1966 Mullard EL37 Matched Pair - Made in Great Britain

Mullard EL37 Matched Pair – Made in Great Britain – Rare 6L6GC Substitute

The Altitude Summary

Here’s a true gem for the tone chasers: a matched pair of vintage Mullard EL37 power "Coke Bottle" tubes, made in Great Britain and known for their rich harmonic depth, warm mids, and legendary clarity. These rare glass giants have been fully tested and both come in excellent working condition. They test strong to factory spec on a calibrated tube tester—no gas, no shorts, and balanced output across the pair. The glass is clean, the pins are solid, and the only markings are "EL37", "Made in Great Britain", and the etched code “R61 B8 H.” Perfect for audiophiles or vintage amp restoration.

These tubes carry the etched production code R61 B8 H, which dates them to the 8th week of February, produced at Mullard’s famed Mitcham Works in the UK— in 1966. That detail alone will spark joy in any collector or tone purist looking for true British pedigree.

British Power, Cult Tone

The EL37 isn’t just a tube—it’s a tone signature. Designed as a high-grade alternative to the 6L6GC, the Mullard EL37 offers a smoother response curve, tighter low-end, and a sweeter top-end breakup. Whether you’re chasing hi-fi richness or classic guitar amp warmth, this pair brings unmistakable British mojo to your rig.

Matched and Ready

This is a genuine matched pair—tested and verified for consistent performance. Expect smooth symmetry in push-pull circuits and zero guesswork during install. They're ready to drop into your next hi-fi project or classic tube amp build.

Rare Find for the Right Ears

Tubes like these don’t surface often, and when they do, they don’t stick around. These are true Mullard builds—no rebrands or relabels—just pure British engineering from one of the most revered names in tube history. A must-have for serious tone aficionados or restoration purists.

Key Features

• Matched pair of vintage Mullard EL37 tubes

• Made in Great Britain in 1966 (etched “R61 B8 H”)

• Power pentode design – 6L6GC-compatible

• Balanced output – both tubes test to factory spec

• Excellent condition with clean pins and markings

• Highly sought after by audiophiles and amp builders