Propeller Head Plaza

RE: The real issue with switch boxes

67.164.165.165

In Reply to: RE: The real issue with switch boxes posted by Dan Banquer on March 08, 2008 at 06:33:42

Are the grounds connected? The diagram does not appear to identify this clearly so I am assuming that they are.

Good point. For the speaker group, there are six connections. One would hope that the "grounds" are not connected here. If one or more of the amps were a bridged amp, bad things would happen if the "grounds" were connected together :-). Hopefully they thought of this. For the "Group I" low-level signals, I agree with (what I think is) your view that the grounds should not be connected together either. A good choice for the switching would be a "make before break" arrangement on the ground switching such that an open ground could not occur during switching. I agree that it's not at all clear what's going on in that area. It would be nice to see a schematic of the box. Also, I think the device whose input is disconnected should have its input shorted to ground. They do mention that the amp whose output is disconnected has a dummy load connected to it to avoid the case of a tube amp with an open-circuit load.

Secondly, as JJ pointed out when he was posting here is that in order to have a proper ABX test one must have the listeners trained on what to listen for. I believe Harmon Kardon did this and they may still do it.
Without the training I would expect predominantly null results.

Wasn't JJ working with lossy codecs among other things? In that case, training would be straightforward. Start the listener off with low bit-rate codecs that have obvious artifacts and gradually move to higher bit rates. For hardware, it seems like there is a catch-22. In general there is no a priori knowledge of what, if any, the differences will be. That's what the test is trying to find out :-).

Follow Ups:

RE: The real issue with switch boxes - Dan Banquer 08:30:24 03/08/08 (4)
- RE: The real issue with switch boxes - andy_c 09:53:16 03/08/08 (3)
  - RE: The real issue with switch boxes - Dan Banquer 13:19:12 03/08/08 (2)
    - Pat Tobin knows about this stuff,too - Atexanathome 11:06:43 03/09/08 (1)
      - It's a major problem in this business: - Dan Banquer 16:51:13 03/10/08 (0)

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