It is possible to use the dynamic link with any combination of ISA 220, ISA 430 MkI and ISA 430 MkII for stereo dynamics processing. Simply connect a TRS jack cable between the dynamic link sockets on two units and follow the Dynamic Link instructions outlined in any of the ISA User Guides.

There are a few issues to be aware of regarding sonic differences:

• The 430 MkI has transformer balanced outputs whereas the other two models have electronically balanced outs. Therefore if linking a 430 MkI and a different model and using the analogue outputs, there will be a very subtle increase in harmonic distortion on the 430 MkI output.
• The 430 MkII has three compressor modes; VCA compressor (standard), vintage opto and VCA limiter. When linking the 430 MkII with a different model ensure the compressor is in VCA compressor mode so it matches the other unit.
• The 430 MkII mic pre has a variable input impedance. If recording using stereo miking and compression then ensure that the input impedance is set to 'ISA 110' (1K4Ω) as the input impedance of the 430 MkI and 220 is fixed at this. Also ensure that the 'air' switch is not engaged.
• The 430 MkII has a compressor blend control which balances between the pre and post compressor signals. This is unique to the 430 MkII so if linking it with a different model ensure that the blend button is switched out so as to disable the blend control. The 220 has a blend button which, when engaged, mixes the pre and post compressor signal by a fixed amount. Ensure this is not engaged when linking the 220 to a different model. NOTE: the blend controls do not link and must be set to the same on both linked units, even if they are the same model.

The controls need to be set a certain way when using the dynamic link. With the compressors, on the slave unit you need to set the threshold to fully right and all other knobs fully left. Then the other unit can be used as master (the knobs will control both compressors). For linking the gates make sure the gate knobs on one unit are all fully left and then adjust the controls on the other unit to control both gates. Note that buttons are not linked and so will have to be set to the same on each unit individually.