Grace Design’s Felix 2 can supply a minimum of 12V phantom power, but that will work just fine for the K&K Trinity electret mic — despite a persistent myth that the mic won’t work with more than 9V.
I love your magazine and live here in Cambridge! I recently bought a Grace Design Felix 2 preamp blender to use with a dual‑source system on an acoustic guitar, and I was just now reading Bob Thomas’ review for SOS of the original version. Bob said he used a [K&K Sound] Trinity electret microphone that’s rated to shut down if it receives more than 9V phantom power, and he sent it the 12V minimum that the Felix 2 can send. It seemed to go well for the review, but I’d love to know if he had any further experience with this setup, as I’m hoping to use the same microphone.
Matthew Caws
SOS contributor Bob Thomas replies: Thank you for getting in touch and for loving SOS — and for reading my review of the Felix. It’s always great to hear from a reader that a review has proved useful. The 12V electret microphone bias voltage is the same in both the original Felix (the model that I reviewed) and your Felix 2, and my review went so well that I bought the review unit, so yes, I do have a little more experience!
Although I’ve been using K&K Sound pickups for longer than I care to remember (and own examples of all their blenders and preamps, plus a good few more from other manufacturers), until I followed up on your email I wasn’t aware that a myth existed that a supply voltage of more than 9V would shut down a Trinity mic. It appears that a myth sprung up around this Trinity mic and 9V phantom in the early 2000s, the source of which appears to be the specification of the Silver Bullet, which requires 5V from the dedicated Silver Bullet preamp. But although that looks like the Trinity, it isn’t the same microphone.
The Trinity 9V maximum myth seems to have taken hold quite widely...
Still, the Trinity 9V maximum myth seems to have taken hold quite widely and, at least from what I can find online now, K&K don’t appear to have done anything to dispel it other than a solitary post on the company’s Facebook page in April 2017 that reads as follows:
“K&K friend Tomas sent me a question today that I think will interest more musicians, asking about using our Trinity mic with a different brand preamp. Here are the facts: the Trinity mic is designed to work at its very best with our Trinity preamp or the K&K Quantum Blender. They provide a 5‑9 V low‑voltage power to the microphone, which is the optimum range for it. The Trinity mic itself has a built‑in limiting circuit that only allows it to function with up to 12V maximum power. It shuts off if more than 12V are going to the mic, to avoid blowing it up and destroying it. Some preamps made by other companies supply more than 12V and then the mic will not work at all, even though it’s fully functional, just not at this voltage.”
As far as I can see, there hasn’t been any more from K&K on the subject. Yet, there’s so much out there on the web around the myth from earlier times (for example, an Acoustic Guitar Forum thread from April 2005 that carries the myth came up on the first page of my Google searches on the subject), so I’m not surprised that you’ve come across it.
Anyway, the bottom line is that you won’t have to worry about feeding your Trinity mic with 12V. It should work perfectly! Also, please don’t forget to set the input impedance on the piezo channel to medium impedance (1MΩ), which is what K&K pickups require. Using the phase control on the Felix 2 will also help you optimise your sound by allowing you to get your piezo pickups (which respond immediately to bridgeplate vibrations) and the microphone (which responds a fraction of a millisecond later as sound has to travel through air to get to it) perfectly in phase; I had to buy an external phase controller in order to do that with the original Felix.