ZAPCO ST-64D SQ Mini Amplifier Owner’s Manual

June 5, 2024
ZAPCO

ZAPCO ST-64D SQ Mini Amplifier

ZAPCO-ST-64D-SQ-Mini-Amplifier-
product

A new level of Sound Quality

Zapco has a reputation for sound quality that is unsurpassed. It is our dedication to sonic purity and our passion for performance that built that reputation. With all the new amplifiers coming into the market, none has been any threat to Zapco’s standing as the premier amp and processor company for pure sound quality. Just check out the audio competition scene. The pros know what to use to win. Competition amps, however, do not come cheap, and not everyone wants to compete.  The challenge then was to put Zapco’s 40-plus years of experience to use in the development of an amplifier that would bring Zapco sound a line of products for everyday use and that everyone could afford. And the studio line is just that amplifier. In the time it has been out it has built a reputation as the best-sounding amp in the class. Of course, not everyone buys strictly by sound (although they should). Maybe it’s the wrong color, maybe it’s too big… or too small. But one thing is constant. Everyone who hears the studio amps agrees; it sounds better than any other product in the class.

History of the Studio Series

Perfection cannot be achieved. But that does not make its pursuit less valuable. Zapco is committed to making every product we make better than the last. We introduced the ST-X amps in 2013. In 2015 we improved the PCB design and upgraded components to make the sonically improved ST-X II. Three years ago we introduced the Studio SQ amplifier to take affordable sound quality to a new level. We added the proprietary RCA connectors from the Z-LX amplifiers, changed the capacitors to a higher-end audio cap, and made a few other small changes. All this takes took the Studio sound to a new level of sonic performance for an affordable amplifier. This year we bring you the Studio-SQ III series with a new high-efficiency finned chassis and temperature- controlled fans to assure that your amplifier plays all day long with no problems of overheating, even when you get that urge to really boogie. And with the new chassis, we even made a few tweaks to the internal components to take the sound quality up another notch.

The Studio-D SQ MINI Amplifiers

With the new Studio-D SQ MINI amps, you get the sound quality that other companies offer only in their big competition amps (and better than many of them) in an incredibly compact chassis. But these little beasts aren’t just small, and they aren’t just powerful. They had to earn the Zapco name before we put them into production. They have all the advanced features you would expect… and more. Thanks to a brandnew technology, we are able to use the NXP Class D solution to get amazing power and performance in an incredibly compact chassis with over 90% efficiency. The Mini-Amps Series includes two 4-channel amps with 50 Watts RMS/Ch @ 4Ω (ST-64D  SQ MINI), and 95 Watts RMS/Ch @ 4Ω (ST-104D SQ MINI) at less than 0.5% distortion, and a 530 Watts Mono amp (ST- 501D SQ MINI).m The ST-64D and ST-104D have also the HD Bluetooth Module port, so you can fire up the music on your phone, tablet, or other Bluetooth smart device. Equipped with crossover controls, high and low inputs, sub outputs, etc… they are the perfect choice for any application where the minimum space is important. Efficiency is also very high, so they are optimal for the powerful systems in electric cars.

  • What makes the MINI amps truly amazing are their extremely small sizes.
  • The ST-64D MINI measures only 15,1 cm (6”) x 8,6 cm (3,4”), and the ST-104D MINI is only 23,6 cm (9,3”) x 9,5 cm (3,7”).

Before you start your installation

ZAPCO highly recommends that a fuse or circuit breaker be placed within 18″ of the battery. Although you will add a fuse or fuse block near the amplifier it is still a possibility that a pinched power wire between the component fuse and the battery could result in a short, or even a fire. The protection device should be placed where it can be accessed easily and all wiring should be routed safely and correctly according to the following guidelines:

  • Do not run wiring close to hot or spinning objects
  • Always use wire grommets when routing wire through the firewall or any other metal panels
  • Make sure that the potential for pinched wiring is avoided by routing all wires away from moving objects, including brake, gas and clutch pedals, etc

When connecting our amplifiers to pre-wired stock speakers, care must be taken that there are no common connections between left and right speaker wires, i.e. two or more speakers using the same ground connection (very common in pre-85 cars), as this will cause the amplifier to go into immediate protection or may cause damage to the amplifier. Output connections are not common chassis ground. Please follow the hookup instructions in this owner’s manual. Any questions should be directed to your local ZAPCO dealer.

All Wire is not created equal

Please do not use CCA wire with Zapco amplifiers

It is easy to think of wire as just wire but the fact is there are major differences between the types of wires being offered today. The price of copper has gone up quite a bit lately, but you will notice that you can still buy heavy primary wire at very reasonable prices. How can this be? Simple… That lower price wire is not all copper, it is CCA wire. CCA stands for Copper Clad and Aluminum. That means it is aluminum wire with a thin coating of copper around the outside of the wire. Does it look like copper wire? Absolutely. But does it conduct electrical current like copper? Absolutely NOT!

