3W 4 OHM Speaker

Thanks for starting the thread. To continue the discussion on speakers in this thread:

The loudness of a speaker primarily depends on the following three factors:

1. Speaker sensitivity - MOST IMPORTANT!!! See https://www.lifewire.com/speaker-sensitivity-3134850. This is frequently published in the datasheets for speakers by reputable manufacturers. Please note that sometimes it maybe published for different conditions like 0.1m or 0.5m or a different power level. Make sure to compare the numbers for the same units. To convert from one set of units to another, check out this calculator: https://www.cuidevices.com/product/resource/calculators/speaker-spl

Usually, it transcends to a larger cone area or in other words, a larger speaker will be generally more "sensitive".

2. Power - Each speaker is rated for the power before it will "burnout". It should match the power output of the audio amplifier. A higher wattage speaker can try to draw more power from the amplifier than the rating of the amplifier and damage it in return. On the other hand, a lower wattage speaker can burnout if the amplifier ends up pumping more current into it. Power combined with the impedance of the speaker should match the rating of the amplifier. This is also called impedance matching.

3. Baffle - One of the most important factor in loudness (and even making sound direction) is the baffle. There's a lot that goes into constructing a good baffle. It's more of an art than science. Generally speaking, bigger baffle can produce more bass (provided it falls within the speaker frequency range). Make sure there are no air gaps the sound can leak through. Combined that with the construction material of the baffle can change the sound loudness dramatically. As a rule of thumb, try to make the depth of baffle a multiple of one of the harmonics of the resonant frequency. To put simply, harmonics are factors of 8 and the box depth can be calculated by (speed of sound / resonant frequency / some multiple of 8) depending on available space.

As it pertains to LocoFi™, the module comes with an onboard audio amplifier that will accept a speaker of 8ohm 1.5W or 4ohm 3W (most common impedance values found in speakers). If you're careful about keeping the volume not too high, slight variations in speaker wattage are acceptable. Based on these parameters, following are some additional large speakers that may produce an adequate volume depending on the available space inside the shell. They may be available from other retailers as well. Shop around.

8ohm 1.5W

• https://www.digikey.com/en/products/detail/mallory-sonalert-products-inc/PSR66N08AK/9951985

4ohm 3W

• https://www.digikey.com/en/products/detail/pui-audio-inc/AS07104PO-R/2763867

• https://www.digikey.com/en/products/detail/pui-audio-inc/AS04004PR-R/3189932

Please check out their shapes and sizes on the corresponding pages and do not forget to include extra dimensions for the baffle.

If you still need louder volumes, you may consider adding a second stage of audio amplifier and an appropriate speaker. Make sure to match the input impedance with the output impedance for this stage.

Hope this helps!

Please feel free to add any more other information or anything we have missed or any other feedback.