FeedPress API

Since FeedPress’ wee early years, it’s had a fairly robust and easy to use POST or GET method API, with answers formatted in JSON (YAY). This has given developers access to many parts of the web app. As we’ve been working on things, I realized we’ve never talked about it much on this blog, so this serves as an official announcement as well as update on the latest additions to the FeedPress API (up to July 2018).

I’m pleased to announce today that we’ve added numerous methods that bring the API closer to parity with the web app. Some of the most requested features you’ve asked of us are methods to access our podcast hosting service, such as uploading and deleting media files (MP3s).

Our most recent addition this summer is adding access to Custom Hostnames. For the uninitiated, Custom Hostnames allow you to fully whitelabel your RSS feeds by utilizing your own domain name with FeedPress, providing the ultimate in flexibility over the structure of your feed as well as complete ownership of your intellectual property.

With our new API method, you can register your hostname and path, which previously you could only do via the web app. Adding one hostname and path for an RSS feed isn’t a big deal, but if you need to add a lot in bulk, our API makes it very convenient and efficient. We’ve already had customers utilize this functionality when creating 50+ RSS feeds in one fell swoop via their Content Management System.

Our API documentation with full details are available for free. In order to utilize the API, you must have a FeedPress account.

Here’s an overview of the things you can do with the API

GET /login.json

Redirects the user to the FeedPress authentication page. See Authentication for more details.

GET /logout.json

Deletes the authenticated user’s token.

GET /account.json

Retrieves various informations about the authenticated user.

POST /feeds/create.json

Creates a new feed for the authenticated user.

POST /feeds/update.json

Updates a new feed for the authenticated user according to the submitted parameters.

GET /feeds/subscribers.json

Retrieves subscribers statistics for the last 30 days about a specific feed.

GET /feeds/readers.json

Retrieves the last readers statistics about a specific feed.

GET /feeds/ping.json

Tells FeedPress to refresh the specified feed.

GET /feeds/hit.json

Tells FeedPress to record a “virtual” hit for the specified feed.

GET /feeds/tracking/items.json

Returns the tracked items for the specified feed.

GET /feeds/tracking/url.json

Returns the FeedPress tracking URL for the specified feed and original URL.

GET /feeds/newsletter/subscribers.json

Retrieves the subscribers list for the feed’s newsletter.

GET /feeds/newsletter/check.json

Check the status of a particular email in your feed’s newsletter.

POST /feeds/newsletter/add.json

Adds an email address to the feed’s newsletter.

POST /feeds/hosting/upload.json

NEW: Uploads an audio file to your podcast hosting storage.

POST /feeds/hosting/delete.json

NEW: Deletes an audio file in your podcast hosting storage.

POST /hostnames/record.json

NEW (July 2018): Create a record for a specified hostname.

Coda

We would love to hear from you if you have build an app using the FeedPress API. Get in touch and let us know what creative ways you’ve used it in your projects and how it’s improved your workflow.


The FeedPress API is now closer to parity with the web app. Some of the most requested features you’ve asked of us have been added, such as podcast hosting media and Custom Hostname management.
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Podcasting Gear Guide

Preamble

We’ve never written about podcast gear before, and since many of our customers are just getting started, it’s time we made a guide to get you started. This article will break down what you need and will cover different budgets, from beginner to advanced. Some of you have questions about how to record multiple guests via Skype and how to do mix-minus setups, but that’s something we’ll leave for a separate article as it involves more complexity.

For the purpose of this guide, all equipment is carefully selected from our personal experience. We don’t recommend anything we haven’t tried ourselves, or trust. We don’t receive kickbacks for product recommendations. There are some items on this list that you’ll need for any of the recommended gear, such as headphones and cables, of which we itemize at the bottom of this article. Note that all prices quoted are recent as of the writing of this article and are in U.S. dollars.

Entry Level

Audio-Technica has a long history of making professional microphones for musicians. The ATR-2100 ($64) is a well built and incredibly inexpensive dynamic USB microphone. It’s unique in comparison to other USB microphones in the market as it also features an XLR connector, should you wish to connect it to a more professional audio interface. At less than $100, you can’t beat its value. A stand and all the cables you need to hook it up are included. Just plug it into your Mac or Windows-based computer and start recording.

Mid Level

When you first consider starting a podcast, you may not want to invest a lot of money on equipment. Thankfully, you can have a great sounding podcast without investing thousands of dollars.

Samson Q7 Dynamic Microphone ($79): This is a fantastic sounding microphone with good rear rejection, meaning it will better pickup your voice as you talk directly into it and not as much background noise. It’s ruggedly built, reliable, and affordable.

