Preamplifier Dispre 2 - JFET

Hi Pavel,

I like your Jfet design the Jfet as a input is unbeaten.

I would like to see the small signal response of the 100kHz square wave 50mV/div .

172044d1274300011t-preamplifier-dispre-2-jfet-d2-jfet-100ksq.jpg


Keep on the good work.

Regards, Helmuth
 
Hi Helmuth,

the response shown is without capacitor in the input RC filter. I do not have that option at the moment, but as soon as I build further module I can measure it before completition.

Basically, there is almost no difference between large and small signal responses, as the SR is very high.

I am attaching step (square) response at 200 nanoseconds per division, again without input cap. Load is ultimate 50 ohm - to prevent cable reflections.
 

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Dispre 2 jfet preamp board and PS complete

Here is the assembled board of Dispre 2 Jfet and it's regulated power supply.
Measured (+/-) 14.9V from the output of the PS.

Main preamp board is awaiting the arrival of an 10K ALPS stereo pot.
It is configured for a gain of 1X. (max is 5X)

Can't wait to hear this glorious jfet diamond buffer !!
 

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Dispre 2 jfet completed and playing on main system

Dear all,

The Dispre 2 jfet is all completed and playing on my main system. I have yet to drill holes in the alu case and mount the PCB's in. Power amp is a Rod Elliot P3A with Cambridge Audio Azur 550C CD player as source. Speakers are my 8'' 2 way MTM Scanspeak based DIY.

Well I am in shock. From the moment the first few notes were played, goosebumps erupted all over. The sonic image was extremely 3D and I never expected the speakers to image so well. Texture and tone was extremely lifelike and neutral. There is no grainy SS sound; what results is a smooth and organic musical presentation that seduces you to listen forever. I've had a few quiet preamps that the ear could hear nothing when placed 1cm from the cone. The Dispre 2 redefines "quiet". Notes emerge out of the darkest background and the transient attack shocks the soul. The goosebumps that broke out earlier still remain.

I do not hear bass, midrange or highs. They blend so well that you get lost in the music. For every other preamp that I have used, there is usually one aspect that stands out; like the sweet midrange from a tube pre etc. The dispre lets nothing stand out. Purest music. Straight wire with gain.

Pavel - You have created a masterpiece !!
 

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