Inline Microphone Preamps

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A while ago I ran into a situation where the audio interface that I was using did not have enough preamplifier gain to get a decent signal from a microphone I had. Instead of switching out the audio interface, I decided to have a shop around for some pre-preamps that would boost the microphone’s signal before it hits my audio interface’s own preamps. These inline preamps are phantom powered at the sink end, where some active circuitry amplifies the mic-level signals coming from a microphone. The unit can therefore be placed anywhere in the signal chain between the mic and the sink preamplifier - whether it be directly to the microphone, or lying on the floor connected to cables on both ends. Here is a hands-on look at the Klark Teknik Mic Booster CT1, and the Triton Audio FetHead Phantom.


Klark Teknik Mic Booster CT1

Product Page: www.klarkteknik.com
Gain: +25 dB
Price: AU$65

The CT1 is an inline mic preamp for dynamic/ribbon/tube microphones. Compared to the Cloudlifter CL-1 (+20-25 dB, AU$270), or sE Electronics DM1 Dynamite (+28 dB, AU$189); the Klark Teknik CT1 comes at a bargain price of only AU$65, providing +25 dB of gain.

Construction wise, the CT1 comes in a weighted metal shell - totalling the weight of the product to be around 100g (0.22 lbs). Perhaps the weight contributes to helping shield the internal circuitry from EMF, but you can definitely feel its weighty-ness; especially when attached to a handheld microphone. Speaking of circuitry, there isn’t really much going on - not really too sure what exactly makes this product AU$65… That said, it performs as expected, and gives a pretty clean +25 dB of gain. Unfortunately it doesn’t pass on the phantom power…


Triton Audio FetHead Phantom

Product Page: www.tritonaudio.com
Gain: +18 dB
Price: AU$125

This FetHead Phantom unit is somewhat special, as it it is the only inline preamp I found that has phantom power pass-through - which allows the product to be used on condenser microphones which would otherwise not work with the other inline preamps. The target market would be quite niche (since condenser microphoners are phantom powered, they offer better signal to noise ratio, and often have a higher output - so it’s unlikely that you will need even more preamplification gain) - but somehow I was convinced to spend AU$125 on it. I guess my el’ cheapo gooseneck condenser can be redeemed now? You can still connect it to other types of microphones, though I would be careful if connecting it to a more delicate microphone (though generally not a problem for modern microphones)

At around 50g (0.12 lbs), this unit is smaller and lighter when compared to the CT1. Blah blah blah looks kinda nice. Anyway! This time we’ve got some relatively large ceramic capacitors on the circuit board, which appears to have less components on it (I guess since we don’t need additional components to filter out the phantom power). That said, I wonder what exactly makes this $125…


How do they fare?

I did some tests by running some pink and white noise through the preamplifiers, into my Steinberg UR44 audio interface (gain knob at the 9 o’clock position).

Noise Floor (no audio)

Well, they bring up the noise floor - obviously.. 🤷‍♂️

Pink Noise

Top left - Floor Noise
Top right - Klark Teknik Mic Booster CT1
Bottom right - Triton Audio FetHead Phantom
Bottom left - Reference

White Noise

Top left - Floor Noise
Top right - Klark Teknik Mic Booster CT1
Bottom right - Triton Audio FetHead Phantom
Bottom left - Reference

Observations

The Klark Teknik Mic Booster CT1 looks pretty transparent in terms of gain boosting - I saw no real noticeable change in response.

The FetHead seemed to shelf the sub-bass frequencies by around -4 dB, consistent in both the pink noise and white noise tests - would make sense since the unit uses ceramic capacitors. However, if connected to a microphone I’d probably be applying a HPF and discarding those frequencies anyway; so it’s not really an issue at all. It also seemed to have a very subtle high shelf in the pink noise test, though I would believe that to be just experimental sampling issues.


Conclusions

The Klark Teknik Mic Booster CT1 is an absolute bargain - performing perfectly well in providing +25 dB of gain to a microphone source, at a quarter of the price of a Cloudlifter!

The Triton Audio FetHead Phantom is a niche tool to provide preamplification to condenser microphones. At the moment I don’t have any immediate need for it, but will be grateful to own one when the time comes!

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