Life really got in the way on me, and a lot of other projects, but i'm back to working on this.
I have ordered and received all the parts except for the rack face plate so far.
I am working from my latest version (schematic attached), which has been tuned down to 30hz - 18khz range and is testing out pretty well on my simulator.
I would love to get some input on the following stuff if any of you have some ideas:
1) Will the output need to be further buffered to go into a line-level device upstream?
2) What sort of transformer could i use for the output if i wanted to add one anyway? Would it need to be a line-level matching transformer?
3) I have some line-input and 1:1 vintage Ampex transformers; what would be the story on adding an input transformer to this?
I have ordered and received all the parts except for the rack face plate so far.
I am working from my latest version (schematic attached), which has been tuned down to 30hz - 18khz range and is testing out pretty well on my simulator.
I would love to get some input on the following stuff if any of you have some ideas:
1) Will the output need to be further buffered to go into a line-level device upstream?
2) What sort of transformer could i use for the output if i wanted to add one anyway? Would it need to be a line-level matching transformer?
3) I have some line-input and 1:1 vintage Ampex transformers; what would be the story on adding an input transformer to this?
Quick update:
I'm still tweaking this thing; the next schematic will have a few changes.
1) removing all "Q" pots (they're really not needed since this design starts the Q off at a very low ratio at low gain, and as you increase gain, the Q narrows along with it).
2) higher plate voltage going to the tube
3) adding a highpass filter in addition to the lowpass already on there.
just got my package in the mail with the power xformer and the blue jewel light...
almost ready to roll.
I'm still tweaking this thing; the next schematic will have a few changes.
1) removing all "Q" pots (they're really not needed since this design starts the Q off at a very low ratio at low gain, and as you increase gain, the Q narrows along with it).
2) higher plate voltage going to the tube
3) adding a highpass filter in addition to the lowpass already on there.
just got my package in the mail with the power xformer and the blue jewel light...
almost ready to roll.
Gonecat, my only first-hand experience with old input transformers was when I worked on an Ampex 601. I used a UTC A-10 input transformer. The first gain stage was an EF86 (6267) pentode, being used in single grid mode. I'm not sure how well a 1:1 input transformer would work with a 12AU7, but one way or another, only one leg of the secondary would go to the grid, and the other leg of the secondary would go to ground. Might work.
Sorry I don't have any specific advice on your output transformer. I've used an Altec 15095A as an output transformer for the same Ampex 601 mic preamp I spoke of above, and it worked pretty well. I'm sure there's less expensive present-day options about.
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