tinybox specification

tinybox portable microphone amplifier
tinybox was discontinued in 2015.

Naiant no longer supplies replacement batteries for tinybox.  The replacement Li-ion and NiMH battery packs may be purchased directly from the vendor.  The customer must terminate the battery pack to the tinybox connector.  On request, Naiant can supply replacement connector pins without charge.

Input configuration

  • 6-pin mini-XLR male jack
  • stereo 3.5mm TRS minijack
  • 5-pin Binder® series 711 female jack

The mini-XLR input/output pin configuration is as follows:


pin 1: low-voltage mic power supply, right submix input, right line output, or ground
pin 2: right noninverting input
pin 3: left noninverting input
pin 4: high-voltage mic power supply, left submix input, left line output, or ground
pin 5: right inverting input
pin 6: left inverting input

chassis: ground

Each signal input pin may be configured as a power pin and/or signal pin, with or without DC termination. This allows the pairs of signal pins (noninverting and inverting) to be used to support different microphone types. For example, the inverting inputs can be configured for plug-in power microphones (which are typically reverse signal polarity), and the noninverting inputs together with the microphone power supply pins 1 and 4 may be used with “three-wire” lapel microphones.

The microphone power supply pins 1 and 4 may be used to enable many different custom configurations. For maximum flexibility, all signal pins may be left unpowered and supply resistors may be located in external cable connectors to enable support for each type of required microphone. In this manner, a single tinybox can support multiple microphone types.

The high-voltage microphone power supply offers +54V capsule polarization with maximum current of 100uA to enable certain “active” microphone capsules to be directly connected to tinybox, or +48V for P48 phantom powered-microphones with a maximum of 6mA per microphone.

Output configuration

tinybox with cables

  • 3.5mm TRS minijack with direct line, line/headphone, 50V tolerant, mid/side decode/encode, channel offset trim, or submix output options
  • optional output transformer (600Ω:600Ω)
  • optional direct line output (pre-transformer) on 6-pin mini-XLR
  • optional dual minijack output with several available functions

tinybox is a one- or two-stage amplifier device; the 6-pin mini-XLR input pins (2,3,5,6) are routed to the microphone amplifier, with configurable gain of +0dB to +44dB (+56dB max with low-noise amplifier option). The direct line output is sourced from the input amplifier stage; with output impedance of 220Ω, it is capable of driving loads to 2kΩ.  The output of the microphone amplifier is internally routed to the output amplifier, connected to the front panel minijack output. The output amplifier has five possible configurations: line/headphone, 50V tolerant, mid/side decode, channel offset trim, or mixer.

The standard line/headphone output is capable of driving line loads to +13dBV, and low- to high-impedance headphones (16Ω to 300Ω) at up to 175mW per channel. The main minijack output may be internally attenuated (fixed attenuation) to calibrate desired direct output and headphone output levels. This option can be customized for a selected headphone impedance. Alternatively, the customer may wish to use an external inline headphone attenuator.

The headphone amplifier circuit uses a modified class G power supply, which increases efficiency for low-impedance loads while maintaining maximum possible headroom for high-impedance loads. This circuit can reduce output amplifier power consumption by up to a factor of two compared with a standard class AB amplifier.

The 50V tolerant output has output impedance of 7Ω, and is capable of driving loads to 600Ω.  It is recommended where the tinybox output may be exposed to a phantom-powered input.  The direct line output will tolerate external DC voltage to 16V; the headphone amplifier should not be exposed to external DC voltage.

The mid/side decode feature enables monitoring of a mid/side microphone pair as left/right (or a left/right pair as mid/side).

The channel offset trim allows gain offset of up to 9dB between channels. Nominal gain is +3dB; maximum gain is +11dB at full offset (+2dB gain on opposite channel). Offset trim is set with internal trimpot accessed via a hole in the top of the case. A small phillips head screwdriver is required to set trim. Channel offset trim may not be combined with headphone or transformer output.

