Well - first make sure the attenuators are OFF....sounds like they are turned ON - hence the low output - (and these mics have low output to start with!)
All of these Primo OEM mic parts are interchangeable - I dont think mixing these NAK parts is going to make a huge difference in performance...
The capsules are the same on the 100 and 300...
Yes, I do have the attenuators off. And I tried them on, just in case I had it backwards. I ran them through an MX-100 mixer -> Line in. Also tried Nak -> old cassette deck "Mic in". No dice. These aren't 10db low, they are more like 80db low. I don't have a scope handy, but if I crank all the gains up on everything, put them 1" from my mouth and yell, I get a small blip on the meter. I haven't tried to tape a live show, but it I set everything up in the living room with my stereo blasting, turn up the preamp gains all the way, you can just barely hear some sound through the noise floor.
If you look at
http://computorney.com/nak/ he has the actual schematics for the different mics in the owner's manuals. Most of the compenent's values are listed, although some are deliberately missing. The CM-100 and CM-300 have a lot of subtle circuitry differences. I have an EE degree, but that was 20+ years ago, and I most of the details are pretty fuzzy... I expect there are folks here who have this a lot fresher in mind than me. I remember sweating over "FET bias curves" and that getting the bias voltages and pull-up resistors was absolutely critical to getting an amplifier circuit with the right gain. Certainly mixing and matching these parts was not something the designers intended. I don't remember much about impedence matching, I think I killed that braincell at a dead show in '88
Yes, the capsules are interchangable, but that was a design decision, and they designed the amp circuits around that. It's common knowledge the CM300 can take a lot more BPL than the CM-100. Where does that come from? If it's not in the capsule, it must be in the amp circuit, half of which is in the attenuator, and half is in the barrel. Based on science, and this limited experience, I believe there are not interchangable. Somewhere there is an opposite set of CM-100 attenuators/CM-300 bodies with the leftover parts from my set, and that probably has gain up the wazoo. That guy is probably complaining about brickwalling...
I looked quickly at Primo. I think they just make/made capsules. The bodies and attenuators where nak design and manufacture.