Mackie Onyx USB interface ($99): This audio interface allows you to connect either one microphone or line level device and is bus powered, meaning no clunky external power supply needed. Mackie includes a great sounding preamp that provides enough headroom for dynamic microphone. It’s quite, trouble-free, and affordable.

You’ll need to mount your microphone on something, and there’s no better choice in this price range than the Heil PL2T boom ($129). Once you use a boom you’ll never look back. You can clamp it to the side of your desk or permanently mount it using the supplied hardware kit. It allows you to easily swivel and move your microphone into a comfortable position, but it also mitigates the translation of low rumble into the microphone from your arms moving around on your desk. it also features built-in cable management so you can hide the cable from view.

Advanced

Shure SM7B ($399) microphones are our universal application recommendation for professional sound. They’re incredibly rugged and ubiquitous and you’ll find them in radio stations, voice over studios, and other professional environments. They’ve been used for singers, podcasters, broadcasters, and even on some instruments. We’ve yet to find a voice that didn’t sound good on this microphone. The only caveat is that it is a very low output microphone, which means it requires a lot of gain from your preamp, so you’ll need a good one that isn’t noisy and can provide a minimum of 60dB of gain.

As the SM7B is a low output microphone, we strongly recommend getting Triton Audio’s Fethead ($89). It’s a small inline device that connects between your microphone and preamp and smartly converts 48v phantom power into 27dB of clean, noise-free gain. This means you won’t need to drive your preamp as hard, which is always a good thing since that lowers the noise floor.

When you get to a point where you’re ready for broadcast quality sound, you’ll want a capable dynamics processor/channel strip like the dbx 286s ($199). The 286s is a single microphone preamp and dynamics processor, featuring compression, de-essing, low and high-frequency effect, and noise gating/expansion. This is what we use for our podcasting and it’s one of our favourite pieces of gear. Even though we’re recommending this as part of our advanced podcasting package, it’s not as expensive as you might think. There isn’t a better channel strip out there at this price and ad this level of quality.

For someone that’s been podcasting for a while and wants the ability to record multiple co-hosts and leave room for expansion, such as the ability to create a Skype/remote caller mix-minus, Allen & Heath’s ZEDi-10 ($199) mixer is a solid choice. It has four quiet, high-powered microphone preamps, multiple line level channels, and one auxiliary out so you can create a mix-minus setup for remote callers. It’s well built and has an excellent multi-channel audio interface, meaning you can record each input channel of the mixer discretely for separation and easier editing.

To connect your dbx 286s channel stripe to your Allen & Heath mixer, plug it into one of the mono line level inputs on the mixer via a 1/4″ TRS cable (from the output of the dbx)

Accessories: Cables And Headphones

Headphones are essential for monitoring your own voice during a performance as well as for mixing. We recommend the Sony MDR 7506 ($99) headphones for several reasons: they’re well made, sound great, and are comfortable to the point where you can wear them for hours without fatigue. These headphones are inexpensive and are ubiquitous in the broadcast industry. They’ve become a staple because of all the reasons we’ve enumerated.

To connect your microphone to your audio interface, you’ll need a female to male XLR cable. You can use any brand, however, we recommend Mogami cables ($20) because of their superior quality and shielding.

If you’re connecting your dbx 286s to a mixer, make sure you get a 1/4″ TRS to TRS cable, which connects the output of the dbx to the input of your mixer on a line level channel.

A headphone amp is a necessity if you have a co-host that records with you. The PreSonus HP4 ($129) is a well built and extremely high quality headphone distribution amp. It provides four independent headphone mixes so each guest can adjust their own volume. It sounds fantastic and can power the most demanding low impedance headphones.


Podcasting Gear Guide: This article will break down what you need and will cover different budgets, from beginner to advanced. All selections have been carefully selected from our personal experience.
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Conclusion

At the top of the article, we talked about recording multiple remote guests via Skype. This requires further explanation and a completely separate article since it’s too involved in the scope of our podcast gear guide. Subscribe to our blog to make sure you don’t miss that.

Are you hosting your podcast somewhere else or need a place to host a new podcast? Signup for a no commitment 14-day trial today and use promo code PodcastGear on checkout to receive a free month of hosting!

If you have any questions before getting started, don’t hesitate to reach out to us. You can tweet us @FeedPress or reach out on Facebook.

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Stitcher Makes Technical Changes Affecting Podcasters

Stitcher has announced some favourable changes that will impact podcasters who have content in their directory. What started with initially removing the re-hosting of files and downloading direct to the source, further changes are being made to align themselves better with current analytics methodologies.

