This Check Bench explication focuses on the Dayton Audio Epique MMAG E150HE-44 “full-range subwoofer,” in itself an fascinating idea. Like its bigger E180HE-44 brother within the Epique line, the E150HE-44 relies on the patented A number of Magnet Air Hole (MMAG) know-how invented by Enrique Stiles. The 2 new Dayton Audio Epique MMAG woofers have been designed with direct help by Enrique as an unbiased transducer engineering marketing consultant, working along side the engineering crew at Dayton Audio. This text was initially printed in Voice Coil, December 2021.
MMAG was invented by Enrique Stiles, and the MMAG patent (there are a number of) that applies to the E150HE-44, US6,917,690, was assigned to Step Applied sciences, Inc. Step Applied sciences was initially a partnership between two of the very best transducer engineers with whom I’ve had the distinct pleasure of working—Enrique Stiles and Patrick Turnmire (Patrick has finished a lot of the Klippel LSI evaluation that has appeared on this column).
In observe, this dynamic duo had Enrique doing quite a lot of the conceptualization and Patrick heavy into software. This partnership additionally included Richard Calderwood, a world-class patent legal professional, who’s at present the Director of Mental Property at Nvidia, and was the previous senior mental property legal professional for Intel Corp. Collectively this proficient trio fielded greater than 40 transducer patents, which is kind of spectacular. Whereas the partnership is now not collectively, Enrique remains to be growing MMAG woofers, the most recent instance being this month’s first driver to be examined the Dayton Audio Epique E150HE-44. Enrique is now an unbiased transducer engineering marketing consultant and developed the 2 new Epique full-range subwoofers along side the engineering crew at Dayton Audio.
The Dayton Epique E150HE-44 is promoted as a full-range subwoofer, which in itself is an fascinating idea, and one that’s ideally suited to the MMAG know-how given the standard high-excursion/low inductance facet of this motor design. The EP150HE has a considerable function set that begins with a proprietary six-spoke cast-aluminum body, composed of slim (about 9mm) spokes, fully open beneath the spider (damper) mounting shelf for cooling (Photograph 1 and Photograph 2).
Further cooling for this driver is offered by six 4mm diameter vents within the voice coil former, in addition to three 8mm diameter vents within the again plate. Further cooling happens because of the MMAG multi-magnet configuration. The first magnetic drive is offered by the 121mm×25mm ferrite rear ring magnet, instantly offering flux to the second rear 7mm hole. Nevertheless, the secondary magnet system is comprised of six 28mm×8mm ferrite disks. These magnets don’t add flux to the higher 7mm hole, however quite act as magnetic “diodes” (aka hole balancing magnets) pulling the flux from the primary magnet into the highest 7mm hole. These disks additionally present an 8mm area between the 2 7mm gaps in addition to a standard cooling path for the voice coil because it travels between the 2 gaps.
The cone meeting consists of an especially stiff curvilinear-shaped carbon fiber cone fitted with a 1.6” diameter carbon fiber mud cap. Compliance is offered by 21mm large NBR encompass that has a largely shallow transition to the cone attachment, with the remaining compliance coming from a 4” diameter flat fabric spider (damper).
The motor is an FEA-optimized dual-ferrite magnet sort with milled plates and prolonged copper sleeve shorting ring (Faraday Shields) on the pole piece. Driving the cone meeting is a 38mm (1.5”) diameter twin voice coil (two 4Ω coils) wound with spherical copper-clad aluminum wire (CCAW) on an aluminum former. Final, RMS energy dealing with is rated at 200W and the voice coil tinsel lead wires are stitched into the spider. The leads are then terminated to gold-plated solderable terminals situated on reverse sides of the previous to discourage rocking modes.
