Simolio SM-621D Wireless TV Speaker Review

The Low-Down!

Simolio’s SM-621D Wireless TV Speaker is a great device for those that are hard of hearing. It allows the user to hear the dialog of their favorite television shows better without disturbing the rest of the household. It also works great as a wireless headphone connection. As a limited-range wireless speaker used for music playback, you’re better off getting a speaker dedicated to high-quality music playback.

simolio wireless tv speaker

Simiolio SM-621D

Frequency Range:
100 Feet


6 Hours

Battery7.4V / 1000mAh Lithium-Ion Battery
Power Connections2 x 9V / 1.5A PSU’s with DC 4.0 x 1.7mm barrel jack
Battery Charge3 hours charge (not in use)
Battery Duration6 hours discharge (in use)
Weight2.9 pounds
Dimensions10.67 in x 9.65 in x 4.49 in
Speaker DriversDual 2,5 Watt, 6 Ohm
Base Station Input ConnectionsOptical Audio (PCM), ⅛-inch AUX
Speaker Connections⅛-inch AUX Input, ⅛ inch AUX Output
Built-In EQ OptionsTreble, Normal, Bass
Front ControlsVolume
Volume ControlAutomatic Signal Control (ASC)

Simoilio (or Shenzhen Simolio Electronic Co., Ltd) makes audio products specializing in listening devices designed for people that are hard of hearing. Having said that, their products aren’t only suited to the elderly or hearing impaired – many people might find the benefits of their products useful in their lives.

The Simolio SM-621D Wireless TV Speaker is an ingenious device, allowing users to connect a base station to their television audio output and wirelessly monitor the audio at up to 100 feet away. This isn’t limited to only television audio, but any audio devices with compatible output connections.

Simolio offers other products like the SM-825D Pro Voice Enhanced TV Headphones, which do a very similar job to the SM-621D, but output to headphones only.


The Simolio SM-621D is a fairly compact set consisting of a base station and a removable set-top speaker. It comes in two colors, black and blue. For both colors, the base station is completely black plastic, with a status LED on the front.

The speaker is primarily black plastic with a gray (black model) or navy blue (blue model) mesh speaker covering, also with a status LED on the front below the speaker mesh. The Simolio name sits above the speaker mesh in white on the black model and white with a red background on the blue model.

The speaker fits onto the base station snugly using two block guides, one of these blocks houses the charging connection. The rear of both the base station and the speaker host the power and audio connection options.

The unit stands just under 11 inches tall, with the speaker on the base station. The speaker is lightweight for its size, coming in at just under 3 pounds.

Blue Simolio Wireless TV Speaker Features


The Simolio SM-621D features a 2,4GHz wireless link between the base station and speaker, allowing the units to be 100 feet apart without any signal loss. Automatic Frequency Hopping Spread Spectrum (FHSS) technology is employed to ensure minimal interference, allowing two units to be used simultaneously no less than 30 feet apart.

The base station’s audio connections provide a ⅛-inch AUX input, and it ships with two cables allowing stereo RCA and 1/8-inch AUX connection to your television or audio device. If you need to connect a digital device to the base station, an optical connection is provided with an optical cable. Bear in mind that this digital connection only supports PCM audio streams, so consult your audio device’s specifications to see if it is compatible.

The wireless speaker’s audio connections provide ⅛-inch AUX input and output. When the output AUX is connected, the speaker is muted. This output is meant to connect to headphones for listening when others nearby don’t want to be disturbed. The AUX input lets you connect your mobile phone or other devices close to the speaker.

Powering the units is relatively straightforward; it comes with two identical power supplies, one for the base station and the speaker. The speaker has a battery compartment housing a replaceable Lithium-Ion battery, which allows the speaker to operate remotely for up to 6 hours, depending on the output level. The battery reaches full capacity in 3 hours by either placing it on the base station or connecting it remotely to the power supply.

Once an audio source is connected to the base station or the AUX input, the volume is controlled by the large volume knob on the front of the speaker, which also serves as the power button. Further audio level control is built into the speaker for safety, but it is not user-controllable. This is an audio-level limiting circuit called “Automatic Signal Control (ASC)”.

It will control any loud noises, like plugging input connectors into the base station or speaker while the speaker is active. It will also mitigate program-level changes to a certain degree, although I doubt this will be very effective if the advert breaks are much louder than the program content.

