Secret Stereo

We supply a fantastic range of Classic Car Stereo radios, amplifiers and speakers from Retrosound USA, but what if your car has no position for a radio?

What if the old period radio in your car isn’t working but you want to keep it in the dash for aesthetics’ and still want to listen to music and radio?

You could just use a battery-operated Bluetooth speaker and pair it to your smartphone. Something like this… however, you would need to interact with the phone to control it (not a good idea when driving).

We have a better solution for your car, boat, caravan etc. In fact, anything with a 12-volt negative earth supply can have the Hidden Audio Bluetooth Amplifier Secret Stereo.

The amplifier is tiny:  78 x 100 x 39 mm and will fit in the smallest of spaces. When it is connected to the Bluetooth Interface Controller which can be mounted in, or hang under the dash the magic begins.

Simply pair it up to your phone and you will be able to stream music and control it from the dash.

Better still if you want to listen to the radio you can download radio-player apps (this is a good one).

The beauty of listening to the radio this way is you don’t need to fit an ugly aerial to the car since the signal comes from your mobile phone 3G or 4G cellular connections.

You will need speakers, we have the full range here... or again if the vehicle does not have factory speaker positions we have several solutions for that too….

Read the full specifications for this secret hidden car stereo system.

Bluetooth Interface Controller PXBTC

Add Bluetooth to any audio system with this simple, weatherproof controller. Built as tough as the trails you ride, the PXBTC makes it easy to change the source, volume or track at any speed - on any terrain.

Equipped with a stereo RCA output and 3.5mm AUX input, the Bluetooth Controller automatically pairs with your phone and mutes the music for incoming calls (this unit does not provide hands-free calling).


- Frequency Response - (-3 dB): 20Hz-20KHz

- THD (250mV 1kHz, AUX input, 2.5V output) - <0.01%

- S/N Ratio (AU-Weight) ref 5V, minimum volume - >100dB

- 3.5mm Stereo Aux Input sensitivity - 500mV

- RCA Output Voltage - Max. (1kHz input, 1% THD) - 5V

- Mounting Depth - 2 9/16" (65 mm)

- Protrusion From Surface - 5/8" (16 mm)

2 Channel Amplifier CA75.2

Micro compact super small 2-channel amplifier with a combination of 150W



- Max power output 2 x 75W 4 Ohm

- RMS output 2 x 25W 4 Ohm

- 3.5mm Aux In or RCA Input

- Input Sensitivity - 130mV - 2.5V

- Input level control

- Low pass/High pass filter - 80Hz-120Hz

- Short circuit protection

- Thermal protection

- Dimensions: 78 x 100 x 39 mm


The enclosure has to have at least 5 cm (2”) ventilation space at all sides, to allow the heat to rise away from the amplifier. Be sure that the power and signal cables can enter the enclosure in a straight line, to avoid the risk of malfunction. Always place the power- and signal cables at -opposite sides of the vehicle to reduce any noises. The amplifier should be protected from exposure to moisture and direct sunlight.


Remember to always disconnect battery ground before working on a vehicle’s electrical system! Always place a fuse or circuit breaker no more than 30 cm (12”) from the battery, no greater than the fuse(s) of your amplifier for optimal protection.


     •     First, the +12V terminal is connected directly to the battery of your car. Use a cable of at least 10 mm2, and make sure that the connectors are of the same value.  -    Don’t forget the extra “Vehicle protection” fuse.  -   The +12V terminal should NOT be connected to the car fuse box.

     •     Second, the ground terminal (GND) must be fastened securely to the chassis of the vehicle with the same mm2  cable as the positive cable (the same amount of

power has to run through it). Ensure that all paint, undercoating or any other insulation is removed from the area where you want to make your ground connection to.

     •     Finally, there is still one wire to connect, to switch the amplifier ON or OFF. This is the yellow wire. Connect this wire to the ignition of your vehicle, for switching           ON and OFF simultaneously with the vehicle. Or connect it to a separate switch, so that the amplifier can be switched ON or OFF whenever you want.


     •     Pay attention in connecting your speakers and/or sub-woofers. Be sure to observe correct speaker output connections for the front, rear and their polarity.

     •     Do not use the negative speaker output commonly for left and right speakers (common ground). Improper polarity causes a loss of bass response.

     •     Never connect the negative speaker output to the chassis of your vehicle. This can cause severe damage to your Car Audio System.


     •     Put the input level adjustment knob to the minimum.

     •     Put the volume of your radio to 3/4 of the maximum.

     •     Now adjust the input level of the front channel. Slowly turn up the input level and listen carefully until you hear the amplifier begin to distort. A Caliber Amplifier     “clips” very softly, so this can sometimes be a difficult adjustment. 

Contact us if you would like any more information on this system.

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