I started testing the Dayton E150HE-44 full-range subwoofer utilizing the LinearX LMS analyzer and the Bodily LAB IMP Field to create each voltage and admittance (present) curves. The motive force was mounted to a inflexible check fixture in free-air at 0.3V, 1V, 3V, 6V, 10V, 15V, 20V, and 30V with the oscillator on time between sweeps to simulate the precise thermal course of over time. The 30V curves have been too nonlinear to get a adequate curve match and have been discarded. Nevertheless, having a 5.5” driver testing out to 20V is spectacular as most 5” drivers don’t make it previous 10V.
Following my established protocol, I now not use a single added mass measurement and as an alternative use the bodily measured Mmd knowledge (26 grams for the E150HE-44). The collected knowledge, on this case the 14 550-point (0.3V to 20V) sine wave sweeps for every Epique pattern have been post-processed and the voltage curves divided by the present curves to generate impedance curves, with the section derived utilizing the LMS calculation technique. I imported the information, together with the accompanying voltage curves, to the LEAP 5 Enclosure Store software program. Determine 1 exhibits the 1V free-air impedance curve. I chosen the 1V TSL knowledge within the transducer parameter derivation menu in LEAP 5 and created the parameters for the pc field simulations. Desk 1 compares the LEAP 5 LTD/TSL Thiele-Small (T-S) parameter knowledge and manufacturing unit parameters for each of Dayton Audio E150HE-44 samples. Be aware that the E150HE voice coils have been wired in sequence.
LEAP LTD and TSL parameter calculation outcomes for the E150HE-44 subwoofer seem to correlate fairly effectively with the manufacturing unit printed knowledge. I adopted my established protocol and proceeded to arrange laptop enclosure simulations utilizing the LEAP LTD parameters for Pattern 1. For those who ever puzzled why I take advantage of the LTD parameter set over the TSL parameter set, it’s as a result of the LTD mannequin gives a extra correct most tour estimation.
Two simulated enclosures have been programmed into the LEAP 5 software program, each specified by Dayton Audio. The primary, a sealed field (Qtc or alignment not specified) with 0.12ft3 air quantity with 50% damping materials (fiberglass), and a vented alignment (alignment not specified) with a 0.25ft3 quantity with 15% damping materials tuned to 41Hz.
Determine 2 shows the field simulation outcomes for the E150HE-44 full-range subwoofer within the sealed and vented enclosures at 2.83V and at a voltage degree that achieves tour equal to Xmax + 15% (16.9mm for the E150HE). This resulted in a F3 of 64Hz (-6dB=51Hz) with a Qtc=0.60 for the closed field and a -3dB for the vented simulation of 45Hz (-6dB=38Hz). Growing the voltage enter to the simulations till the Xmax + 15% tour was reached resulted in 108.5dB at 78V for the sealed enclosure simulation and 111.5dB with a 90V enter degree for the bigger vented field. Determine 3 exhibits the two.83V group delay curves. Determine 4 exhibits the 78V/90V tour curves.
Klippel evaluation for the Dayton 5.5” woofer was not carried out this month by Patrick Turnmire (Redrock Acoustics) with the Klippel DA2 analyzer (courtesy of Klippel GmbH), because the DA2 is on its technique to Germany for recalibration. This month’s knowledge was as an alternative offered by a Dayton Audio provider.
The Bl(X) curve proven in Determine 5 is reasonably broad, however with an apparent however small diploma of coil-out offset. The Bl symmetry curve in Determine 6 exhibits a 0.82mm Bl coil-out (ahead) offset when you attain an space of affordable certainty (about 10mm) and remaining fixed as much as the 14.7mm Xmax tour level.
Determine 7 and Determine 8 present the Kms(X) and Kms symmetry curves for the E180HE driver. The Kms stiffness of compliance curve seen in Determine 7 can also be fairly symmetrical and with a small diploma of rearward (coil-in) offset. The Kms symmetry vary curve proven in Determine 8 displays small 1.8mm coil-in (rearward) offset on the 14.7mm Xmax location.
