Guides / Parts / Design for Manufacture

Panel Cutouts for XLR, RCA, IEC and Jack Connectors

September 23, 2026

Connector cutouts are where a beautiful panel meets a part somebody else designed. They are also the most common source of the sentence “the panels arrived and the connectors do not fit”, which is almost always a panel thickness problem rather than a hole size problem.

How to use this table

These are the figures used to lay out a panel. They are typical for the common families and they are not a substitute for the drawing of the part you are actually buying. Cutout diameters are reasonably standard across manufacturers. Mounting screw positions are not.

Connector	Typical panel cutout	Notes
XLR, D-series chassis (3 pin)	24 mm round	The industry standard D-hole. Two M3 fixings. Panel thickness typically 1 to 3 mm
XLR, A-series (older)	24 mm round	Larger flange, different screw pattern from D-series
IEC C14 inlet, snap-in	27.4 x 19.8 mm rectangular	Fits a thin panel only, commonly 1 to 2 mm maximum
IEC C14 inlet, screw mount	27 x 20 mm rectangular plus two fixing holes	More tolerant of panel thickness than snap-in
RCA / phono, panel jack	8 mm or 10 mm round	Varies by make. Insulated types need the larger hole
RCA, PCB mount behind panel	9 to 11 mm clearance	Panel hole is clearance only, the PCB carries position
6.35 mm (1/4 in) jack socket	9.5 to 10 mm round	Threaded bushing, nut on the front face unless specified otherwise
3.5 mm jack socket	6 mm round	Small threaded bushing
Binding post, single	8 mm round	10 mm on some heavy duty types. Needs an anti-rotation feature
Speakon style, 4 pole chassis	24 mm round, D pattern	Shares the D-series hole and fixings
Toggle switch, miniature	6.35 mm round	Plus an anti-rotation notch on many types
Rotary potentiometer, 9 mm	7 mm round	Plus anti-rotation tab hole if the pot has one
Rotary potentiometer, 16 mm	9.5 mm round	Bushing thread commonly M9 or 3/8 in
LED, 3 mm	3.2 mm round	Or a bezel with its own larger cutout
LED, 5 mm	5.2 mm round	Or a bezel

Two figures on this page that are worth stating plainly because they cause the most trouble: the XLR D-series 24 mm round cutout, and the IEC C14 snap-in 27.4 by 19.8 mm rectangle. Everything else varies more than people expect.

Panel thickness is the real constraint

A snap-in connector has a fixed latch travel. A threaded bushing has a fixed thread length. Both assume a panel in the 1 to 3 mm range, because that is what mass market equipment uses.

Hi-fi does not use that. A 10 mm billet front panel is the whole point of the product, and no snap-in part will ever fit it.

The three ways out:

1. Counterbore from the back. Machine a pocket so the local thickness at the connector drops to 1.5 or 2 mm, leaving the cosmetic face untouched. Costs a machining operation and is invisible.
2. Sub-panel. Put the connectors on a 2 mm plate behind the faceplate, and give the faceplate a clean clearance hole. This is what most well made gear does.
3. Choose connectors rated for thick panels. They exist, they cost more, and the range is narrower.

Say which one you are doing on the drawing, because a shop given a 10 mm panel and a 24 mm hole will simply machine the hole.

Positioning, which matters more than the hole

The hole size is forgiving. Position is not, because connectors are seen in a row and the eye reads the row before it reads any single hole.

• Dimension every cutout from one datum, usually the panel centreline in both axes. Chaining from hole to hole accumulates error, and the last connector in a row of eight will visibly sit off.
• Give the row a spacing tolerance, not just individual positions. Even spacing is what the eye checks.
• Check the connector body envelope, not just the hole. XLR flanges are wider than the hole and two adjacent XLRs can collide even when their holes do not.
• Check the mating plug envelope too. A row of RCA plugs with moulded strain reliefs needs more pitch than the sockets do. This is a common fault on dense back panels.
• Leave clearance for the fixing screws and the assembler’s fingers.

Cosmetic considerations

On a rear panel, nobody cares. On a front panel, the cutout edge is a cosmetic feature.

• Deburr both sides and break the edge. A raw machined edge inside a 9.5 mm hole is visible and catches on a plug.
• Decide whether the hole is chamfered or square, and whether the chamfer is brushed with the face or left bright.
• Anodize goes into the hole. If the connector needs to bond electrically to the panel, mask it or use a star washer, or the finish insulates it.
• A front panel jack with a visible nut is a design choice. So is a counterbored nut hidden behind a bezel. Pick one on the drawing.

Before you release the panel

• Every cutout checked against the drawing of the exact part number, not a family
• Panel thickness checked against each connector’s stated maximum
• Counterbores or sub-panel decided and drawn
• Body and mating plug envelopes checked for collisions, not just hole centres
• All cutouts dimensioned from one datum
• Row spacing toleranced
• Edge breaks specified on both sides
• Masking specified anywhere a connector must bond to the chassis

Frequently asked questions

Keep reading

• How a CNC Volume Knob Is Made and What Drives Its Price
• What a Turntable Platter Needs From the Shop That Machines It
• Machining Headphone Cups and Yokes That Match Left to Right

This guide is part of Knobs, Platters, Cups and Feet, one of four sections in the guide library.