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The Audio Builders Workshop offered an expanded program at the 2019 convention of the Audio Engineering Society, held at the Javits Convention Center in New York City, October 16-19. The culmination of this year's program was a three-hour Build Clinic on the last day of the convention. Owen Curtin and Chris Kincaid ran this session, and attendance far exceeded their expectations. There were more than 40 participants, and each person was required to purchase a kit for the session, which they assembled onsite. Participants were given a choice of three kits, depending on their level of experience - the L2A Passive Preamp, the ABW Metronome, or the S-25 microphone.
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Two audio builders assemble S-25 microphone kits at the AES Audio Builders Workshop Build Clinic. The microphone was one of three kits that participants could purchase.
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The L2A Passive Preamp is a mono, transformer-based unit with a balanced XLR input and a 1/4-inch phone unbalanced output. The transformer is an Edcor 1437, and volume adjustment is done with a potentiometer on the transformer secondary. Details can be found on the DIY RE website. The ABW metronome is a very basic design based on the veteran 555 timer chip, and was also used at the 2018 session. Details are on the Clockworks website.
A more ambitious project was the S-25 microphone kit. Despite its modest price of $229 US, the S-25 is a real electret condenser microphone (ECM), with very good performance characteristics. Full details on the S-25 microphone kit can be found on the Micparts website. The description on the website notes: "The S-25 is a professional quality condenser microphone kit. The finished microphone has a Cardioid polar pattern and a switchable -10 dB pad (the switch is internal). It is sold in DIY kit form, designed for first-time DIY microphone kit builders as well as professional recordists in need of an affordable, high-performance workhorse microphone... Some people think a 'real' microphone needs to cost $500 or $1000 or more. We disagree. So do celebrity engineers who use this mic."
The microphone is built around a Transound TSB-2555 medium-size capsule, with a broad, smooth presence boost between 4 kHz and 12 kHz. The electronics consist of an ETL1 microphone preamp, which is designed for electret condenser capsules, and which can also be purchased separately. The circuit is transformerless, and is based on the Schoeps CMC5, which is one of the most highly-regarded microphones in the world. The website has a review of the microphone published in TapeOp magazine, along with audio clips comparing it to several other popular condenser microphones.
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These high school students participated in a special "Learn to Solder" session at the Audio Builder's Workshop Build Clinic.
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Several high school students were invited to the session to learn how to solder. When I was in high school in the late 1960s, quite a number of students tried their hand at kit building, even though most would never pursue audio or electronics as a career. With the disappearance of names such as Heathkit, KnightKit, DynaKit, and Eico, soldering became a somewhat forgotten skill. This was an extremely important addition to the Build Clinic, in my view. The more hands-on electronics building experience young people can get, the better. The Audio Builders Workshop extends a special thanks to Mouser Electronics, and to the Audio Engineering Society (AES) for its continued support of this most worthwhile program.
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Buddy Lee Dobberteen (right) mentors a participant during his session on building a BA500 microphone preamp kit. The session was one of several held at the Audio Builders Workshop booth on the AES exhibit floor.
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Tony Santa Ana builds a BA500 microphone preamp kit at the Audio Builders Workshop booth. Like Dobberteen, Santa Ana is also a US Army veteran.
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During the three days exhibits were open, the Audio Builders Workshop ran a series of half-hour sessions on various topics, all held at their booth on the exhibit floor. "Build a BA500 Kit" was a session given by Buddy Lee Dobberteen, proprietor of His Little Studio and Mentoring in Spring Branch, TX. Dobberteen got into DIY audio, recording and music to help him recover from severe depression after serving in Iraq. His company is dedicated to teaching people how to build equipment and use this equipment in their studios, and he has a special interest in the well-being of our veterans.
The BA500 is a high-quality microphone preamp kit that can be purchased for $168 US. The assembled price would be roughly three times that amount. The manufacturer, JLM Audio, notes that the kit contains every part needed "down to the last nut and bolt." The preamp is based around a transformer-coupled input and output, along with op-amp-based active circuitry. The BA500 is a module that is intended to be inserted into a JLM 500-series rack. The rack contains the appropriate input and output connectors.
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The 2019 AES International Convention in New York once again included an Audio Builder Workshop booth and a series of events on the exhibition floor, featuring hands-on demonstrations with kit makers and expert builders, as well as in-depth sessions in the All Access Technical Program.
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Full details on the BA500 can be found on the JLM Audio website, which donated the kits for this workshop. Unfortunately, the presenters at these booth workshops were forced to compete with loud music being played in two adjacent booths, the most annoying offender being the John Lennon Educational Tour Bus. The live music from this booth could be heard throughout the exhibit area. The AES used to have rules regarding allowable playback levels on the exhibit floor. Next year, I hope it will go back to enforcing them, in fairness to the other convention exhibitors. The Audio Builders Workshop is a workgroup of the Boston section of the Audio Engineering Society, and continues to be a most worthwhile endeavor.
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