Can I connect FireWire 400 (6-pin) to FireWire 400 (4-pin)?

Yes, FireWire 400 (6-pin) and FireWire 400 (4-pin) are directly compatible — you can connect them without an adapter.

Do I need an adapter for FireWire 400 (6-pin) to FireWire 400 (4-pin)?

No, FireWire 400 (6-pin) and FireWire 400 (4-pin) can be connected directly without an adapter.

Will connecting FireWire 400 (6-pin) to FireWire 400 (4-pin) cause signal loss?

No significant signal degradation is expected when connecting FireWire 400 (6-pin) to FireWire 400 (4-pin).

What is the best standard achievable with FireWire 400 (6-pin) to FireWire 400 (4-pin)?

The best standard achievable when connecting FireWire 400 (6-pin) to FireWire 400 (4-pin) is FireWire 400 (IEEE 1394a), which supports up to 0.40 Gbps.

FireWire 400 (6-pin) ↔ FireWire 400 (4-pin)

Compatibility check and signal path analysis

Compatible

These connectors can be connected directly or with a standard cable.

Signal Path

FireWire 400 (6-pin) Unknown

Cable

Max: FireWire 400 (IEEE 1394a)

FireWire 400 (4-pin) Unknown

FireWire 400 (6-pin)

Family Legacy Data

Form Factor Rectangular with notch

Pin Count 6

Reversible No

FireWire 400 (4-pin)

Family Legacy Data

Form Factor Small rectangular

Pin Count 4

Reversible No

Notes

6-pin provides bus power, 4-pin does not. Otherwise identical.