Power Supply
It might be easier to use two seperate supplies.
I'm using a small toroid, rectified through 1/2 of a BrianGT gainclone power supply board instead of using the preamp rectifier section. (better filter) This will be the 35v input.
I removed a 6v transformer from a wallwart and modified the other half of the ps board for it. I just used the diode bridge and cap/res pair from the wallwart itself. This gave me enough space at the output end of the board to add a voltage regulator to keep the power at 6.3v to the heater.
Chipamp Power Supply Kit | Chipamp.com
Note: The ps board, when wired for a gainclone is +V~+PGND~-PGND~-V. By using each half seperately, it gives you +v~gnd, which is what this preamp uses.
It might be easier to use two seperate supplies.
I'm using a small toroid, rectified through 1/2 of a BrianGT gainclone power supply board instead of using the preamp rectifier section. (better filter) This will be the 35v input.
I removed a 6v transformer from a wallwart and modified the other half of the ps board for it. I just used the diode bridge and cap/res pair from the wallwart itself. This gave me enough space at the output end of the board to add a voltage regulator to keep the power at 6.3v to the heater.
Chipamp Power Supply Kit | Chipamp.com
Note: The ps board, when wired for a gainclone is +V~+PGND~-PGND~-V. By using each half seperately, it gives you +v~gnd, which is what this preamp uses.
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Testing 6111
Finished this today, as described above, and did a temporary hookup to test it. Connected it to a gainclone and some old Infinity bookshelf speakers. Sounds very nice, no hiss or hum. I left it playing for a while to make sure nothing smoked.
I built my gainclone in an old IBM PCjr computer case and there's plenty of room to add this pre inside. I'll add a bypass switch and test it with better speakers.
Finished this today, as described above, and did a temporary hookup to test it. Connected it to a gainclone and some old Infinity bookshelf speakers. Sounds very nice, no hiss or hum. I left it playing for a while to make sure nothing smoked.
I built my gainclone in an old IBM PCjr computer case and there's plenty of room to add this pre inside. I'll add a bypass switch and test it with better speakers.
Attachments
6N16b tubes would work well in this circuit (they are reportedly far more linear than the 6111 tube) – does anyone have access to a datasheet which is in English?
I think the only real changes we will need to make will be a higher B+ (around 100v), but the resistances should be roughly the same....correct me if I’m wrong. It would be good to reduce the gain on this one a little in order to use it as a gain stage after a DAC (or as a preamp) as there is no need for > 20dB gain.
I think the only real changes we will need to make will be a higher B+ (around 100v), but the resistances should be roughly the same....correct me if I’m wrong. It would be good to reduce the gain on this one a little in order to use it as a gain stage after a DAC (or as a preamp) as there is no need for > 20dB gain.
I used the 6111wa for a run of line stage preamplifiers about 15 years ago, it produced very nice sounding results. Used it off an LCLC filtered HT at around 200V, with a 15K Rp and 220R Rc, certainly not at the low voltages used on this board. Also needed dc for the heaters to avoid hum.
Found that a good number of the 6111 go noisy, mainly hiss, over the first 20 to 30 hours, if they get through that quiet, they remain quiet for good.
I believe Audio Note used them in their Zero range line preamp and DAC and found similar issues with hiss.
If you have too much gain from the board, consider a potential divider at the input.
Best of luck, Simon
Found that a good number of the 6111 go noisy, mainly hiss, over the first 20 to 30 hours, if they get through that quiet, they remain quiet for good.
I believe Audio Note used them in their Zero range line preamp and DAC and found similar issues with hiss.
If you have too much gain from the board, consider a potential divider at the input.
Best of luck, Simon
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