Helios module type numbers


This is the numbering system that was used for Helios modules.

The following is taken from the original paper documentation with some mild re-formatting applied to aid clarity.


Every module or plug-in panel has a four figure type number:

  • the first figure gives the panel size of the module
  • the second and third figures (00 to 99) define its function
  • the fourth figure identifies the particular design within the size and function, ie No. 1, No 2, etc.


0 = module 1.8” (45mm) wide, any height (fits earlier Helios equipment, e.g. PS series)

1 = not used for modules to avoid confusion with custom consoles whose numbers are e.g. 1068

2 = 40mm wide (1.6”), 190mm high (7½”)

3 = 40mm wide, 285mm high (1½ units)

4 = 40mm wide, 380mm high (2 units)

5 = 40mm wide, 475mm high (2½ units)

6 = 80mm wide

7 = modules designed for the Series 7 (standard) console range

8 = 35mm or 30mm wide

9 = any other size of plug in unit


Sizes 2 to 6 conform to the European broadcast panel sizes but the depth and connector arrangement are not identical.

A unit designed to be a direct plug-in in German broadcast equipment will be prefixed D, or for Nordic N10 system N.

Units designed to fit North American dimensions (1½” x 7” etc.) will have the prefix A instead of the first figure.


00 0 Blank front panel

00 1 Empty module with chassis

01 Input and equaliser

02 Input, equaliser and routing

03 Input and routing, no equaliser

04 Routing (auxiliary)

05 Equaliser

06 Echo send

07 Echo send and return

08 Echo return

09 Foldback (cue) send

10 General auxiliary output

11 Talkback send

12 Return Talkback/Intercom

13 Compressor Limiter

14 Expander or noise gate

15 Track Monitor (single track)

16 Tone Oscillator

17 Headphones Monitor

18 Loudspeaker Monitor Drive

19 Meter Switching module

20 Phasing Effect

21 Fuzz-Distort unit

22 Telephone effect or filters

23 Modules containing various switches

‘9’ units (odd sizes)

Function may be designated as above, but in addition there are the following categories:

93 (+01 - 99) = Central Monitor Units “CMUs”

94 01 etc = Track Monitoring (multiple panels)

95 01 etc = Channel to Group Selection arrangements