Tech Talk: Subwoofer Suspension Options

Tech Talk | WRITTEN BY AARON TRIMBLE | March 2018

This month’s tech question comes from Derek Walls of Virginia, he asks,

“Can you explain the suspension options Soft, Standard, and Extra Stiff; and how they apply to box design, output, and inductance?”

When you’re looking at DD subs for your next sound upgrade, it can be a little intimidating to see all the options that are available. Cosmetic options are easier to pick, like the logo color or powder coat color for the basket. What about the other important performance features, like the type of suspension? DD offers three distinct suspension set-ups to choose from: Hi-Def Tuned (Soft Suspension), Power Tuned (Standard Suspension) and Extra Stiff Suspension.  

Hi-Def (Soft Suspension) – Designed for systems where fidelity is the focus, and everyday listening will be done primarily inside the car. Hi-Def subs offer the perfect mix of control and efficiency.

The Hi-Def Suspension or Soft Suspension, is for subs that will spend their days in compact vented or sealed alignments. These subs appeal to users who concern themselves with TS parameters. Hi-Def subs certainly look better on paper with their higher Q values and lower FS values. Being of higher compliance it is important to note that RMS power handling and mechanical (peak) power handling are going to be much closer to each other with these subs because it requires so much less power to propel the drivers to XMax and even XMech. The low FS of the driver becomes very appealing in sealed alignments where the resonance of the sealed chamber can be aided by the resonance of the driver, allowing the system to more faithfully reproduce low frequency play without the use of a port.

Power Tuned (Standard Suspension) – Designed to push performance limits, yet still maintain a high level of control. Power Tuned subs feature additional mechanical and electrical damping to handle the rigors of crazy lows in daily high output applications.

Anyone who has used a DD sub is probably familiar with the Power Tuned or Standard suspension. This level of compliance has been a hallmark of the DD sub since the 90’s. The low compliance of the Power Tuned spiders allows the sub to maintain a great deal of control in the large vented enclosures they’re intended to operate in. When you consider the average listener, what are they after? They want the sub to sound good of course, but they also want volume, don’t they? The more air you can compress and rarefy, the more volume you can achieve. A huge component of this is the enclosure. As most of you know, we at DD Audio believe that “Space Makes Bass.” You can read about in our “Does Size Really Matter” article. Having a lower compliance driver means the driver relies less on the air spring effect of the enclosure to remain in control, which in turn allows the user to put a sub in a larger enclosure to make more bass. This also holds true with the subs’s ability to keep it’s excursion in check at frequencies outside of the port’s control in vented alignments. This suspension will be able to satisfy 90% of users.

Extra Stiff Suspension – Designed for the most extreme spl competitors.

Now, what happens when we add more to the suspension, add additional spiders, under the cone body and decrease the compliance of the speaker even further? Well, you’ve heard too much of a good thing, right? While it’s true that you could hypothetically put a stiff suspension sub in an even larger box, there is a point of diminishing, and even, no return where the listener simply won’t benefit from a larger enclosure for a given sized sub. In fact, users of the stiff suspension subs are almost exclusively high level car audio competitors. The Extra Stiff Suspension is simply a means by which a competitor can shove more power into a sub without the driver exceeding its mechanical limitations (you know, when the voice coil becomes a projectile). In this application, the suspension becomes so stiff that the sub will actually overheat over time near RMS power levels because the suspension is inhibiting the sub’s ability to cool itself. If the sub can no longer sustain itself for longer term musical use, RMS wattage is basically thrown out the window and mechanical power handling becomes all that matters. It is here where users will see drivers accepting 10’s of thousands of watts for short runs of 3-5 seconds – just enough time to register on an SPL meter. Many of these users couple this suspension profile with a small enclosure to increase the mechanical power handling of the driver even further. This suspension is completely unnecessary for all but the most extreme SPL competitors.

When considering a build, there are a few relationships that the suspension will share with the enclosure being used for the build. These relationships will assume that spiders used for suspension are the only thing being changed.

Softer Suspension = Smaller Enclosure
Stiffer Suspension = Larger Enclosure

Softer Suspension = Lower Mechanical Power Handling
Stiffer Suspension = Higher Mechanical Power Handling

Softer Suspension = Lower Fs
Stiffer Suspension = Higher Fs

The compliance of the suspension is not going to have a direct effect on the inductance of the sub. Applied power as a result of a stronger suspension will however affect the level of inductance observed in the coil though. A lower compliance driver will be able to accept more short term power handling, as a result a coil (inductor) will create additional back EMF which raises inductance.

Simple things like changing the suspension of your subsubs can have wide ranging ramifications on a system. If you’re not sure how to build your subs for the stereo system you have in mind, you can always ask your local Authorized DD Audio Dealer, or give us a call at (405)239-2800, we’ll be more than happy to help steer you in the right direction.

