[quote="IngOehman"]Den såväl trevlige som duktiga elektronikkonstruktören Ole Lund Christensen i Danmark driver företaget GamuT, och helt nyligen har försteget D3 släppts.
Thank you for those nice words. however I sold GamuT in September 2003, and I left GamuT in February 2004.
Men, det som förbryllar mig är, att Oles nya försteg GamuT D3 är en rätt igenom fenomenalt ingenjörad (distorsion och brus är av världsklass) apparat, med ett andantag: Bandbredden!
Yes, High Fidelity measured THD +N at 1 V on the GamuT D 3 at 0.001 %, the same as the Mark Levinsson reference 32.
D3 har enligt test i senaste High Fidelity en bandbredd om ynkliga 55 kHz (-3dB) och cirka -0,5 dB @ 20 kHz. Detta är osedvanligt lite för att vara ett modernt försteg.
However they measure only 7dB down at 100 kHz.
It is a slow roll off, and it is only 14 dB down at 200 kHz. That is 7 dB pr octave, which means the GamuT D 3 has a very fine phase and impulse response.
Let us compare that to other parts of the HiFi chain:
Most microfones and loudspeakers have little response above 55kHz. Many have sharp resonances peaks before they give up.
CDs are sharply limited at 22 kHz.
LPs and pickups have little response above 55kHz
Analog tapemachines have little response above 55 kHz.
Most digital recordings are shaply limited at 48 kHz.
Most SACD players have little response above 55kHz
Many power amplifier have trouble with signals at 100 kHz.
Switching amplifiers especially have problems.
So I find it likely that having a preamp filter -7 dB at 100 kHz will improve the sound on most recordings in many systems.
Please also note, that air act as a filter in the 50 to 100 kHz range.
Just 10 meters of air reduce 100 kHz signals a lot.
Talking about -3dB points are missleading, the roll off is more important.
Ole Lund Christensen
PUNKT !
)
