JBL S100 Synchros
A 9mm dynamic driver in a die-cast aluminum shell, tuned for bass. It was sold in two variants, and the remotes only behave properly on the platform they were built for.
Overview
The JBL S100 Synchros is an in-ear headphone from JBL's Synchros line. The documentation frames it as a consumer product: headphones for mobile audio devices, with an emphasis on style, comfort, and JBL's signature sound tuning. This is not a monitor, not a reference tool, and not studio gear. It is a phone companion with a specific tonal personality.
The transducer is a single advanced 9mm dynamic unit. JBL's official specification sheet rates the earphone from 10Hz to 22kHz, with a maximum SPL of 106dB at 5mW and a rated power input of 5mW. It terminates in a 3.5mm jack. Those numbers describe a normal, phone-friendly in-ear of its class. The 10Hz bottom figure lines up with the tuning the company chased. Nothing in the available documentation suggests the S100 was built to do anything other than make portable listening sound full at the bottom end.
There are two variants. The S100a is described as the Android version. The S100i is effectively identical apart from a slightly different in-line remote and is oriented toward iOS, with JBL's own product page titled around an iOS three-button remote. Sources also list three possible cable configurations across the line - an Apple three-button mic/remote cable, a universal three-button mic/remote cable, or a straight cable. So the remote is the first thing to settle on any used pair. The button behavior tracks the variant, not the phone in your pocket.
One warning before any search: the "S100" designation is badly overloaded. The name has been applied to a JBL Bluetooth speaker, a JBL center-channel speaker, an aquarium air pump sold in Turkey as a "Hava Motoru," a diving snorkel, and an air-motor gasket. A 1997-era wedge-shaped S100 satellite speaker from JBL's home audio line is a different product again. None of those are this earphone, and secondhand listings mix them up constantly.
Key Features
Advanced 9mm Driver with PureBass Tuning
The single 9mm dynamic driver is the only transducer specification the documentation gives. JBL's own materials frame the sound around proprietary PureBass performance. A Polish retailer listing credits the model with "technologią Pure Bass" outright, and rms.pl cites "JBL Professional Audio Sound with PureBass." That tuning is the whole point of the earphone. PCMag's bottom line called it a bass lover's mix that doesn't overpower, aimed at listeners who want subwoofer-like low frequency response rather than a crisp, bright signature. Anyone shopping for a flat, analytical in-ear should look elsewhere. The 10Hz - 22kHz rating should be read as headroom for the low end, not a claim of neutrality.
Die-Cast Aluminum Earpieces
The shell is die-cast aluminum with metal accents, described across sources as an ultra-light, highly durable aluminum frame and an ultra-light, die-cast aluminum construction. The practical case for it is low mass plus rigidity. The housing stays portable while resisting the knocks that finish off plastic earphones. No dimensions or weight figures are published anywhere, so "ultra-light" stays qualitative.
Three-Button Remote, Microphone, and Cable Options
A three-button remote with an integrated microphone sits on the cable, putting call handling and track control at thumb's reach. The documentation is inconsistent on this. A spec table calls the remote "universal," while the variant notes route iOS compatibility through the three-button remote with microphone and identify the S100a as the Android version. Expect the remote's behavior to follow the variant, and confirm which cable is attached before handing over money.
Ear Tips, Carry Case, and One-Year Warranty
Retail packaging included the earphones, one set of silicone ear tips in three sizes (S/M/L), and a carry case. The case is the inclusion that disappears first. There is no market data for this model, so no established premium for a complete example.
Historical Context
The S100 was released as part of JBL's Synchros line, which the company positioned as consumer headphones for mobile audio devices, emphasizing style, comfort, and JBL's signature sound tuning. Within that family the split ran along platform lines - S100a for Android, S100i for iOS - with the in-line remote as the practical difference. The model is referenced alongside the S200, which one site reviewed together with the S100. No production years, release date, or original manufacturer's suggested retail price appear in the available documentation. The only price statement found is PCMag's reference to $100.
A 1997-era home audio line also carried the S100 name on wedge-shaped satellite speakers priced at $200 a pair, as reported in HiFI-Stereo (September 1997, p.78). That is a different product entirely from this earphone.
Collectibility & Value
There is no market data for this model - no current prices, no established premium for complete examples, and no genuine owner reviews, failure reports, or repair information turned up in research. The reception signals that do exist are mixed and should be read as weak. PCMag, at the $100 price, judged it a bass lover's mix that doesn't overpower and a thoughtful array of accessories, worth considering for lovers of deep low-end. The site headphone.ph, reviewing the S100 alongside the S200, found the pair decent but a bit expensive for the sound quality on offer.
The practical advice is about identification rather than price. Confirm the item is the Synchros in-ear headphone and not one of the many other products wearing the S100 label, confirm which variant's remote is attached, and confirm the ear tips and case are present.
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