OPERATION MANUAL MODEL : ZMA - ZEN MYSTERY AMP REV 1 MAR 2014 ZEN MYSTERY AMP Reference Vacuum Tube Amplifier Model ZMA PAGE 1 OF 21 WWW.DECWARE.
OPERATION MANUAL MODEL : ZMA - ZEN MYSTERY AMP lightning flash with arrowhead, within an equilateral triangle, is intended to alert the user to the presence of uninstalled “dangerous voltage” within the product’s enclosure that may be of risk of electric shock to persons. AVIS RISQUÉ DE CHOC ELECTRIC-NE PASOUVRIR. WARNING- TO REDUCE RISK OF FIRE OR ELECTRICAL SHOCK, DO NOT EXPOSE THIS EQUIPMENT TO RAIN OR MOISTURE. To prevent the risk of electrical shock, do not remove cover or bottom.
OPERATION MANUAL MODEL : ZMA - ZEN MYSTERY AMP REV 1 MAR 2014 Thank You _______________________________ Table of Contents _______________________________ By purchasing this amplifier you are helping to preserve the art of finely crafted audio products with absolute world class reference fidelity.
OPERATION MANUAL MODEL : ZMA - ZEN MYSTERY AMP REV 1 MAR 2014 Unpacking Your Zen Mystery Amp is shipped in a military grade waterproof case. The insides of the case contain a foam impression of the amplifier and the amplifier is stored upside down inside the case and without tubes. ! As you can see, there are wheels and a pull out handle on the case making it easy to transport. Please do not try to carry the case because with amp it weights over 50 lbs.
OPERATION MANUAL MODEL : ZMA - ZEN MYSTERY AMP REV 1 MAR 2014 Unpacking Continued: Once you have the amplifier setting right side up in a location where it can be tested, make sure it has come to room temperature before doing anything else. This is especially important in cold climates. Cold steel will condensate in a warm house and this is a high voltage amplifier so wait until the steel is room temperature before installing tubes or the power cord. This can take up to 24 hours in extreme cases.
OPERATION MANUAL MODEL : ZMA - ZEN MYSTERY AMP REV 1 MAR 2014 What’s what ! There are only three things on this layout that are common to both channels. The IEC connector for the power cord, the power switch and the master gain control. ! ! ! ! IEC Connector with Fuse Holder ! 6.8 amp 20mm fuse Power Switch ! ! ! Master Gain Control These three items serve both of the mono amplifiers that make up the Zen Mystery Amp.
OPERATION MANUAL MODEL : ZMA - ZEN MYSTERY AMP REV 1 MAR 2014 Speaker Connections The ZMA has heavy duty gold plated binding posts that can accept up to 8 AWG bare wire, banana jacks, or the larger spade connectors commonly found on hi-end speaker cables. ! 8 OHM! + - 4 OHM! 8 OHM! ! ! ! ! ! ! RIGHT CHANNEL 4 OHM! LEFT CHANNEL + - - + - + As you can see, there is a separate positive and negative post for both 4 ohm and 8 ohm speakers. Use only one pair at a time.
OPERATION MANUAL MODEL : ZMA - ZEN MYSTERY AMP REV 1 MAR 2014 Input Connections The ZMA comes standard with single-ended RCA input jacks rated at 2 volts for maximum power. Transformer balanced XLR inputs are optional and located directly next to the RCA input jacks on either side. If your amp was built with these you can use either balanced XLR inputs or RCA inputs but not both at the same time.
OPERATION MANUAL MODEL : ZMA - ZEN MYSTERY AMP REV 1 MAR 2014 Components Please refer to the diagram below to identify the remaining components of a Zen Mystery Amp.
OPERATION MANUAL MODEL : ZMA - ZEN MYSTERY AMP REV 1 MAR 2014 Installing Tubes Refer to the illustration below for tube placements. Right channel is shown, simply do the same for the left channel. ! OA3 6N23P KT66 KT66 6N23P WARNING: If the amp was plugged into the wall, and the power switch was turned on and then off again, enough time would have passed to fully charge the large 500 volt caps. Do not insert tubes if the 500 volt caps have been charged.
OPERATION MANUAL MODEL : ZMA - ZEN MYSTERY AMP REV 1 MAR 2014 NOTE: The OA3 tubes are different in that they will often flash a few times during start up and during shut down. This is a normal characteristic of the tube. OA3 tubes (also known as VR75’s) do not get hot. Therefor it is safe to hide the bias level controls behind these tubes and safe to put the power switch in front of these tubes.
