The DuoSlim by PERI is the latest edition to the Duo family of iPhone charging and speaker cases for the iPhone 7 and iPhone 7 Plus, featuring a high-fidelity docked speaker system and 200mAh/3000mAh battery, providing a completely new way to experience your favorite music. They have just launched their IndieGoGo funding project today and they need your help in supporting them to make this speaker a reality.

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Personally I think this would be a cool little thing to have for those of us that like to listen to music all day while at work or something like that and don’t have to worry about disturbing others. Just put the case on your device, start your music and jam out with much better sounding music than your phone itself can provide.


  • Play digital audio directly from the iPhone to the Duo Slim’s high-fidelity speaker system via a docked iPhone lightning connection
  • Full-range 3-watt speaker and passive radiator for enhanced bass
  • High-resolution DAC (Digital-to-Analog Converter) for improved hi-fidelity audio
  • 3.5mm headphone jack connected to the case’s integrated DAC for an amazing headphone audio experience
  • 80% extra battery life to your iPhone or enjoy 8+ hours of audio playback with the Duo’s integrated 2200mAh battery for the iPhone 7 case or 3000mAh for the iPhone 7 Plus case
  • Simultaneously charge the Duo Slim and docked iPhone via lightning connector in half the time of other leading battery cases
  • Backwards compatible to the iPhone 6 and iPhone 6s models – Plus included

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The challenge in achieving good audio is always a balance between audio cavity, speaker frequency response, and equalization engines that help compensate and flatten out the response curve. Through countless iterations of intricate cavity design, custom development of our own speaker drivers, and rigorous equalization testing, PERI has developed an unmatched expertise in designing amazing audio into small portable form factors.

Audio Cavity

We take immense care in designing our audio cavities to ensure complete air tightness and to maximize air volume and air flow. Maximizing air pressure and directing air flow is important to ensuring that our active speaker driver works in tandem with our custom-tuned passive radiator to produce as much bass as physically possible.

Speaker Frequency Response

We design our own speaker drivers including customization of the cone material, magnet type and size, and coil density. The Duo Slim uses our proprietary XDS-100 slim driver that features at a minimal 10mm depth, XX excursion, XXX air pressure, and frequency response range of XX Hz to XX KHz.


The audio Codec used in the Duo Slim is a highly-integrated codec with functional blocks that allow us to maximize audio in small cavities. The codec provides 96dB SNR (A-weighted) and 86dB THD+N with great channel separation of 80-85dB from 10kHz to 1KHz respectively. The Duo Slim maintains its high-fidelity audio quality even when the user enables the case’s charging feature thanks to the enhanced power supply rejection capability of the codec and proprietary circuit design that effectively filters the power supply lines. The 5-tap equalizer and DRC (Dynamic Range Compression) engines work together to provide distortion-free bass, crisp vocals and brilliant mid–range frequency response given the small cavity of the Duo Slim.

At PERI, our passion is Audio, and our expertise is engineering and Power design. The Duo Slim brings together these two elements in one amazing product!

About the author

Cliff Wade

Founder and Chief Editor of TechDissected. I'm an avid Linux user, that's addicted to music, electronics, the internet, computers, Android, iOS and everything tech related! Rocking a Google Pixel 3 XL, iPhone XS Max and several other devices that go beep. Lover of #Cheeseburgers #Android #Penguins #Tech and the #HoustonTexans. Gadgets and Gizmos are my specialty. Customer Suppport Specialist and Social Media Manager for TeslaCoilSW, the makers of Nova Launcher, Nova Launcher Prime and TeslaUnread. If you have any questions just ask as I'm always happy to help.