. It could be NOS. Is it normal for certain tubes to be harsh when 1st listenig to them? Hopefully the 6hm5 smooth out over time.

New Posts  All Forums:Forum Nav:
  Return Home
  Back to Forum: Headphone Amps (full-size)
Head-Fi.org › Forums › Equipment Forums › Headphone Amps (full-size) › Little Dot Tube Amps: Vacuum Tube Rolling Guide