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AudioAcoustics

Serving the Acoustics Community Since 1994

Cross-Spectrum Acoustics Inc. offers Sound & Vibration Consulting Services

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Jul 31, 2008

Since I started my microphone measurement service, one of the questions I’m asked the most is “do you sell calibrated Behringer ECM8000 microphones?”

The answer to the question was no… until today.

I am pleased to announce that Cross-Spectrum Labs will be selling individually calibrated Behringer ECM8000 microphones. Each microphone will ship with a report of its specific measured characteristics as well as a mini-CD with the data in electronic format. The price is $100 plus shipping ($10 USPS Priority Mail or you can select parcel post, UPS or FedEx).

I’m in the process of setting up an automated online ordering process for the mics. For now, you’ll have to contract me through my online form to order mics. Payment is currently handled through PayPal but the automated process will allow you to use credit cards without going through PayPal.

Please note that quantities, for now, are extremely limit. The mics that you see on the sales page are what I have in stock. The popularity of the program will determine how many I stock at any one time and how often I restock. If you wish to purchase a mic, use the form and let me know the serial number of the mic you wish to purchase. First come, first served. Feel free to contact me if you have any questions.


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Jul 28, 2008

Time has posted a brief discussion with Children’s Hospital Boston’s ( and two-time GBC-ASA guest speaker) Dr. Brian Fligor about hearing loss and iPods.

Two things that Dr. Fligor emphasized in his GBC-ASA presentations and in this article:

  1. Hearing loss is not only a potential problem for iPods - other portable music players (inlcuding digital media/mp3 and analog tape players) can put out enough volume to damage your hearing.
  2. Hearing loss is not directly a function of the type of headset/earbud you’re using. It’s a function of loudness. The earbud at a quiet volume will have less potential for hearing loss than the circumaural headphone at high volume. There is the issue that earbuds may let more ambient sound into your ear which in turn requires you to turn the volume up to hear the music over the ambient noise but that’s a different phenomenon.

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Jul 22, 2008

It’s not big secret that alcohol is the real money-maker in restaurants. It’s also pretty clear to readers of this blog that restaurants are loud.

Put one and one together and you get “Loud Music in Bars Hastens Drinking”:

The observations took place over three Saturday nights, with the consent of the bar owners who allowed the volume of the bar music — primarily top 40 tunes — to be adjusted randomly (from 72 dB, considered normal, up to 88 dB, considered high) throughout each night.

Finding that higher volumes appeared to egg the men on to drink more and faster, the researchers theorized that louder background sound might be stimulating higher arousal levels among the patrons. They also considered the possibility that louder music might simply make verbal communication less viable, leading to more drinking as a result of less opportunity to interact socially.


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Jul 10, 2008


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Jul 06, 2008

I originally went into business for myself so I could experiment with acoustical measurement hardware and methods. The reality of business being what it is, I’ve gotten away from that but I hope to start returning to my hardware roots later this year. In the meantime, I have been playing around with hardware in an attempt to make my own life a little simpler.

Two weeks ago Saturday marked the end of an era for me as I traveled to Springfield’s hazardous waste disposal facility to divest myself of four lead acid batteries.

Like many consultants, I used lead acid gel-gel batteries to power equipment deployed in the field. Gel cells have the advantage of being ubiquitous and relatively cheap. The downsides, which became more and more apparent to me over time, is that they are heavy and too easy to fry.

The weight was a problem for me because 85% of the time I’m working on a project by myself and hauling these batteries around as part of my kit got annoying really fast - for example, my smallest noise monitoring kit weighed 12 pounds, and half of that was the battery. I was also running into issues with reliability. My digital recording gear (I often make 24-hour sound recordings for project work) is fairly power-hungry. If I don’t pick up the kit within 26 hours of deployment, I run the risk of the recorder draining the gel cell below the threshold from which I can recharge it. I can use more than one gel cell battery for these kits to avoid the problem, but then there’s the weight issue again.

I’ve wanted to try out lithium-ion or lithium-polymer batteries for some time. They have a much higher energy density than gel cells, but cost more. Much more. As a comparison, 12V/7Ah gel cell goes for $35 at your local Radio Shack, and you can find them cheaper at specialty electronics shops. An 11V/4.4Ah Li-on battery goes for about $50. On the other hand, the gel cell weighs 5 pounds compared with the Li-on at 10 ounces. Li-on packs also have built-in circuity to prevent over-charging and over-discharging of the battery.

The 6V/1.2Ah gel cell in my Audio Toolbox finally gave up the ghost last year and I figured that to be as good an opportunity as any to begin my foray into Li-ons. I ordered a 7.4V/2.2Ah battery pack and rapid charger from All-Battery.com for not much money. It worked very well - my meter was now noticeably lighter and I was getting noticeably more measurement time out of each charge.

The natural next step was to go bigger - I bought an 11.1V/4.4Ah Li-on for one of my noise monitoring kits. Again, this proved successful; the battery lasts essentially indefinitely (my unit runs out of memory after 4 days and the battery was still going strong) and adds negligible weight to the kit.

11.1V Li-on vs gel cell
11.1V/4.4Ah Li-on vs 12V/7Ah gel cell

My most recent acquisition was a 14.8V/9Ah battery pack that I use with my Marantz PMD670 for long-term audio recordings. I get well over 30 hours with the one battery back versus 22-24 hours I got with the 7Ah gel cell, at about a quarter of the weight.

14.8V Li-on vs gel cell
14.8V/9Ah Li-on vs 12V/7Ah gel cell

What are the downsides? Well, there are a few:

I’ve been happy enough with Li-ons that I use them exclusively now for field equipment - my last two gel cells have been relegated for use in my uninterruptible power supplies. My next purchase will be a couple of sets of Li-on 9V batteries for use in my ICP power supplies. If any consultants out there have tried Li-ons, I would love to hear about your experiences.


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