If this sparks debate in your mind, or causes you to have more questions about car audio, be sure to send us a message with your car audio related question below. Each month we’re going to select one Tech Talk reader’s question to answer here on the DDownlow, so be sure to check in next month to see if your question gets answered.

Tech Talk Question Submission

Install Highlight: 1969 Camaro


Most of the people who are truly into car audio cut their teeth on a basic love for the basis of our hobby, the cars themselves. Just as we’ve all sat around with friends, waxing poetic about dream systems, many of us have also dreamed large about what our dream car would be. Few of us ever get to realize one of these flights of fantasy, let alone both simultaneously.

This brings us to 806 Autoworks in Amarillo, TX. Bryan Turvaville, owner, and his group of technicians were kind enough to share the results of what happens when dream car and dream system collide. Personally, the roar of 600 screaming ponies would be all the stereo I need, and the Hot Rod Power Tour agrees, as this street animal is slated to participate in the event this year. To his credit, Bryan isn’t one to stop at good enough, opting to fully upgrade the sound instead.

When this Camaro was brought into the shop, it was full of audio equipment that the team at 806 found to be… Just Lacking. It had Just Lacking components in the front, some equally Just Lacking 6x9s in the rear deck, and a pair of Just Lacking 10’s all on a 5 channel amp. Feeling that the current audio setup did no justice to the vehicle, Bryan’s team tore back into it, opting to utilize split amplifiers. The first was an M1d amplifier to power a quartet of REDLINE 506 subwoofers. To make sure the amp had all the current available that it would need, an upgraded 250 amp Mechman alternator was installed, and all of the support wire was upgraded to Z-Wire 0 AWG. A supplemental battery was added to further aid the electrical system on the car, which remember, it was originally built 49 years ago! After rebuilding the front kick panels to house a set of the C Series components, the rear deck was customized with pressed grilles to house a pair of D Series coax drivers. All of the full range duties were relegated to a C4.100 amplifier nestled in the trunk opposite the M1d. A full complement of beauty panels and LED lighting later, and you have the striking beauty seen here.

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Dealer Spotlight: Car Tunes of The Shoals

Shop Name: Car Tunes of The Shoals
Shop Location: Muscle Shoals, Alabama, USA
Owner’s Name: Justin Thornton

Cartunes of the shoals

DD: How long have you been in business?:
Justin: We are a new shop, and have been in business for 9 months.

DD: How did you get started in car audio?
Justin: I started years ago competing and things developed over time where I was able to turn my hobby into a full time career.

DD: What made you decide to do car audio for a living?
Justin: I saw a need in my area for quality, custom installs and a higher level of customer service.

DD: Does your shop specialize in anything specific?
Justin: We are a full service shop. If you’re looking for basic factory integration or a full custom build, we are able to handle any request.

DD: How long have you been a DD Audio dealer?
Justin: 8 months.

DD: Where did you first hear about DD Audio, and why did you decide to become a DD Audio Dealer?
Justin: I started out years ago using DD Audio as a competitor. So, when I decided to open my own shop naturally I wanted DD to be my main line. I wanted to offer my customers the best!

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Product Spotlight: VO-B4 Super Tweeter

DD Audio Product Spotlight | WRITTEN BY KEVIN DOYLE | February 2018

Ever since we introduced the VO-B3 to our customers it’s been one of our most popular tweeters ever! So, why not up the ante with a bigger, louder version? Behold, the VO-B4 SUPER TWEETER!

VO-B4 super tweeter

When comparing the VO-B3 to the VO-B4, customers will notice increased frequency response, higher efficiency and a higher max power handling. This was accomplished by using a larger diaphragm and voice coil coupled to a stronger motor. The VO-B4 is truly a high-output, PA-Style, bullet tweeter designed for the mobile environment. The VO-B4’s custom CNC machined body and die cast motor are designed to be as short as possible to allow for easy mounting in door panels and motorcycle applications. The B4’s horn body is designed to project a wider field of sound in close proximity when compared to similar styled tweeters. Another unique feature of the VO-B4 is it’s dual mounting options. The installer has the option to flush mount with the trim bezel and back nut, or for more space constrained installs it can be top mounted using the machined screw holes in the tweeter body.

B4 Bullet Tweeter


38.6mm CCA Voice Coil
Titanium Diaphragm
37oz Neodymium Motor
Custom CNC Aluminum Body
Dual Mounting Options
Impedance: 4Ω
SPL: 108dB
Frequency Response: 2kHz-20kHz
Power Nom. 50 W (Max 150 W)
Mounting Depth: 1 ⅜ in  (motor depth), 2 (total height)
Mounting Diameter: 1 15/16 in

For more information contact your local DD Audio Dealer or visit the product page.

Choose your Adventure and enhance it!

Motorcycle utv boat

Tech Talk: Why are car audio manufacturers still using RCA interconnects for their hardware?

