2. amps-preamps
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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
georgehifi's avatar
georgehifi
10,312 posts
 
Buy switching to an unused input your subjecting the input first active stage to an open circuit.
The simple fix is not to switch to it, if it’s not used.
By putting blanking/shorting plugs on the unused inputs doesn’t make the used inputs sound any better.

Cheers George
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gdhal's avatar
gdhal
1,641 posts
 
Buy switching to an unused input your subjecting the input first active stage to an open circuit.
The simple fix is not to switch to it, if it’s not used.
By putting blanking/shorting plugs on the unused inputs doesn’t make the used inputs sound any better.

Hi George. To clarify, I'm not wanting or expecting the unused input to sound better. What I am expecting, however, is that by shorting an unused input, its potentially negative effect that it has (if not shorted) on a *used* input is minimized.
georgehifi's avatar
georgehifi
10,312 posts
 
If it’s not used why switch to it?? And negative affect to what??

Cheers George
gdhal's avatar
gdhal
1,641 posts
 
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?

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