Headshell connector types
Headshell connectors are a key part of matching tonearms and cartridges. There are several main connector types used in tonearm–headshell systems, depending on the arm design, vintage, and manufacturer. Here’s a breakdown:
SME / Universal Bayonet (H-4 or EIAJ Type)
Most common type worldwide
Used by: Technics, Jelco, Ortofon, Audio-Technica, Pioneer, etc.
Connection: 4-pin bayonet plug with collar that twists to lock.
Pin layout: Standard 4-pin arrangement (L+, L–, R+, R–).
Standard distance: 12.7 mm (½ inch) between mounting screws.
Advantages: Quick-swap headshells; universal compatibility.
Example: Ortofon LH-2000, Technics SH-4.
✅ This is what people usually mean by “standard headshell.”
EMT Connector (Broadcast Type)
Overview
The EMT connector is a professional, broadcast-grade tonearm–headshell interface developed by EMT (Elektro-Mess-Technik) in Germany for their studio turntables and tonearms (e.g. EMT 929, 997, 950, 948, 930st).
It is a large round coaxial connector system with a locking pin from below, designed for precision alignment, rigidity, and electrical reliability under studio use.
Physical Design
Shape: Large cylindrical plug with three concentric contact pins and a ground shell.
Locking: Small retaining screw or locating pin engages from below to secure the plug.
Contacts: 3 or 4 conductors depending on version:
L+, R+, shared ground(s), or balanced configuration (some EMT systems used true balanced output).
Orientation: Plug slides directly into the tonearm socket — no bayonet rotation.
🧲 Compatibility
✅ Compatible with EMT tonearms (929, 997, 750, etc.) and EMT-mount cartridges.
⚠️ Not interchangeable with:
SME / H-4 bayonet (standard hi-fi headshells)
Ortofon “G” (SPU plug) — although visually similar, the diameter, pin count, and locking mechanism differ.
ESL (UK) arms, which use a similar plug form but with slightly different pin layout and the fixing screw from below — the ESL is EMT-inspired but not identical.
🔧 Adapters
There exist EMT→SME and SME→EMT adapters (Stanley-Engineering), but:
They often alter effective length and VTA.
Use only when necessary for modern cartridge compatibility.
Thorens TP Series
(Thorens TP11, TP13, TP16, TP60, TP62, etc.)
Thorens had several proprietary headshell connector systems, depending on arm generation:
💡 These TP shells (e.g. TP60) are Thorens-only — not compatible with SME or Ortofon.
🧠 They have an elegant internal 4-pin connection and often light magnesium shells.
➡️ Compatibility: Thorens → Thorens (specific TP version).
Lenco L75 / L70
(Lenco-made tonearms before aftermarket SME-fit upgrades)
L75/L70 stock tonearms:
🧩 Use Lenco proprietary bayonet connector, not SME.
Looks similar but slightly different collar and pin alignment — the bayonet tangs are wider.
4 pins (L+, L–, R+, R–), but contact spacing differs.
🧠 L75 headshells (and L70 earlier type) are unique — not interchangeable.
🪛 Solution: People often replace the original arm with SME-type arms (Jelco, Ortofon, etc.) or modify the arm socket to accept SME shells.
➡️ Compatibility: Only Lenco → Lenco.
➡️ Aftermarket note: Reproduction L75 headshells are available from Stanley-Engineering.
ESL Headshell Connector
🧭 Overview
The ESL tonearms use a unique proprietary connector, sometimes called “ESL-style”. It is neither SME-type nor EMT-type, though it shares some broadcast-style robustness.
Designed for high-precision alignment and mechanical stability.
Common on professional turntables and high-end audiophile arms from the 1960s–1980s.
Often seen on ESL S-1000 / S-2000 tonearms and similar UK arms.
🧩 Physical Design
Locking mechanism: A pin from below secures the headshell into the arm.
Pin layout (diamond): 4-pin signal (L+, L–, R+, R–) inside the cylinder.
Ortofon SPU “A” Connector
🧭 Overview
The Ortofon SPU “A” connector is an early Ortofon headshell interface, used on SPU cartridges before the “G” version.
Designed for precision alignment of SPU cartridges on compatible tonearms.
Mechanically similar to SME bayonet but not electrically or mechanically interchangeable.
Provides robust mechanical fit for the relatively heavy SPU cartridges.
🧩 Physical Design
Shape: Cylindrical plug with 4-pin contacts (L+, L–, R+, R–).
Mounting: Slide-in insertion into tonearm socket.
Locking: Retaining/fixing pin from the bottom — unlike SME, which uses a twist-lock bayonet.
🧠 Function & Use
Designed to carry both signal and mechanical alignment for SPU cartridges.
Works with Ortofon “A” type tonearms, including early Ortofon RF/RMG series.
Supports the heavier SPU cartridge bodies without compromising tracking geometry.
Slide-in design ensures precise overhang and VTA alignment.
🧲 Compatibility
✅ Compatible with:
Ortofon SPU “A” cartridges
Ortofon tonearms designed for “A” type plug
❌ Not compatible with:
SME H-4 bayonet
Ortofon “G” plug (later SPU)
EMT or ESL connectors
Empire & Rek-O-Kut headshell connector
(e.g. Empire 98, 980, 990, 108, 598, etc.)
Connector Type: Proprietary Empire bayonet
Usually a large brass bayonet or slide-in shell unique to Empire.
Headshells are specific to the arm model (different collar diameters and pin depths, pins are "pogo pins" or "spring-loaded pins").
Adapters don’t exist for most Empire arms — you need an original Empire shell (e.g. model 980 headshell).
These shells are collectible and quite heavy (often 12–16 g).
➡️ Compatibility: Only Empire → Empire.