6Sj7 to 6SL7 or the other way

[Ed_Chambley]

Hi guys, been a while since I posted, but have been lurking.  I am working on a preamp using a makeshift breadboard and have not really found anything until last weekend and I wanted to ask for some experience.  I have tried using a 6sl7 pushing 1/2 of a 6Sl7 to a 1 meg volume and back to the second 1/2 6SL7 and I really like the initial tone.  Just a preamp and I have it running into Fender PA with 2 5881 and a 12AX7 like a brownface 6G6B.


I read through some of the older posts regarding hotrodding SE amps and found a lot of folks prefer to use the 6Sj7 as an overdrive tube, but I sort of like it first.  The tone seems better in a Push Pull with the Pentode first IMO.
I am having a little battle with noise so a humdinger solved a lot and I am sure once I punch a chassis I will get it quiet.


I am looking for some custom schematics Anyone?  I would like to try some different values for both tubes and not opposed to moving the positions.  Mind you I am just at the scribble on paper stage, but what a nice warm tone.


Please if anyone has built a similar preamp or complete amp and don't mind sharing, I would be much appreciative.  In particular, the 6Sj7 values and voltages you have found to work well for you.  I tried some old Valco values and the are ok, but using EF86 values from a DC30 Matchless is a bit better, but the tube is a tad on the harsh side.


Any and all comments are welcomed, even if you think it is stupid to be using old metal tubes.    Since I have a bucket load of em I am going to use some.  I love the smell of old tube boxes in the morning.

[terminalgs]

Please if anyone has built a similar preamp or complete amp and don't mind sharing, I would be much appreciative.  In particular, the 6Sj7 values and voltages you have found to work well for you.  I tried some old Valco values and the are ok, but using EF86 values from a DC30 Matchless is a bit better, but the tube is a tad on the harsh side.

I built this.  12ax7->6sj7,  not exactly what you are talking about.   I built it 10 years ago. I thought it sounded good.  I still have it, I'll plug it in and see if it stood the test of time.  It might benefit from more filtering out front, but I don't remember it being noisy.  nothing magic.  Champ gain stage,  fender reverb box CF,  standard tonestack and a 6sj7 all jammed together.  I'm not sure were I got the 6SJ7 values,  but it was probably from a Gibson or a Valco.





I found the PA522 to be a handy PT for preamps.  If you wire it for 240 pri. and feed it 120 you get a 165-0-165 and 6.3.


I built a dozen or so preamps & tube pedals and eventually figured out the following was the best way to make a preamp circuit hum/noise free.  It was based on trial and error and Merlin's grounding chapter (and other chapters I'm sure).  If it's just preamps with small currents R1 and R2 can be big, like 4.7K or so.

Any and all comments are welcomed, even if you think it is stupid to be using old metal tubes.    Since I have a bucket load of em I am going to use some.  I love the smell of old tube boxes in the morning.

Me too, but I sometimes wonder if that smell is toxic.

[Ed_Chambley]

Please if anyone has built a similar preamp or complete amp and don't mind sharing, I would be much appreciative.  In particular, the 6Sj7 values and voltages you have found to work well for you.  I tried some old Valco values and the are ok, but using EF86 values from a DC30 Matchless is a bit better, but the tube is a tad on the harsh side.

I built this.  12ax7->6sj7,  not exactly what you are talking about.   I built it 10 years ago. I thought it sounded good.  I still have it, I'll plug it in and see if it stood the test of time.  It might benefit from more filtering out front, but I don't remember it being noisy.  nothing magic.  Champ gain stage,  fender reverb box CF,  standard tonestack and a 6sj7 all jammed together.  I'm not sure were I got the 6SJ7 values,  but it was probably from a Gibson or a Valco.





I found the PA522 to be a handy PT for preamps.  If you wire it for 240 pri. and feed it 120 you get a 165-0-165 and 6.3.


I built a dozen or so preamps & tube pedals and eventually figured out the following was the best way to make a preamp circuit hum/noise free.  It was based on trial and error and Merlin's grounding chapter (and other chapters I'm sure).  If it's just preamps with small currents R1 and R2 can be big, like 4.7K or so.

Any and all comments are welcomed, even if you think it is stupid to be using old metal tubes.    Since I have a bucket load of em I am going to use some.  I love the smell of old tube boxes in the morning.

Me too, but I sometimes wonder if that smell is toxic.

Thank you.  The values look different from a Valco or at least the ones I looked at.  I agree, I will not have any noise when built.