« previous next »
Pages: [1]   Go Down

Changing 12AX7s to 6SL7s....What to do??

0 Members and 1 Guest are viewing this topic. Read 1974 times.

LarryD56

  • Jr. Member
  • Posts: 126
Changing 12AX7s to 6SL7s....What to do??
« on: 13 Nov 2016, 12:53 am »
   I've been searching around for a schematic for my friend's JE Labs Full Function preamp, but there's none to be found. I'm planning on going ahead in switching back from the 12AX7s (put in sloppily by a modder) to the original design of the 6SL7s. Is there anything I should look out for in doing so? I plan to just follow the tube schematics and switch one wire at a time from the nine pin layout of the 12AX7 to the corresponding pins of the octal 6SL7.

   Would that make it so that I should use a 12SL7 instead of a 6SL7? I'm just not wanting to mess up my friend's preamp, but get it done and sent back to him. Thanks for your help.

Larry D.
Logged

denny9167

Re: Changing 12AX7s to 6SL7s....What to do??
« Reply #1 on: 19 Nov 2016, 01:52 pm »
Quote from: LarryD56 on 13 Nov 2016, 12:53 am
   I've been searching around for a schematic for my friend's JE Labs Full Function preamp, but there's none to be found. I'm planning on going ahead in switching back from the 12AX7s (put in sloppily by a modder) to the original design of the 6SL7s. Is there anything I should look out for in doing so? I plan to just follow the tube schematics and switch one wire at a time from the nine pin layout of the 12AX7 to the corresponding pins of the octal 6SL7.

   Would that make it so that I should use a 12SL7 instead of a 6SL7? I'm just not wanting to mess up my friend's preamp, but get it done and sent back to him. Thanks for your help.

Larry D.

Here is a shot of the phono stage of the SP-1B, I have been using active equalization, but this passive design works extensively well, plus with it mated to the reference series power supply, it performs flawlessly!

Logged

DaveC113

  • Industry Contributor
  • Posts: 4352
  • ZenWaveAudio.com
Re: Changing 12AX7s to 6SL7s....What to do??
« Reply #2 on: 19 Nov 2016, 03:36 pm »
If the heater voltage is currently 12V then go with 12SL7 unless you change the heater voltage back.
Logged

FullRangeMan

  • Volunteer
  • Posts: 20894
  • To whom more was given more will be required.
    • Never go to a psychiatrist, adopt a straycat or dog. On the street they live only two years average.
Re: Changing 12AX7s to 6SL7s....What to do??
« Reply #3 on: 22 Nov 2016, 02:36 am »
12SL7 is even cheaper than the 6V version.
Logged

LarryD56

  • Jr. Member
  • Posts: 126
Re: Changing 12AX7s to 6SL7s....What to do??
« Reply #4 on: 25 Nov 2016, 02:35 am »
   I'm not sure what Denny9167 is trying to show me with the SP-1B schematic. Besides not being readable when small or enlarged, it's not the same preamp I'm trying to fix. I'm not wanting to change anything, just get this put back together, off of my shelves, and back to it's owner.

Larry D.
Logged

sfox7076

  • Full Member
  • Posts: 1327
Re: Changing 12AX7s to 6SL7s....What to do??
« Reply #5 on: 25 Nov 2016, 02:51 am »
12ax7 is center tapped, so it might be run off 6v.  You need to check with a voltmeter before assuming a 12sl7 would work. 
Logged
Pages: [1]   Go Up
« previous next »