Synopsis: The Aurisonics AS-1b is a very nice custom-fit monitor with a sound tuned for the needs of professional musicians performing on stage. It gives the listener a mid-centric sound that emphasizes the vocal range so a singer stands out in the mix. The large 15mm dynamic driver has an excellent, rich bass and on top there is a non-fatiguing, flat treble. The AS-1b offers musicians and audiophiles a lot of versatility in terms of a user-adjustable bass vent and ambient port, plus replaceable cables. It’s well-designed and well-tuned and, at $599, it comes in a mid-range price for a custom-fit stage monitor. Introduction: Aurisonics is a relatively new company and it has generated a splash among audiophiles with its blend of interesting custom and universal fit stage monitors plus friendly and responsive customer service—much of it directly from Dale Lott, the owner of Aurisonics, himself. Dale has been a pro audio engineer for over 20 years and he is quite articulate about the sound he’s found works best for performing musicians. It’s been very nice to see how responsive he’s been in working with musicians and audiophiles, soliciting their feedback, and evolving his products. This review is part of that process. I am reviewing the AS-1b version 1.2—Dale has added a new filter to improve the sound from the original version. In fact, this review will be updated as Dale comes up with ways to make the AS-1b even better. Disclaimer: I always have one of these in my reviews to let readers know how I came by the set of earphones I’m reviewing. I believe being open and transparent leads to a review you can trust. In this case, these were provided by Dale so I could give feedback and review them. He was clear that he only wanted an honest review and I wouldn’t have it any other way, so here we are. Custom Fitting: The process, as many of you know, involves going to an audiologist to make a set of impressions of your unique ears. Getting a perfect fit with a custom monitor is the key to getting the best sound, the best comfort and the best isolation. Your fit will be only as good as your set of impressions, so it’s very important to work with an audiologist who has experience specifically taking ear impressions for pro musicians’ stage monitors. My advice is that the audiologist should use a 1” bite block—this holds open your mouth as the impressions are made. This is necessary because as you open your jaw to sing (or yawn, I suppose, it’s your music), the shape of your ear canal changes. Try to relax your jaw as much as possible during the process as that effects the ear canal as well. And don’t sneeze. Customer Service: This is really second only to the sound in importance when buying a custom fit earphone from any company. It’s very, very common for a set of custom earphones to not quite fit perfectly the first (or second) time around even with a great audiologist. And there are many tiny parts in a custom earphone which can fail or otherwise break. So, you need to work with a company that’s responsive. Aurisonics has done a great job so far and Dale has shown he has your back when you need it. Just the way he has listened to customers’ feedback and added a special acoustic filter to this version 1.2 is an excellent sign. Listening and responding to customers’ needs is the definition of good customer service and it gives me a lot of confidence in Aurisonics. The AS-1b: The AS-1b has a single 15mm dynamic driver. A dynamic driver is basically a smaller version of the same kind of speaker that’s in most people’s home stereo systems. In an earphone or headphone, a single dynamic driver can cover the frequency spectrum. This is different from the balanced armatures often found in custom monitors and which were originally developed for use in hearing aids. Armatures often do well in multi-driver set-ups, but dynamics are most commonly found on their own. So, don’t be surprised by use of a single dynamic driver here. Build Quality: The build quality seems very good as it’s a sturdy design and the hard plastic shell seems quite tough. The socket for the replaceable cable is particularly well designed. In fact, it looks more secure than any custom earphone I’ve seen. The only issues I see are that the little screws for the bass vent and ambient port need to be treated carefully as they are threaded into the hard plastic shell directly. Of course, you should be treating your several hundred dollar earphone carefully to begin with, so maybe that’s common sense. The two screws on the left are the user adjustable bass vent above and the ambient port below. The gold ringed disk is the face of the dynamic driver itself. You can see a hint of the black acoustic filter inside the nozzle. The AS-1b comes in a sturdy otter box. You can see the key used (with the red at the end of the handle) to adjust the bass vent and ambient port. It may not look like much in the picture, but for