The mixer configuration enables use of pins 1 and 4 on the 6-pin mini-XLR input connector as a submix input mixed with the output of the microphone amplifier.

Maximum headphone output power is reduced with mid/side decode, channel offset trim, or mixer configurations, but line level headroom is maintained at +13dBV.  Where these alternate outputs may be exposed to external DC voltage, tinybox will be configured with a 50V tolerant output instead of the headphone output option.  The 50V tolerant output will limit load-driving capability to 600Ω.

The direct line output from the microphone amplifier is available on the 6-pin mini-XLR connector, bypassing the output amplifier stage or output transformers. The direct line output can also drive a 2kΩ or greater line load to +12dBV (headphones not recommended with 6-pin line output feature). The direct line output and main line/headphone outputs are independent and may be used to drive separate loads simultaneously to monitor while recording.

The dual minijack output option can be selected with several configurations: pre- and post-transformer, transformer balanced, direct and headphone out (may also be used to select two different headphone levels). The output amplifier can also be configured with gain or attenuation, where the dual output jacks may operate as high/low gain range. The output amplifier can be configured as a low-cut output with customized corner frequency and slope (first- or second-order), such that the dual minijack outputs provide a flat/bass rolloff EQ selection.

Due to space constraints on the tinybox panel, the spacing between jacks is 8.5mm OC. Thus, narrow gauge plugs are required for both outputs to be used simultaneously.

Microphone power options and power switching

  • +12V, +16V, or switchable +16V/+48V phantom power
  • +8V plug-in power
  • +8V power for “three-wire” lapel-style microphones (balanced or unbalanced configuration)
  • +12V T-power
  • +54V capsule polarization voltage (switchable to +16V for -10dB attenuation at capsule)
  • optional three-position customizable power switch
  • available high-impedance 1/4″ jack input adaptor cable

The master power switch (rightmost switch on the front panel) may be a two-way (on/off) or three-way switch (on/off/on). Three-way switching has several customizable options; it may operate either as a line/mic input switch (turns microphone power off and headphone output amplifier to low impedance in line mode) or a high/low microphone power switch (to select between microphone power options or phantom power voltage).  When the power switch is configured as a high/low selector, the voltage supplied as the phantom or capsule polarization supply will switch between either +48V (phantom) and +54V (capsule polarization for active systems) on high and +8v or +16V on low, according to the required input configuration.

For phantom power, using +16V phantom can result in decreased power consumption and a corresponding increase in autonomy for microphones that can support operation on low voltage.  For “active” remote capsule microphones, the high power setting provides full capsule polarization voltage at +54V (may be set lower as required), while the +16V low power setting reduces capsule sensitivity by -10dB, which increases the maximum SPL handling of the capsule and reduces the input level to tinybox.  If the low voltage power supply is set to +8V, that will act as a -16dB capsule attenuator.

The switching options for each pin (if powered) and the output amplifier are:

pin 1: low-voltage microphone power on/off
pin 2: microphone power on/off
pin 3: microphone power on/off
pin 4: high-voltage microphone power on/off
pin 5: microphone power on/off
pin 6: microphone power on/off

output amplifier: high-impedance/low-impedance mode

The output amplifier mode switches to a lower voltage supply for higher efficiency (net maximum 40% vs. 25%) with low-impedance headphones (<100Ω)

The high-impedance input cable incorporates a discrete FET buffer inside a 1/4″ jack to 6-pin mini-XLR cable, offering 1MΩ input impedance. The adaptor cable may be mono, stereo, or dual 1/4″ jack, balanced or unbalanced input.

