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Mentor 1 Build Quality

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Introduction

DALI is a loudspeaker company whose name seems to come up from time to time both online and in casual conversations with my Audioholics peers. Everyone kind of equates them with high end, but typically haven’t heard a pair- at least not here in the USA. My first exposure to their product line was back at CES 2007. I was most impressed with the Mentor product line build quality, aesthetics and most importantly – the sound. They put on quite a nice demo at the show and the group of DALI reps was very courteous and knowledgeable about their product line. I was eager to get a pair in for review and was happy to see DALI make good on their promise to give us the exclusive on their brand new bookshelf speaker the Mentor 1.

IMG_0042001.jpgWhen the Mentor 1’s arrived, they did so in two boxes. I thought, "Boy those speakers must be bigger than I was told and certainly much heavier." To my surprise DALI accidentally sent two pairs of Mentor 1’s by accident (hey, I am not complaining). It was a refreshing surprise to get a hold of a bookshelf speaker that occupies a small footprint. As you can see in the image, these speakers are the smallest of the pairs I had at my disposal – about 2/3rds the size of the Bose 201’s. Now all I had to do was determine if they delivered the sonic goods to satisfy the Audiophile at heart whose constrained by the WAF factor.

Build Quality

Design Overview

IMG_0032001.jpgThe DALI Mentor 1’s are a bit out of the norm from the typical bookshelf speaker system we’ve encountered. They are a ported two-way design, but employ a separate dome and ribbon tweeter system. The advantage here is extended frequency response, higher power handling, and greater transparency. The Mentor 1’s employ a 5” wood fiber pulp cone woofer, 1.1” soft dome tweeter and a 2” ribbon tweeter. DALI claims these speakers are time coherent and employ a linear impedance profile – two of many design attributes in their products which constitute their design philosophy. It sounds good to me.

The Mentor 1’s drivers are mounted on a 1/2” MDF baffle which is isolated from the actual enclosure to reduce mechanical vibration transfer from the drivers to the enclosure. All of the drivers are countersunk into the baffle as any good loudspeaker should to minimize diffraction. The cabinet appears to also be constructed of 1/2” MDF, making the front baffle total thickness a whopping 1”. A quick knock test on the cabinet and front baffle revealed they had uniquely different sonic resonances.

The WooferIMG_0050001.jpg

According to DALI, the ultra lightweight, stiff wood fiber paper cone is responsible for its very fast & agile response. The motor structure utilizes a die-cast rigid aluminium chassis (no wimpy stamped baskets) to minimize resonance. The rear side of the spider assembly is open (6mm air gap) to reduce air compression around the (17mm) voice coil. Upon inspection it was clear to me this was a quality driver. The cone was stiff as it should be and had a very linear response when moving within the limits of its excursion capability. The driver is not magnetically shielded so keep this speaker clear of computer hard drives or CRT displays. The woofer was well secured to the cabinet with seven (7) screws making it clear to me that DALI understands the importance of reducing mechanical vibrations by ensuring the drivers are firmly planted into the front baffle.

Tweeter(s)tweet.jpg

The Mentor 1’s employ a hybrid tweeter module consisting of a dome and ribbon driver topology. DALI claims the dome tweeter is specifically designed to have a natural acoustical roll off response to blend seamlessly with the ribbon tweeter without the need of a passive low pass filter network. According to DALI, the tweeter array sports a floating waveguide behind the dome for optimum support of the dome shape and resonance damping without blocking the free airflow. I was particularly impressed with the large acoustical rear chambers on the dome and ribbon drivers. Their primary functions are to lower compression and the resonance frequency, taking some of the pressure off the woofer to produce the upper midrange.

CrossoverIMG_0052001.jpg

The brains of the speaker – DALI employed all air core inductors for greater precision and lower losses due to core saturation. Tight tolerance ceramic resistors were utilized in the crossover design but to my surprise DALI used what appeared to be electrolytic capacitors instead of polypropylene. Poly caps tend to be more linear at high frequencies at the expense of increased cost factor and footprint. I’d be curious if DALI offers an upgrade path to these crossover parts for future designs.

The network was carefully designed to help make the speaker system behave more like a resistive load allowing for a more consistent sound when playing on a variety of amplifiers. You’d be surprised how many manufacturers overlook this important engineering design principal in their designs.

The crossover was firmly secured down to the back of the cabinet via screws and the internal cabinet was generously damped with Dacron insulation on the side walls and bottom though curiously missing insulation at the top of the cabinet.

The BacksideIMG_0038001.jpg

The DALI Mentor 1’s have a really nice rear end. From the contoured shaped back panel (which serves for aesthetics reasons and reduction of standing waves in the cabinet), the heavy duty WBT binding posts, to the neatly tucked away inclined port, these speakers demonstrate efficiency in design and function. In fact, the clever inclined port was likely implemented as a space saving method of extending port length in a small cabinet to lower the tuning frequency and increase bass extension. My only minor concern is for people using garden hose thick speaker cables which could potentially block the port. I suggest using some common sense here. If you think you need to use wire gauge any heavier than 10AWG on these speakers, perhaps some therapy is in order.

To wrap up our tour of the speaker, I felt it prudent to mention that DALI has taken the right steps to design quality into their product, including paying special attention to the little things. For example, the grill cover is top notch. It’s tightly woven fabric, and from my performance measurements very transparent.

I felt it prudent to mention that DALI has taken the right steps to design quality into their product....

The grill itself is constructed of wood instead of cheap plastic so commonly found in loudspeakers these days. The overall fit and finish of these speakers is excellent from the woodwork right down to the drivers which all utilize real ferrite magnet motor structures. The collection of parts truly scores high points in the 'pride of ownership' department.

 

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