OPERATION MANUAL MODEL : ZMA - ZEN MYSTERY AMP REV 1 MAR 2014 Biasing your Mystery Amp Biasing your mystery amp is easier than almost every other tube amp on the market thanks to an extremely well thought out and tested set of controls. Left Channel ! Bias Level Right Channel Bias Level Left Channel ! Bias Balance Right Channel Bias Balance These controls consist of four meters (one for each output tube) and four knobs.
OPERATION MANUAL MODEL : ZMA - ZEN MYSTERY AMP REV 1 MAR 2014 STEP 3 Plug in the amplifier and turn on the power switch. As the tubes heat up you will see the bias meters start to rise. After the needles have stopped rising simply use the bias balance control for each pair of meters to make them match. ! STEP 4 Adjust the bias level controls so that the meters read 50ma. 50ma is exactly in the middle of the meter’s range. ! STEP 5 As the amplifier warms up you can re-adjust things.
OPERATION MANUAL MODEL : ZMA - ZEN MYSTERY AMP REV 1 MAR 2014 WARNING This amplifier is designed to operate with a 50ma bias on each output tube. Running higher bias currents for any length of time will overheat the power supply transformers and could cause pre-mature failure. We recommend no more than 60ma per tube at any point. Running less is not an issue for the power supply but doing so will reduce the power output of the tubes and change how they sound.
OPERATION MANUAL MODEL : ZMA - ZEN MYSTERY AMP REV 1 MAR 2014 OPERATION Once the amplifier is on, and the bias meters have risen and settled into their proper position, connect your source to the input of the amplifier and slowly raise the volume.
OPERATION MANUAL MODEL : ZMA - ZEN MYSTERY AMP REV 1 MAR 2014 BURN IN When you receive your Mystery Amp, it will have approximately 72 hours on it, in some cases more. This is accomplished during multiple testing cycles during the QC process. Since this amplifier uses such large capacitors it takes longer than average to fully burn in.
OPERATION MANUAL MODEL : ZMA - ZEN MYSTERY AMP REV 1 MAR 2014 DESIGN This amplifier is designed and manufactured from scratch as the final word in the Zen TORII lineage of amplifiers dating back to the first TORII amplifier in 2002. Intended to be a scaled version of our signature TORII Monoblocks in a single chassis, it evolved to take the unique power supply design a step further to become 100% direct since there are no resistors or chokes used.
OPERATION MANUAL MODEL : ZMA - ZEN MYSTERY AMP REV 1 MAR 2014 Things that determine voicing are all the internal parts, ie., resistors, capacitors, transformers, wire and solder combined with the circuit itself. To take this reference amplifier to a place very few manufactures are able to go, we developed proprietary signal capacitors for the amp.
OPERATION MANUAL MODEL : ZMA - ZEN MYSTERY AMP REV 1 MAR 2014 ABOUT The Zen Mystery Amp is a class A push-pull tube amplifier featuring an ultra linear output stage with zero negative feedback. It is built it a high mass solid steel plate that has been machined and designed to damp out resonances.
OPERATION MANUAL MODEL : ZMA - ZEN MYSTERY AMP REV 1 MAR 2014 SPECIFICATIONS ! OPERATION: CLASS A1 INPUT TUBE CHOICES: 6N23P, 6922, 6N1P,7DJ8 OUTPUT TUBE CHOICES: EL34 6CA7 KT77 KT66 7027 5881 INPUTS: OPTIONAL TRANSFORMER BALANCED XLR INPUTS INPUTS: SINGLE-ENDED RCA INPUT OUTPUTS: 4, 8, or 16 OHM SPEAKERS IDLE CURRENT: 40~60 MILS PER OUTPUT TUBE - ADJUSTABLE HIGH B+ VOLTAGE: 410 VDC WITH LOAD INPUT IMPEDANCE: 100 K OHMS INPUT SENSITIVITY: FULL POWER @ 2.
OPERATION MANUAL MODEL : ZMA - ZEN MYSTERY AMP REV 1 MAR 2014 BALANCED XLR INPUT SPECIFICATION JT-11P-1 LINE INPUT TRANSFORMER 1:1 FOR "BALANCED BRIDGING" INPUTS M M M M M Ideal for balancing any high-impedance unbalanced input Wide bandwidth: !3 dB at 0.25 Hz and 95 kHz Recommended for levels up to +20 dBu at 20 Hz High input impedance: 13 kS S with 10 kS S load High common-mode rejection: 107 dB at 60 Hz This transformer is designed for use in wideband line input stages.
