The ECC83 high impedance amplifier triode was designed specifically for audio use and has a high amplification factor of 100. Mullard describe the ECC83 as a high μ double triode, having separate cathodes, primarily intended for use as a resistance-coupled amplifier or phase inverter.
This Mullard valve has white lettering together with the older Mullard logo and the BVA logo it was made in Great Britain.
The holes in the end of the stitched anode reveal the control grid within.
The anode face view showing the copper grid supports.
The thin glass tube envelope is 20 mm in diameter and, excluding the B9A base pins, is 48 mm tall.
References: Data-sheet, 3002 & 1040. Type ECC83 was first introduced in 1954.