If the wire does not say OFC Copper wire or Solid Copper wire do not use

it

Two things can and likely will happen:

  • Because CCA wire can not conduct DC electrical current like copper wire can, your amp will not get the current it needs to produce its rated power.
  • That means you get less power and more distortion. It also taxes the amplifier that is trying to make its power, shortening the life of the amp.
  • If the wire does not say OFC Copper wire or Solid Copper wire do not use it.

Two things can and likely will happen:

  • Because CCA wire can not conduct DC electrical current like copper wire can, your amp will not get the current it needs to produce its rated power. That means you get less power and more distortion. It also taxes the amplifier that is trying to make its power, shortening the life of the amp.

Planning your power connections

  • The power end plates of the Zapco ST-D MINI amplifiers carry the power connections and the speaker connections and vary somewhat by the number of channels. The main 12-volt power input, the 12-volt turn-on wire, and the main Ground connection arecommon to both models.
  • The +12V B is the main power input. This must be connected to the vehicle battery’s positive (+) terminal, and the main system fuse should be placed close to the battery
  • The GND is the main ground or negative connection. This must be securely attached to bare metal at the vehicle frame, or another heavy chassis component with a direct connection to the frame

Note: Seat belts and seat belt bolts are NOT good ground points

  • The terminal between the main power and ground is the +12 turn-on input (REM) and can be connected to the head unit turn-on output wire.
  • If none is available it can be connected to an accessory (ACC) terminal. You should avoid using any ignition-on (IGN) wire, as they can be noisy.

Some words about Power and Ground

The second most common cause of underperforming amplifiers is insufficient to power current or a poor power connection. The most common cause of underperforming amplifiers is insufficient ground current or a bad ground connection. 12-volt current: Battery power works only if it travels in a complete circuit from the battery positive terminal to the battery negative terminal. The main power input, of course, is attached to the battery-positive terminal. Ground current is returned to the battery through the chassis to the point where the battery is grounded. The current available for your amplifier to use to produce power will be restricted by the smallest gauge of wire in the circuit and by the weakest physical connection in the circuit.

Wire Size

It’s often surprising how many people will obsess about signal wire but routinely provide the amplifier with only a fraction of the current it needs to do its job. The most common wire gauge used in-car audio is 10-gauge, and the most common location for amplifiers is in the trunk.

Wire Sizing Chart

Let’s look at a fairly small system. If you use a 50 watt/ch amp (25 amps) for the highs and
a 100 watt/ch amp (40 amps) for the woofers, you need at least a 4-gauge and maybe a 2-Guage wire to provide 65 amps at the trunk. Use the Wire Sizing Chart. Add up the fuse values on the amplifier(s) then choose the proper size wire based on the distance from the car battery to the amplifier location. Always use the same gauge wire for the main ground as you do for the main power. Always make your ground as short as possible and secure it to a clean solid surface, preferably the vehicle frame.

Mounting your amplifier

Mounting your Zapco amplifier is easy. Just keep in mind a few guidelines:

  • The amplifier can be mounted in any direction, on wood, metal, or carpet
  • The metal chassis of the amp can be grounded or left isolated
  • The amplifier requires adequate ventilation. Creating power creates heat, and cooling requires air. Position the amplifier with sufficient surrounding area for air supply and keep the end plates clear for future access
  • Keep the amplifier out of the engine compartment or other locations that may cause excessive heat or moisture
  • Do not mount the amplifier to a subwoofer box or other place that may have excessive vibration

Setting Gains: Gain pots are not volume controls. Before you first turn on your system, you should make sure all gain controls are set to a minimum. Gain controls should be used only if absolutely necessary. Turning up gain controls causes increased noise, makes distortion more likely and reduces the dynamic range of your system. If your head unit does not have sufficient output, you will get much better results by investing in a line driver to provide more signal to the amplifier.