As this speaker was designed for the hard of hearing, there are 3 EQ settings that the user can engage: Treble, Normal, and Bass. You can compensate high or low frequencies depending on the user’s hearing deficit. Another feature built into the SM-621D is “Voice Highlighting Tech”, which increases the content’s dialog level for better intelligibility. The EQ is user-controllable, but the voice highlighting is not, so this might be a detraction if you want to use this speaker for listening to music.

Back of SIMOLIO_Wireless_Portable_TV_Speakers


Battery and Power

As handy as it is to have a speaker that can be both powered by a battery or by a connected power supply, it could lead to a potentially hazardous situation. Lithium-Ion batteries like to be treated in a particular way to allow for safe and sustained usage.

Keeping a Lithium-Ion battery on charge after it has reached its full capacity shortens the battery’s life and could lead to overheating and possible bursting. This would be a very unpleasant and potentially dangerous thing to happen, so how can you avoid this?

The first solution is to remove the battery from the speaker entirely and power it solely from the mains connected power supply. Sure, it makes the unit less portable, but there is another option if that sounds too limiting. The second solution is to keep the battery in the unit but get into the habit of powering it up for about 2,5 hours (80%) only and never letting it run fully flat (20%). As the unit doesn’t have a battery meter, this will prove to be mostly a guessing game.

This is not a problem unique to the SM-621D, but it affects many electronic devices that don’t have microcontrollers limiting the charge to the battery as most modern cell phones do.

2,4GHz Wireless Connection

Bluetooth and WiFi operate in the 2,4GHz band and potentially interfere or interrupt the connection between the base station and the speaker.

When WiFi connections are made to smart televisions, care must be taken to not place the transmitter between the WiFi router and the television or anywhere near the WiFi router itself. The same would apply to any Bluetooth connections nearby.

Other Device Settings

Every audio device has its own level and processing control which may or may not affect the output connections. To ensure that the Simolio SM-621D receives decent audio levels and quality, ensure that no processing is engaged on the playback device (e.g., television, DVD player, or computer) and that the output level is not lowered.

Some television sets allow you to set the built-in speakers to disengage when an external output is chosen. If this is not an option, you will have to mute the speakers or turn the level down to zero. Some older televisions might have the audio output linked to the built-in speaker level, which means that if you turn the level down or mute the speakers, the SM-621D will also be affected.

You must read through your device’s technical documentation to ensure that you will be able to get a clean and unaltered signal to the base station.

The Simolio SM-621D Compared With Pyle PTVSP18BK

simolio wireless tv speaker
Pyle_PTVSP18BK wireless tv speaker
FeaturesSimolio SM-621DPyle PTVSP18BK
Wireless Band2,4GHz2,4GHz
Analog Inputs⅛-inch AUX⅛-inch AUX
Analog Outputs⅛-inch AUX⅛-inch AUX
Digital InputsOptical (PCM)No
Voice ClarifyingYesNo
Dimensions (H x W x D)10in x 9in x 4in8in x 8in x 2.9in

An alternative to the SM-621D is the Pyle PTVSP18BK. The Pyle PTVSP is a bit more expensive than the SM-621D, and the.

The Simolio SM-621D and Pyle offer the same direct analog connections. The SM-621D comes with converter cables, so the onboard connections don’t matter as much in this case. All units offer ⅛-inch AUX output for headphones, so there’s no competition there. The only unit that does not accept a digital input is the Pyle PTVSP.

The Pyle unit does not employ voice clarifying technology, unlike the other units. This singles the Pyle out as a possible high-quality music listening device over the other two. Batteries are included with the Simolio SM-621D but not in the Pyle. This could turn out to be quite a cost-saving, depending on the quality of battery you’re looking at.

What’s In the Box?

  • SM-621D transmitter (base station)
  • SM-621D receiver (speaker) with a replaceable rechargeable Lithium-Ion battery
  • 2 x power adapters
  • Noise isolating stethoscope headset
  • ⅛ inch mini-jack audio cable
  • Stereo RCA to ⅛ inch mini-jack audio cable
  • Optical fiber cable
  • User manual
  • Quick start guide
Whats in the box Similio Speakers
Matthew Cox - Author
Written by
Matthew Cox

Matthew is an audio engineering graduate with a strong passion for post-production, recording engineering, and audio technology. Matthew is also an experienced musician with over a decade of experience in recording, touring, and performing. Matthew enjoys studying the inner workings of audio equipment and acoustics theory.

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