RCA Shorting Plugs


I am coming to the conclusion that success in home audio reproduction is largely about lowering the noise floor. There are so many different types of “noise”, from so many different sources, that we only really “hear” by their absence.

I have had caps on the unused RCA inputs of my ASL passive autoformer preamp, ever since a friend suggested them way back. I recently got some actual shorting plugs (with resistors), from Hifi Collective in the UK, to replace them. I was surprised by how much difference they made. Transparency, resolution and musical flow all increased, along with the “realness” of instruments and voices. There is also more sense of the space around them.

I know some preamps short the unselected inputs, but, if yours doesn't, these shorting plugs are inexpensive, and definitely worth trying.
tommylion
If it’s not used why switch to it?? And negative affect to what??

Cheers George
If it’s not used why switch to it?? And negative affect to what??

I believe it has already been clearly established as FACT [on the basis of this and other related (shorting inputs) threads here on Audiogon], that shorting unused inputs **can only be advantageous, even if only theoretical** (electrical theory).

In other words, there can be no disadvantage in shorting an unused input from an electrical perspective.

So, in consideration of the aforementioned....

I would switch to an unused and un-shorted input to glean whatever noise I can, in order to subsequently switch to the same input *when shorted*, in an attempt to then determine if the noise - from that input -has been reduced.

So, in consideration of the aforementioned....

The negative effect *can* be "input cross-talk" that the amplifier is unable to filter.

Meaning, while the amplifier is amplifying the signal it is receiving from its currently in-use input, it is also amplifying the un-wanted noise resulting from the unused input(s).

So, in consideration of the aforementioned....

The benefit is that while listening to the in-use input, the overall systems noise floor has been lowered. In this context, "lowered" means "reduced by any decibel level greater than zero".

So, in consideration of the aforementioned....

Is there a shorting plug for USB B input?

Elizabeth, I’ve never understood why some people put resistors in shorting plugs for analog inputs. As I mentioned earlier in the thread, from the perspective of the input circuit a plug providing a direct short would be little different than if the input were connected to a powered up component having very low output impedance, that is not providing a signal.

Hal, I’m not particularly familiar with the design of integrated circuit chips which provide USB interfaces, but I suspect that what you read to the effect that USB inputs should not be shorted is correct. First, USB interfaces are bidirectional, with communications occurring in both directions on the same differential pair of signal lines when something is connected that can be communicated with. So a USB "input" is also an output. Second, I believe such chips are designed to pull those lines to certain voltages when nothing is connected to them, via internal resistors, and shorting them may affect those voltage states in adverse and/or unpredictable ways. So I would recommend against doing that.

Best regards,
-- Al

I just installed a raft of Cardas non shorting caps all of which are in my LG HDTV and LG Blu Ray player. But what I really wanted were the new Telos caps that are really cool looking and undergo some special infrared treatment, alas they’re out of my price range.