AF Out Meaning: A Plain Explanation
AF out means "audio frequency out" — an output that carries an audio-frequency signal (roughly 20 Hz to 20 kHz, the range humans hear). In practice, an AF out is a line-level audio output on a mixer, amplifier, processor or KTV machine that sends sound to another device: a power amplifier, a recorder, a zone speaker system or a streaming encoder.
You will see the label most often on:
- Karaoke and KTV processors and players
- PA and zone mixers
- Commercial amplifiers with multiple inputs and outputs
- Some AV switchers and conference systems
The term is common in Asian-manufactured pro audio gear (where "AF" distinguishes audio from "VF" video frequency), and it appears on many export models sold worldwide. It is not a standard connector type or a standard signal level — it is a function label. So the important question is always: what signal comes out of this particular AF out, and at what level?
What Actually Comes Out of an AF Out
An AF out is almost always line level, unbalanced or balanced, carrying a full mix or a selected source. Typical characteristics:
- Level: consumer −10 dBV or pro +4 dBu line level; rarely mic or speaker level
- Connector: RCA, 1/4" TRS, XLR or 3.5 mm depending on the device
- Content: the main mix, a selected input, or a dedicated zone feed
- Control: often affected by the master volume knob; sometimes fixed
Before you connect anything, check the manual or the panel for two things: the level (line vs. speaker) and whether the output follows the master volume. Connecting a line-level AF out into a power amplifier input is normal. Connecting it into a speaker-level input, or the reverse, is not.
AF Out vs. Aux Out, Line Out and Record Out
These labels overlap, and that causes most of the confusion.
| Label | Typical purpose | Level | Independent of master? |
|---|---|---|---|
| AF out | General audio output to another device | Line | Often follows master |
| Aux out / send | Sending a mix to monitors, effects or a zone | Line | Usually independent |
| Line out | Fixed or variable line-level feed | Line | Varies |
| Record out | Feeding a recorder or stream | Line | Usually fixed |
| Speaker out | Driving passive speakers | Speaker | Follows master |
A simple rule: *aux sends are for choosing what goes where; AF out is usually for sending the finished audio somewhere.* If your device has both, use aux for monitor mixes and zones, and AF out for the main feed to the amp or recorder.
Practical Wiring Scenarios
KTV room to power amplifier
A KTV processor's AF out feeds the amplifier's line input. Keep cable runs short, use shielded cable, and set the amplifier gain so the system reaches full output with the processor around 70–80% of its master. This leaves headroom for loud vocal peaks.
Feeding a second zone
If the AF out is fixed and you need separate volume in a bar area or lobby, insert a zone volume controller or a small mixer rather than splitting the signal blindly. Splitting a line output across too many inputs can drop level and introduce hum.
Recording or streaming
A fixed record or AF out into an interface or encoder is the cleanest path. If the AF out follows the master volume, your recording level will change every time the room volume changes — check this first.
Bridging to powered speakers
Many modern installs skip the amplifier and send AF out directly to powered (active) speakers. That works, but confirm the AF out is line level and not a speaker-level tap.
When you are building or upgrading a venue, matching output types to the right amplifier and speaker set matters more than any single label. Acoustrade supplies tested used power amplifiers, mixers and speakers for KTV rooms, bars and multi-zone venues, and each unit is checked before shipping so the input and output labels on the panel actually match what the box does.
Common Mistakes and How to Avoid Them
- Assuming AF out is fixed. Test with the master at zero and at full; if the level changes, it is variable.
- Plugging a speaker output into an AF out. Speaker level will damage line inputs. Read the panel, not the cable.
- Ignoring impedance and cable length. Long unbalanced RCA runs pick up hum; use balanced cable or a DI/line driver for runs over about 10 metres.
- Chaining too many devices. Every extra stage adds noise. Feed the amplifier directly where possible.
- Forgetting ground loops. If you hear hum, try a ground-loop isolator on the AF out path before replacing gear.
FAQ
Is AF out the same as line out?
In most cases yes — an AF out is a line-level audio output. The difference is that "AF out" is a function label used by some manufacturers, while "line out" describes the signal level. Always confirm the level in the manual.
Can I connect AF out directly to speakers?
Only to powered (active) speakers with a line input. Passive speakers need an amplifier between the AF out and the speaker.
Why does my AF out volume change with the master knob?
Because that output is wired post-master. For a fixed feed to a recorder or second zone, look for a record out, a fixed line out, or a pre-master aux send instead.
Does AF out carry video too?
No. AF means audio frequency only. On combined AV gear, video usually has a separate VF or video out.
What if my mixer has no AF out label at all?
Use the main line out or a post-fader aux send. Functionally it does the same job; only the naming differs between manufacturers and regions.
