Introduction
Every driver knows the feeling: you turn up your favorite song on your daily commute, only to be met with muddy vocals, distorted bass, and a flat soundstage that completely ruins the music. Factory car speakers are notoriously cheap, usually built with flimsy paper cones and tiny magnets that degrade rapidly. If you are looking to breathe new life into your driving experience without spending a fortune, upgrading your car speakers is the single most cost-effective modification you can make.
Today, we are taking an in-depth look at the Infinity REF507F 5-1/4” Reference Series Coaxial Two-Way Car Audio Speaker (Renewed). Selling at a highly competitive price point of $68, this pair of speakers promises audiophile-grade performance at a fraction of the cost of brand-new retail units. In this comprehensive review, we will explore the engineering behind the Reference series, analyze its pros and cons, explain why the “Renewed” label shouldn’t scare you away, and help you decide if these are the right fit for your vehicle’s audio system.
Product Overview
The Infinity Reference REF507F is a 5-1/4″ (5.25-inch) two-way coaxial car speaker designed to deliver pristine sound quality and high efficiency in a compact package. Infinity, a brand under the Harman International umbrella (which also includes JBL), has a long-standing reputation for producing clean, balanced sound signatures. The Reference series is engineered specifically to bring that signature studio sound into the challenging acoustic environment of your vehicle.
Let’s break down the key technical specifications and engineering features that set these speakers apart:
- Power Handling: 45 Watts RMS per speaker (90 Watts per pair) and 135 Watts Peak per speaker (270 Watts per pair). This makes them highly versatile, capable of running smoothly on a standard factory head unit or a dedicated aftermarket amplifier.
- Impedance: 3.0 Ohms. This is a clever design choice. While most aftermarket speakers are rated at 4 ohms, Infinity uses a 3-ohm impedance. This lower impedance safely extracts slightly more power from your amplifier or factory radio, compensating for the high resistance of thin, factory-installed speaker wires.
- Sensitivity (@ 2.83V): 92 dB. High sensitivity means these speakers are incredibly efficient. They do not require a massive amount of power to get loud, which is perfect if you are keeping your stock car stereo.
- Frequency Response: 67 Hz to 21,000 Hz. This wide range ensures you hear everything from the mid-bass punch of a drum kit to the high-pitched shimmer of cymbals.
- Plus One™ Woofer Cone Architecture: Infinity’s patented Plus One cone design extends the surface area of the polypropylene woofer cone closer to the outer basket. This provides up to 35% more active cone area than competing 5.25″ speakers, resulting in stronger bass output and enhanced midrange performance.
- Edge-Driven, Textile Tweeters: Instead of using cheap, harsh plastic “balanced dome” tweeters, Infinity utilizes edge-driven textile dome tweeters. These premium tweeters disperse high frequencies more widely and smoothly, offering clear, detailed highs without fatiguing your ears over long drives.
- Adjustable Tweeter Output Level: The speaker face features a selectable toggle switch that allows you to boost the high frequencies by +3dB. This is incredibly useful if your car’s speaker slots are located low in the doors, where high frequencies are easily absorbed by your legs and the vehicle’s carpeting.
- Optimized Frame Size: The basket has been engineered to be compact with a shallow top-mount depth of 1-15/16 inches and a cutout diameter of 4-1/2 inches, making it easy to drop into almost any factory 5.25″ speaker mount.
One notable detail in the manufacturer description is that Infinity Primus speakers are carefully tuned to ensure each line has the consistent Infinity sound signature. This highlights Infinity’s commitment to acoustic consistency across all of their product tiers, ensuring that even their budget and mid-tier Reference speakers benefit from the same rigorous sound tuning as their top-of-the-line components.
The product we are analyzing here is sold as an Amazon Renewed unit. This means the speakers are pre-owned, returned, or open-box items that have been thoroughly inspected, tested, and cleaned by qualified Amazon-approved suppliers to work and look like new. At $68, they offer a massive discount compared to their normal retail price of around $110, representing an excellent value proposition for budget-conscious car audio enthusiasts.
