Banana Plug: A Standardised 4 mm Pin
Quick answer / TL;DR: Short answer: choose 4 mm plugs for standard binding posts, locking types where cables hang vertically, and dual plugs only where the terminals are 19 mm apart. Match the plug body to the wire gauge: most accept 12 to 18 AWG. Gold plating is corrosion resistance, not a sound quality upgrade.
Four gauges, four distances: the conductor size follows the run.A banana plug is a 4 mm sprung pin that fits binding posts and speaker terminals. The variants differ in how the wire attaches and whether the plug locks.
The 19 mm spacing of dual plugs is the other dimension worth knowing.
Variants
| Type | Feature | Use |
|---|
| Solder | Crimped and soldered | Permanent |
| Screw | Grub screw clamp | Field repair |
| Locking | Expanding spline | Vertical hangs |
| Dual | Two plugs, 19 mm | Older terminals |
The locking type prevents the slow creep that happens when a heavy cable pulls on a sprung pin.
Fitting Practice
- Strip to insertion depth
- Twist strands in one direction
- Tighten then re-tighten
- Check adjacent terminal clearance
- Label polarity
Clearance matters on close-spaced terminals: a wide plug body can bridge to the neighbouring post.
Real-World Applications
A hi-fi amplifier with 19 mm spaced posts accepts dual plugs. A modern AV receiver with close-spaced terminals needs slim single plugs.
Standards and Verification
| Reference | Relevance |
|---|
| IEC 61010-031 | 4 mm shrouded probes |
| IEC 60268-5 | Loudspeakers |
| RoHS | Plating materials |
Terminal spacing for a specific amplifier is not provided in the knowledge base. Measure it.
References
- IEC 61010-031, Safety requirements for test probes
- IEC 60268-5, Loudspeakers
- RoHS Directive 2011/65/EU
Practical Notes
Measure terminal spacing before ordering dual plugs. The 19 mm convention is common, not universal.
Related reading: banana plug — blogs/news/banana-plug
Related reading: solderless banana plug — blogs/news/solderless-banana-plug
Related reading: banana plug to rca — blogs/news/banana-plug-to-rca
Frequently Asked Questions
What size is a banana plug?
4 mm pin.
Do locking plugs matter?
For vertical cable weight, yes.
Does gold improve sound?
No. It resists corrosion.
What is the dual spacing?
19 mm on older equipment.
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