Podcast microphone

Last year, we began a process of implementing changes to the way Stitcher communicates with podcasters’ hosting providers. We started by moving all podcasters to direct streaming from the source–the Stitcher apps now make a direct file request to your hosting infrastructure whenever a user chooses to play or download an episode of a show.

This change, which we previously made on an ad-hoc basis for podcasters who requested it, gives you better insight into your overall download metrics and better facilitates server-side dynamic ad insertion.

To give podcasters more standardized, accurate and granular data about their shows, we will be making additional changes to align Stitcher’s downloading definitions with some of the emerging standards put forth by the IAB.

On October 2, 2017 we will remove this pinging behavior. This will provide clarity for all of our partners and it will support the IAB’s measurement initiatives. We will:

  • Make downloading new episodes in user Favorites the default app behavior
  • Record as a download any playback that downloads at least 200 kb (standard put forth by the IAB)
  • Present a separate “Front Page Impressions” metric in our partner portal.

We’re pleased to see these technical changes at Stitcher. As for how this affects FeedPress customers, it’s possible you may see an increase in downloads because of these changes.

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Podcast Editing Tips: Part 3 – Phase Shifting to Recoup Loss of Headroom

I’ve talked before about utilizing high-pass filtering to roll-off undesirable low frequencies in audio. This can be done in software via plugins or done in hardware (E.g., on a mixing console or microphone preamp). I suggest reading our primer on high-pass filtering before proceeding with today’s topic, which is phase shifting.

What happens to audio when processed through a high-pass filter?

So what exactly is phase shifting? Well, let’s first understand what happens to an audio signal as it travels through a high-pass filter. In the example below, you can see I’m rolling off frequencies below 75 Hz at 12dB per octave. High-pass filers typically allow the user to specify just how much is rolled off below the frequency cut off. The higher the decibel value is, the slop increases and a greater roll off occurs. Look at the screenshot above and you’ll see the slope.

75Hz-High-Pass-Filter

After applying the filter, you can see that on one axis, the energy of the waveform is displaced. The human voice is often said to be asymmetrical in nature, however high-pass filters can further increase asymmetry. This does not indicate a problem necessarily with the sound quality, but does pose challenges for podcast audio producers as it decreases headroom.

Asymmetric-Waveform

What is headroom?

Headroom is essentially the “wiggle room” you have as an engineer when processing audio before the source exceeds zero decibels relative to full scale (dBFS). Decibels relative to full scale (dBFS) is a unit of measurement for amplitude levels in digital systems, which have a defined maximum peak level. In the digital realm, 0dBFS is the absolute peak ceiling before audible clipping occurs (or distortion as it’s also known).

Now that you understand basic terminology, you see why displaced energy in a waveform can decrease headroom, creating processing challenges as you prepare for loudness normalization. Loudness normalization is an essential step after optimizing your audio (applying compression) as it targets optimal perceived average loudness. This creates consistency for the listener so they don’t need to crank the volume in louder environments and also aids intelligibility of spoken word. If you were to check the maximum true peak of your audio, pre phase shift, you’ll notice the loss of headroom. In the example below, the source checks in at -1.3dB. This is not the worst example, but you’ll get a better idea later on as we shift the phase of the source.

LM-Correct-pre-phase-shift

To better understand loudness normalization, please read “Loudness Compliance And Podcasts” and “Your Podcast Might Be Too Quiet Or Too Loud“.

Optimizing headroom through phase shifting

To restore headroom in your audio source after high-pass filtering, you can use third party tools to do so. This demonstration uses Waves’ InPhase plugin, however other tools such as iZotope RX suite contains an adaptive phase correction feature that is even easier.

Step 1.

My Digital Audio Workstation (DAW) of choice is Pro Tools. On a mono audio source, I select the clip and instantiate the LT (non live) version of Waves InPhase. I have created a default preset to handle phase shift correction, which you can download from here. Note that this preset is meant as a starting point, so values such as input gain and delay may be tweaked depending on the source you’re working with.

Here’s how I have the plugin configured:

Waves-InPhase

As illustrated in the screenshot, you can set the all-pass frequency 200 Hz and Q bandwidth to 2.0. ” Type” sets the phase shift filter type, and toggles between Off, Shelf (using the 1st order allpass filter) and Bell (using the 2nd order allpass filter.) In the example we use the bell filter type. Allpass filters to correct phasing issues between tracks. Here’s a quick rundown of what these settings are doing, as documented in the plugin manual:

An allpass filter is a signal processing filter that affects only the phase, not the amplitude of the frequency-response of a signal. This example demonstrates using a 2nd order filter, which is defined by the frequency at which the phase shift is 180° and by the rate of phase change. The rate of the phase change is dictated by the Q factor. Q sets the width of the 2nd order (Bell) allpass filter: A narrower Q results in a faster phase transition toward the selected frequency, leaving a larger portion of the frequency intact.

