Pass XA30.8 vs Luxman m600-a vs Hegel H20


Hi! 

I would like to know if anyone has any insights on how those may compare. Any help would be welcome :)

Thanks in advance,
Joao
128x128vermeer

Showing 3 responses by almarg

A potentially VERY IMPORTANT POINT that needs to be looked into before choosing the Pass or Hegel amps: Both of these amps have balanced outputs, meaning that their negative as well as positive output terminals have full amplitude signals on them. Therefore their negative output terminals must not be grounded. Since the Triton One has a built-in low frequency amplifier, and the only input terminals the speaker provides are a single speaker-level input and an LFE input, it is quite conceivable that the negative speaker-level input terminal is connected to the circuit ground of the speaker’s built-in amplifier, and from there to its AC safety ground either directly or via some impedance that is low at some or all frequencies. And the AC safety grounds of the speaker and the external power amplifier will of course be connected together through the AC wiring.

In that event connecting one of those amps to that speaker would cause the signals on the amp’s negative output terminals to be either directly shorted to ground, or connected via a low impedance within the speaker through the AC wiring and from there through some probably low impedance within the amp to the amp’s circuit ground. Which may either trigger a self-protective shutdown of the amp or result in damage.

The method that is commonly used for driving the speaker-level inputs of subwoofers with balanced amps, whereby the sub’s negative input terminal is connected to a chassis screw or a circuit ground terminal on the amp (the Pass amp in fact provides the latter) will not work in this case because the amp would then be unable to drive the passive section of the speaker properly.

What I would suggest is that you contact GoldenEar and ask them about driving the speaker with an amp having balanced outputs. And if they can tell you specifically how or if the negative input terminal of the speaker is isolated from the speaker’s AC safety ground, or if it is not isolated if they can tell you through what impedance those points are interconnected.

Good luck. Regards,
-- Al

Good!  So it may very well be ok to connect the speaker to a balanced amplifier.  It hadn't occurred to me that it might use a two-prong AC receptacle.  But a rear panel photo I just found via Google shows what appears to be an IEC type C18 inlet, which (as you indicated) can accept a three-prong power cord but omits the safety ground pin.

I suppose that part of their rationale for omitting the safety ground pin, in addition to perhaps double-insulating the internal AC wiring, is that in contrast to separate electronic components there is no exposed metal that might result in a shock hazard if an AC short to chassis were to develop.

Good luck.  Regards,
-- Al
 
Thanks very much for the nice words, Bob.  Glad my post stimulated a thought that proved to be helpful.

Best regards,
-- Al