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6SN7/6CG7 Based Line Level Preamp

petrnyc

petrnyc

Active Member
Hello,
Looking for a good 6SN7/ 6CG7 Preamp Schematic. 1 tube 2x triodes per channel.
Gain of 12AU7 (20) is good for my need (that's SRPP preamp I have now) .
I have both of these tube types and plan on using octal to mini 9 adapter when using the 6CG7's.

Thank you
 
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If you want something simple yet very functional, you could build a clone of the Audio Electronics Supply AE-3 preamp. Works extremely well. It is the preamp I use in my main system. I built mine from the kit in something like 2007, but the circuit is simple enough you could scratch build it with parts your source on your own from places like Mouser or Digikey. Schematic here. Also this thread describes some upgrades that you could think about.
 
only major functional difference between those is direct coupled vs cap coupled between the amp and buffer stages. Shouldn't make a lot of difference so long as the cap is of good quality. Need a fair bit less B+ with the cap coupled design too.

honestly its kind of hard to go wrong with such a simple circuit, and there are very limited ways to actually design one. Its just datasheet Class A operating conditions. Variables are just in your available supply voltage, what you want to do for input and level controls, and if you want any extra features. I might suggest an output muting circuit with a time delay. Cap coupled designs like this will make a hell of a "whump" noise as the cap charges up. If you include a relay that grounds the output until the preamp has been on for 60 seconds or something you won't have to worry about that. Also eliminates the same noise on power-down. Maybe use relays for the input switching to keep the signal path short. Can also set those up to ground the non-selected inputs to minimize bleed-through. You can get those boards pre-made with a remote control to select input and run a motorized volume control too.
 
nerdorama said:
Slightly more complex but I have a 6SN7 Aikido line stage. Very quiet and clean sounding. I got the PC board but it could readily be done point to point.
John
Click to expand...

John,
Do you have a schematic to see for this Aikido?
And Thank you all.
 
The Aikido is from TubeCAD Journal and GlassWare for the boards and kits. You can use just about any triode for it, especially if you point to point from scratch. First and second stages don't have to be the same tube.

Here is the Glass ware page for the pcb's and kits:
https://glass-ware.stores.yahoo.net/newhardware.html

The TubeCAD journal original article:
https://www.tubecad.com/2004/blog0011.htm

He has posted many follow-on blog posts about this scheme. Search through here for others.
https://www.tubecad.com/

Have fun,
John
 
nerdorama said:
The Aikido is from TubeCAD Journal and GlassWare for the boards and kits. You can use just about any triode for it, especially if you point to point from scratch. First and second stages don't have to be the same tube.

Here is the Glass ware page for the pcb's and kits:
https://glass-ware.stores.yahoo.net/newhardware.html

The TubeCAD journal original article:
https://www.tubecad.com/2004/blog0011.htm

He has posted many follow-on blog posts about this scheme. Search through here for others.
https://www.tubecad.com/

Have fun,
John
Click to expand...



thank you
 
I built an Aikido using 12AU7's, then 12AX7's. I liked it so much I wound up buying an octal version using 6SN7's. I've been really happy with them.
 
Tubes4hifi and Erhard Audio sell line stage and power supply boards along with complete kits. I built a preamp using Erhard's like stage and power supply boards. My son is using it now that I bought an octal version. Tubes4hifi power supplies use tube rectifiers, and Erhard uses SS.
 
Try tubecad "6SN7 Gnd-K Anode Follower Line Amplifier". Blog #544. Conventional common cathode to cathode follower cannot hold a candle to it. Build as shown with a simple tube rectifier and clc filtering. Did not use fancy parts.
 
Having built a couple of the 9 pin Aikido versions and now using an octal version, I do prefer the octal. The differences were very subtle though.
Having listened to them back and forth on a switch box playing various material, to my ears the 6SN7's just sound more open. That's the bast I can describe it.
The 9 pin versions did sound very good also though.
 
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