I wonder if anyone would be interested in helping out. I have bought on spec a modded Akai (Roberts badged) M8 preamp section. I understand these bits of kit are used quite often as highish end studio kit. Small problem is i am utterly electronics illiterate and can't work out how it's configured input/output wise even - it appears to be 2 separate pres and i can't even figure out how the switching works, how to engage the added xlr input (the seller wasn't really able to explain how things worked)... also wondering if it would be possible to rig it to include phantom power and balanced out (if there's any advantage to that) plus  any other upgrades that might be worthwhile. Happy to pay going rate etc or  offer a skills-swap (my  "expertise" is probably limited to  dementia care  though). UK based. thanks for reading.


rackmonkey

Welcome to the forum. These things have sadly been getting torn apart and modified at least since the early 00's when a guy posted his mods over on the old Tape Op message board. There are 2 or 3 popular mods I've seen, and they could be modified in any number of ways given the components in the stock unit. (Always seemed like a lot of nit picky work for what you end up with to me, but to each his own). Without knowing how your unit has been modified it'll be difficult to help you out, but if we assume that that the mods were based on the most popular version, you could try the following:

Looking at an old post/Schematic, it appears the the "Mic" Input is typically modified by adding a 1:10 transformer, so this would be your primary mic Input.

The Wayback Machine (archive.org) has the now dead website of the guy who originally popularized the mods with a project description (just look up beyondsanityproductions.com on archive.org and you'll find it). It says that once the project is complete, you'll have the following configuration:

The Microphone jack will be replaced with an XLR jack = (Mic Input)
The Phono Radio jack (Marked Line on some units) will be the 1⁄4” EF86 stage output.
The Preamp Output jack will be the input of the of the 12AX7 preamp
The Head Output (Phono Playback on some units) jack will be the output of the of the 12AX7 preamp The Volume knob will be the level for the EF86 preamp
The Tone Knob will be the level for the 12AX7 preamp
The Tape speed switch will not be functional (removed when the tone control is changed)
SW1 will be eliminated, cleaning the chassis up a lot.

So you could try this. If this doesn't work, it's anyone's guess what was done to yours.

Good luck,

BT
Whether you think you can or you think you can't, you're probably right.

Thanks Rackmonkey.

I appreciate the welcome. I will take a look at the unit tomorrow and report back!