TRN BT20 Truly Wireless Adapter – Review


TRN BT20 Truly Wireless Adapter

| Bluetooth |

🎧 We are reviewing the TRN BT20, a Bluetooth adapter with the capability to turn into truly wireless nearly every earphone on the market.

The fundamental benefit of the TRN BT20 is that you can transform any of your favorite in-ear headphones with detachable cables into a sort of Alpha & Delta JAAP – even if your model has a bi-pin 0.75mm, bi-pin 0.78mm or MMCX cable connector.

The main difference of the TRN BT20 with other Bluetooth cable/adapters like the TRN BT3, KZ Bluetooth cable, KZ Bluetooth Waterproof cable is that TRN BT20 has no cables attaching each side to each other – they are truly wireless.

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TRN BT20 Truly Wireless Adapter Review

Tests & Scores


Operation & Control

The remote of the TRN BT20 Truly Wireless Adapter has 1 button per side that allows you to do the following:

  • 3 second press and hold: Power On
  • Longer press and hold: Power On and set to pairing mode
  • A single press: Play, Pause music
  • Double press: Skip to next song (according to manufacturer), during our tests a 2x press redialed the last number called but did not skip tracks.
  • Triple press: Previous track (according to manufacturer), during our tests a triple press had no effect.

Calls Commands:

  • Single press: Answer/End call

LED Status Light: The TRN BT20 have one LED light per earpiece, right below the multifunction button. These lights allow the user to easily know the status of the unit.

Charging: To charge the TRN BT20 users need to open the rubber gasket on the bottom of the units and connect them with the bi-ended male micro USB cable (included with the package). The brand recommends to charge the device with a power adapter that can provide 5V 1A – a full charge should take 2 hours.

Battery life: According to the brand, the TRN BT20 can provide as much as 6 hours of battery life – through out our tests the unit was able to run for +/- the 6 hours stated.



Accessories & Packaging

The TRN BT20 Truly Wireless Adapter come in rectangular packaging that is nearly identical to the one of the TRN IM1, with a clean design and a book-like sideways opening with a magnetic closure system.

After unboxing the TRN BT20 you will find the charging cable and no other additional accessories.



Design of the TRN BT20 Truly Wireless Adapter is fairly basic with no special design details nor accentuated forms.

The hook section of the unit is rubberized and flexible but not moldable and will always revert to it’s original form.

Each side has a single, multifunction button that can control the unit.

gramophone-25660    3.25/5

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TRN BT20 Truly Wireless Adapter weight in Ounces and TRN BT20 Truly Wireless Adapter weight in grams.

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Size & Dimensions

The TRN BT20 is a small Truly Wireless adapter with reduced size and dimensions, specifically:

  • Hook girth: 2.4mm
  • Module height: 10.5mm
  • Module length: 45mm
  • Module width: 17mm
  • Overall Weight: 6.25 g (per side)

gramophone-25660  4.5/5

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TRN BT20 and Alpha and Delta JAAP
TRN BT20 and Alpha and Delta JAAP



The TRN BT20 Truly Wireless Adapter can be bought with a bi-pin 0.75mm, bi-pin 0.78mm or MMCX cable connector – being these connectors among the most diffused and popular on the market, the TRN BT20 becomes with an endless amount of in-ear monitors/earphones with detachable cables.

Some insane combinations of unimaginable true wireless headphones that can be made include the (but not limited to):

gramophone-25660  5/5

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TRN BT20 with TRN V80
TRN BT20 with TRN V80
TRN BT20 with KZ AS10
TRN BT20 with KZ AS10


Construction & Build

The TRN BT20 Truly Wireless Adapter costs just a couple of dimes/bucks and the ultra-cheap price comes at a cost, construction quality and aesthetics.

The entire unit is made of plastic, with a plain and dull look with no bells nor whistles – at the end of the day this is an accessory for functionality and not for runway models.

You will not be getting the same construction quality of the Alpha and Delta JAAP but you will get many of the freedom features of the JAAP for a couple of bucks.

gramophone-25660     3/5

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TRN BT20 and Alpha and Delta JAAP
TRN BT20 and Alpha and Delta JAAP



The TRN BT20 have a modern Bluetooth v5.0 which gives them fast transfer rates and low latency with mild lag and non too frequent signal drops, with brief disconnection of one side – this is a pretty normal issue with truly wireless headphones that the TRN BT20 exhibited far less often than many truly wireless headphones that we have tested to date.

gramophone-25660   4/5



Any audio signal that gets transmitted through Bluetooth from one device to another goes under a much more complex process than a direct wired connection.

This process involves elements such as audio processing, signal conversions, data transmission, Bluetooth codecs, etc. and can consequently modify the sound properties and/or quality of the original audio signal.

In the case of the TRN BT20, the device works flawlessly, being able to provide a clean and neutral audio response. This translates in non-modified sound, nor boosted nor recessed.

After measuring the frequency response curve of the TRN BT20 we could verify that the TRN BT20 does not boost nor recesses the sound on any frequency range (except above 20kHz, though an irrelevant range for 99.999% of listeners), remaining flat and pure.

In addition to this, the unit has a very strong volume output.

gramophone-25660  4.75/5

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TRN BT20 with TFZ Series 2 and BQEYZ BQ3
TRN BT20 with TFZ Series 2 and BQEYZ BQ3



The small unit fits snugly behind the ears and cannot be seen nor protrudes as the A&D JAAP. On the other hand, this makes it also sit a bit more on the back of the ears and could be a bit tight and too precise for users with bigger ears.

Still the super light weighted units, being only 6.25 gr. per side makes them weight far less than any detachable cable.

gramophone-25660   4/5


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TRN BT20 with KZ BA10
TRN BT20 with KZ BA10

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Scores Scores

TRN BT20 Truly Wireless Adapter Scores

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TRN BT20 with KZ ZSN
TRN BT20 with KZ ZSN

Frequency Response (raw)

TRN BT20 Truly Wireless Adapter Frequency Response Curve

TRN BT20 frequency response curve
TRN BT20 frequency response curve with TFZ series 2

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TRN BT20 Truly Wireless Adapter Technical Specifications

TypeTruly Wireless
Connectors optionsBi-pin 075mm, bi-pin 0.78mm, MMCX
Battery life6 hours
Charging time2 hours
Charging current5V 1A
Bluetooth version5.0
Charge connectorMicro USB

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We highly discourage anyone from trying to apply our testings to your own earphones, the risk of damaging or permanently breaking your iems is absolutely probable to happen. With our standardized equalization and amplification tests we push the limits of the earphones to the extreme. If anyway you decide to do so, we cannot be held responsible of the damage done to your equipment. Do it at your own risk.






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