Reference Series · Bass
How to Choose the Right Bass Upgrade for Your Harley
Quick answer: Work out which of five stages you are at, then buy for that stage. Better coaxials improve clarity and balance but are not a bass upgrade. A dedicated mid-bass driver in a factory position is the first real bass step and costs you no luggage space. An 8-inch saddlebag driver adds serious low end while keeping most of the bag usable. A 10-inch driver is maximum saddlebag bass. A traditional subwoofer is for builds with a real enclosure to put it in. The enclosure you can realistically build, and the luggage you refuse to give up, decide this more than any specification does.
The right Harley bass upgrade depends on three things: how much luggage space you will give up, whether you will cut or fabricate, and how much amplifier and charging capacity the bike can support. Answer those and the choice narrows quickly.
If you have read Motorcycle Subwoofer vs Mid-Bass Driver, you know why the label on the box settles less than riders expect. This guide is the practical half.
Best option by goal
- Simple factory-position upgrade: a dedicated 6.5-inch mid-bass driver
- Keeping most of your luggage space: an 8-inch saddlebag driver
- Maximum saddlebag output: a 10-inch motorcycle mid-bass driver
- Deepest extension: a traditional subwoofer in a correctly sized enclosure
- No cutting at all: a factory-position coaxial or a 6.5-inch mid-bass driver
Each of these still depends on the enclosure and amplifier behind it. The sections below explain why.
The single most useful thing to understand before spending anything is that these stages are not five sizes of the same product. Each one improves a different part of the result, and moving up costs something real in space, power or install work.
In this article
- Three questions that decide it
- The five stages at a glance
- Stage 1: better coaxials
- Stage 2: a dedicated mid-bass driver
- Stage 3: an 8-inch saddlebag driver
- Stage 4: a 10-inch saddlebag driver
- Stage 5: a traditional subwoofer
- Why the spec sheets will not decide this for you
- Which stage suits which rider?
- The enclosure is half the decision
- Amplifier and charging
- A note on model years
- Frequently asked questions
Three questions that decide it
Before looking at a single driver, answer these. They eliminate more options than any spec comparison will.
1. How much of your saddlebags are you genuinely willing to lose? Not in principle, in practice. A rider who tours with luggage and a rider who commutes empty are looking at different stages, and the honest answer here rules out Stages 3 to 5 for a lot of people straight away. There is no shame in that. A Stage 2 build done properly beats a Stage 4 build you resent every time you pack.
2. Are you prepared to cut or fabricate? Stages 1 and 2 fit factory or lightly modified positions. Stages 3 and 4 need a mounting ring, a template and usually a cut. Stage 5 needs an enclosure built to a specification. That is a decision about the bike, not just the budget.
3. What is your amplifier and charging plan? Bass costs current. A 500W or 800W driver on an amplifier that cannot feed it, on a stock charging system, will underperform a smaller driver run properly. Read Can Your Harley's Charging System Handle an Audio Upgrade before committing to the top of the ladder.
The five stages at a glance
| Stage | Typical products | What actually improves |
|---|---|---|
| Stage 1 | CX, CXX, CH, CHX coaxials | Overall clarity, output and balance. Not a true bass upgrade. |
| Stage 2 | CXXM and CM mid-bass drivers | More punch, body and impact. The first genuinely bass-focused upgrade. |
| Stage 3 | CMB8.S4 | Dedicated low-frequency reinforcement while preserving luggage space. |
| Stage 4 | CMB10.S4 and CMB10.S4 NEO | Maximum saddlebag bass performance. |
| Stage 5 | Hertz CS 250 S4, MPS 250 S4 | Traditional subwoofer extension, where genuine enclosure volume exists. |
Stage 5 is numbered for navigation only. It is not a higher-performance version of Stage 4; it is an alternative enclosure strategy, and on a conventional bagger it is often not available at all. Stages 3, 4 and 5 are also not simply better than 1 and 2. They are further along a path that costs space, power and install work. Most riders should be at Stage 1 or 2, and a large number of disappointing systems are the result of jumping to Stage 4 without doing Stage 2 thinking first.