The InPhase settings came recommended by Paul Figgiani, but they’re meant as a starting point. The significance of the settings are fairly complex. I will continue to explore their significance.

Step 2:

Clicking “Render” will process the selected audio and should shift the phase slightly so that the energy of the waveform isn’t lopsided.

Asymmetric Waveforms Processed

Now that the phase has been shifted slightly in the correct direction, we have an optimal source to work with for loudness normalization. When the process was started, our our source checked in at -1.3dB. Analyzing the corrected version below, you can see we’ve restored quite a bit of headroom.

LM-Correct-post-phase-shift

Hot damn, look at that. Our source is now -2.5dB, a full 1.2dB of headroom recouped!

Step 3: Loudness normalization can be done on the source audio with the phase shifted in the correct direction. Headroom has been regained, which means when processing the audio with a true peak limiter, excessive limiting should not occur (this is a good thing as that can squash the dynamics of the human voice).


#Podcast editing tips: Phase shifting audio to recoup loss of headroom
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Conclusion

You should have a good understanding how most high-pass filters affect the human voice. It should be noted that the source audio worked with in these examples was high-pass filtered in hardware, not software. The reason why this matters is because linear phase filtering helps avoid the displaced waveform energy discussed, provided the source was not already high-pass filtered in hardware. Linear phase filters are a topic for another day, but effectively they ensure the original phase is not altered in any way during processing.

If you have any questions about how the aforementioned workflow is accomplished, don’t hesitate to reach out to us on Twitter and Facebook.

Acknowledgements

Many thanks to audio engineer Paul Figgiani, whose experience and breadth of knowledge rivals my own. He continues to be an inspiration and aided in the accuracy of this piece. Make sure to check out his blog: ProduceNewMedia.com.

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FeedPress Adds Support for New Apple Podcast Tags

Apple Podcast Spec Updates

The week of Apple’s World Wide Developer Conference (WWDC), Apple announced that they have updated their RSS podcast spec to include additional tags for podcast publishers. These tags will provide support for additional functionality inside of their own “Apple Podcasts” app. The tags themselves add features that many podcasters have been looking for, such as the ability to specify an episode as trailer, bonus, or full episode.

Apple Podcast Spec Updates

New Podcast Tags

We have added support for the following podcast tags:

  full
  trailer
  bonus

Customers who use FeedPress’ podcast publishing platform can use the “Episode Type” field to specify an episode as a trailer, bonus episode, or full episode, as illustrated below.

FeedPress Publisher Supports New Apple Podcast RSS Tags

it should be noted that whilst the tags can be included now, we won’t see the changes reflected until Apple releases iOS 11 to the public, which won’t be until September and likely after the release of iPhone 8.


FeedPress adds support for new Apple #Podcast tags
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Conclusion

It’s really exciting to see Apple moving the needle on podcasts to improve both the listener’s and publisher’s experience. What do you think of the new podcast tags and the changes to Apple’s podcast app on iOS 11? Leave a comment below to chat with us.

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FeedPress Adds Automatic JSON Feed Support

JSONFeed

Beloved Mac developers and long time bloggers, Brent Simmons and Manton Reece have launched JSON Feed. The take away for developers is as follows:

For most developers, JSON is far easier to read and write than XML. Developers may groan at picking up an XML parser, but decoding JSON is often just a single line of code.

Why care?

So why should anyone care about this with respect to podcasts when Apple controls the ecosystem? Although its early days for the spec, our opinion is that innovation in a space with an established, albeit old spec is a healthy thing.

RSS is and continues to be a workable transportation method for podcast data, but even RSS–which has been around since 1999–needs enhancement. That’s why open source initiatives like syndicated.media exist to take podcast functionality and RSS to the next level (we’re closely watching this).

What impact does it have?

Does this mean that JSON Feed will make any significant impact? That remains to be seen, but we’re pleased to see people move the needle forward.

Co-creator, Manton Reece wrote about how JSON Feed relates to podcast functionality:

JSON Feed includes an attachments array, which is similar to the enclosure element in RSS that enabled podcasting. We love podcasting and included an example podcast feed in the JSON Feed specification.

How FeedPress supports JSON Feed

Experimental JSON support is live on FeedPress. JSON Feed is generated every time the XML feed is refreshed and is not a replication from the source, it’s a creation. The JSON feed validates and it handles podcasts on RSS and Atom.