ST-64D SQ MINI Controls/Speakers

  1. Comm Port for HDR-BT Module

  2. Rear channels variable gain control

  3. Rear crossover function switch for high pass, full range, or low pass

  4. Rear Low Pass frequency control

  5. Rear channels Variable Bass Boost

  6. Green power-on LED and red protect LED

  7. RCA input and Preamp output (see labels on harness)

  8. Speaker level input plug for OEM hookup

  9. Front channels variable gain control

  10. Front High Pass frequency control

  11. Ch1/2 speaker output (Ch1+/Ch2- Bridge)

  12. Ch3/4 speaker output (Ch3+/Ch4- Bridge)

  13. +12V at Battery positive terminal

  14. Turn-on trigger wire

  15. Ground to frame or chassis part directly connected to the frame

ST-104D SQ MINI Controls/Speakers

  1. Input mode 2Ch/4Ch

  2. Front crossover function switch for high pass or full range

  3. RCA input and Preamp output (see labels on harness)

  4. Rear crossover function switch for high pass, full range, or low pass

  5. Comm Port for HD-BT Module

  6. Front High Pass frequency control

  7. Front channels variable gain control

  8. Rear channels variable gain control

  9. Rear High Pass/Low Pass frequency control

  10. Ground to frame or chassis part directly connected to the frame

  11. Turn-on trigger wire

  12. +12V at Battery positive terminal

  13. Speaker level input plug for OEM hookup

  14. Ch1/4 speaker output (Ch1+/Ch2-, Ch3+/Ch4- Bridge)

ST-501D SQ MINI Controls/Speakers

  1. RCA In/Out (Linked)

  2. Variable gain control

  3. Low Pass frequency control

  4. Bass boost frequency control sets the center point of the boost

  5. Subsonic filter

  6. Green power-on LED and red protect LED

  7. Master/Slave selector when linked

  8. Remote control

  9. RCA input (see labels on harness)

  10. Phase selector

  11. Ground to frame or chassis part directly connected to the frame

  12. Turn-on trigger wire

  13. +12V at Battery positive terminal

  14. Speaker output

Strapping the ST-501D SQ MINIZAPCO-ST-64D-SQ-Mini-Amplifier-
fig-10

The ST-501D SQ MINI amplifier is a true mono unit and you can double its power by “strapping” two units of the same model together to drive a single voice coil. Always keep in mind that each amp must see a minimum load of 2 Ohm (1V per amp).

  • Decide which amplifier will be the “master” and which will be the “slave”, and move the LINK selector to the corresponding position
  • Connect the head unit output (Full range or bass if available) to the LOW (RCA) input of the master amplifier
  • Connect the RCA link of the master amplifier to the RCA of the slave amplifier with a single RCA cable
  • Connect the Bass Remote to the Remote In of the master amplifier

The master amplifier is now the control amplifier. All the adjustments you make to the bass remote and to the master amplifier’s other controls will be transferred to the slave amplifier, and the slave amplifier will be driving the negative side of the signal and have no control functions of its own. Go to Pag. 18 to see how to strap the outputs.

Speaker Wiring

The Very Basics

No speaker wires can be shorted to, or touch either ground or each other. This will put the amp into protection and may damage the amplifier. When bridging the left and right channels of any ST-D SQ MINI amplifier, you use the left channel (Ch1) positive and the right channel (Ch2) negative, as indicated on the chassis by the speaker terminals.

4-Ch. Amplifier – Stereo Mode

  • A simple 4 channels hookup for a right and left stereo pair.

4-Ch. Amplifier – High Power 2-Ch. Mode

Similar to bridging a stereo amp to a mono woofer, you can use the 4-Ch amp in a dual-mono mode to create (in this case) a stereo amp with 150 watts (ST-64D) and 240 watts (ST-104D) RMS/ch. As with any bridged setup the speakers must be a minimum of 4Ωmimpedance. If you are using the active crossovers you should be sure that they are set to the same frequency.

4-Ch. Amplifier – 5-Ch. ModeZAPCO-ST-64D-SQ-Mini-Amplifier-
fig-13

A 3-way system with front stage, rear stage, and subwoofer in mixed mono configuration. The 5-speakers system requires a passive crossover between the front highs and the mono woofer, with capacitors on the front highs positives and a coil on the woofer positive. All amplifier channels are full range.

Mono Amplifier – Single Voice Coil SubwooferZAPCO-ST-64D-SQ-Mini-
Amplifier-fig-14

Mono Amplifier – Strapping the Outputs

  • Connect the master amplifier’s speaker output + terminal to the + (positive) terminal of the woofer
  • Connect the slave amplifier’s speaker output + terminal to the – (negative) terminal of the woofer
  • Connect the two amplifier’s speaker output – (negative) terminals together

You are creating a much more powerful amplifier in this way and doubling the output. Make sure your speaker wire can transfer the power, we recommend a minimum of 12 gauge speaker lead, and for best performances, you should use 10 or 8 gauge.

Mono Amplifier – Double Voice Coil SubwooferZAPCO-ST-64D-SQ-Mini-
Amplifier-fig-16

Technical Specifications

ZAPCO-ST-64D-SQ-Mini-Amplifier-
fig-17

Continuous exposure to excessive sound pressure levels may cause permanent hearing loss. ZAPCO strongly advises that you use common sense when setting volume levels. Everything written in this manual is for the proper use of the products. Some features or specifications could be modified during production to improve product performance. The technical specifications and functionalities stated here are current as of the time of publication. General instructions and safety warnings are intended in any case to be always effective for this type of product. The latest manual with any updates is always available at www.zapco.com/download

  • APEX USA:  ARPA of AMERICA, 801 Davis St. Unit C, Vacaville, CA 95687 – USA
  • APEX EUROPE: APEX Europe Srl, Via Della Meccanica, 14 – 04011 Aprilia (Latina) – ITALY – PI 02496950599
  • APEX GROUP:  APEX Business Development (ABD) CO LTD, Bright Way Tower, office 04 7/Fl, 33 Mong Kok Road Kowloon City, Hong Kong 999077
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