#wes dooley

[fionaapplerocks]

Fiona with Wes Dooley in 2018

[fionaapplerocks]

zelda hallman:  Continuing Birthday week photos. Fiona with the amazing Wes Dooley - look him up. Fiona and I got to spend a couple of days learning about ribbon mics and Wes’ incredible and inspiring journey. We met Wes at the former @prairiehomecompanion now @livefromhereapm show.

[fixitinthemic]

Ribbon Mics and Mic Preamps

© 2004, 2006

by Wes Dooley

ribbonmics.com / [email protected]

Studio ribbon microphones offer smooth and versatile performance that sounds good on a wide variety of music. They’ve proven themselves in daily use for more than 70 years. However, to achieve this great sound quality, using them with the right mic preamplifier is essential. This presupposes an understanding of how mic preamps interact with mics, in this case, with an emphasis on ribbon and other dynamic mics. Which mic preamps are best? Although this appendix will present some criteria for you to evaluate them, you should trust your ears and start listening carefully to mic preamps you own, borrow, or are considering purchasing.

As you gain experience, you’ll discover that a quiet, distant, solo acoustic guitar, for example, will need 70 dB or more of clean, quiet gain. Older classics such as the ‘class A’ Neve units were designed to provide this gain. Likewise, many contemporary, stand-alone mic preamps sound good and can be ordered with extra gain.

High performance, specialty preamps start at around $700, and choices multiply amazingly as you get to $1,000 per channel. Ribbon mics deliver extraordinary dynamic range, especially with percussion. Your experiences will tell you whether a specialty preamp might help you best capture the sounds you value.

Mic preamps with transformers tend to have a sound of their own and lower input impedance. Transformerless designs tend to be more neutral and open sounding, generally are quieter, and have higher input impedance. The input impedance should be at least 1,000 ohms for ribbon mics, although 1,500 ohms is better. The lower range of impedances influences wider ribbons less, such as those found in AEA and Coles mics. Narrower ribbons, such as in the RCA 77 and the Speiden/Royer stereo mics, are more susceptible.

Ribbon microphones with integrated, DC-powered active electronics, such as the old Cambridge or the Royer P48 powered ribbon mics, reduce the influence of a mic preamp’s input impedance. Transformers are still used between the ribbon and the internal electronics, but these internal electronics keep the recording electronics from being affected by a ribbon’s low frequency resonances.

As always with P48 powering, the 6,800 ohm current limiting resistors place a limit on the maximum current or voltage available. Ribbon mics have the potential, especially on percussion, for handling extreme transients and dynamic ranges. Thus in many cases it is better to use a ribbon mic with user-controlled external electronics. Completely transformer-less ribbon mic signal chains are possible, but their current requirements would be high enough that P48 powering would be impractical.

Mic output loading is another term for the interaction between a mic’s output impedance and a mic preamp’s input impedance. Richard Werner of RCA published an AES paper in 1955 showing that the overall frequency response is altered by this interaction. He measured an RCA 77’s impedance variation with frequency, and an RCA mic preamp’s input impedance at the same frequencies. His paper demonstrates how this changes the overall frequency response.

The nominal source impedance of a balanced output professional mic can be as low as 20 ohms, is typically from 150 to 300 ohms, and occasionally is as high as 600 ohms. A balanced low impedance design minimizes hum pickup, and reduces high frequency loss and slew rate limiting caused by the higher capacitance of longer mic cables.

Mics are not designed to drive a matching load. If your mic’s output impedance is 300 ohms and the preamp’s input load is 300 ohms, you‘re attenuating the mic’s signal by six dB. Raising the input impedance to 2700 ohms, reduces that attenuation to one dB, and increases the system’s signal to noise factor by five dB.

Mic output and preamp input impedances can vary with frequency, sometimes significantly. Richard Werner’s AES paper documented a worse case scenario: He paired a 250 ohm output RCA 77D, narrow ribbon mic, with the 1,500 ohm input of a transformer-coupled tube mic preamp. The mic’s nominal 250 ohm output impedance soared to 1300 ohms at its 50 Hz resonance. At this frequency the preamp’s nominal 1500 ohm input impedance sagged to around 600 ohms. The result was a deep hole in the bass response of this combination below 100 Hz.

