[sdiy] Tube weirdness

[Seb Francis]

Hmm ... trying to acheive the nicest sounding D/A conversion ... you have to wonder whether a PC motherboard (with switch-mode PSU and all that high frequency digital stuff) is really the best place to do this at all ;)

Seb


Dave Krooshof wrote:

> >Okay, maybe it's just me, but I think this might be carrying the "tube
> >sound" thing a little too far...
> >
> >http://www.aopen.com/products/mb/ax4b-533tube.htm
> >
> link was posted here before.
>
> Putting tubes behind your DAC is a reealy good idea!
> It's like this:
> a dac converts from digital code to _current_.
> converting that to voltage could theoratically done with a resistor.
> But practically, if that resitor is to big, the voltage gets to high,
> so it confuses the dac, as diodes will be opened that shouldn't have been.
>
> So you convert to a small voltage and crank it up over an opamp,
> or worse (soundwise) in a current to voltage IC.
> The sh!t comes in here. Those IC's tend to sound harsh.
> Amplifying a low voltage over a tube, however, works beautifully.
>
> Often the lowpass filter is left out as well. 8 times oversampling
> gives a samplerate-tone thats way out of the range of your
> amplifier/speakers anyways, so they figure.
>
> Several friends of mine have trown tubes in their cd-player.
> Lot's of fine details were revealed.
> Downsides:
> - most cd's sound quite dark. As if distorion was calculated in.
> - Bjork sounds very depressed on her lasts album. Is joy captured
> in high freqs?
> Upsides:
> - Top freqs are spotlessly clean and transperant.
> - Noise disappears, even from my recordings!
> I wonder where all my noise went, and why it is present on my system.
> Spectrometers show no high cut, so the effect is psycho-acoustic.
> We compared with the same but non-tubed cdplayer. What a difference.
>
> BTW have you seen my old cdplayer?
> http://www.xs4all.nl/~krooshof/tech/cdspeler.html
>
> Dave
>
> --
> fruitpower movie (with huge partly tube synth):
> http://pages.vpro.nl/3voor12/journalism/index.shtml?2534202+2584688+2584508+7333367