Pros
If you are considering upgrading your car’s factory sound system with these coaxial speakers, there are several standout advantages that make the Infinity REF507F a compelling choice:
Exceptional High-Frequency Clarity
The textile edge-driven dome tweeters are the stars of the show here. Cheap factory speakers—and even many budget aftermarket options—use PEI plastic or metallic tweeters that sound harsh, tinny, and painful at high volumes. Infinity’s textile dome design produces a smooth, natural, and airy high-frequency response. Vocals, acoustic guitars, and brass instruments sound lively and incredibly detailed, allowing you to hear subtle details in your favorite tracks that you never noticed before.
Innovative Plus One Cone Architecture
Because these are 5-1/4″ speakers, they have a naturally smaller surface area than larger 6.5″ or 6×9″ speakers. However, Infinity combats this limitation with their Plus One woofer cone design. By pushing the surround further outward, the physical surface area of the polypropylene cone is increased significantly. This larger cone moves more air, giving these speakers a much more robust mid-bass punch and a richer, warmer midrange than other standard 5.25″ speakers.
High Volume Even on Factory Power
Many high-end aftermarket speakers require a dedicated external amplifier to sound good. If you plug them directly into a low-powered factory radio, they can sound quiet and lifeless. Thanks to the high sensitivity rating of 92dB and the 3-ohm impedance design, the REF507F is incredibly easy to drive. It extracts maximum wattage from your existing system, allowing you to enjoy a massive boost in volume and dynamic range without having to buy or install an external amplifier.
Custom Tuning via the Tweeter Switch
In many cars, the 5-1/4″ speaker locations are located low down in the door panels or footwells. Because high-frequency sound waves are highly directional, they can get blocked by your vehicle’s interior. The REF507F features an on-speaker toggle button that lets you boost the tweeter’s output level by +3dB. This simple mechanical adjustment lets you lift the “soundstage” of your music, making it sound like the singer is performing on your dashboard rather than down by your feet.
Easy, Hassle-Free Installation
The optimized frame size is specifically tailored to fit standard factory speaker locations with minimal fuss. With a modest top-mounting depth of under 2 inches, you won’t have to worry about the speaker magnet obstructing your car’s window glass when you roll the windows down. It is a true “drop-in” upgrade for vehicles that take 5-1/4″ drivers.
Fantastic Value-to-Performance Ratio
At the standard retail price of over $100, the REF507F is already a solid buy. However, getting them for $68 under the Amazon Renewed program is an absolute steal. You are getting top-tier, audiophile-grade engineering from one of the most respected names in car audio for the price of basic, entry-level speakers.
Cons
While the Infinity REF507F speakers offer exceptional performance for their price, no product is perfect. To keep this review honest and balanced, here are a few drawbacks you should keep in mind before making your purchase:
Limited Deep Bass Response
It is important to manage your expectations regarding the low-end performance. Although the Plus One cone design maximizes the bass capability of a 5.25″ speaker, physical size limitations still apply. With a frequency floor of 67 Hz, these speakers cannot produce deep, rumbling sub-bass. If you are looking for window-shattering bass, you will still need to pair these speakers with a dedicated subwoofer in your vehicle.
Highs Can Sound Bright in Certain Setups
While the textile tweeters are incredibly detailed, Infinity speakers are historically known for having a “bright” sound signature. If your car already has tweeters mounted high up in the dashboard or A-pillars, adding these coaxial speakers with the +3dB switch activated might make the high frequencies sound slightly harsh or piercing. You may need to spend some time adjusting your head unit’s equalizer settings to find the perfect acoustic balance.
“Renewed” Cosmetic or Packaging Variances
When purchasing an Amazon Renewed product, you must be comfortable with the possibility of minor cosmetic blemishes on the non-visible parts of the speaker, such as the mounting bracket or magnet. Furthermore, renewed items often ship in generic brown cardboard boxes rather than the flashy original retail packaging, and they may not always include extra installation accessories like speaker grilles or mounting screws. While the speaker itself is guaranteed to perform like new, the unboxing experience will be more utilitarian.
Power Limits for High-End Systems
With an RMS power rating of 45 Watts, these speakers are perfect for stock stereos and mild aftermarket amplifiers. However, if you are planning to build an extreme, high-power competition system running 75 Watts to 100 Watts RMS per channel, these speakers will not be able to handle that level of amplification safely and could blow if pushed too hard.
