Since people seem to get confused over the different Grado cords/cables, I'll repost my observations...
Grado HP-1000 Signature Series
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Grado HP-1000 Signature Series Drivers
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Trasducer type: dynamic
Operating Principle: Open Air
Frequency Response: 18-24 kHz
Nominal impedance: 40 ohms
Drivers matched: 0.05 dB (HP-3 drivers are described as "not matched as closely")
Notes: The UHPLC used in the voice-coils of the HP-1000 drivers was also used in the connecting cables. I've read that the factory-equipped Ultra-Wide Bandwidth Grados also used this cord in the voice-coils. This seem to indicate that there may have been as much as three types of drivers (one for every type of signal cord). Some people have stated that there are drivers with inscriptions on the back (i.e. "Joseph Grado Signature Products") and some without any inscriptions. The Grado SR-200 headphones use the same drivers as the HP-1000 Signature Series.
Grado HP-1000 Signature Series Aluminium Earcups
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1st Series: matte surface machined aluminium alloy, flat metal mesh
notes: The earcups don't appear as reflective as the later series
2nd Series: shiny surface machined aluminium alloy, flat metal mesh
notes: Lettering seems to shine a little bit brighter than the earlier series. The surface on which the lettering is placed seems a tiny bit more narrow than the previous matte series.
3rd Series: shiny surface machined aluminium alloy, domed metal mesh
notes: Domed metal mesh appears matte, otherwise similar to 2nd series.
Grado HP-1000 Signature Series Signal Cord
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1st generation: UNSIGNED
reviewed as: dark, bass firm, treble roll-off (reviewed in The Absolute Sound)
2nd generation: Joesph Grado Signature Ultra-Wide Bandwidth Reference Cable ->
reviewed as: light, bass subdued, treble extended (reviewed in comparison with the "unsigned" cable, The Absolute Sound)
notes: developed by Joe Grado as a response to the alleged treble roll-off of the unsigned cable and offered as an upgrade.
3rd generation: Grado Signature Laboratory Standard Audio Cable
reviewed as: Sufficient bass and extended highs in comparison with the earlier cables
notes: developed by Joe Grado through the accumulated experiences/responses of the two earlier cables to perform as neutral as possible.