TVC Sound

Surely a pure 4KHz sqaure wave would not have anything but 4KHz in it?

 

A 4KHz sine wave is just pure 4KHz. A 4KHz square wave is basically a 4KHz sine wave with the addition of all of its higher frequency harmonics. So it contains some very high frequency components and is much more difficult for a wound component to 'pass' accurately.

CD, being limited to 20KHz, can't carry more than perhaps the 5th harmonic of 4KHz, so as a source for playing square waves it ain't much cop. I think you do need a square wave signal generator.

Somebody please correct me if I'm talking bollocks!


I just found this

"A rectangular-shaped (step-function) periodic wave with a positive and negative half-cycle of equal lengths of time or duration. A square wave consists of a sine wave's fundamental frequency combined with the odd harmonics (multiples) of its fundamental frequency."

So it contains 4K, 12K, 20K, 28K, 36K, 44K, 52K..... etc etc.

 

Ahh so if you use the TVC from a CD source you are alright for one

I could try the test again using my external soundcard which is 24/192 capable.

 

A deicated wave form genny is a basic must in this type of proceedure Simon.

 

Why would it be any different from a high resolution external soundcard?

If it is, then it begs the question, why are we not using such superior wave-form generators in our hi-fi?

 

Some of us do. They are called record players


only kidding

 

I should hope so!

 

Seriously though, its how CD players deal with and interpolate what the higher order harmonics might be doing that has a very large influence on the way they sound. Using filtering that doesn't ring. Referencing to stable, clean clocks and quiet power supplies is what distinguishes the better players from the bargain basement machines.

I remember when CD first came out the magazines used to publish square wave response plots. They stopped that pretty damn sharpish!

 

Simon, I have an old wave generator that I picked up for fiver recently in a moment of madness.

We can play around with it on Friday and you can take it back with you, assuming that it works.

 

Hmm... cd is bandwidth limited. Dont you mean the interpolation and filtering of artifacts from the D-A process rather than harmonics exactly?

 

WTF r u on about Nick?

Edit: or should I ask what r u on?

 

What murray said - assumming I have understood him correctly.

 

Lets just say there is an awful lot of "happy" on the menu in Tiger Leaping Gorge.

 

I think what Murray was saying is that similar ringing occurs in the filters of CD player that remove the nasty HF. That, or that the filter doesn’t remove all of the nasty HF so some can still excite the transformers.

Anyway, an update. I used my external soundcard at 192KHz sample sate and tried again.

1KHz without the transformer



1KHz with the transformer



4KHz without transformer



4KHz with transformer



So it does look a lot worse now. Still not as bad as Murray's but not ideal. I wonder how an equivalent priced active pre would measure, and where it might measure worse?

 

That is some bad ringing, I would hope an active pre would do better.
I may have to drag mine in to work now and try it.

 

wtf?

 

Don't get paranoid folks
Some of the best sounding amps around use glass bottles designed for transmitters and TV sets, transformers which do some very strange things to the signal and use circuits which produce very audible distortion - but still sound superb.
Different ways to skin the cat and all that (sorry Simon if the cats are looking in )

Think of all those CD players with ripples in the HF output due to the filtering used - some sound quite superb.

My own pre has output tranformers and was designed to use an RC network on the output, to prevent ringing presumably. I don't use it as it sounds better without it.

 

From now on, Thorsten's baby will be known as 'The Bell' :duck:

 

You can't be serious! Nothing added nothing taken away and everything...

Ask BBV. Try female vocal.

 

At what level of attenuation is that?

Try it one, two or three notches above full attenuation (near minimum volume)