2. amps-preamps
  3. 132930-84906

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
almarg's avatar
Ag insider logo xs@2x
almarg
9,670 posts
 
If you want to learn more try this, then report back:1. Solder a 100 ohm resistor across a working input, not an unused input.2. Listen.3. Post your findings here.
Keep in mind that most source components and most preamps and line stages cannot drive 100 ohms with good or even half-way decent results.  And as you may be aware the manufacturers of many tube-based source components and preamps recommend **minimum** load impedances in the area of 20,000 to 50,000 ohms.

There are some source components and preamps which can do that, and of course 100 ohms would be a reasonable load for many low output moving coil phono cartridges.  But the great majority of components providing line-level outputs can't come close to driving an impedance which is that low, while providing reasonable results.

Regards,
-- Al
  
Post removed 
johnny121
11 posts
 
Do you think 100 ohms across an analogue input may damage something
Thanks.
almarg's avatar
Ag insider logo xs@2x
almarg
9,670 posts
 
While I suppose there may be some poor designs that could be damaged working into a 100 ohm load, eventually if not sooner, in general I would expect the combination of the 100 ohm load and the output impedance of the component itself to limit the resulting current to values that would not cause damage.  Some components providing line-level analog outputs can even withstand a direct short, i.e. zero ohms.

Regards,
-- Al



More to discover