Portable Recorder Noise:
The Sounds of Silence

Introduction

You may have wondered why our new speech samples have gaps of silence in them. We made them that way intentionally, in response to several customer requests for quieter -- even silent -- sound samples in order to assess the relative noise floor of each recorder.

By "noise floor," I mean the background noise generated by the unit itself when it makes a recording.

As you might have guessed, quieter is better when it comes to portable recorder noise.

Portable Recorder Noise

Compared to what was available 3-5 years ago, today's portable audio recorders are very quiet. Not perfectly pristine, mind you, but very quiet. Even the most economical recorder we sell, the Zoom H2, sounds noticeably better than a mini disc recorder and much better than any cassette deck.

For casual live recording and CD burning, portable recorder noise may not be a big concern, especially if you record relatively loud sounds or have a knack for setting your levels well (as high as possible without clipping or distortion).

On the other hand, if you record relatively quiet (acoustic or ambient) sounds, portable recorder noise can be your nemesis, especially if you want to layer or otherwise process your sound files after recording.

Tips for Minimizing Noise

1. If you can hear the difference, buy the best unit you can afford. A higher price usually means better build quality and electronics, which in turn usually means less portable recorder noise.


2. Try using an external mic. A good external mic may be less noisy than the internal mics in your handheld recorder.

   The problem you may run into, however, is that most external MIC IN ports on handheld audio recorders are unbalanced, 1/8" stereo jacks that only supply low-voltage plug-in power. (Exceptions to date: M-Audio MicroTrack II and Zoom H4). They tend to have relatively weak pre-amps too, which in turn can add noise to your system.

3. Try using an external mic + an external preamp. To avoid the relatively weak preamp in the external MIC port of the handheld recorder, try connecting your external mic into an external preamp, and then feeding that signal into the LINE IN port of your recorder. (The MIC IN port on your recorder has a small amplifier in it to boost the mic signal. The LINE IN port doesn't have an amplifier, so you need to bring the signal to line level before you plug anything into the LINE IN port).

   Although this may be an effective way to get "cleaner" performance from your recorder, adding more gear to your setup tends to defeat the purpose of having a convenient, handheld recorder.

An Easier Way to Minimize Noise

However, if from time to time you need something better, we suggest a simpler albeit more expensive solution: use 2 recording setups.

For your critical recording situations, use your 2 best condenser microphones and plug them into a field recorder that has balanced MIC IN ports like the Korg MR-1000, Marantz PMD671 or Tascam HD-P2.

For more casual circumstances, or those times when you just don't want to haul around a lot of gear, use your trusty handheld recorder on its own. You'll still get perfectly good if not excellent results. No sense in trying to make a handheld recorder do what it really wasn't meant to do.

Noise Floor Samples (UPDATED)

We updated this article by making 3 samples each of a few of our recorders. The 1st is with built-in mics only; the 2nd is with an external Audio Technica AT822 mic; and the 3rd is with the AT822 going through the FEL 3.5SX3 mic preamp - a nifty little device that looks like an ordinary mic cable but uses your recorder's plug-in power to boost your external mic's signal.

Can you hear any difference?

Definitions

What do you mean by "unbalanced"?

By "unbalanced," I mean "not grounded." A balanced connection uses 3 wires. Two separate signal wires inside a shield carry + and - signals (opposite polarity). The shield is connected to ground. It encases the signal wires and protects them from outside interference.

A balanced connection is less susceptible to noise from things like electric motors, computer hash and radio frequencies because those interferences hit the shield and are directed to ground.

An unbalanced connection uses 2 wires. One of the signal wires is the shield, the other is the + signal. Any noise picked up on the shield is fed directly into the mic amplifier.

What's plug-in power?

Plug-in-power is a small voltage (3-5V) required by certain consumer-level electret microphones (like the Edirol CS-15 or one of the small Sony Stereo mics -- they can be pretty good) and delivered by many portable audio recorders.

It's similar to phantom power, but not interchangeable with it. You can't power a standard, pro-level condenser mic with plug-in-power, nor can you run a plug-in-power mic from standard phantom power.

What's phantom power?

Phantom power is a dc voltage that is fed back through a microphone cable from a mic preamplifier or mixer to a condenser microphone in order to run its internal electronics. The term "phantom power" was coined because no additional wires or connections are used to distribute the dc power.

Most condenser mics have 3-pin balanced (XLR or 1/4" TRS) connectors and require 48V phantom power.

Most mixers or mic preamps have a built-in, 48-volt phantom power supply that can be sent to the condenser mic through the mic cable.

What's a mic pre-amp?

A mic preamp is a device that supplies preamplification to a microphone. Preamplification is not the same as phantom power. All microphones require preamplification to raise signal levels by approximately 60dB, but only condenser microphones require phantom power in addition to preamplification.

"Good" mic pre-amps are those that deliver sufficient microphone preamplification without adding a lot of noise to the mic signal. In our experience, most handheld recorders have decent preamps for their internal mics, but relatively weak preamps for their external mic jacks.