Stage 1: better coaxials
A coaxial is one driver covering the full range with the tweeter built in, and fitting a good one in the factory fairing, lower fairing or saddlebag-lid position is the most common first upgrade on any Harley. Cicada's CXX65 and CXX69 pro coaxials and the CHX horn range all live here.
Here is the honest part, and it is the reason this stage exists in the guide at all: a coaxial upgrade is not a bass upgrade. It will make the system clearer, louder and much better balanced than factory, and a high-output coaxial may well improve upper-bass output over the speaker it replaces. What it will not deliver is the punch or the system flexibility of a dedicated mid-bass driver, because a coaxial has to compromise between covering the highs and producing low end, and that compromise lands squarely on the bass.
Buy at this stage if your complaint is that the system sounds thin, harsh or quiet. Do not buy at this stage expecting the bass problem to be solved, because it will not be, and that misunderstanding is one of the most expensive in motorcycle audio.
Stage 2: a dedicated mid-bass driver
This is the first genuinely bass-focused step, and for most riders it is the right one.
A mid-bass driver does one job: the punch region, roughly 60 Hz to 250 Hz, where kick drum, bass guitar and the weight of a male vocal live. It is paired with a separate tweeter rather than carrying one, which is exactly why it can commit to producing low end instead of splitting the difference. Cicada's Kevlar-cone CXXM range and Carbon Matrix CM range both sit here, in 6.5-inch, 8-inch and, in the CM line, 6x9 formats that suit factory and lightly modified Harley positions.
What you gain: the part of the spectrum wind noise attacks hardest, restored. Music gets its body and impact back at speed.
What it costs you: a separate tweeter, an amplifier channel per driver, and realistically a DSP to set the crossover properly. Little or no luggage loss, though fabrication requirements depend on the size and location you choose.
On fitment: a 6.5-inch installation can often use a factory or adapter-based position without sacrificing luggage at all. Eight-inch and 6x9 options may require modified fairings, replacement lids or cut-in hardware depending on the bike and the position, so confirm before ordering.
Our CXXM vs CM-X comparison covers choosing between the two ranges. A note on the names, because they cause genuine confusion: CXX is the pro coaxial line and CXXM is the mid-bass line. One letter, completely different products.
Common Myth
You have to cut your saddlebags to get proper bass.
Reality
A dedicated mid-bass driver in a factory fairing or lid position restores most of what wind noise takes away. Cutting bags is how you chase the bottom octave, not how you get punch.
Stage 3: an 8-inch saddlebag driver
The Cicada CMB8.S4 is an 8-inch, 4Ω motorcycle mid-bass driver rated at 500W RMS on a Y30 ferrite motor. It is where a build stops supporting the front stage and starts having a dedicated low-frequency section.
The reason it exists is space. A 10-inch driver plus its mounting ring plus its enclosure volume takes a serious bite out of a saddlebag. An 8-inch does not, and at 99.5mm mounting depth it asks for meaningfully less depth than the large-format Cicada 10-inch drivers it is most directly compared with. That changes the question from "how much bass can I fit" to "how much bass can I fit while still carrying a jacket and a wet weather kit".
Choose Stage 3 when:
- You want dedicated bass but refuse to give up the whole bag
- Mounting depth is tight, or you are running a single-side bass build
- Your amplifier plan lands around 500W bridged per pair rather than 800W
- You want impact and slam more than the last few Hertz of extension
On amplifier matching, Cicada designs it to run bridged off an FLX1000.4, published at 461W x 2 bridged into 4Ω at 12.5V and 530W x 2 at 14.4V. Quoting both matters on a motorcycle, because actual charging voltage moves around. An FLX1400.4 also works, with output controlled through proper gain structure and a verified DSP limiter rather than by the gain knob alone.
8" 4Ω motorcycle mid-bass driver, 500W RMS, 99.5mm mounting depth. Dedicated bass from a bag that still carries your gear.
View the CMB8.S4 →Stage 4: a 10-inch saddlebag driver
The Cicada CMB10.S4 NEO is a 10-inch, 4Ω driver rated at 800W RMS on an N42 neodymium motor with a Carbon Matrix Composite cone. This is maximum saddlebag bass, and it is where the mid-bass label genuinely stops being useful.