Displacement limiting numbers calculated by the Klippel analyzer for the full-range woofer utilizing standards for Bl was XBl @ 82% (Bl dropping to 82% of its most worth) equal 13.6mm for the prescribed 10% distortion degree. For the compliance, XC @ 75% Cms minimal was 15.6mm, which signifies that for the Dayton Audio woofer, the Bl is the extra limiting issue for attending to the ten% distortion degree. Nevertheless, if we use the much less conservative 20% distortion standards, XBl @ 70%=17.7mm and XC @ 50% >17.7mm, exhibiting the Bl quantity on the driver’s bodily Xmax.
Determine 9 offers the inductance curve Le(X) for this transducer. Motor inductance will usually enhance within the rear course from the zero relaxation place because the voice coil covers extra pole in a standard motor, which is what you see within the graph. Extra importantly, the inductive “swing” from most inductance to minimal inductance from 14.7mm coil-in to 14.7mm coil-out is a comparatively small 0.09mH, which is excellent.
For the remaining check procedures, I mounted the Dayton E150HE 5.5” full-range subwoofer in a foam-filled enclosure that had a 15”×6” baffle. Then, I measured the system beneath check (DUT) utilizing the Loudsoft FINE R+D analyzer and the GRAS 46BE microphone (courtesy of Loudsoft and GRAS Sound & Vibration) each on- and off-axis from 200Hz to 20kHz at 2.0V/0.5m normalized to 2.83V/1m utilizing the cosine windowed FFT technique. All of those SPL measurements additionally included a 1/6 octave smoothing.
Determine 10 offers the E150HE-44 on-axis response indicating a reasonably easy rising response with no break-up modes or peaking out to about 5kHz, with a 7dB peak within the response at 7kHz, the place it begins its low-pass roll-off. As marketed, this 5.5” subwoofer is certainly appropriate for full-range purposes.
Determine 11 shows the on- and off-axis frequency response at 0°, 15°, 30°, and 45°, and -3dB at 30° with respect to the on-axis curve happens at 2.8kHz. A cross level in that neighborhood or decrease ought to work effectively to attain a great energy response, once more validating the full-range facet of the lengthy tour subwoofer.
Determine 12 offers the normalized model of the picture proven in Determine 11. Determine 13 shows the CLIO pocket horizontal polar plot (in 10° increments) for the Dayton Epique 5.5” woofer. And at last, Determine 14 offers the two-sample SPL comparisons for the E150HE, exhibiting an in depth match to inside lower than 1dB via most of its working vary.
For the remaining sequence of exams on the Epique E150HE-44, I employed the Hear, Inc. SoundCheck AudioConnect analyzer and SCM microphone (provided to Voice Coil by the parents at Hear, Inc.) to measure distortion and generate time-frequency plots.
For the distortion measurement, the 5.5” driver was mounted rigidly in free-air, and the SPL set to 94dB (my standards for dwelling audio transducers) at 1m (16V), utilizing a SoundCheck pink noise stimulus. Then, the distortion was measured with the Hear microphone positioned 10cm from the driving force. This produced the distortion curves proven in Determine 15, which is distinguished by very low third harmonic content material above 1kHz, and fewer than 1% beneath 1kHz.
I then engaged the SoundCheck software program to get a 2.83V/1m impulse response for this driver and imported the information into Hear’s SoundMap Time/Frequency software program. The ensuing cumulative spectral decay (CSD) waterfall plot is given in Determine 16. The Wigner-Ville plot (chosen for its higher low-frequency efficiency) is proven in Determine 17.
Taking a look at all the information exhibits this driver to be in a class all by itself. It produces good low-frequency efficiency for a 5” driver, and certainly is able to being utilized in two- and three-way design. Given the general design and construct high quality, this can be a well-crafted product particularly supposed for the compact two-channel, dwelling theater, or studio monitor market. VC
This text was initially printed in Voice Coil, December 2021.