Lamington Junior – construction

Introduction  I   Design   I   Construction

A kit of all parts, and a construction manual for the Lamington Junior are now available!

The Lamington Junior prototype was constructed in a small (28cm X 19cm) baking dish allowing for plenty of room underneath for construction while making for a compact amp build. The layout for the transformers, valves and controls can be seen in this photo:


The M1112 output transformer was mounted underneath the chassis to eliminate any hum induction from the power transformer. Front panel controls are input socket, volume, tone and on/off switch with the AC input socket for the plugpack and speaker output socket mounted on the rear panel.

The Lamington Junior sounds great driving a 12″ speaker, but will happily drive a speaker from 8 ” to 12″. Ideally, the speaker should be 8 ohm impedance, but should be fine with any speaker from 4 – 16 ohms.

Parts List:

C1 47uf63v
C2 22uf25v
C3 47nf100v
C4 22uf350v
C5 1nf 100v
C6 10nf 100v
C7 10nf100v
C8 22nf400v
C9 22nf400v
C10 100nf 100v
C11 220uf16v
C12 100uf350v
D1 1N4004  diode
D2 1N4004  diode
D3 1N4004  diode
D4 1N4004  diode
MPF102  field effect transistor
1N4751  30V zener diode

R1 1M
R2 68K
R3 10K
R4 1K8
R5 100K1W
R6 100K
R7 470K
R8 100K
R9 3K3
R10 22K
R11 10K
R12 470K
R13 470K
R14 470K
R15 10K
R16 330 1W
R17 10K
R18 1K
R19 1K

V1, V2 6BL8 valve or equivalent
SPST power switch
T1 M1112
T2 12V1A AC plugpack
T3 240-12V  M2155
Tone 500KA
Volume 500KA