RADIAL JDV MK3
Owner's Manual

JDV Mk3 Owner�s Manual
e n g i n e e r i n g

JDV Mk3 Owner�s Manual
e n g i n e e r i n g

The overload LED never goes on. Why? Because the JDV has such a huge internal rail voltage, instruments are typically unable to drive sufficient current into the JDV to cause it to overload. Kinda' like having 12 cylinders on a car. You don't need them until you are racing. Kick 'em in and the extra horsepower makes all of the difference! Can I overload the JDV's input? We could only get the JDV input to overload when we drove the output from the line level of a mixer directly into the JDV and turned the volume up high. It is unlikely, under normal use, that you will ever overload the JDV. Can I connect a guitar amp head to the JDV without speakers? No. The JDV is not a load box. This means that you must connect the amp to a st load 1 (like a speaker) and then you can connect the JDV to the load. Can I connect a guitar amp head to the JDV with a load box? Yes. However you should be careful to ensure that the load box properly emulates a speaker. Make sure the -30dB pad is engaged and monitor the JDV's input to make sure the overload LED does not go on. What level is the JDV output? The JDV is a unity gain device. This means that although it is designed to output a mic level signal, the output can be significantly higher depending on what input is being sent to it. This is why there is an output PAD on the JDV. This allows hot signals to be padded down so that they do not overload the input to mixers or mic level isolation transformers. Why don't you put the power supply inside the JDV? Noise. Due to the JDV's abnormally high input impedance, the internal working level of the JDV is extremely low. This means that we must do everything we can to ensure unwanted noise stays out of the JDV circuitry. Power supplies tend to be a major contributor to noise. Keeping the noise outside is a good thing! What are the differences between the old JDV and the new JDV Mk3? The original JDV and the new JDV share the same audio circuit topology and philosophy. Both use the same Class-A feed forward designs. The old JDV used a rechargeable battery as a primary supply while the new design does not. We found that although the original JDV worked well, many users were confused about charging the battery and unless you read the manual, you could get some pretty awful distortion or worse yet, you would think the unit was defective. The Radial JDV Mk3 is the third generation JDV and in developing this box, we set goals in place that included making the unit more user friendly, lowering the self-noise and expanding the dynamic range. All of the good things that were in the original have been maintained or wherever possible improved upon. Obviously the new JDV has many more features. But that is not all: The new JDV has gone from using SMT (surface mount technology) to the higher capacity and precision of discreet components. In order to expand the headroom, we developed a totally new power supply with a floating ground scheme for less noise, and we got rid of the rechargeable batteries! Why did you not put a knob on the Drag control? Originally, the Drag control was supposed to be recessed so that once set, the control would not be touched. However we found that it was so darn musical that people would be adjusting it all the time. Because the JDV will probably live on the floor most of the time, we felt that a knob would stick out and get kicked and broken. So no knob. Kinda' looks weird at first, but you'll get used to it.

Instrument and Amplifier Matching
One of the most beneficial features of the JDV is its ability to handle a wide range of instrument levels and pick-up configurations. Because of the exceptionally high internal rail voltage, the JDV does not require an input pad except for excessive levels such as parallel speaker connections. (This is detailed later in the manual). It is important to note that even though the JDV can handle any level, to truly capture the essence and detail of an instrument, a more precise control is required. Thus the reason we have incorporated Drag� control. When a guitar is connected to an amplifier, the amplifier and the pick-up will interact. In fact, different cables will also affect the tone. This direct loading is a normal and essential part of what makes a guitar sound the way it does. Lower output pick-ups such as those found on vintage instruments are most affected. When, for instance, a bass is connected to a regular direct box and then to the amplifier, the pickups are no longer driving the bass alone; the signal is split between the musician's amplifier and the XLR output that is going to the mixer. In live situations, the mixer can be as far as 300 feet away. This means that when using a passive direct box (transformer style) the lowly pick-up must drive the signal all 300 feet while still driving the amplifier. This loading effect can sometimes cause the instrument to sound listless and lack punch.

JDV JDV
Mk3 Mk3

Active direct boxes solve the loading problem by presenting the pick-up with a high input impedance, thus limiting the energy from the pick-up being sent to the direct-box and sending most of the pick-up's energy to the instrument amplifier. The higher the input impedance, the more natural the tone going to the musician's amplifier. Only one problem; the lower the instrument signal to the direct box, the more difficult it is to amplify the signal to a usable level without adding noise, phase distortion and inter-modulation distortion. (Nothing good is ever free!) Most direct box input impedances range from 10k-Ohms to 1 meg-Ohms while the JDV is outfitted with a very high 3.9 meg-Ohm input impedance. The JDV is able to present this unprecedented input impedance due to the ultra-low noise design and the unique Class-A circuit that can amplify the signal without adding distortion.
The 3.9 meg-Ohm input was chosen to reduce loading and for use with piezo pick-ups such as those typically found on stand-up basses. These are normally in the 3 to 4 meg-Ohm range and thus when used with the JDV provide optimum impedance matching for best tone.

14

3