Samson Q9U: two "Max Sensitivity" lines, −57 dBV/Pa and −16 dBFS/Pa — which one is the microphone?
Samson's specification sheet puts two identically named rows one under the other. They are in different units, against different references, and one of them already contains a preamp and a converter. Only one belongs in a gain calculation.
Signal Chain Compatibility Matrix
Select gear and parameters for live gain, impedance and SPL calculations.
Input Equipment Setup
PASS: Optimal Signal Chain
Requires minimum +60dB of clean pre-amp gain. Most budget entry interfaces max out at +50dB to +56dB and introduce hiss at max pot. An inline preamp booster (Cloudlifter CL-1 / FetHead) is strongly recommended.
The interface preamp provides sufficient headroom.
$538
$405
-25%Tonal & acoustic characteristics: Flat, wide-range frequency response for clean music and speech. Smooth, warm acoustic character with air-suspension shock isolation.
Technical advisory: With +69dB max gain, the Gen 4 Solo can drive demanding dynamics like the Shure SM7B natively without requiring an external inline booster.
Physical Interconnect Topology
Shure SM7B
Direct Cable Connection (No Intermediate Box)
1x Shielded Balanced XLR Cable (3-Pin XLR Male to XLR Female)
Focusrite Scarlett Solo (Gen 4)
Host: Apple MacBook Pro (M1/M2/M3/M4)
Short answer: −57 dBV/Pa is the microphone. −16 dBFS/Pa is the microphone plus Samson's own preamp and converter, and it cannot be used in the same arithmetic.
Here is the specification block as Samson publishes it:
| Row | Value | |---|---| | Max Sensitivity | XLR −57 dBV/Pa (1 kHz) | | Max Sensitivity | USB −16 dBFS/Pa (0 dB gain, 1 kHz) |
Two rows, one name, no explanation. They look like a range. They are not comparable at all.
dBV is an analogue voltage referred to one volt. It describes what leaves the XLR pin, and it is the number a preamp calculation needs. dBFS is a digital level referred to the converter's clipping point. It describes what arrives in the computer after the capsule, Samson's preamp at zero gain, and Samson's 24-bit converter have all had their turn. Subtracting one from the other, averaging them, or reading "−16 is louder than −57" are all meaningless: the two scales have different zeroes and different units.
What the honest number gives you. In XLR mode the Q9U is a plain dynamic microphone at −57 dBV/Pa — tied with the Rode PodMic for the lowest output in this catalogue. At 85 dB SPL that is about −63.8 dBu on the cable; against the SSL 2 MkII's +9.7 dBu clip point and a −18 dBFS target, the chain needs 55 dB, and the SSL has 64. Comfortable, with 9 dB to spare. On an Audient iD4 mkII (58 dB) the same microphone lands exactly on the ceiling with nothing left over.
The gem. The USB row quietly tells you something the XLR row cannot: at 0 dB of Samson's gain, one pascal — a loud voice up close — lands 16 dB below digital full scale. That is a designed-in headroom figure, and it is why the USB path sounds level-managed out of the box while the XLR path needs 55 dB of somebody else's preamp. The catch is what the sheet does not say: nowhere does Samson publish how much gain that internal preamp offers. Our catalogue therefore has no gain figure for USB mode, and the calculator falls back to a generic default when you select it. If you want a number you can defend, use the XLR path — it is the only one of the two whose arithmetic is fully sourced.
Practical. The Q9U's XLR and USB sides are two separate signal paths in one body, and the specification sheet is really two specification sheets stapled together. Decide which mode you are in before you quote a number from it — and if a shop page shows you "−16 dBFS" as "the sensitivity", it is quoting the wrong row.