To hear a mic as its designer intended, the preamp’s input impedance should be at least 1,500 ohms and consistent across the audio band. Even in the ranges above and below the 20-20 kHz audio band, the input impedance should remain high, as out-of-band load changes can affect in-band sonics. A rule of thumb is that a mic’s load impedance should be five or more times the mic’s source impedance. For a 300 ohm mic, such as the Coles 4038, this would translate to a 1,500 ohm load. For a 150 ohm source mic, such as most Neumann mics, this would mean a minimum load of 750 ohms, however, higher is even better.

Thus, microphone impedances and preamp loadings seem to be a perpetual source of confusion. Ideally the mic’s source impedance should be as low as practical, and the load impedance it feeds should be as high as possible. Microphone preamplifier input impedances have been at 1,000 ohms or above now for decades. (Although 19th century voice-powered carbon telephone transmitters had to be loaded into matching 600 receivers for maximum power transfer, even the BBC abandoned that approach well before the 20th century ended.)

As mentioned above, with such low impedance loads, P48 phantom powered electronics run out of current at high sound pressure levels. With such mics, the sound can improve significantly if loaded into a higher input impedance. The lower preamp input impedance a mic must drive, the harder it has to work. For condenser mics or others with built in electronics, driving too low of a load impedance is heard as decreased headroom, increased distortion, and especially when driving long mic cables, as high frequency limiting at high SPL.

With the recent resurgence in popularity of “vintage” equipment, some contemporary mic preamp manufacturers provide selectable mic input impedances, as if this is a useful feature or a wonderful effect. Unless you are working with antique 30 or 50 ohm microphones, however, it is neither. Impedance matching is bad for signal to noise, increases distortion, and reduces headroom. The 1955 STC 4038 30-ohm version, built for the BBC was the last major studio microphone designed to be operated into a matching load. More recent versions have a 300-ohm source impedance. Both the 30 and 300-ohm versions, however, operate more efficiently with a bridging rather than a matching load, and the BBC has now recognized this.

Studio mics are not designed to feed a matched impedance load. You don’t get the sound you paid for when you force your mic to operate into loads that are less than five to ten times their own source impedance.

In 1985, AEA built a limited run of transformer-coupled, stereo mic preamps with 84 dB of gain.

These preamps had a user adjustable input impedance switch so that different mics could achieve their best square wave response. A number of mic preamps now offer user adjustable input impedances. Such mic preamps can alter the load a mic drives in a variety of ways. These changes range from simply varying the resistive loading a mic must drive, to the complexity of changing the turns ratio (impedance transformation) of an input transformer, and / or its secondary loading.

Changing the turns ratio and secondary loading of a mic input transformer, can change a mic’s sound on transients from dull, to open, to ringing. Mic preamp designers typically aim for transients that are neither over-damped, i.e. dull and lifeless, nor under-damped with excessive ringing. However these designers have no control over which mics their preamps will be used with. Thus the same mic, used with different preamps, can yield a quite different sound.

Transformers, like ribbon mics, look simple, but are deceptively complicated. Here are five common and uncommon events that will change the sound of any transformer.

1. When the source impedance (the mic output in this case) changes

2. When the turns ratio is changed

3. When the load on the transformer’s output side (secondary) changes

4. When the audio is softer or louder than the transformer’s linear operating range

5. If DC through a winding magnetizes the core material and it becomes less linear

These variables can alter a preamp’s overall sound in quite complex ways, both in the 20-20kHz audio-band frequency response, and the frequency response above and below these points. Interestingly enough, changes in the out-of-band response will impact a preamp’s sound, especially with regards to transient response. As with any signal processing, the judgment is yours whether this is a change for the better or worse.

