"Explain Like I'm 5": Filters

Paul Wolff has designed more legendary pieces of gear than most of us have used. In his years with API alone, Paul designed the 550B EQ, 512 and 3124 mic preamps, Legacy console, and 2500 compressor. He was recently honored by NAMM TEC hall of fame for inventing the Lunchbox and 500-series format, which he helped turned into a cottage industry. I was honored to have Paul on the podcast to discuss console design and how he's seen the industry change in the last 40 years. Just a few of the things we discussed: The origins of the 500-series How Steve Perry became the first customer of the Lunchbox The uphill battle to make gear that’s authentic to the API sound What happened in 1978 to change the sound of most audio equipment Paul's opinion that cloners "should be burned to death” Download the mp3 or subscribe via iTunes Some Notes on API Jargon As much as I try to keep our podcasts fairly jargon-free, I was guilty of using a lot of API model numbers without explanation this episode. These are: 550A: Late 60's, 3-band EQ 2520: The discrete operational amplifier (DOA, or "opamp") that's at the heart of most API designs 2488: Early 70's console 512: 500-series mic preamp designed by Paul 312: 60's mic preamp 3124: A 4-channel 312 designed by Paul 2503: The output transformer in most API gear 2500: Bus compressor designed by Paul  

I've often fantasized about building a huge analog synth. But besides the obstacles of cost and not having a spare room in my house for it, I've always found the DIY synth world to be a bit intimidating. In this podcast, synth wizard Abby Echiverri walks me through the basics, such as: Is it feasible to build your own synth? How much should I budget? What are the basic modules I need to build? Abby is a composer, DJ, DIYer, and audio gear designer. I caught up with her when she was on the road as the synth/keyboard tech for Soulwax. Download the mp3 or subscribe via iTunes

We audio nerds love to talk about particular parts and circuitry—transformers, op-amps, discrete vs integrated, passive vs active, etc—but we rarely discuss the biggest part and the one we actually interface with the most: the chassis. In this episode of our resurrected podcast, I talk to Jon Erickson about the ins and outs of chassis design and manufacturing. Jon Erickson has been involved with some of the most delicious-looking audio gear on the market: the A-Designs Pacifica preamp, JHS Pedals' line of 500-series modules, and his flagship Tonecraft 363 DI/preamp. Download the mp3 or subscribe via iTunes

Sticker shock is a common malady in the recording world. It takes a lot of money to outfit and maintain a studio. But why? What are the factors that drive the price of professional recording gear? Why does gear cost so much more than the sum of its components? Are the prices justified, or is someone getting ripped off? In this month's podcast, Peterson and Chris discuss what goes into the cost of a piece of gear, and how you can short-circuit some of these costs by doing it yourself. Download the mp3 or subscribe via iTunes

How do filters work? As audio engineers, we use filters every day. We're all intimately familiar with high-pass, low-pass, band-pass, shelf, etc. filters. But how do they actually work in analog gear? The basic operating principles of analog filters are actually very simple. In this quick (10 minute) podcast, Peterson and Chris explain the very basics of high-pass and low-pass filters so that any 5-year-old could understand. Download the mp3 or subscribe via iTunes View the circuits we discussed in the podcast on Upverter:

What's the difference between "pro" and "consumer" line levels? Is it ok to plug an instrument into a line level input? What's the difference between peak and RMS levels? In the long-awaited return of our "Explain Like I'm 5" podcast series, Peterson and new DIYRE team member, Chris, explain the basics of audio levels. Download the mp3 or subscribe via iTunes Topics discussed: Can you damage equipment by plugging the wrong thing in? In analog audio Volume = Voltage The difference between peak and RMS volume RMS is a way of measuring AC as if it were DC The most common levels you'll encounter in the studio: +4dBu, pro line level (1.22V) -10dBV, consumer line level (.316V) Mic level Instrument level Tangent: why are microphone output levels so low? Subscribe to the DIYRE podcast

