Stereo Tool

Indeed, it might be nice to purpose build something like this. I think you've got us interested!

So many questions though...

I imagine you might have a low impedance output driver stage capable of 3.5 V peak to peak plus? How is the dc offset?

Any hassles using USB with an 'on air' pc? Is current consumption reasonable via USB or are you using an external source?

What is the spectral purity like? Regulators and noise?

I don't know why, that rules have many companies especially far east.

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Urban Junglist

It need extarnal supply, because high speed high current amplifier was used, DC offset not present, some kind of DC servo.
Possible to use only USB supply, this is next thing to do.
Purity spectral best possible, avery part is low noise.

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Urban Junglist

The real question : Is it DC coupled? If not, little else matters from my experience. When you play Three Dog Night's song Black and White, the first several seconds will FM modulate 125% or so even if tilt compensation is applied. Leif explained that the bass is asymmetrical and even Tilt adjustment that looks perfect on the screen fails to control it--but the DC coupled Trace Alpha tames it without breaking a sweat. That said, I'd love to see someone build a 192kHz DC Coupled Sound Card that we can buy in the USA at a reasonable cost with shipping in the $10 range rather than $75 or whatever it costs to ship a Marian Trace Alpha here.

Hmm bandwidth is flat from DC to 0,45 x sample rate and absolutely no tilt.
This main problem is not in sound card but with too fast PLL in transmitter, recommended frequency response for composite and exciter is from 0,15Hz@-3dB for best tilt results.
Of course some sound cards have output capacitors and tilt is very big.

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Urban Junglist

So are there any capacitors in output? When i play a 1V flat line will it stay at 1V or will it go slowly to 0V ?

If you play maximum DC signal output can be eg. 1V constant.
But actually is used DC servo and below 0,1Hz DC is cutted because true output DC is not necessary.

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Urban Junglist

I was reading another thread about sound cards and then remembered this.
How's this project going?