some reason, the AS-1b is a compliment magnet. I've gotten friendly comments on it, from women and men, in the subway, the supermarket, everywhere I go. It's actually generated more positive feedback than my other, ostensibly higher-end, custom earphones with fancy wood inlays. The Adjustable Bass Vent and the Adjustable Ambient Port: As you can see in the pictures above, a key is used to adjust both the bass vent and the ambient port. These are two separate user-adjustable features and they add a lot to the versatility of the AS-1b. The Bass Vent: Opening or closing the bass vent allows more or less air to the driver and that means that you can adjust the bass response (particularly the lower-register bass rumble) from fully rich and present to something more meek and subdued. I prefer the more fully present bass, but you may roll differently. It’s up to you with the AS-1b. The Ambient Port: The ambient port reduces isolation when opened. This can be good when you need to hear the crowd on stage or in situations when you need maximum situational awareness. With the ambient port open, you can easily have a conversation, hear that important call come in, not get hit by a bus—all the times when you need to pay attention to something more than your music. Otherwise, keeping the port closed gives you the best isolation. And the isolation is reasonably good on the AS-1b. Assuming you’ve closed the ambient port, you’ll close out a good percentage of outside noise. It’s in the same league as the usual acrylic shelled custom earphones out there, just a tiny bit less with the bass vent open. Sound: Overall, the AS-1b has an upper midrange centric, specifically vocal-centric, sound, with a good-sized rise around 1-3khz. It’s a warm, darker sound whose up-front vocals and excellent backing bass give it a rocking sound. There’s a good thickness of note so a piano, violin or voice doesn’t sound thin or frail. Instead, each strike of the keyboard resounds with a good weight and decay. Generally, the AS-1b does very well with giving a realistic and natural sound to strings, pianos, etc. The sense of a soundstage is intimate with a good depth to it. The soundstage may not be the largest, but it does well. The soundstage sounds more left-right oriented than to the front to my ears, but it is an engaging and enveloping presentation. Spatial cues can come across well depending on the recording. For example, I have a field recording where the person holding a microphone stands with their back to a stream and you can hear the waters swooshing gently behind you just as it originally happened. Keep in mind that for any earphone or any headphone that many of the cues for soundstage come from the recording itself. The 15mm driver is quite resolving for good detail, although it’s a bit smoothed over, perhaps by the filter. Bass: The bass is truly excellent. It’s quite rich and also has great punch. There’s very good extension into the sub bass, which makes for nice bass rumble. One thing that stands out to my ears is that the mix between midbass and sub bass is very well done, it just sounds how awesome bass should sound. It’s adjustable, too. Bravo. Midrange: It’s voices to the fore, perhaps the main signature for the AS-1b. This is great for stage as it allows the singer or main instrumentalist to be heard over everyone else’s playing as well as the roar of the crowd. It tends to add a sense of immediacy to the singing that I like. Generally, the filter allows the midrange to rise without harshness. In some recordings, however, you’ll find there’s already an emphasis in this range, so the beep of a pop song will seem to stand out a bit more than with other earphones. This is something I’m sensitive to and I didn’t have a problem with the AS-1b, so the filter did a great job. I would like a little more sense of transparency, but there is good detail. Treble: This is a non-fatiguing treble for hours of comfortable use on the stage. The treble sings well with violins and soprano voices and has a flat, accurate sound as high as it reaches. However, it’s a bit rolled off (not fully extended) on the very top. You can hear this a bit with cymbals on the drum kit. They tend to lack that extra shimmer on top--the "air" that audiophiles talk about. So, there’s a lack of sparkle and a slightly dark sound which contrasts with the rise in the midrange. Dale says the AS-1b responds well to EQ and it does. I think many users will choose to add a rise to the treble. Conclusion: The AS-1b is very nice stage monitor with a sound focused on the vocal range for a mid-level price. Its bass vent and ambient ports give it a versatility not found even in custom monitors for twice the price. I expect the sound quality and tuning will quickly draw a following among the stage musicians for whom it is intended and also among audiophiles who prefer a non-fatiguing dark treble, vocal emphasis and excellent bass.