To summarize everything above, the most relevant aspects of a mic preamp’s input impedance are:

1. How does it change the useable output level and linearity of a mic?

2. How does it alter the frequency and transient response of its mic?

For more than forty years, I’ve listened to, set up, used, repaired and manufactured ribbon mics. The RCA-44 and RCA-77, among others, were the high performance standard when I was young and began being supplanted by moving coil and condenser mics as I learned my craft. More recently ribbon mics have enjoyed a renaissance. Throughout all these years, however, a number of competent audio engineers have continued to use them daily. Why? Because they deliver a warm, flattering sound in a wide range of situations that cause them to be the mic of choice for engineers, producers and musicians.

[fixitinthemic]

#TBT to AEA's Meet The Maker with Wes Dooley at @vintagekingla. Photo via @stevechannell - As Steve puts it, "the man behind the ribbon!" (at Vintage King Los Angeles)

[fixitinthemic]

AEA Fix It In The Mic - Chuck Ainlay The Stories, The Secrets, The Sound In this video interview, Grammy-winning producer/engineer Chuck Ainlay explains his approach to recording and how he uses microphones to get great sounds right away. Besides specific recording advice, this episode features insights into Chuck’s engineering philosophies and secrets such as embracing experimentation and chance. Learn how to use different microphones to create full and well-rounded records, how to utilize leakage (or bleed), and why a cardioid microphone isn’t always the best choice. Chuck’s acclaimed engineering career, which has spanned a twenty-eight year period, has allowed him to work with many of the world’s finest artists, musicians and producers and develop a diverse list of clients that ranges from George Strait to Dire Straits. His engineering dominance in the country field has been recognized by many, including NARAS with multiple Grammy nominations for his numerous critically and commercially successful albums. In 1999 Chuck entered into a partnership with Sound Stage Studios to create Back Stage Studio, a state of the art, surround sound studio. —- —- —- —- —- —- —- —- AEA’s Fix it in the Mic video series is aimed at sharing the microphone secrets and tricks of industry professionals in a time when mentoring and real knowledge is hard to come by. Whether it’s a hidden gem from the history of ribbon mics or the latest chart-topping record, the series offers application specific insight into the depths of ribbon mic technology and how the masters use it. AEA’s mission is to help engineers get the sound they envision right from the start instead of “fixing it in the mix”- a craft and art that often gets lost in the midst of the hype about the latest new toy. Thus, the name Fix It In The Mic was born. We encourage you to comment, ask questions, and to send us suggestions for future episodes of “Fix It In The Mic” to [email protected]! —- —- —- —- —- —- —- —- For more information visit: http://www.ribbonmics.com http://www.fixitinthemic.com Follow AEA on Facebook and gain access to exclusive bonus footage: http://www.facebook.com/ribbonmics Featuring music from the song “Unbelievable” by Sean Michel from his Electric Delta album Filmed on location in Nashville by Brian Totoro Edited by Jeremy Jettho Thomas and Julian David Produced by Julian David 2013 - Copyright Audio Engineering Associates

[fixitinthemic]

AEA presents Ronan Chris Murphy - Recording Tricks & Secrets

For the third episode of the Fix It In The Mic webzine, AEA product engineer Julian David had the pleasure to interview the renowned producer/engineer Ronan Chris Murphy at his own Veneto West studio in Santa Monica, CA. In the video Ronan talks about his recording tricks and secrets that he has developed during the years. He explains how to use microphones effectively and how to enhance your recording by choosing the right front-end. Ronan also shares why and how he likes to use ribbon microphones on certain instruments to capture the sound he wants rather than resorting to EQ and other mixing tools later on. Finally, Ronan shares his basic recording philosophy focusing on the needs of the performance rather than on technology, and explains the goals of his Recording Bootcamp lectures. The video gives insight into the recording process for a recent album that Ronan produced with the singer-songwriter Dave Nachmanoff. Ronan extensively used the AEA KU4 Unidirectional Ribbon Microphone on almost all the acoustic guitars and was very pleased by the fact that the guitars would fit into the mix with only minimal processing: "I mostly doubled the acoustic guitars, panned them out, and they sat right where they needed to sit. That's a great mic!"

Visit www.ribbonmics.com for more information!

[fuzzywenzel-blog]

Now this is a MAN microphone.  good thang I have one :)