Gain control

  • Stereo three-position configurable gain switch
  • +0dB to +44dB gain range for either standard or high-efficiency amplifier
  • +0dB to +56dB gain range for low-noise amplifier
  • Standard gain settings: +4dB, +18dB, +32dB

Gain is set via the three-position gain switch (centered on the front panel).  The standard gain settings are +4dB (middle position), +18dB (bottom position), and +32dB (top position).  tinybox has three input amplifier options; standard, low-noise, and high-efficiency.  The standard tinybox amplifier offers an excellent compromise between low input noise and power efficiency; it is recommended for all condenser microphones.  The optional low-noise microphone amplifier provides reduced equivalent input noise at the cost of higher current consumption. It is mainly recommended with low-sensitivity balanced-output microphones, including dynamic microphones. Standard gain settings for low-noise amplifier are +4dB, +21dB, +42dB.  The high-efficiency amplifier offers increased autonomy with adequate noise performance for most condenser microphones with sensitivity of -37dBV/Pa or higher, when used in typical recording environments.

The optional output amplifier may be configured with additional gain as required, either to supply a higher maximum gain, or together with the dual output option to provide additional gain settings.

Metering & Power

tinybox v1_5 front and rear

  • Front panel green/red LED indicates power, clipping, and low battery.
  • Rear panel green/red LED indicates charge status.
  • Internal rechargeable 4.8Wh NiMH battery

The front panel LED is a dual green/LED that has three functions.  The front panel LED will glow green when unit is switched on; it also acts as a low battery indicator which will light red when the battery voltage drops to +5.5V (at 20% remaining battery life). The front panel LED will also briefly light red at signal clipping—the meter threshold may be customized upon request. Standard clip LED setting is +6dBV (7dB headroom above clip indication).

The internal rechargeable NiMH battery provides 800mAh at +6V, for life of 4.8Wh. Battery is recharged via 2.1mm center-positive power jack. When the charger is connected, power supply to tinybox will be interrupted and tinybox will not operate properly. While tinybox will not be damaged if left on while charging, since normal function is not possible tinybox should be switched off.  The charger is rated for 100VAC to 240VAC input; US-style plug. International adaptor plugs are not supplied by Naiant.

The rear panel green/red LED is active only when the charger is connected.  It will indicate red while charging and green for full charge.  Because tinybox was not originally designed to use the NiMH battery pack, the rear panel LED may not switch to green at full charge, but continue to indicate red even when the NiMH battery is fully charged.  The NiMH battery will be fully charged after six hours of charging.  tinyboxes that are equipped with the original Li-ion battery pack will accurately indicate charge status.

tinybox v2.1 and later (with rear panel LED) may be recharged with any supply from 9-15VDC, center-positive; 0.3A minimum required for maximum charge rate.

tinybox v2.0 and earlier (without rear panel LED): to avoid risk of battery damage and possible fire, charger provided by Naiant (8.4VDC with regulated charge current) must be used to recharge battery.

Battery removal procedure

Remove the tinybox battery using the following steps, and reverse for reinstallation.

  • remove rear jack nut;
  • remove rear jack screws;
  • remove rear panel;
  • NiMH battery packs have five-cell battery packs.  NiMH battery packs do not need to be removed for shipment.
  • Li-ion battery packs have two-cell battery packs.  Li-ion battery packs must be removed before shipment.  DO NOT return a Li-ion battery pack when sending tinybox for service.  Retain the Li-ion battery pack if you intend to reinstall upon return, or if you are having your tinybox converted to NiMH, dispose of the Li-ion battery pack in accordance with your local regulations.
  • remove input jack nut;
  • remove front panel screws;
  • slide front panel/PCB assembly with battery out of the front of the case;
  • disconnect battery.

