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Helios Professional Audio Limited

Pro-audio equipment in the Helios tradition

Type 69 Passive Equaliser

The original Type 69 was produced in a number of different versions — the early ones being developed while Dick was at Olympic Studios and the later versions for Island and others. The principal differences related to the transformer type and whether germanium or silicon transistors were used. Since Helios was a custom console manufacturer, these differences were quite normal.

2018 issue

Type 69 Passive Equaliser
Prototype Type 69 Equaliser

This version features:

The Lustraphone clone

The materials from an original Lustraphone transformer were analysed at the UK's National Physical Laboratory so that this clone would be as accurate as possible.

Changes from the original

The original bass switch was doing two separate jobs: above the 0 you could boost at a selected frequency and below the 0 it cut at 70Hz in decibel steps of 3, 6, 9, 12 and 15dB. The 70Hz cut has been removed and is now on a switch with just -6dB and - 15dB cut. By separating these functions, they can be used independently.

Comparison to Tony Arnold's version

For those who know Tony Arnold's version of the Type 69, here are some of the differences: