The Terminator !!!!

My main pre-amp is fine, it's just my main headphone amp that has rather too much gain for my sensitive headphones. I ought to make some attenuators for it really, would be sensible to do when I order bits for the digital terminators. Do you have a link to somewhere describing how to make an attenuator?

 

Making a pair of attenuators is simple. Or you can buy them for about £40. Commercial ones give some improvement but inadequate and made with cheap parts.

However, to get the optimum result, you need to calculate resistor values to suit your particular system. I use a special spreadsheet with a chart.

 

I've just ordered some Russ Andrews shorties (half price!). I'll take one apart when it arrives and let you know what's in it, and whether I notice any difference!

 

Look forward to it. Thanks

 

Have you had a chance to do this yet?

How are you finding them?

 

What happened to Suzy?

Did MO! frightened her away with his avtar?

 

so whats the difference with useing shorting plugs and them cardas caps?

 

From what I have heard Cardas does not short anything. Though being a metal cap it can shield against RFI. Some people said that they are a very tight fit (unlike RCAs) and are difficult to take them out. And they cost many times more than a cheap phono plug.

 

YEAH i gathered that but sound wise do they work as well as actual shorting plugs ?

 

May be not unless the effectiveness of the shielding not 100%.
Mainly because of the price difference, I have'nt seriously considered Cardas.

 

I've not tried the proper Cardas jobs, but I did try using kitchen foil to try and form a similar screen. On my old Pioneer A400, if the input selector is on an usused input, and you whack the volume up, you get very noticeable hiss from the speakers. Sticking a pair of shorting plugs on the same inputs dramatically reduces this. Using kitchen foil, and manually holding it in place to try and ensure a good contact, made no descernable difference. Naively I'd have assumed that the foil would have performed similarly, although not as well, as the Cardas caps, but maybe I was being optimistic.

The shorts and the caps do perform slightly different roles. The shorts fix the signal potential to 0V, whilst the caps leave the input floating whilst providing a better screen from RFI.

Of course what really matters is how the noise from an unused input affects the signal from the ones you're trying to listen to, but I need to do a bit more listening before I comment on that.

 

Aside from some (marginal?) RFI shielding I'd have thought the Cardas caps did little apart from keeping bugs and dust out. For which task they seem over-engineered and over-priced.

 

Out of interest, in what sense are you saying the RFI screening is marginal? As in do you mean you don't think they screen the area they claim to very well, or that adding a screen over the small area of an RCA input won't do much?

 

My sense is that if putting a screen over a phono socket has an appreciable effect on RFI then the equipment probably has more severe problems. I could easily be wrong. As I say, I suspect that the main benefit is keeping dust and bugs out.

 

The 'logic' of course is that you're screening the input terminal, which is presumably going to be more sensitive to picking up stray signal than anything else? Also, for most HiFi that has an earthed metal case this should form an effective screen pretty much everywhere else, so it's a question of plugging the obvious holes, so to speak.

I can see where you're coming from with your amp having "severe problems" comment if you mean in terms of capping unused inputs affecting the sound through inputs you're actually using. If you listen to an unused amp input, screen it and find a reduction in noise, this doesn't to me immediately smack of bad design however.

 

sfunny this one in my old house i used a monster clean power2 av block and whatever input i used with a blank phono plug in i got no noise at all now im my new house with dedicated spur and new kit i get a slight hiss if i crank the volume up? i tried an olson block but it made no difference at all maybe that monster av block really worked?

 

Or if this really is an RFI issue (I'm not convinced) then your HiFi in now in a noisier environment than before.