INSIGNIA HiFi
USER MANUAL
CUSTOM 50 Tube Amplifier
INTRODUCTION
This amp head is made by taking inspiration from vintage hand-crafted amplifiers made
by Dave Reeves. A look inside the amplifier will immediately bring your attention to
the hand-wired assembly & point-to-point wiring philosophy used. Needless to say this
gives unmatched robustness to the amplifier. The Power transformer used in the
amplifier is unconventional to the Guitar amps, as it is a Toroidal transformer custom
made by one of the best transformer manufacturers in India. These transformers are
common in HiFi as they are inherently noiseless & there is no leakage field outside. The
components are carefully chosen and hand selected with 2-3 time overrating to further
enhance the robustness. The chassis is made out of Aluminium sheet to ensure rust-free
life and excellent shield to noise due to external electromagnetic interference. The entire
amplifier is made with ultimate care and by a single person and we trust it will give you
ultimate sonic pleasure and glitch-less operation for many decades.
You are requested to go through this document well to ensure you adhere to safety
instructions and maintenance of the amplifier.
BEFORE OPERATING THIS EQUIPMENT
SAFETY IS MOST IMPORTANT ASPECT AND IN NO CIRCUMSTANCES IT SHOULD BE
OVERLOOKED. THIS IS A VALVE AMPLIFIER AND BY DESIGN IT CONTAINS VERY
HIGH VOLTAGES EVEN AFTER IT IS UNPLUGGED. IN NO CIRCUMSTANCES IT
SHOULD BE OPERATED BY THE USER WITH THE BASEPLATE REMOVED. THE
TRANSFORMERS AND VALVES SHOULD NOT BE TOUCHED WHILE THE AMPLIFIER IS
POWERED.
1. This amplifier is designed to operate at 220-230V, 50Hz ac, ensure the voltage
levels and frequency before turning it on.
2. Ensure that the power supply has proper ground. You can test the supply outlet
with fault tester to ensure the same.
3. Make sure you connect the speaker system of correct impedance (4 or 8ohms) in
the designated outputs.
4. There are 2 fuse sockets installed, one for Mains & one for HT. Boith are rated
at 1 A Slow Blow type, make sure you do not used fast blow type fuse.
5. Before turning on the amplifier make sure the standby switch is OFF. Turn it on
only after the tubes warm up, typically 30 secs at least.
DOs and DON’Ts
DO
Always keep the standby in OFF position while powering on
Always keep the standby in OFF position while amplifier is not in use for a
short time and you want to resume playing shortly and you intend to keep the
valves warm.
Always check the input voltages
Always check the correct speaker impedance
Always keep a track & monitor the health of output valves (EL34s).
o If the tubes show red-plating or they have become too old (2 years) or
they have turned microphonic then replace with matched pair of EL34s
Time-to-time (Typically weekly) monitor the bias voltage at the back (Red
terminals), they should be less than 35-40mV.
Do have the amplifier serviced quarterly by a qualified technician
DON’TS
Never attempt to modify or repair the amplifier in any manner
Never allow a third person to change anything on the back panel
Never touch the valves/transformers or open the baseplate while the amplifier
is in ON state or valves are hot
o In case you need to inspect the amplifier keep the power cable plugged,
power switch OFF & Standby switch ON
DO NOT attempt to clean the amplifier while it is ON
TECHNICAL SPECIFICATIONS
Design: PUSH-PULL
Power Tubes: El34
Preamp Tubes: 3 x ECC83 (12AX7)
Phase-Splitter Tube: ECC81 (12AT7)
Controls:
o Normal Volume
o Brilliant Volume
o Bass
o Treble
o Mid
o Presence
o Master Volume
o Mains Toggle Switch
o Standby Toggle Switch (HT)
o Bias Adjustment Trimpot
Fuse Rating
o Mains: 1A Slow Blow
o Standby: 1A Slow Blow
Output Impedance
o Default: 8 OHMS
o Optional: Selector switch with 4/6/8/16 OHMS
Input Power: 160VA
Output Power: 50W (max @ 50 mA Cathode Current)
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