Thanks for the advice & guidance. My tech is serious about this stuff, whereas I'm more curious,,, and I do not perform mods of any kind. I have lots if rectos & octals lying around, & while i know there are probably NO direct drop-ins for tubes, except for for the 12**7 family. And & know that different rectifiers, if acceptable to the circuit, can change the amp's attitude, albeit not greatly, being a recto. But I am curious about the 6SC,SN,SL,SJ7 family. With appropriate design tweaks, which of these octals share the same pinout, and could be subbed, w/o a total rewiring, if any....?? Thanks Phil,,, as I'm legally blind, it's often difficult to easily download & investigate these stats, which is why I come to this place, hoping for some quicker results.
Again, I don't do mods, & all I'm good for is a 3 prong cord, change out an old resistor or cap, install a fuse receptacle, & change tubes. With the octals, I'd like to know what subs are possible, even w/some rewiring, & what their gain factors are....
Basically, I'm having someone modify some 50/60's mono tube PA amps for guitar use, & was curious to know what tubes that I have in my best collection, can be swapped in for some better gain.
Thank you again, Kenny
TY, PHIL_S, & others
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dorrisant
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Re: TY, PHIL_S, & others
Here is a bit of notes I saved on this subject while researching a 5E3 build with all octals.
"The 6SN7 has specs that are almost identical to 12AU7. Aside from one being octal and the other noval, they will interchange very well. The big differences are 1) 6SN7 has a maximum plate voltage of 450, which is well over the 12AU7, and 2) the physical plate size is comparatively enormous. These features make it decent low gain preamp tube, but it can really excel as an output tube due to both of these features. Try a pair (4 triodes) in PP for a 10-15W amp -- it makes a great clean tone. Half of one of these makes a good concertina.
The 6SL7 is a bit of a different tube. Let's call it a first cousin to the 12AX7 and 5751. Gain is more like the 5751, but plate resistance is lower. It is good as a gain hole tube and by tweaking plate and cathode resistors you can probably milk quite a bit of gain from it. It is probably not nearly as good as a 12AX7 for a tremolo oscillator due to the lower rated plate resistance value.
6SN7 push pull (Use the Mojo 1580 output( http://www.mojotone.com/amp-parts/trans ... -PP-Output)) makes a wicked little push pull output....
6SL7 is like a 12AX7
6SN7 like 12AU7
The same circuit values do work.
The 6SC7 has a shared cathode for both triodes. The 6SL7 has two cathodes. Internal plate resistance is 53K for 6SC7 and it is 44K for 6SL7. Otherwise, probably not much difference. I think I'd prefer to have separate cathodes. If you need an oscillator tube for a tremolo, stick with the 6SC7 for the higher Ra. 44K is on the low side for a tremolo circuit.
https://tubeamparchive.com/viewtopic.ph ... 79a185c986
Type 1
1 - Grid 2
2 - Plate 2
3 - Cathode 2
4 - Grid 1
5 - Plate 1
6 - Cathode 1
7 - Heater
8 - Heater
V1 - 6SN7 Amp=20 - @250v - mmhos=2600 - PlateR=7.7k - PlateA=9.0mA
Max 450v - Heater 0.6a@6.3v
V2 - 6SL7 Amp=70 - @250v - mmhos=1600 - PlateR=44k - PlateA=2.3mA
Max 300v - Heater 0.3a@6.3v
Type 2
1 - Shell
2 - Plate 2
3 - Grid 2
4 - Grid 1
5 - Plate 1
6 - Cathode (common)
7 - Heater
8 - Heater
6SC7 Amp=70 - @250v - mmhos=1325 - PlateR=53k - PlateA=2.0mA
Max 250v - Heater 0.3a@6.3v
Pentodes - 6SJ7, 6SK7, 6AG7, 6AC7"
Take it with a grain of salt, hope that it helps.
"The 6SN7 has specs that are almost identical to 12AU7. Aside from one being octal and the other noval, they will interchange very well. The big differences are 1) 6SN7 has a maximum plate voltage of 450, which is well over the 12AU7, and 2) the physical plate size is comparatively enormous. These features make it decent low gain preamp tube, but it can really excel as an output tube due to both of these features. Try a pair (4 triodes) in PP for a 10-15W amp -- it makes a great clean tone. Half of one of these makes a good concertina.