The engineering explains why. The neodymium motor develops its flux in a much lighter structure than an equivalent ferrite magnet, which matters on a lid or stretched bag where the weight is carried by hinges and mounting points. A 3-inch six-layer voice coil, a vented voice-coil gap and Vortex Flow Venting are all intended to manage heat and hold output during sustained high-power use. In a properly engineered enclosure it reaches into frequencies most riders associate with a subwoofer while keeping the output and control of a mid-bass driver.
The word doing the work there is properly. Dropped into an unbraced, unsealed, undersized bag, it will disappoint, and so will every other driver in this guide.
There is also a ferrite version, the CMB10.S4, at a lower price and the same 800W rating. Be clear about what the neodymium buys: weight, not space. The NEO's mounting depth is marginally greater than the ferrite version's, so if depth is your constraint the neodymium motor is not the fix. If lid weight is your constraint, it is exactly the fix.
Power matching moves up accordingly: an FLX1400.4 running bridged channels, or an FLX1600.1 mono for a dedicated high-power bass channel. At this power level, amplifier configuration, final impedance and limiting have to be designed together. A verified DSP limiter is essential whenever the available amplifier output can exceed the thermal or mechanical limits of the driver.
10" 4Ω neodymium mid-bass driver, 800W RMS. Serious low-frequency extension from a driver engineered for saddlebag enclosures.
View the CMB10.S4 NEO →Stage 5: a traditional subwoofer
Stage 5 is not the top of a performance ladder. It is a different tool, and it is the right one when your build can give a conventional subwoofer the enclosure it was designed around: a Tour-Pak, a trike boot, or a purpose-built box.
The Hertz CS 250 S4 is a conventional 10-inch, 4Ω subwoofer with a polypropylene cone, a single voice coil and 300W RMS. Hertz publishes 12.5mm Xmax and states that its electroacoustic design is optimised for sealed enclosures from 16 litres. That figure is the whole story of this stage: 16 litres is not a large car-audio box, but it is meaningful volume once you try to package it inside a saddlebag, which is why it more naturally suits a Tour-Pak, a trike boot or a purpose-built enclosure than a saddlebag you still want to use.
If mounting depth is the constraint, the MPS 250 S4 is the same idea packaged tighter: 82.6mm mounting depth against the CS 250 S4's 115mm, 500W RMS, and an ultra-compact sealed-box requirement in the region of 14 litres. Hertz's published reference enclosure is 14.2 litres with a system resonance of 49 Hz. It remains a true subwoofer with a true subwoofer's enclosure requirement, just a considerably easier one to package.
10" 4Ω sealed-box subwoofer, 300W RMS, optimised for enclosures from 16 litres. For builds with a real box to put it in.
View the CS 250 S4 →Why the spec sheets will not decide this for you
It is tempting to shortcut all of the above by comparing numbers. Here is what happens when you try, using the three drivers above.
| Driver | Official type | RMS | Sensitivity | Published response | Mounting depth | Designed for |
|---|---|---|---|---|---|---|
| Cicada CMB8.S4 (8") | Mid-bass | 500W | 87.2 dB | 35 Hz to 3 kHz (±5 dB) | 99.5mm | Custom saddlebag |
| Cicada CMB10.S4 NEO (10") | Mid-bass | 800W | 88 dB | 35 Hz to 1.8 kHz (±3 dB) | 115mm | Custom saddlebag |
| Hertz CS 250 S4 (10") | Subwoofer | 300W | 84 dB | Response graph published, no range or tolerance stated | 115mm | Sealed, from 16 L |
The sensitivity figures follow the expected broad pattern. The two Cicada mid-bass drivers are rated at 87.2 dB and 88 dB, while Hertz rates the CS 250 S4 at 84 dB, which suggests more output per watt from the Cicadas under each manufacturer's stated test conditions. That is useful, but it is not a finished-system comparison, and three things in the table matter more than the sensitivity column.
