Legato Tweakers Thread...

[needsp]

Hi Russ, avr300

I've tried removing the 15n caps too. Leo first tried this, and was astonished how much better it sounded. As was I. (I'm using just CD source material).

Several other people have heard the same. It really isn't subtle. But I nearly didn't try it on the basis that, even if the filtering did no good, it could, in theory, do no harm, so why not leave it in.

Well it seems theory is deficient. I've no idea what's going on here, but I like it!

[needsp]

Hi francolargo

I am using Auricaps, which don't even remotely fit the board but have nice multistranded flexible leads. For a number of years I've been using them wherever transparency is needed. But just tonight I discovered something I didn't know about them (plus a review confirming small polarity effects):

* In signal path applications the black lead is "in" and the red lead is "out."

* In power supplies the black lead should be connected to ground and the red lead to the + or - voltage.

*In loudspeaker crossovers the red lead should be connected toward the + terminal on the drive unit.

Huh? Any comments on this by the "cognoscenti"? My caps are apparently in backwards because before reading this I would never have soldered a black lead into a location labeled "plus" and vice versa for red leads! I'll try changing them the next time I have everything apart...

It's to maintain optimum screening (I assume- ask Auricap). In a cylindrically wound cap, it minimises stray signal pickup if the outer foil is connected to the path with lowest impedance to ground. This marked by the black wire (Hovland caps were the same, only with a green wire). Usually, for a coupling cap, this means that the red wire should be connected to the output terminals, and the black to the circuit driving it

Paul

[MartinC700]

For wound film caps there in some instances a marking, in your case the lead color, that designates the outer foil, so there are instances (in theory) where it may be better to have the outer foil connected one way around.

I suspect that in practice in makes little or no difference.

Regards

Originally Posted by francolargo

I am using Auricaps, which don't even remotely fit the board but have nice multistranded flexible leads. For a number of years I've been using them wherever transparency is needed. But just tonight I discovered something I didn't know about them (plus a review confirming small polarity effects):

* In signal path applications the black lead is "in" and the red lead is "out."

* In power supplies the black lead should be connected to ground and the red lead to the + or - voltage.

*In loudspeaker crossovers the red lead should be connected toward the + terminal on the drive unit.

Huh? Any comments on this by the "cognoscenti"? My caps are apparently in backwards because before reading this I would never have soldered a black lead into a location labeled "plus" and vice versa for red leads! I'll try changing them the next time I have everything apart...

[barrows]

Originally Posted by needsp

Hi Russ, avr300

I've tried removing the 15n caps too. Leo first tried this, and was astonished how much better it sounded. As was I. (I'm using just CD source material).

Several other people have heard the same. It really isn't subtle. But I nearly didn't try it on the basis that, even if the filtering did no good, it could, in theory, do no harm, so why not leave it in.

Well it seems theory is deficient. I've no idea what's going on here, but I like it!

Could you possibly explain the sonic difference heard without the 15 nF caps? I guess that these are part of an analog filter stage, to remove out of band artifacts-what are the ramifications of allowing these artifacts through?
Russ: what might be the R that applies to these caps for filtering, perhaps raising the corner frequency some might provide sonic benefits without eliminating this filter alltogether?

[Russ White]

Basically the filter is formed between output impedance of the I/V stage (which is dominated by the I/V resistor) and the cap. In the stock configuration (150R I/V) the corner is about 65khz. The filter is 1st order.

If you increase the I/V resistor you will get a lower corner. For example 357R would get about 30khz corner.

The presence and value of the cap are totally up to the user. Though I would never suggest omitting it.

Cheers!
Russ

[barrows]

Russ. That's exactly what I need to know.

[Spev]

It's bizarre though that so many have subjectively come to the same conclusion, that a whole load more HF info is getting through without the 15nf cap, and that the circuit sounds somewhat strangled with it in place?

[Russ White]

Originally Posted by Spev

It's bizarre though that so many have subjectively come to the same conclusion, that a whole load more HF info is getting through without the 15nf cap, and that the circuit sounds somewhat strangled with it in place?

For what it's worth, nobody I have asked has ever made such comments. I would take anything like that with a grain of salt. I am not saying people aren't being honest, just that my experience is definitely not the same.

[avr300]

Pleasant distortion ?

[Russ White]

The filter will indeed reduce high order distortion as well as increase dynamic range by excluding some noise.