If the tinybox has a belt clip, then it will also be necessary to remove the front panel in order to remove the battery. Together with the input jack nut and front panel screws, remove the output jack nut to remove the front panel. Slide the PCB assembly backward with the battery to remove.

tinybox version history

blue tinybox

v1 (May 2010 to January 2011): +16V maximum microphone power, 5-pin mini-XLR input.

v1.5 (February 2011 to January 2012): +45V polarization, 6-pin mini-XLR input, headphone output option.

v2 (February to May 2012): +48V phantom power, +54V polarization, increased headphone output power, mid/side, mixer, and transformer output options.

v2.1 (May and June 2012): internal battery charge regulation.

v2.2 (July 2012 to April 2013): channel offset trim, dual minijack output options.

v2.3 (May and June 2013): switchable polarization voltage (+16V/+54V) for “active” remote microphones.

v2.4 (July 2013 to March 2014): second-order low-cut option on output amplifier.

v2.5 (April 2014 to March 2015): NiMH battery replaced former lithium-ion battery.

tinybox Specifications:

v2 and later:

Type: two-channel battery-powered microphone amplifier.

Phantom Voltage: +48V supplied across 7kΩ equivalent resistance, +16V supplied across 1.2kΩ (16V only) or 2.2kΩ resistors (switchable 16V/48V), or +12V supplied across 680Ω resistors
Phantom Current: 6mA max per microphone, +48V; 14mA per microphone, +16V
Plug-in Power: +8V supplied across 6.8kΩ resistor, 1mA maximum
“3-wire” Power: +8V supplied across 6.8kΩ resistor, 1mA maximum
T-Power: +12V supplied across 180Ω resistor, 5mA maximum

Current (from 6.0V NiMH battery):

  • Standard amplifier, no microphone power load: 20mA
  • Standard amplifier, +48V phantom power, 5mA per mic load: 120mA
  • high-efficiency amplifier, no microphone power load: 20mA
  • high-efficiency amplifier, +48V phantom power, 5mA per mic load: 120mA
  • low-noise amplifier, no microphone power load: 50mA
  • low-noise amplifier, +48V phantom power, 5mA per mic load: 150mA
  • maximum load: 300mA

Typical autonomy, standard amplifier, low-voltage (8V) and “active” remote capsule microphones: 12 to 30 hours
Typical autonomy, standard amplifier, +16V phantom power: 8 to 24 hours
Typical autonomy, standard amplifier, +48V phantom power: 4 to 10 hours

Input Impedance: set by microphone power supply resistors
Input Impedance, high input impedance adaptor cable: 1MΩ
Output Impedance, direct line output: 220Ω
Output Impedance, line/headphone output: 7Ω (12Ω for alternate* output)

* alternate output: channel offset trim, mixer, or mid/side decode

Minimum Load Impedance, direct line output: 600Ω
Minimum Load Impedance, line/headphone output: 16Ω

Gain Range: +0dB to +44dB; standard settings +4dB, +18dB, +32dB
Gain Range, low-noise amplifier: +0dB to +56dB; standard settings +4dB, +21dB, +42dB

Maximum Input Level, 1kHz @ 1% THD: +13dBV
Maximum Output Level, direct line output, 1kHz @ 1% THD: +12dBV
Maximum Output Level, transformer output, 100Hz: +8dBV
Maximum Output Level, line/headphone output (high/low power/alternate output), 1kHz @ 1% THD:

1KΩ load: +13dBV/+8dBV/+13dBV
600Ω load: +12dBV/+8dBV/+12dBV
300Ω load: 65mW/23mW/65mW
200Ω load: 90mW/35mW/90mW
100Ω load: 150mW/60mW/150mW
50Ω load: 175mW/110mW/150mW
16Ω load: 160mW/160mW/125mW

net efficiency*, 100Ω load, 60mW: %/%
net efficiency*, 16Ω load, 160mW: 25%/40%

* net efficiency figure includes power loss to DC converter and power regulation circuits.