Tech Talk | WRITTEN BY AARON TRIMBLE | February 2018

If you checked in with last months article you’ll remember that this year the Tech Talk is on open mic. All of 2018 is going to be user submitted questions, and boy were there some questions! A lot of you asked questions about the inner workings of speakers, or which sub they should choose for their next bowel shaking bass build, but this month I want to address something that a lot of folks don’t think about.

Charlton from Louisiana, USA asks:

“Why are car audio manufacturers still using RCA interconnects for their hardware? Home A/V has evolved tenfold in comparison to the changes we don’t see in car amps. Why not optical or CAT6 or something better?”

This is a great question. Signal path isn’t something that a lot of folks address in mobile electronics and there are certainly advantages to a digital signal. To answer this question though, let’s first look at analog vs digital. What is analog? Analog is alternating current (AC). It is an electrical reproduction of real sound waves. Digital on the other hand is a series of samples of the original sound at a given rate. Digital is a series of ones and zeros. Now, we’re not overly concerned with the digital vs analog recording process, nor are we here to argue the merits of which is better on a whole. If we look at new cars and trucks with premium audio systems, it is not uncommon to see digital signal transfer over wire. The challenge here though is that very little of it is done with one platform of digital transference. Some manufacturers use MOST by wire, some still use an older CAN-BUS, while still others make use of their own system or a different version of one of the others. To make use of this in the aftermarket, the signal needs to be decoded to analog at some point so that it can be used by your speakers. This decoder, commonly called a DAC (Digital to Analog Converter), must either be able to decode all types of digital signal or there must be a converter for each type, which means an install shop must carry whichever ones they choose to address. So, it makes it difficult to simply put this DAC in an amp. It’s more logical to make an external DAC that can feed into your amp, but then you have analog that goes into the amp anyways, which sort of defeats the purpose of it, doesn’t it?

Now, despite the aftermarket head unit losing market share at an alarming rate, which is a different article on its own, why haven’t the radio companies adopted this? It is in this journalists opinion that it is a logistical problem. DD Audio doesn’t make head units of course, so we can only make conjecture here. It is a logistical issue in much the same way as integrating into digital with the factory systems. Who is responsible for the decoding? Compact Disk, Bluetooth, USB and various other sources are all digital signals. All aftermarket radios have DAC’s in them to decode these signals. This is done at the radio to allow for both the low level signals we use RCA’s for and for the speaker level outputs that most radio’s have (the classic “50×4” watt amps in the decks). In order to maintain the speaker outputs on a radio, the radio must still have a DAC. Now, that doesn’t mean that an aftermarket radio can’t have a digital output. However, it will again come down to the amp manufacturer to have a digital input and its own DAC to do this conversion. Now we don’t have our blinders on. Digital, mostly optical, has been used on some high end aftermarket radios in the past, a few DSP’s (in fact our own DSI-1 has an optical input for some audio codex’s and some gaming devices), and even a few amps, but having 2 of these; a source, and an amp that support digital can not only be difficult to find, but it can also be prohibitively expensive. Seeing wide-scale adoption in car audio would be very expensive for the industry and would require a lot of cooperation between head unit manufacturers, processor manufacturers and amp manufacturers, all at a more competitive price point. This brings up the most important question, should car audio adopt digital signal transfer?

The answer is a resounding, yes, with the caveat that it really isn’t necessary. Digital signal transfer over mediums like fiber optic and CAT6 do have some distinct advantages, most notably among these is that they are not susceptible to electrical noise, engine noise, or hiss like conventional analog signals that are generally transferred over RCA’s. Of course these issues are only common in installs that are performed incorrectly/poorly. Other digital benefits like distributive/multiplexed audio (being able to pass more than one signal along the wire) and long distance transfer are far less relevant to car audio. Odds are your car audio install isn’t going to be a 7.2 home theater set-up (mainly because we’re not watching movies while we’re driving, yet) and you’re certainly not needing a 100 foot run in your new F-150. So it comes down to noise. If an RCA is installed correctly, away from noise producing wires like power wires or fuel pumps in a vehicle, it is going to have the same signal integrity as a digital source. Digital signal mediums like fiber optic are also less flexible and cheaper, plastic optical lines can become brittle over time or crack during an install. Wires, like RCA’s, are much more durable. A good RCA, with durable ends and solid noise rejection, like the DD Audio Z-Wire RCA System, are all that is necessary to create a great sounding audio system.

Z-Wire RCA System

I hope this answer has been helpful Charlton. We’re definitely not against digital audio, but it will certainly take a major industry shift for things like Optical or CAT6 to become commonplace in the average system.

If this sparks debate in your mind, or causes you to have more questions about car audio be sure to send us a message with your car audio related question below. Each month we’re going to select 1 Tech Talk reader’s questions to answer here on the DDownlow, so be sure to check in next month to see if your question gets answered.

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