DW Fearn knows tubes. Since he rediscovered the sound of tubes in 1991, DW (Doug) has crafted a legendary line of all-tube, all-red-front-paneled recording gear. In April I had the pleasure of visiting Doug at his home and workshop outside Philadelphia. Doug and I sat down on either side of a ribbon microphone and had a great conversation about tubes, electronics, and sound. During our conversation Doug tells the story of how he returned to tubes after decades of operating an all sold-state studio, and outlines the theory behind why tubes and transistors sound different in a clear and straightforward way. Download the mp3 or listen on iTunes . Subscribe to the DIYRE podcast Topics discussed: How Doug pieced together his first console from standalone amplifiers What happened when he replaced that tube gear with a solid-state console "We couldn't admit that it didn't sound good, so we just got used to it." How a demo tape from college in 1966 led him back to building tube amps "We didn't listen to recorded music in my household... live music was what I was exposed to. So when the time came to build a mic preamp, that's the sound I had in my mind." Tubes vs transistors: why it's all about headroom Even vs odd harmonics and how they relate to tubes vs transistors "The less you torture it, the better it's going to sound. So you keep the signal path as simple as possible." What Doug's new product design process looks like The one equalizer that knocked DW Fearn out DW Fearn refuses to wrestle a piece of gear into existence Many thanks to Doug for having me out to his home and sharing his knowledge so freely. Thank you also to Paul K of Firehouse Recording for connecting us. You can learn more about DW Fearn gear at DWFearn.com.

When I sent out the newsletter announcing the last "Explain Like I'm 5 Podcast," I asked which audio topics you wanted to hear explained to a 5-year-old. As as result I now have a list of over 25 topics for future shows! But the response I got the most was "impedance." One reader even taunted me: "Haha, explain impedance like I'm five..good luck with that ;)" Challenge accepted, buddy! Impedance is one of those audio concepts that comes up at almost every recording session or live sound gig, even if you're not aware of it. Grasping the basics of input and output impedance can make you aware of potential problems before they happen, and help you problem solve more quickly and confidently. And the truth is that the fundamentals of impedance are simple enough that you can learn them from a 15-minute podcast. In today's ELI5 podcast, I begin with a discussion of acoustics before moving to electronics to show you that you already know more about impedance than you probably think. I go on to cover exactly what input/output impedance specs mean, illustrate the concept of impedance with examples from the studio, and explain what impedance mis-matches can do to your sound. Download the mp3 or subscribe via iTunes. Subscribe to the DIYRE podcast Do you understand impedance now? How easy was the podcast to understand? Is there any other topic you'd like to hear explained as if to a 5-year-old? I welcome your feedback in the comments.

This podcast marks the first of a new series in which I attempt to explain complex audio subjects so that a 5-year-old could understand them. In this first "Explain Like I'm 5" podcast, I tackle the important subject of balancing. What is the difference between balanced and unbalanced connections? How does balancing work? Why do we need balanced connections? In less than 15 minutes, I answer these questions the way I wish someone had for me: assuming no electronics knowledge, sticking to the basics, and using only terminology that a musician would understand. Download the mp3 or subscribe via iTunes In order, I discuss: What are balanced and unbalanced connections? How can I identify the difference? Why are there these two types of connections in the studio? How does balancing reduce noise? What is Common Mode Rejection Ratio (CMRR)? If balanced connections are so great, why isn't everything balanced?

In this month's DIY podcast, I talk to Dafydd Roche of Expat Audio about their new Eden Mic Preamp. Download the mp3 or listen on iTunes . Subscribe to the DIYRE podcast Dafydd and I get into some good stuff about mic preamp and general audio design, including: The difference between surface mount (SMD/SMT) and through hole components in terms of sound and performance. Are SMDs good for audio? Should we audio folks resist industry's march toward all surface-mount parts? The concept of "parasitics" in audio electronics design and when their effects can be critical. Dafydd gives us a guided tour of the Eden circuit from the input to output jacks--a great way to get a grasp on the basics of mic preamp design.