DIY - Look McIntosh for Passive Preamplifier on vintageshifi.com

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)

Plug Speakon NEUTRIK Female NL-4FX

amplifier Quad 405

Speakon chassis socket NEUTRIK Male

Speakon plugs for professional HP connections. 4 poles.

amplifier Quad 405

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.

Creating a 12 volts regulated power supply with a LM338K.

passive preamplifier for Quad 405

PCB Transformer 12 volts Gerth PT481201F.

passive preamplifier for Quad 405

Circuit of the attenuator for QUAD 405

passive preamplifier for Quad 405

Passive attenuator schematic for QUAD 405. (click)

passive preamplifier for Quad 405

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

passive preamplifier for Quad 405

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

passive preamplifier for Quad 405

VU-meters Circuit in 12 volts

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