The figures are not measured on a common basis. Cicada publish response ranges with stated tolerances of ±5 dB and ±3 dB. Hertz publish a response graph rather than a range, so there is no directly comparable endpoint at all. Hertz publish 12.5mm Xmax; Cicada do not publish an Xmax figure for these drivers. You cannot line these numbers up next to each other and read off a winner, because they were not produced to answer the same question.
The two 10-inch drivers need the same mounting depth. Both sit at 115mm. Whatever separates them, it is not how far they intrude into the bag.
The enclosure column is the one that decides it. The Hertz is optimised for a sealed box from 16 litres. The Cicadas are designed to work in whatever a fabricated saddlebag enclosure can offer. That single difference determines which driver can even be considered for your build, and it is nowhere in the sensitivity, power or frequency figures.
Important: published frequency response is not a promise of equal output across that range, and figures quoted at different tolerances, or without one, are not directly comparable. Enclosure design, filtering and amplifier matching determine how much usable bass the finished installation actually produces. Use the table to understand the drivers, not to rank them.
What genuinely separates them is the job each was designed for: 300W of smooth reinforcement from a 16-litre sealed box, 500W from a compact custom saddlebag enclosure, or 800W from a purpose-built bag. What the Cicadas clearly publish is far greater thermal power handling and a design intended for high output in motorcycle enclosures. That is the decision, and it is a decision about your build, not about the numbers.
Specifications and sources: Cicada figures are taken from the MAA product listings. Hertz figures are taken from the manufacturer's published technical documentation, the CS 250 S4 tech sheet and the MPS 250 S4 tech sheet. Manufacturers revise specifications, so check the current documentation before finalising a build.
Which stage suits which rider?
Highway touring
Stage 2, moving to Stage 3. Wind noise takes the biggest bite out of the punch region, and thermal headroom keeps the system out of protection over long runs. Very deep bass is heavily masked at 100 km/h, so spending space and power budget there is the weaker trade. If you still tour with luggage, Stage 3 is the ceiling worth considering.
Daily rider
Stage 2. Space is at a premium because the bags still have to carry things, and the electrical system is stock. One well-installed mid-bass driver in a factory position delivers more than a compromised saddlebag build ever will, and it costs nothing in luggage.
Weekend and pillion riding
Stage 3. Bags are usually lighter, one side is often free, and the appetite for a cut is higher. An 8-inch driver in a properly built enclosure is the sweet spot between real bass and a bike you still use normally.
Show bike
Stage 4 or 5. If the bike is judged and demonstrated parked, wind masking disappears and low extension becomes audible and impressive again. If there is a Tour-Pak or custom enclosure in the design, Stage 5 becomes viable. The fabrication plan often drives this as much as the acoustics.
Competition bike
Stage 4 and 5 together. Competition builds run dedicated drivers for dedicated bands, each in an enclosure built for it, each on its own channels, with the DSP arbitrating. When the whole bike is available as enclosure volume, the constraints that force a choice on a daily rider do not apply.
The enclosure is half the decision
A brilliant driver in the wrong enclosure is disappointing. An appropriate driver in the right enclosure is incredible. This is the single most reliable pattern in motorcycle audio, and it is why the stage you can properly execute matters more than the stage you can afford.
Riders routinely spend serious money on a driver, mount it in an unbraced saddlebag with an open back, no consideration of volume, no port design and no DSP time, and conclude the driver was overrated. It was not. It was never given the conditions to work.
From Stage 3 upwards the enclosure hardware is not an accessory, it is half the system. For 2014 to 2023 Touring bags, the 14HD Saddlebag Foundation Bundle packages the mounting ring, template and port kit that turn a saddlebag into an actual enclosure. If your budget forces a choice between a bigger driver and a properly engineered enclosure for a smaller one, take the enclosure every time.
Amplifier and charging
Every stage above Stage 1 needs the amplifier matched to the driver's real limits rather than to a headline wattage figure, and set with proper limiting rather than by the gain knob. How to Match Speakers and Amplifiers covers the method.
Two rules worth carrying into the decision. An amplifier that cannot deliver the driver's rated power will underperform a smaller driver run properly, so the driver and the amplifier are one decision rather than two. And an amplifier that can substantially exceed the driver's rating is not safe just because it sounds clean, so limiting is not optional at Stages 3 and above.
