ART DJPRE II Phono/Line Pre-Amplifier

Product Information

Input Impedance: The input impedance optimizes the input for the most extensive range of microphone sources feasible. The ability to modify the input impedance of a VoiceChannel's preamp alters the load that the microphone 'sees' in the system, substantially changing its performance and character. This opens up a world of new audio possibilities with any condenser, ribbon, or dynamic microphone, modern or old (47k Ohms in parallel with either 100pF or 200pF) Since this Op.Amp needs to amplify the signal from the turntable whose resistance in the case of the MM head is below 1k Ohm, FET and CMOS solutions with low In in the fA/√Hz range are no advantage, moreover the high resistance at their input increases the thermal noise (Johnson-Nyquist noise). We've never lost the motivation that comes with the development of developing technologies over the previous four decades, and we appreciate you, as well as the thousands of ART users, for your continuous support and commitment. This firm proudly manufactures pro Audio DJPRE II. The DJPRE II from ART is designed to amplify and EQ your vinyl records and allows you to play and record into a number of sources such as your digital audio sound card, workstation, primary monitor system, or home stereo.

I'm a musician and I care about sound quality, but I'm hesitant to go down the rabbit hole with pricey audio gear, nor could I really afford to. I imagine anything will be an upgrade from the screechy Crosley unit I've endured in the past few years. At some point, I could imagine upgrading my turntable, so I'm also open to buying a somewhat better phono preamp than I need for now, assuming that I'll take fuller advantage of it down the road. They are generally considered low grade crap, so I began the hunt for something better, and decided after reading probably way too much about the subject that an Elna Silmic II would be a substantial upgrade. The ART DJ Pre II provided a very flexible and clear way of boosting the phono signal to match the volume of the AppleTV. Unlike many other phono preamps, this one has an easy gain knob that lets you dial in a specific amount of amplification. As you see, the DJPRE II has "low cut" filter switch together with input capacitance selector (100 or 200 pf). It also has a clipping indicator and variable gain switch. I looked at the one they suggested from Parts Express, but given that it is made by Mean Well, who to my knowledge only makes switching type supplies (which would introduce a lot of switching noise) I chose instead to build my own ripple filtered & regulated supply.Finally, let's look at distortion and noise of a 1 kHz tone with 5 millivolt input but without a-weighting: Spec do not show its en(Equivalent Input Noise) value but it si perform better then 3-4nV/√Hz devices on 10, 100 and 1kHz so it have to be below 4nV/√Hz. added 1nF caps to rectifing diodes (even if I would like to test a DC supply, since I guess that those wires (and traces) going/coming to/from the switch, even if twisted, spread some noise

The ART QC engineer consulted the Design engineer who both shared their knowledge of this circuit and helped me to get rid of that last 100pf load capacitance, which in turn got rid of the resonant peak (at least to my ears). As you see, the output is 0.306 millivolts which corresponds to a gain in db of 35.6 or so. This matches the specification of Pluto and is within the range that DJPRE has. So for a good solution we need any bipolar Op.Amp that can give at least SVR of -110/120dB, and below 8nV/√Hz at 10, 100Hz and even at 1kHz (and not in the ultrasonic range at 100kHz like TS972).

Customer reviews

A-weighted signal to noise ratio ("SINAD") is 83 dB for DJPREE II beating the 80 db for Pluto. Both companies spec 90 dB. ART (Applied Research and Technology) is a corporation composed of musicians, audiophiles, and engineers. They have been aiming to reinvent the performance versus price barrier with a succession of revolutionary new audio devices developed with the musician's demands in mind since their start in 1984. A-weighted signal to noise+distortion ratio ("SINAD") is 83 dB for DJPREE II beating the 80 db for Pluto. Both companies spec 90 dB.

Because of this, it was incredibly easy to manually adjust it so the two signal strengths roughly matched. Frequency Response: This ranges from 10Hz to 50KHz, with a +/-.5dB tolerance that is enough for the size and functionality of the Pro Audio DJ PRE II.

C36 & C37 are both 100pf capacitors which are switched in parallel with the fixed capacitors (C20 & C23) to achieve 200pf loading.

For starters, I adjusted the variable output of the ART DJPRE II to match that of u-turn Pluto. This setting was just past the "zero" dial (around +1). This is good as it means the DJPRE II has good range of input sensitivity.Also, I know these particular stages are budget stages, but why don't the more upmarket ones provide balanced inputs as standard? One gets unnecessary balanced inputs on line stages and domestic power amps, yet unbalanced inputs on the only items where they would be fully justified. Another added bonus is on this receiver (TX-870), the CD input has a "CD Direct" setting, which allows you to bypass the receiver preamp and associated tone controls. So, if you are in a listening situation when you desire a perfectly flat audio response, just switch to "CD Direct". Otherwise, you can adjust all the tone settings as usual. The ART DJPRE II is a great bargain here. Other than some strange phase shift at low frequencies and lower input dynamic range, it actually beats the more expensive u-turn Pluto in the rest of the measurements. added 1000uF alu-polymer cap on opamp pins (I assume they have the same rails so doesn't matter which one)