Are all inputs equal?

This is probably a stupid question, but as I don't know the answer I shall pose it anyway.

Phono aside (as I know it is different), are the CD/Tuner/Tape inputs typically equal in how much amplification is applied to them, i.e. are they all simply line level? Does it depend on the manufacturer? I know that CD players typically have a higher output than most tape decks and tuners......etc.....

Can anyone part the clouds for me?

 

Quick extra note: I'm talking separate preamp here, not integrated amp-land, if that makes any difference........

 

Yes they're the same. Generally they all share a ground rail and the signal wires/bars just go to different points on the input selector (or some similar configuration)

 

If you only have one source, you may find on some amps that the best sound is obtained by connecting it to the tape out sockets! It seems counter intuitive but definitely works on my Sugden headmaster pre/headphone amp.

 

Alan, that definitely counts as a 'research finding'!

 

I read it years ago in a hifi mag and discounted it completely.... then when I had the AS Passion pre-amp, the instructions for it said the most direct signal path is through the Tape out sockets, so use them if only connecting one source.

The other inputs are rendered redundant and the input selector is ignored, but it works.

It may not work on all amps...

 

How can connecting an input to an output work? Surely it cannot work? Can somebody explain in electrical but non mathematical terms how this works?

 

Thanks for the clarification, I suspected that they were all the same but wasn't sure. The actual reason for my question is that my preamp (Croft) pre-dates CD and and I had wondered whether it would make any difference if I connected my CD to the tape inputs or tuner inputs.......but obviously not so I won't worry about it anymore!

Thanks again, Dave.

 

AT: As a guess I'd say-
The input chain is (or near enough):
Phono socket on the amp
Phono to input selector
input selector to volume pot

Inbetween the input selector and volume pot I assume there is a tap off (just a piece of wire) that connects to the tape outs. When there is signal running from the input selector to the vol pot, some of that signal will go to the tape outs but if you pass a signal INTO the tape outs, it simply passes the other way along the tap and straight into the volume pot, thus bypassing the (degrading) input selector.

 

Very old amps (talking valve here) were, I believe, designed for a lower input level than modern amps so you may want to check that.

What do CDPs output? I seem to remember it being 100mv or there about but I could well be remembering it wrong!

 

The average CDP output is in the region of 2V. 100mV is much more like the average input sensitivity of an amplifier for this type of input.

 

I think even the venerable Nad3020 had slightly different input characteristics. To accomadate the differing line level output of various devices. I think some modern amps use some attenuation on the cd input to.

 

If you believe all the hype some people bring out, than "Tuner" on the Naim 32x/42x/62/72 is supposed to sound best. ALL amps have mildly differing signal paths between inputs, so it'll vary from model to model.

 

My Arcam Alpha 6 has an output level of '2.4V rms at MSB (0db)' according to the manual, so the average 2V figure suggested earlier sounds about right.

My Croft preamp is valve but is only about 20 years old (sprightly young thing compared to my Quad II's which are about 40 years old, and my Tannoys which are about 30 years old) and predates the CD input option (just) on this particular model.

Maybe I'll see if I can pick up some in-line attenuators to try to reduce the CD output a tad, just to see if it makes any improvement. I did have a pair of the Rothwell ones for a previous setup but sold them a while ago, ho hum.