A7S-450 Measurements and Analysis
Measurements were performed using the Sample Champion program developed by Paolo Guidorzi of Purebits. The program is a Maximum Length Sequence (MLS) program that generates an impulse response in the time domain from this pseudorandom signal. Fast Fourier Transformation is applied to the impulse response to generate the system frequency response. The operating principle is the same as that of the well known MLSSA program.
Test samples were taken using 16 bit resolution with a 48 kHz sampling frequency. Fast Fourier Transformations were performed at 64K allowing for a frequency resolution of .73 Hz, which is more refined than even 1/24th
octave resolution at the lowest octave; the A0 key on the piano has a fundamental frequency of 27.5 Hz.
All measurements of the driver were taken nearfield at the approximate acoustic center of the driver and referenced to a simultaneous, independent SPL measurement taken at 1 meter from the subwoofer. For these measurements, the low pass filter and the 25Hz bass boost were defeated.
Figure 1: Nearfield Impulse Response
Figure 1 shows the impulse response of the A7S-450 subwoofer measured nearfield at an SPL of 80 dB at 1 meter. This fairly typical response curve for a bass driver shows the A7S-450 damping out the impulse input quickly within two cycles of free vibration.
Figure 2: Nearfield Frequency Response
Figure 2 shows the nearfield frequency response of the A7S-450 at an SPL of 80 dB at 1 meter. The frequency response curve shows peak output at approximately 60 Hz with tapering of output below 50 Hz at approximately 12 dB/octave. No inflection point indicating significant roll off to the bass response occurs in the subwoofer’s response, which has a smooth roll off to 10 Hz. The specified 22 Hz appears to be dependent on the presence of either room boundary effects or utilization of the 25 Hz bass boost and perhaps a combination of both.
Figure 3: Nearfield Frequency Response at Various SPL
The curves in Figure 3 are overlays of the nearfield frequency response of the A7S-450 measured at various SPL. The green curve was measured at a peak SPL of 80 dB at 1 meter with the red curve at 90 dB, the blue curve at 100 dB SPL, and the purple curve at 104 dB, all measured at 1 meter from the subwoofer.
From the identical shape to the plotted curves at various SPL, it is clear that the sub had more to give before suffering the ill effects of compression even if my computer soundcard did not. Based on my experience with the sub, I would anticipate at least 3-5 dB more output is possible from the A7S-450 without any significant sonic troubles.
See also:
Recent Forum Posts:
croseiv;641641
yep, same here. Wait a minute, i did...:d
lol :d :d
croseiv;533454But if it has a nice frequency response and sounds good, who cares? A sub's a sub right?
Sounds like they are just slapping a car subwoofer into a box...
I have had my A7s-450 for almost two weeks now. I begged the wife to let me get it as I already had an A2-300 that has worked wonders in our old, smaller living room. However, a new house meant more room and a higher ceiling...the A2-300 was struggling on some movie scenes that had the lowest bass (i.e, Master and Commander, Terminator, etc.) as I had to turn the gain higher than before, despite a corner location. I just needed to move more air.
I e-chatted with Brett to great effect; he was very knowledgeable from a design standpoint and had much insight into what was mechanically and electrically required from a subwoofer to accurately reproduce bass. I learned a lot and centered on the A5-350 15" ported and the A7s-450 18" sealed units. Brett helped me figure out how much air i needed to move (as in total driver linear displacement and the proper amp power to take advantage of it.) and the type of sound I was looking for for my music listening. We had an extremely productive chat and Brett was both very friendly and very professional. I was taken aback because it was much more like speaking with a friend on IM than a person I've never met in Iowa (I'm in Florida). His open-ness to share specific figures and specs on his products sold me. Having a background in live pro-sound mixing, I know enough to know that he did not BS me. Not even once. He didn't even try...he just knew his stuff inside and out. Then I pried it out of him....he had a direct hand in the actual DESIGN of several eD sealed subwoofers, to include the A7s-450. We talked turkey for about 15 minutes and then I let him go. NO pressure and he got ZERO info from me. There was no guarantee of a sale on his part...he just poured out the info.
Days later, I spoke with Matt over the phone, who was equally knowledgeable and helpful. I verified the free eQ.2 promo for the A7s-450 and ordered one over the phone. Wam, bam, thank-you-ma'am. No hassle and I was G2G.
I received it via, as always, free shipping. This sub was so big, I had to un-pack it completely just to fit it in my Hyundai Elantra (don't try this at home boys and girls). After a few sacrificial (and permanent) modifications to my front passenger seat, two little helpers at the UPS depot, I shoe-horned the beast in.
After getting it home and turned-on, it was a revelation; the sub just had no limits in my new living room. This was before tweaking via the included eQ.2 (a steal, I might add). I went to bed, perfectly happy with my purchase.
A few days later I found the time to fiddle with the eQ.2 Long story short, you can dial this sub to make it sound like whatever you want in your room. I've got the mid-bass shelved by about 6db from 60-65Hz on up and the low EQ centered on 25Hz with a Q of 2 and about 7 or 8 dB of boost. It's dynamic from barely audible night-time everyone-else-is-sleeping volume levels to neighborhood-rapport-destroying levels with Terminator:Salvation, Transformers II RoTF, and Master & Commander. Amazing output at well below 20 Hz. I test-toned it down to about 10Hz. Amazing. Just stupid levels of sound from this thing. It left me shaking my head at how low it went and still maintained its composure....it just kept getting louder and louder...I decided to stop testing as it was getting late and the sub just kept getting louder. I became legitimately concerned that it was going to break my sliding-glass-door as it was sitting not far from it.
Music performance is as accurate as I could ever hope. It's dynamic and impactful. It sounds great with Metallica, Anberlin, MuteMath, Diana Krall (her damn-near-perfectly recorded 'Live in Paris'), Van Morrison, Dave Brubek, AC-DC ('Shoot to Thrill' and 'Thunderstruck' will change your life using this sub), John Mayer, Michael Jackson, Jack Johnson, Black Eyed Peas, Red, Breaking Benjamin, Bach, Handel, U2, etc. It sounded great with everything I played through it...Once I got the levels dialed in, NO further adjustments were needed. I have never experienced this...it just disappeared and added depth and impact to what I thought were familiar recordings. Every song had added depth and the soundstage seemed HUGE....much bigger than the room....especially with live recordings (like U2's 'Live in Chicago' DVD). The eQ.2 adds so much versatility to this sub...they should be considered a pair. You can adjust the sub to even out your room response in so many ways, it would be worth the price of the upgrade (even though it's free now). Just amazing. I haven't heard ANYTHING any where near this price point that can even match this performance in a regular guy's living room. I do not have any sound treatments or other goodies...I have a wife who uses her magnifying glass about what the room looks like. The sub sounds so good, she even passes it now. She was able to clearly articulate that it sounds MUCH better than ANY theater she has ever been to. She said that anything that 'sounds this amazing' is okay in her living room, regardless of size. She watches romantic comedies with the sound system now because even she thinks it makes the closing of doors and city scenes seem more real. Who am I to argue?
I can whole-heartedly recommend this sub. The only thing I could imagine that would be better than an A7s-450 would be TWO A7s-450's.
gorillacooch;641815
And buy a subwoofer that is one year into the warranty? If it was 1200 with shipping I'd say yes, but 1350? id rather spend the extra 350 and make sure i get my full 3 years.
Also 3 years doesn't really seem that long. If you look at eD they have a 5 year warranty. Now thats a warranty, that shows they really stand by their product.
That's true, but then I wasn't sure where you are. It could've been a short road trip. Then at $1200 it would've been a steal.
DJ
