A microphone to EQ your living room: from the ECM8000 to a 5-euro electret

Which microphone to buy for room measurement without breaking the bank

Do you need to spend hundreds of euros to EQ your living room with REW, or is a cheap measurement microphone plugged into the PC enough? The question runs through the whole conversation, and the short answer is no: the minimum setup is a measurement microphone and an interface with phantom power. The problem is that hardly anyone is clear on what a "calibrated microphone" actually means or how to connect an XLR to a computer.

The starting point is a Behringer ECM8000, the model that keeps coming up as the basic recommendation: omnidirectional, flat response and cheap. Its drawback is that it needs phantom power and an XLR output, so it can't be plugged straight into a PC. The solution that wins out is a USB external sound card with an XLR input. That's where the pain begins: some people remember paying nearly 300 euros for a Yamaha fifteen years ago, and a Roland Edirol UA-25EX is mentioned as one of the most used with REW. Behringer interfaces for around 35 euros also come up, which cuts the bill considerably.

What it means for a microphone to be calibrated

The initial question was whether "calibrated" means flat response. Not exactly. A calibrated microphone comes with a correction table listing its deviations from the ideal curve, to be loaded into the measurement software to compensate for those imperfections. In other words, the mic isn't perfect: it ships with a sheet of flaws to subtract. For home use, several posts agree that this calibration is very pro and unnecessary, because a mic of this type usually stays within a +/- 1 dB margin, enough to adjust a room's bass and mids.

Can a podcast microphone be used to measure the room?

No. Desk or podcast mics are designed for voice: they are directional and their curve favors certain frequency ranges. A measurement mic is omnidirectional and free of physical obstructions that alter the response. What's more, without a prior calibrated reference there's no way to calculate the real curve of a voice mic, so correcting it is impossible. The cheap alternative that does work is an electret microphone, the kind shipped with home theater receivers for their room correction systems, which plugs directly into the PC's microphone input and costs just a few euros. Less flat than an ECM8000, but good enough to start.

The first measurement attempt and the treble drop

With the electret already recording, the first real measurement comes. The software warns of a low level, and 75 dB can't be reached either by raising the mic gain or the amplifier volume. The graph shows the classic pattern: a bass peak between 50 and 120 Hz caused by the room, balanced mids between 200 and 2,000 Hz, and a treble drop from 2,000 Hz that's fairly sharp. The most repeated diagnosis is that this drop comes from the mic or the computer's input itself, not the speakers: you're measuring with the cheapest equipment possible.

EQing Spotify or YouTube: the player problem

Here comes the practical snag. An equalizer inside Foobar2000 only affects what plays in Foobar2000, and the music is played from Spotify or YouTube. Foobar allows integrating both services, and there are alternatives like Room EQ for Foobar, DRCoP or various VSTs. But direct EQ from a streaming app is limited. The recommendation is to try Room EQ first and, if it improves things, rethink the whole chain. REW, meanwhile, remains very powerful and quite a pain to use.

The last question along the way isn't acoustic but mechanical: whether it's hard to fit banana plugs onto speaker cables at home. With all this, home EQ moves forward by trial and error, and in the end the ear decides more than the curve.