Hello. I'm a DIY noob with decent soldering skills, a big pile of stuff, and some enthusiasm. I've successfully managed to put together an SCA N72 without incident, and I've wired up my studios, racks etc for years, and I really want to expand my skills and knowledge.

I want to build a preamp or two, based around a pile of Triad A67J transformers I have lying around. I found this design by Rod Elliot which uses a single NE5534, which I have a bunch of, and a Jensen JT16A, which I definitely do not have. The Jensen is a 1:2 transformer, as is the Triad A67J. I'm sure you can see where I'm heading with this.

Any chance I can substitute an A67J in this design and have it work? While I'd like to end up with a usable preamp, I would be fine if it ended up on the "colored" side of things. I don't expect it to be my go-to. Funky is fine.

If this design isn't right, would there be another very simple circuit I could make work with an A67J? The only preamp I know of that used them is the Spectra Sonics 101 and 110, which looked harder than I'm ready to take on, and there aren't a wealth of schematics, as SS is still in biz. If there's some other simple design that would work, I'm happy to change gears.

I have plenty of good quality switches, pots, etc.

A few other questions..
Can I do this on a breadboard, or something similar? Designing PCB's is way out of my league.
I'm thinking of using a JLM "Go Between" and one of their power supplies, unless I can find something cheaper. Sound right?
I don't see any outputs in the schematic. Anyone know where they are?

Many thanks!


There is lots of easy to find info about your transformers, looks like they are suitable as a low ratio solid state mic inputs. Try to find this out first and then go on. Veroboard is super fine if you want to build simple mic preamp with IC, not sure which Eliot's design you have in mind, do you have a link? Most of them use similar voltages, so you could try one of simple IC preamps from this forum (meta thread), Jensen have some that are meant to function well with input transformer too, as does Neve and others. It is pretty easy to build a few of them (if my assumption about transformer is correct) and compare. Before adding front end pad you will need psu, check what voltages and currents typical preamp of this type needs.
I built lots of things like this on veroboard when there were few other pcbs than Gyraf's. It goes fast and is easy to correct any mistakes, cost is maybe a few $ for one mic pre board. Good idea, just search around a bit more.