The 6SL7 is a bit of a different tube. Let's call it a first cousin to the 12AX7 and 5751. Gain is more like the 5751, but plate resistance is lower. It is good as a gain hole tube and by tweaking plate and cathode resistors you can probably milk quite a bit of gain from it. It is probably not nearly as good as a 12AX7 for a tremolo oscillator due to the lower rated plate resistance value.
6SN7 push pull (Use the Mojo 1580 output( http://www.mojotone.com/amp-parts/trans ... -PP-Output)) makes a wicked little push pull output....
6SL7 is like a 12AX7
6SN7 like 12AU7
The same circuit values do work.
The 6SC7 has a shared cathode for both triodes. The 6SL7 has two cathodes. Internal plate resistance is 53K for 6SC7 and it is 44K for 6SL7. Otherwise, probably not much difference. I think I'd prefer to have separate cathodes. If you need an oscillator tube for a tremolo, stick with the 6SC7 for the higher Ra. 44K is on the low side for a tremolo circuit.
https://tubeamparchive.com/viewtopic.ph ... 79a185c986
Type 1
1 - Grid 2
2 - Plate 2
3 - Cathode 2
4 - Grid 1
5 - Plate 1
6 - Cathode 1
7 - Heater
8 - Heater
V1 - 6SN7 Amp=20 - @250v - mmhos=2600 - PlateR=7.7k - PlateA=9.0mA
Max 450v - Heater 0.6a@6.3v
V2 - 6SL7 Amp=70 - @250v - mmhos=1600 - PlateR=44k - PlateA=2.3mA
Max 300v - Heater 0.3a@6.3v
Type 2
1 - Shell
2 - Plate 2
3 - Grid 2
4 - Grid 1
5 - Plate 1
6 - Cathode (common)
7 - Heater
8 - Heater
6SC7 Amp=70 - @250v - mmhos=1325 - PlateR=53k - PlateA=2.0mA
Max 250v - Heater 0.3a@6.3v
Pentodes - 6SJ7, 6SK7, 6AG7, 6AC7"
Take it with a grain of salt, hope that it helps.
"Education is what you're left with after you have forgotten what you have learned" - Enzo
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SoulFetish
- Posts: 211
- Joined: Wed Apr 03, 2013 1:50 pm
- Location: Norwood, MA
Re: TY, PHIL_S, & others
Kenny, I'm not sure if your familiar with Max Robinson or not, but he is a retired physics prof and electronics engineer who is also legally blind.zozoe wrote: ↑Mon Aug 17, 2020 9:57 pm Thanks for the advice & guidance. My tech is serious about this stuff, whereas I'm more curious,,, and I do not perform mods of any kind. I have lots if rectos & octals lying around, & while i know there are probably NO direct drop-ins for tubes, except for for the 12**7 family. And & know that different rectifiers, if acceptable to the circuit, can change the amp's attitude, albeit not greatly, being a recto. But I am curious about the 6SC,SN,SL,SJ7 family. With appropriate design tweaks, which of these octals share the same pinout, and could be subbed, w/o a total rewiring, if any....?? Thanks Phil,,, as I'm legally blind, it's often difficult to easily download & investigate these stats, which is why I come to this place, hoping for some quicker results.
Again, I don't do mods, & all I'm good for is a 3 prong cord, change out an old resistor or cap, install a fuse receptacle, & change tubes. With the octals, I'd like to know what subs are possible, even w/some rewiring, & what their gain factors are....
Basically, I'm having someone modify some 50/60's mono tube PA amps for guitar use, & was curious to know what tubes that I have in my best collection, can be swapped in for some better gain.
Thank you again, Kenny
He has a site https://www.angelfire.com/electronic/fu ... index.html that has some really great information about vacuum tube electronics, with audio descriptions accompanying much of the info. Perhaps you might find it interesting and helpful.
EE Web also did an interview with him, which is also an interesting read:
http://www.eeweb.com/spotlight/intervie ... x-robinson