Bluehertz Audio guides offers a portable system for guided tour groups (whisper system), featuring transmission and reception without any interference or noise. The tourist guide speaks by way of a microphone transmitter. His voice is sent via radio, providing a high-quality digital signal to receivers with headphones. Range is up to 300 meters without interference. Transmitter dimensions: 71x45x15 mm. Receiver dimensions: 71x45x15 mm. Transmitter weight 112 gr. Receiver weight 96 gr. EU-UK-US plug.Two-year warranty.

Tour guide transmitter model SPL-1500T

Tour guide transmitter model SPL-1500T

Tour guide receiver model SPL-1500R

Tour guide receiver model SPL-1500R

Diadem microphone

Head microphone

Tie microphone

Tie microphone

Hand microphone

Hand microphone

Earset mono Luna LU-03

Earset mono Luna LU-03

Earset mono Luna LU-02

Earset mono Luna LU-02

Headset AGV

Headset AGV

Headset AGC for radioguides

Headset AGC

Textile suitcase SPL56

Textile suitcase SPL56

Electrified suitcase SPL60

Tour guide transportation and charger suitcase SPL60

Tour guide charger box

Tour guide transportation and charger suitcase

Magnetic loop

Magnetic loop

Hygienic covers

Hygienic covers



A radio guide team or guided group device is a system composed of a wireless transmitting device with a microphone which is used by the guide or speaker and a set of wireless receivers and headphones that are worn by tourists. The wireless receivers allow them to listen to the guide's explanations continuously throughout the tour. The aim of a radio guide is for the tourists to be able to hear the guide clearly without being close to them. They are highly recommended for groups bigger than 10 and essential for even larger groups.

Note: Tour guide systems are an alternative solution to audio guide players which are used by those who wish to take a tour independently without the presence of a guide. Visit the audio guides page to learn more. audioguides 


Tour guide systems allow the user to easily hear the guide at a constant volume without having to worry about how far away the guide is. This ease of use during the tour improves listening attention and, as a consequence, significantly enhances the overall quality of the tour. Users who are given radio guides tend to value their visit more highly.



Tour guide systems were analog until the early 2000s. The appearance of digital transmission in radio guide systems brought about significant improvements: 

The audio volume in the receivers increased.
The coverage range increased to become more than 100 meters.
The background noise or crackling that was constantly present in the recipient's receiver disappeared, even when the guide isn’t speaking.
Interferences or clicks reduced significantly, only appearing when the receiver is about to leave the coverage area.
The maximum number of groups that could be in an area without interference went from two to 20.
Battery consumption reduced significantly, increasing the usage time between charges.
Analogue and digital transmission equipment still coexist in the market. The main advantage of an analog system is its low price point.


In the last two years, a digital technology variant called 2.4G has entered the radio guide market which uses the 2.4Ghz frequency band. It’s cheaper than digital transmission because it uses the same technology as 2.4G wifi routers. However, it has the same range as 2.4G wifi devices, which is around 50 meters at best. In practice, this range is insufficient for a radio guide.


Currently, only two types of batteries are used in Tour guide systems:

Lithium or lithium polymer batteries. These are the best options. Primary advantages include a low weight, a small size, fast charging and a large capacity. However, its price and the need for an intelligent charging system must be considered.

Nickel-metal-hydride batteries (NI-MH) are the same AA and AAA rechargeable batteries found in conventional remote controls. These were the preferred option before the arrival of lithium batteries. The biggest drawback when used in radio guides is their weight which is uncomfortable for the user because the radio guide must constantly hang from their neck. Their most significant advantage is a lower cost.


The group guide or speaker must carry the transmitting equipment and microphone while each listener must carry a receiver with a headset or headphones. The devices are small in size and should be worn around the neck to ensure reliable coverage. Carrying the transmitter or receiver in a pocket is not recommended because it could reduce the range.

All transmitters and receivers of a group must be tuned to the same frequency channel. Numerous frequency channels are available.


There is no limit to the number of radio guide receivers in a group. For listeners to clearly hear the guide's explanations, they only need to be within the coverage area or range of the transmitter. The receivers do not interfere with one another.


There can only be one transmitter at a time in each group. There may be several speakers with a transmitter in the same group, but they must coordinate among themselves so as not to have two active simultaneous transmitters in the same group.


When using digital transmission equipment, there may be several groups in the same area or room (up to a maximum of 20 digital transmission groups). For this to work, each group must be on a different frequency channel.
Note: If using analog transmission equipment, there can only be two groups in the same area. It is not possible to add a third analog group in the same area, even if it is in another channel. This is a limitation of the analog system.


A quality radioguide should allow the receivers to hear the guide comments while being at a distance of at least 100 meters. A range below 100 meters does not offer a large enough coverage area. 


The transmitter can use different microphones. Three types are typically used:

Headset or head microphones: The microphone includes a headband to adjust onto the guide’s head. The microphone is very close to the mouth, approximately 2-3 centimeters away. The guide uses this microphone when in motion. It is also highly recommended for noisy environments. Having the microphone so close to the mouth effectively captures the voice while the ambient background noise is lower. The microphone cap, which is hidden by foam, is L-shaped and directive. The short side of the L should point towards the mouth.

Neck or tie microphones: The microphone has a clip which snaps onto the neck of the shirt, not far from the throat. This microphone is used when the speaker is standing still or sitting down. It should not be used when the speaker is in motion or a noisy environment. The tie microphone will always have a volume lower than the headset.

Pencil microphone: The microphone resembles a pencil. When connected to the transmitter, the set is used as a standard handheld microphone. This solution works wonderfully when several speakers are sharing the microphone because it is easy to pass between presenters.


Visitors can use different types of headphones. Three types are typically used: 

Monaural headphones: These fit on one ear leaving the other ear free. This is the most commonly used type and is effective for guided tours in enclosed and open spaces. In urban areas with traffic, this is the only model that should be used because it does not distract the user from the environment. Its usage in noisy environments is not recommended.

Headphones: These fit over the head thanks to a headband. Audio can be heard through both ears. These are only recommended in noisy environments. They should not be used in areas with traffic because they distract the user from the environment.

Disposable earbuds: Only one user should use them because the button-shaped earbud is inserted deep into the auditory pavilion. They cannot be shared because they are not hygienic. The user does not have to return them upon finishing the tour.