Customer Reviews Analysis
If you search for this specific Renewed listing of the Infinity REF507F on Amazon, you will find that it currently has 0 customer reviews. For many online shoppers, a product with zero reviews is an immediate red flag. However, in the case of Amazon Renewed items, this is completely normal and should not be a cause for concern.
Amazon Renewed listings are created as separate, standalone pages to keep refurbished inventory distinct from the brand-new stock. Because refurbished batches are limited and sell out quickly, these listings rarely accumulate hundreds of reviews. To understand the true performance and reliability of this product, we have to look at consumer feedback for the brand-new, retail-grade Infinity Reference REF507F speakers, which have been widely reviewed across the internet.
On major car audio platforms and retail websites, the Infinity Reference 5-1/4″ speakers enjoy overwhelmingly positive ratings, averaging around 4.7 out of 5 stars. When analyzing verified buyer feedback, several consistent trends emerge:
- Vocal Clarity: The most common compliment from customers is the dramatic improvement in vocal and speech clarity. Many users note that they no longer have to strain to hear podcast hosts or soft vocals in acoustic music, even when driving at highway speeds with the windows down.
- Build Quality: Buyers frequently praise the physical construction of the speakers. The rubber surrounds and polypropylene cones feel premium and durable, holding up well under temperature extremes inside a vehicle.
- Ease of Fitting: Many DIY installers express relief at how easily the compact frame drops into older vehicles, particularly classic cars or older trucks where mounting space is severely limited.
- Renewed Satisfaction: Across other speaker models in the Amazon Renewed program, customers consistently report that the items arrive looking virtually untouched. Any minor scuffs are usually located on the back of the magnet, which is completely hidden once installed. Furthermore, buyers appreciate the peace of mind offered by the 90-day Amazon Renewed Guarantee, which allows for a full refund or replacement if the product doesn’t perform as expected.
Who Should Buy This Product
The Infinity REF507F Reference Series Coaxial Speakers are not a one-size-fits-all solution, but they are an absolute home run for specific types of buyers:
- The Budget-Conscious Commuter: If you spend hours in your car every week and want a significantly better audio experience, but cannot justify spending hundreds of dollars on a custom system, these renewed speakers are perfect. At $68, they offer premium sound quality on a tight budget.
- The Stock Radio User: If you have no intention of replacing your car’s factory dashboard stereo or installing a complicated amplifier, these speakers are an ideal choice. Their high sensitivity and 3-ohm impedance mean they will sound incredibly loud and clear using nothing but your stock radio’s built-in power.
- The DIY Car Enthusiast: If you enjoy working on your own vehicle, the standard 5-1/4″ sizing, shallow mounting depth, and optimized frame make these speakers an incredibly easy weekend project. You can upgrade your front doors in under an hour with basic hand tools.
- The Podcast and Acoustic Music Lover: Because of their incredible midrange vocal clarity and sweet, detailed high-frequency response, these speakers excel at reproducing acoustic instruments, jazz, classical music, and spoken-word audio.
Final Verdict
Upgrading your car audio does not have to involve expensive, multi-component systems and professional custom installation. The Infinity REF507F 5-1/4” Reference Series Coaxial Two-Way Car Audio Speaker (Renewed) is a prime example of how smart engineering can deliver premium sound quality directly to your factory speaker mounts.
By utilizing advanced technologies like the textile edge-driven dome tweeters, Plus One woofer cone architecture, and an adjustable tweeter output switch, Infinity has managed to overcome the physical limitations of the compact 5.25″ speaker format. While they won’t provide the earth-shaking sub-bass that a dedicated subwoofer would, they deliver an incredibly detailed, crisp, and energetic performance that will completely transform how you listen to music on the road.
At the standard retail price, these speakers are highly recommended. At the Amazon Renewed price of $68, backed by a reassuring 90-day guarantee, they are an absolute bargain. If your vehicle uses 5-1/4″ speakers and you want a premium, clear sound signature without breaking the bank, do not let the lack of reviews on this specific renewed listing hold you back. Grab a pair, install them over the weekend, and enjoy your drive again.
