DIY - Look McIntosh for Preamplifier

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Look McIntosh for Preamplifier

The outline of this DIY.

Creating of a passive preamplifier on the basis of the previous
attenuator but with an addition of two vu-meters and a McIntosh look.
This a esthetic favours the production of a silkscreen on front
side with a professional side. Admire this look, it's DIY! No breath,
no noise disturbs listening to the QUAD 405. Plan a neat wiring of
the masses. The potentiometer is in the middle of the cabinet
to avoid disturbances of the power supply.

1

Addition and Creating a 12 volt regulated power supply with a LM338K.
This 12 volt power supply supplies all relays, backlight and vu-meter
lighting and circuitry. Wiring the preamplifier with a switch to be
able to select the mode with or without attenuator.

2

Making a loudspeaker connection between the preamplifier and the
QUAD 405 power amplifier. Cable Connection and Brand cards:
NEUTRIK NL4MP. This cable is necessary for the operation of
the vu-meters and the delay of the loudspeakers.

3

Creating a 12 volt backlight as well as a timer for the speakers. (aliexpress.com)

passive preamplifier for Quad 405

amplifier Quad 405

Plug Speakon NEUTRIK Female NL-4FX

Speakon chassis socket NEUTRIK Male

Speakon plugs for professional HP connections. 4 poles.

The special ELEPHANT SPM4025 combi cable is one of the outstanding
models designed specifically for the woofer and surround systems.
The SPM4025 consists of a total of 4 conductors with a section of
2.5 mm. Due to its wiring mode similar to that of hi-fi drivers,
the SPM4025 reproduces absolutely pure highs and faithful and
dynamic bass.

ADVANTAGES:

Transmission of signals without losses, thanks to special
constitution souls Very flexible, suitable for stage installations
(PVC version only), easy to roll up Compatible with current
Neutrik-Speakon connectors Easy transformation thanks to the
excellent insulation and the numbering of the souls

USE:

Professional acoustic equipment / output amplifier Surround
and woofer systems Fixed installations for buildings.

passive preamplifier for Quad 405

Creating a 12 volts regulated power supply with a LM338K.

PCB Transformer 12 volts Gerth PT481201F.

Circuit of the attenuator for QUAD 405

Passive attenuator schematic for QUAD 405. (click)

Timers for the speakers in 12 volts. (aliexpress.com)

passive preamplifier for Quad 405

Speaker break with 12 volts relay. (aliexpress.com)

VU-meters Circuit in 12 volts