Full-Range Driver Break-In…

My average typical full-range driver sale usually unfolds like this: The customer has just placed the order with me and tells me that he is very excited to receive the speakers and cannot wait to hear them. Then comes the inquiry. “Oh, and by the way, I hear that there’s quite a lengthy break-in period for full-range speakers. How long does this process take?”

The break-in process for pistonic motion transducers (i.e. the conventional loudspeaker) is an intriguing branch in loudspeaker design. Scientifically evaluating the transition from crisp, new transducers into fully functioning and matured devices has always been quite fascinating to me.  I have learned a lot and have implemented much in the way of design from the knowledge that I’ve gleaned from my observations into the subject. However, in my opinion, there is nothing in the full-range speaker movement that has generated more useless and foolish chatter than the so-called “driver break-in period.” It is also the primary header that dubious, and quite frankly, suspect loudspeaker builders cloak their mischief under, using it to pass off to you, the audiophile, their less-than-stellar work.

As I quoted in a previous post, “The greatest thing about speaker building is that anyone can do it and be successful, but the worst thing about speaker building is that anyone can do it and be successful!” So, audiophile buyers, beware!

A few years back, while attending an audiophile tradeshow, I purposely eavesdropped on a conversation involving an interested customer and a sales rep from the rear of a competitor’s (you would know the name!) demo room. Interestingly,  the company’s sales rep turned out to be the company founder and owner. After a few simple questions, the customer asked if there was a break-in period for the speakers. And what I heard next was about the biggest line of tomfoolery I’ve heard in all of my years in audio! “Yes,” he said, and proudly proclaimed that it takes up to 500 hours for their work of art to fully break-in, and that while new, the admittedly timid bass response was going to magically improve at some key point in the future! Not! Now, as a guy who has many years under his belt that are directly attributed to transducer engineering, I really cannot think of another audio-related conversation that was more offensive to me than hearing that one. Sadly, this company does sell a lot of speakers and people believe its twisted spiel.

500 hours break-in! Proper loudspeaker break-in is, indeed, long, and is to be expected. However, let me be perfectly clear – if a loudspeaker that you’re auditioning,  demoing, or have purchased doesn’t sound excellent right out of the box (excluding optimizing placement and final tweaking), immediately pack it up and send it right back where it came from, period! My offerings included!

Now, if you decide to purchase that drop-dead gorgeous pair of $20k High Jinks and choose to follow their strictly outlined homage-inducing burn-in protocol, here’s where it really gets serious. You are about to be sucked into the biggest psychoacoustic hoax in all of audio! I promise you that all of the burn-in and break-in time in the world isn’t going to make an inferior loudspeaker a world-class loudspeaker. What will happen is that over a period of time, the loudspeaker will continue to sound terrible. However, the “break-in” transition is really taking place within your brain. Through long term exposure, your ear/brain is literally psychoacoustically transitioning this inferior device to into a palatable and pleasant experience, and pretty soon, even the worst and most obvious design flaws are fully compensated or masked by the brain. An auditory illusion is far from world class audio! So, you don’t believe in auditory illusions?! Here’s an eerie one for you: http://en.wikipedia.org/wiki/Shepard_tone

Timid bass/poor bass weighting,  midrange shout (a well-known full-range manufacturer’s infamous attribute), a forward-sounding image, directional sound, and poor off-axis power distribution (all of which are common attributes of many full-range loudspeaker designs),  are simply the product of poor or even intentional design, and have absolutely nothing to do with break-in.

Full-range break-in – what you need to know:  All pistonic-type transducers have a very clear and predictable rate of change that occurs within the first few hours and within the extended hours of initial break-in. In the realm of credible transducer engineering, we see major changes (10-15%) occuring within the first 1-15 hours of break-in. This is the period where the major shifts normally occur. Beyond 15 hours, in a properly functioning and typical device, the process really slows down and small, incremental changes are typically observed over time. 

The Key: When a new transducer’s soft parts (cone, surround, spider, etc.) are crisp and tight, there is a specific level of transverse friction within a number of parts in the transducer. Once we get the driver working through its effective range of motion (far from linear), the transverse friction levels immediately begin to predictably drop, and the piston moves more and more smoothly with less and less resistance.

The full-range mystery: The break-in process (with all of its negative attributes) simply happens to be most intrinsically connected to, and is most audibly discerned through a full-range transducer. This is because a full range simply has the ability to augment the very subtle higher frequency centered distortions, squeaks, and squawks that a crisp new speaker is capable of producing.  Once again, if it is a full-range speaker and if it sounds bad out of the box, don’t wait for a miracle to happen; send it straight back to whomever you got it from because the speaker has serious problems. If it sounds quite good but has a very subtle graininess, or a few mild distortions, or the sound is crisp but still pleasant, then you’ve got a keeper! Sit back and be patient, and you will be pleasantly rewarded within 15-20 hours of moderate playback levels – this amount of break-in time will get you to about 80%-complete break-in. Beyond that, a functionally full and nearly complete break-in period of 200+ hours is quite reasonable and is to be expected.

Much more on this subject to follow…

Eric Alexander