• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

6V6 line preamp

Here is my L adapter in a small edition for my filaments feed tube vs Lm317 CCS.
Big improvements in sound more bass and more details realy
Big improvements certify the very good waveform on my scope against waveform of the lm317...
 

Attachments

  • thumbnail.jpg
    thumbnail.jpg
    93.9 KB · Views: 598
  • thumbnail (1).jpg
    thumbnail (1).jpg
    303.8 KB · Views: 539
  • IMG_20190511_143301.jpg
    IMG_20190511_143301.jpg
    821.8 KB · Views: 536
diyAudio Chief Moderator
Joined 2002
Paid Member
Very good news.

For those wanting an upgrade of heaters PSU vs the LM317 one in the original 6V6 line preamp's schematic here's the L-Adapter circuit. Its a general purpose high current PSU that can be set from very low to about 20V. But three red LEDs and the trimmer without setting jumpers are enough in this 6.3V heaters fixed voltage case. For more information, that PSU's thread link is: L-Adapter
 

Attachments

  • L-Adapter schematic.png
    L-Adapter schematic.png
    21.3 KB · Views: 610
Here is my L adapter in a small edition for my filaments feed tube vs Lm317 CCS.
Big improvements in sound more bass and more details realy
Big improvements certify the very good waveform on my scope against waveform of the lm317...

Just dropped in - interesting thread, but did I understand this correctly, you get an improvement in sound by changing one regulated DC supply for another regulated supply for the heater on an indirectly heated valve ? is the heater power transformer separate from the B+ power transformer ?
 
Just dropped in - interesting thread, but did I understand this correctly, you get an improvement in sound by changing one regulated DC supply for another regulated supply for the heater on an indirectly heated valve ? is the heater power transformer separate from the B+ power transformer ?

I dont have any other separate transformer..... All in one...
Before with Lm317 as current limit....
 

Attachments

  • IMG_20190414_120534.jpg
    IMG_20190414_120534.jpg
    757.6 KB · Views: 511
Filament wire is jam packed in the cathode cylinder. If there is noise on it, can couple to the cathode.

Agreed, there can be noise but the subjective results included improved bass and I don't see how that occurs unless it's a) the treble is better which funny enough can result in the bass seeming better even if it's unchanged, b) the heater supply being on the same transformer as B+ has some influence on the plate supply other than coupling rectifier noise.


I never wash my car. It's a sliver colour car, the same colour as dirt :D
 
diyAudio Chief Moderator
Joined 2002
Paid Member
Don't know about the subjectives, he did the listening, I picked the mentioned better scope result thought. The 317 chip CCS supply was high impedance, the new one is voltage source i.e. low impedance, maybe there was interference pick up beyond the new one has less self noise.
 
It is time to put my hand on this simple version.
Nothing special here, just to try things.
I have so many used 6v6 so why not.
No good looking but playing nicely.
Good work Salas, very good!
The power supply!
A generic power supply that I picked up from the trash!
 

Attachments

  • IMG_20190516_122841_BURST1.jpg
    IMG_20190516_122841_BURST1.jpg
    635.7 KB · Views: 452
  • IMG_20190516_122920.jpg
    IMG_20190516_122920.jpg
    491.1 KB · Views: 442
  • IMG_20190516_124128.jpg
    IMG_20190516_124128.jpg
    410.4 KB · Views: 419
Last edited:
diyAudio Chief Moderator
Joined 2002
Paid Member
Good luck and keep us posted if you will go further like boxing it up. ΜΠΑΚΑΚΟΣ TP-4 HV Bench PSU! I did not know there was an old time electronics branding by that iconic Athenian pharmacy firm. It looks like they had been selling some local OEM HV PSUs for chemical work.

An externally hosted image should be here but it was not working when we last tested it.
6165.png
 
diyAudio Chief Moderator
Joined 2002
Paid Member
A scholar version of the language was used by the state, much literature, newspapers, for over one hundred and fifty years. It had very many classic elements as it was something between the ancient and the modern common language. It faded enough until officially abandoned in the seventies.