Another new tweak - comments please

Hi all,

I haven't posted for a while but spotted this RF shorting for the spare co-ax inputs \ outputs....

http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&category=295&item=5727441934&rd=1

Anyone tried or heard of these?

Thanks, Tim

PS. At the risk of shooting myself in the foot, would you pay £850 for Monitor Audio Studio 50 (NON SE)?

 

Pm BlueMax he has details on how to build something similar for abot 36p each. RA was selling these at hal price or less for a dozen.

 

I like this quote

This exact same product is sold by an well known bald man, regarded by some as a demigod of pure sonic pleasure, at a cost of £19.95 for 12, which is £1.65 each, and then the old coot is going to charge you another £3.95 postage on top!! Put an end to his nonsense and buy from me exactly the number you need at a cost of 99p each and only £1 postage for AS MANY AS YOU BUY. This means whereas the baldy man wants £23.90 for 12 - I charge £12.88 for the EXACT same product!

I wonder if he means Mr Andrews by any chance?

 

and short the signal input safely to ground

how exactly do they achieve this?
does this mean they connect the + to the - on the amp inputs?

or are they just cheap phono plugs not connected to anything?

 

I believe there is a resistor that is used to short them so the high restistance makes it safe to short but also completes the circuit and helps stop RFI. Surely the RF signals can travel long this resistor though but I guess because it does have high resitance by the time it reaches the amps circuits the signal is extremely weak.

 

I don't reckon there is a resistor actually. I've been here before, but if you have a resistor there you aren't strictly shorting the input and you won't be totally preventing RFI (you could still have a varying potential difference across the resistor caused by RFI which will enter the amp). For most amps there should be no issue with shorting the inputs whatsoever - there's nothing delivering current to the input so what could the problem be?

Where resistors specifically are used is for shorting digital outputs.

Oh, and the other specific comment to make is to only short analogue inputs, DON'T SHORT PRE-AMP OUTPUTS.

As to whether the items in question make any difference I've no idea I'm afraid, I haven't tried them.

 

There was another un-related thread on either here or HFC about hiss ( I think) . I seem to recall that a bit of experimenting was needed to give a correct answer from my own experience. During this little bit of minor experimentation i discovered that my amp suffered from noise/hiss but only on the unused inputs, when i connected anything to them the noise disappeared, even if the connected equipment was turned off. I remember at the time making a note to sort this out , possibly with 'shorties' but have never gotten around to it, possibly as i never listen to my un-used inputs

So any circuit diagrams ofr Clones of RA's shorties ? Are they shorted out phono plugs or just metal snug fitting caps ? caps would make more sense to me ......?

 

I assume as they're called shorties they do actually short the input. You can buy caps though:



https://www.audiophilecandy.com/prodet.asp?pcode=M-ACC-CCAP&rel2=M-ACC&0=More+Info

but they're somewhat expensive. Interesting you say caps make more sense, I think I can see where you're coming from. I assume you're relying on earthed casework to screen the signal path once inside, so just effectively continue this screen over the inputs right? (I realise the signal return on the iinput isn't connnected to the casework but you get the idea). I'd be tempted to think that actually earthing the input could have an effect too, so possibly a combination of both would be best?

What's kitchen foil like as a conductor? How about kitchen foil with maybe an O ring to hold it in place over each input?

 

That is exactly what i was thinking. The link that you provided is exactly the type of device i was thinking of using to do it too, however at £35 ( + P&P ?) i think i will give then a miss and try to come up with a DIY solution.

Kitchen foil and elastic bands - now we're talking

 

What is wrong with simple covering them with plastic? For example a phono plug with a plastic cap fitted? PS Are RA selling 24k gold plated shorties yet with out teflon insultation? I believe these will improve an amplifier sound quality by 2000%.

 

Radio frequency electromagnetic radiation will pass through a thin bit of plastic with relatively little loss in amplitude, so this on its own would have essentially no effect on the issue being addressed here. Or did you mean what's wrong with a plastic cover over a shorting connection?

 

All found here http://www.siteswithstyle.com/VoltSecond/Shorting_plug_rca/shorting_plug.html

 

If it can travel through concrete it can travel through plastic I think my brain has switched off I feel daft now. The resistor in that circuit diagram posted seems like quite a good way of doing. I don't have a degree in electronics or anything but I assume a high restiance resistor such as a 5K1 will be enough to reduce the RF signal to virtualy nothing.

 

Lee - I've always maintained that a straight short would be better than using a resistor; what do you reckon? My 'logic' being if you have a resistor there this enables the signal line to be at a potential above ground and hence still have some spruious RFI induced signal on it, whereas a straight short would mean no signal. Am I talking crap?

 

Not sure if I really know the answer. The only thing I do know is that I would never have a direct short on any plugs. I'm most of us have at one time taken out or put in an I/C when that channel was live and got various grounding buzzes coming out of the speaker. I know which I wopuld be more worried about if I accidently switched to the wrong input and it wouldn't be RFI

 

I always seem to manage to use all the inputs of every amp I've ever had...

-- Ian

 

Amps are designed that way.

They subliminally encourage you to buy more sources.

They are the secret weapon of the hi-fi manufacturer.

 

OK, this may be a very dumb question, but why would it matter in the slightest if you switched to an input that was shorted? I would expect you'd hear absolutely nothing? Are you thinking of some sort of earth loop problem? Getting a noise if you connect/disconnect a cable I'd have thought was a different thing, possibly due to having the signal return connected whilst the signal pin isn't?

 

Ok so no-body actually answered the question!! What's the science behind this and has anyone seen this work?

Thanks, Tim

 

Not meaning on sounding too harsh!!!
Thanks for the replies so far.