Total Harmonic Distortion, direct output, 10KΩ load, 1kHz @ 0dBV: <0.005%
Total Harmonic Distortion, headphone output, 10KΩ load, 1kHz @ 0dBV: <0.005%
Total Harmonic Distortion, transformer output, 10KΩ load, 1kHz @ 0dBV: 0.1%
Total Harmonic Distortion, transformer output, 10KΩ load, 100Hz @ 0dBV: 2.0%

Frequency Response: 20Hz to 30kHz
Frequency Response, transformer output: 30Hz to 30kHz

Equivalent Input Noise, maximum gain, standard amplifier: -121dBV unweighted; -124dBA
Equivalent Input Noise, maximum gain, high-efficiency amplifier: -115dBV unweighted; -119dBA
Equivalent Input Noise, maximum gain, low-noise amplifier: -125dBV unweighted; -128dBA

Dynamic Range, minimum gain, standard amplifier, unweighted:  125dB

Crosstalk (inputs with 100Ω termination): -70dB @ 1kHz; -50dB minimum across 20kHz bandwidth (certain input and dual output configurations may degrade crosstalk below 100Hz to -30dB).

Common Mode Rejection Ratio: 50dB minimum across 20kHz bandwidth

Case size:  80mm x 54mm x 23mm (3.2″ x 2.1″ x 0.9″)
Weight (with battery):  143g (5 oz)

v1 and v1.5, production dates before February 2012:

Type: two-channel battery-powered microphone amplifier.

Phantom Power: +16V supplied across 1.65kΩ resistors or +12V supplied across 680Ω resistors, 14mA maximum current per microphone
Plug-in Power: +8V supplied across 5.6kΩ resistor, 1mA maximum
“3-wire” Power: +8V supplied across 3.3kΩ resistor, 2mA maximum
T-Power: +12V supplied across 180Ω resistor, 5mA maximum
Polarization voltage (v1.5): +45V supplied across 38kΩ resistance

Current (from 7.4V Li-ion battery), +16V, no microphone power load: 11mA
Current (from 7.4V Li-ion battery), +16V, 5mA per mic phantom power load: 50mA
Current (from 7.4V Li-ion battery), +16V, maximum load: 100mA
Estimated battery life in normal use: 12-20 hours

Input Impedance: set by microphone power supply resistors
Output Impedance, direct output: 150Ω
Output Impedance, high-current output (v1.5): 10Ω
Minimum Load Impedance, direct output: 1kΩ
Minimum Load Impedance, high-current output (v1.5): 32Ω (>50Ω recommended)

Gain Range: +0dB to +44dB, standard settings of +4dB, +18dB, +32dB

Maximum Input Level, 1kHz @ 1% THD, +12V: +10dBV
Maximum Input Level, 1kHz @ 1% THD, +16V: +13dBV

Maximum Output Level, direct output, 1kHz @ 1% THD, +12V: +10dBV
Maximum Output Level, direct output, 1kHz @ 1% THD, +16V: +13dBV

Maximum Output Level, high-current output, 1kHz @ 1% THD, +16V/+12V (v1.5):

10KΩ load: +11dBV/+8dBV
600Ω load: +10dBV/+8dBV
300Ω load: 35mW/20mW
200Ω load: 45mW/30mW
100Ω load: 40mW/35mW
50Ω load: 30mW/30mW

Total Harmonic Distortion, direct output, 1kHz @ 0dBV: <0.005%
Crosstalk, 1kHz @ 0dBV: -80dB
Frequency Response: 20Hz to 30kHz
Equivalent Input Noise, maximum gain: -115dBV unweighted; -119dBA
Common Mode Rejection Ratio: 50dB minimum

Case size:  80mm x 54mm x 23mm (3.2″ x 2.1″ x 0.9″)
Weight (with battery):  143g (5 oz)

Notice of FCC compliance

Pursuant to section 15.103(h), tinybox is exempt from Part 15 of the FCC rules.  tinybox qualifies for exemption as the highest frequency generated by the device is less than 1.705MHz, and it does not operate from the AC power lines or contain provisions for operation while connected to the AC power lines.  The internal NiMH battery is designed to be recharged with the supplied charger. When connected to the charger and AC power lines, the unit’s DC converter circuit is disabled and thus does not operate as an unintentional radiator while charging.  tinybox should be switched off during charging as normal operation is not possible.