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 08:30:24

Hi Dan,
Let me take your second point first.
"As I have posted in some amount of detail, there is no standard for grounding in unbalanced consumer audio, the grounds connected in the ABX box would potentially deny proper grounding of equipment, and the differences in noise between two systems.
I have read and actually studied your posts on this subject, though it was a while back. Unless I've misunderstood, you're using a "whole system" grounding approach in which the signal ground and safety ground are only connected together at one point in the entire system - in the preamp. Further, you are able to do this because the preamp, power amp, and DAC are all of your own design. Did I get this right?
Anyway, I agree that there is no standard system grounding configuration for single-ended audio. But getting back to the ABX box, it's possible to have the grounding configuration with the box in place be the same as if one had simply cabled the components together without the box. Assuming that two power amps are being ABX'ed, from my POV this would require the following:
1) The box does not connect any signal ground to the safety ground anywhere.
2) The signal grounds (L and R) of the disconnected amp (input side) should not be connected to the signal grounds of the connected amp. An exception would occur for a few milliseconds only during the relay switching, using a "make before break" ground connection to avoid loud pops during switching.
3) The box should not connect L and R signal grounds together. It should only provide continuity from the left preamp out RCA jack ring to the left power amp in RCA jack ring - and the same for the right channel. This is only for the connected power amp, not the disconnected one of course (per 2 above). There should be no continuity from the left channel RCA jack ring on the box to the right one when nothing is connected to the box. This is the same as would occur with standard RCA cables and no box.
4) Each power amp output signal return in the box should not connect to anything but the corresponding return of the connected power amp - not the disconnected one.
5) There's probably more, but I can't think of them at the moment
I wrote:
"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 :-). "
To which you replied:
"There are some of us who would dispute that, and I think that would include jj."
Can you clarify? Are you referring to doing sighted tests first to establish perceived differences? If so I agree completely that sighted tests should be done first. If that's not what you were referring to, please elaborate.

Edits: 03/08/08 03/08/08 03/08/08

Follow Ups:

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)

Post a Followup:

FAQ

Post a Message!

Forgot Password?

Moniker (Username):
Password (Optional):
	Remember my Moniker & Password (What's this?) Eat Me
E-Mail (Optional):
Subject:

Message:	(Posts are subject to Content Rules)

Optional Link URL:
Optional Link Title:
Optional Image URL:
Upload Image:
E-mail Replies:	Automagically notify you when someone responds.

To view your new posting or follow-up, click on the RELOAD or REFRESH button on your browser.