Bass also draws real current. Many sensibly powered Stage 2 systems will work with a healthy factory charging system, but total amplifier demand still needs to be checked against the bike, the battery's condition and everything else drawing from it. Stages 3 and 4 make that electrical assessment increasingly important, not optional.
A note on model years
Available positions differ more than most riders expect across the Touring range. On 1998 to 2013 batwing bikes the fairing opening and lid geometry are different again from 2014 to 2023, which is the generation most saddlebag bass hardware is designed around. The 2023.5 CVO models and the 2024-plus Skyline bikes changed both the audio architecture and the bag and lid design, so hardware that fits a 2019 Street Glide will not necessarily fit a 2025 one. Trikes and Tour-Pak-equipped bikes open up Stage 5 in a way a standard bagger does not, because the enclosure volume genuinely exists.
None of that changes the five stages. It changes which hardware executes them, so confirm fitment for your exact year and model before ordering anything from Stage 2 upwards.
Frequently asked questions
How do I get more bass without building a full subwoofer system?
Fit a dedicated mid-bass driver in an existing or lightly modified speaker position. That is Stage 2. A 6.5-inch CXXM or CM driver can often use a factory or adapter-based location without sacrificing luggage. Larger 8-inch and 6x9 options offer more potential output but may require modified fairings, replacement lids or cut-in hardware. Either way you get more kick-drum impact, bass-guitar body and vocal weight without committing to a dedicated 8-inch or 10-inch saddlebag bass enclosure, and without requiring a separate mono bass system or giving up the main saddlebag volume.
Will better coaxial speakers give me more bass?
Not meaningfully. A better coaxial improves clarity, output and balance, and it is often the correct first upgrade, but a coaxial has to compromise between covering the highs and producing low end. If your specific complaint is a lack of punch at speed, a coaxial upgrade will not fix it. A dedicated mid-bass driver will.
Is 8-inch or 10-inch better for a Harley saddlebag?
Whichever one your enclosure, mounting depth and amplifier plan genuinely support. A 10-inch has more potential, but only if you can give it the volume and depth it needs and feed it properly. An 8-inch in a well-built enclosure on a matched amplifier beats a 10-inch in a compromised one every time.
Do I need to cut my saddlebags?
Only from Stage 3 upwards. Stages 1 and 2 fit factory or lightly modified positions. If cutting is not something you are willing to do, Stage 2 done properly is your ceiling, and it is a genuinely good place to stop.
Can I skip straight to Stage 4?
You can, and some riders should, but only if the enclosure, amplifier and charging plan go with it. A 10-inch driver in an unbraced bag on an underpowered channel will sound worse than a well-executed Stage 2 build. The stage you can execute properly beats the stage you can afford.
Do I need a DSP?
From Stage 2 upwards, effectively yes. Crossover control, time alignment and equalisation are what integrate a bass driver with a fairing front stage a metre away, pointed in a different direction. It is the difference between a driver that works and one that sounds like it belongs in the system.
The bottom line
Work out which stage you are honestly at, then execute that stage properly rather than reaching for the next one. The enclosure you can build and the luggage you refuse to lose will decide this better than any specification comparison, and a well-executed Stage 2 build will outperform a compromised Stage 4 every time.
Choose the enclosure first, the driver second, and let the DSP bring the whole system together.
Not sure which stage you are at?
Tell us your bike, your bags, your amplifier plan and how much luggage space you need to keep, and we will tell you what will actually work.
Get in Touch →Written and technically reviewed by Motorcycle Audio Australia, based on Harley audio system design and installation work carried out in our own workshop.
Related guides
- Motorcycle Subwoofer vs Mid-Bass Driver: the concepts behind this guide.
- Cicada CXXM vs CM-X Mid-Bass Speakers: choosing between the two Stage 2 ranges.
- DSP Tuning for Harley Baggers: how crossover and time alignment work is actually done.
- Can Your Harley's Charging System Handle an Audio Upgrade?: before you commit to Stage 3 or 4.
- Stage 1, Stage 2, Stage 3: where bass belongs in the wider build order.
Motorcycle Audio Australia. Sound That Rides.