Conclusion

There is nothing FeedPress customers need to do in order to get JSON compatible feeds. Simply append the ?format=json parameter to the end of your RSS feed.

Here’s an example URL: https://podcast.hologramradio.org/master?format=json

FeedPress customers are encouraged to test this with compatible RSS readers and Podcast apps. We’d love to hear your feedback.


FeedPress adds JSON Feed Support
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Update: As of May 31, 2017, the feed_url paramter has been added. As per JSON Feed spec documentation, it’s highly recommended:

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Your Podcast Might Be Too Quiet Or Too Loud

According to the 2017 edition of Edison Research’s “Infinite Dial” report, 65% of people listen to podcasts on mobile devices. Based on location listened to most often, they further break down that 52% of the sampled audience most listen to podcasts at home, 18% in a vehicle, 12% at work, 3% on public transit, 3% at the gym, and 3% walking around.

The Problem

FeedPress advocates podcast producers pay close attention to loudness compliance with their audio. Irrespective of listening environment, it’s just good practice.

Interest in podcast production techniques and the analysis of podcast audio is a growing trend. Engineers are analyzing many of the top ranking podcasts–including ones repackaged from radio–and are finding they exhibit a multitude of problems. Some of the problems podcasts have include an extended dynamic range, wide ranging degrees of loudness, and even clipped audio.

Why Care?

Overly loud podcasts may contain audible distortion, which can be extremely uncomfortable for listeners. Furthermore, your audience should not be frustrated and have to constantly reach for the volume controls when listening to podcasts. This is why audio engineers advocate that podcast producers aim for a target loudness of -16 Loudness Units relative to Full Scale (LUFS) for stereo files and -19 LUFS for mono files. LUFS is a standard designed to enable normalization of audio levels of broadcast TV, other video, and now podcasts.

There are two reasons why engineers are pushing for audio compliance: maintaining a level of consistency between program audio, and comfort in loud listening environments. Some examples of noisy listening environments include: the morning or afternoon commute by train, car, or walking outside. Working with spoken word requires attention to detail to maximize intelligibility and loudness for mobile device consumption.

Solutions

You are a story teller, editor, and producer and must ensure the quality of your audio matches the high bar set for your content. There are solutions to this complex problem that do not require an audio engineering degree. For example, podcast producers can use tools built into Adobe Audition such as “Match Loudness” to optimize and export their podcasts to recommended compliance targets.

Another solution is to use an online service such as Auphonic, which contains reasonable presets for novices. Note that even though there are tools that can make this job more efficient, you should still understand the fundamentals of why loudness compliance is needed and how it’s achieved.

Audio engineer Paul Figgiani of produceNewMedia blog, and a longtime advocate for loudness compliance, writes:

> I’ve discussed the reasons why there is a need for revised Loudness Standards for Internet and Mobile audio distribution. Problematic (noisy) consumption environments and possible device gain deficiencies justify an elevated Integrated Loudness target resulting in audio that is perceptually louder on average compared to Loudness Normalized audio targeted for Broadcast. Low level, highly dynamic audio complicates matters further. The recommended Integrated Loudness targets for Internet and Mobile audio are -16.0 LUFS for stereo files and -19.0 LUFS for mono. They are perceptually equal.

Conclusion

You now realize the importance of optimizing your podcasts for loudness compliance. To learn more about properly optimizing and mastering podcast audio, please read our in-depth article on loudness compliance.


As story tellers, we must ensure the quality of our audio matches our content.
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Apple Silently Adds Support for Let’s Encrypt Certificates on Podcast Feeds

FeedPress has had SSL support for RSS feeds and hosted podcast media since June 2016. Let’s Encrypt is an open source certificate authority that has been adopted by millions and provides easy access for companies like us to issue free SSL certificates to every customer.

An obstacle podcasters have had since Let’s Encrypt’s introduction is that iTunes Podcast Connect would reject feeds using their SSL certificates. The reason for this is because the iTunes Java Root Store was old and didn’t recognize Let’s Encrypt as a valid certificate authority.

This week we were alerted that the folks at iTunes had silently updated their infrastructure to support Let’s Encrypt. FeedPress has tested compatibility and is pleased to confirm that you can now submit podcast feeds to iTunes using Let’s Encrypt SSL certificates. As of the publication date of this blog post, Apple has yet to update their FAQ on official support for Let’s Encrypt.

Please refer to our tutorial below to learn how to enable HTTPS on podcast feeds:

http://support.feed.press/article/113-enabling-ssl-on-hosted-feedpress-feeds

Conclusion

Note that although SSL is a feature that is available in FeedPress, it’s not a compatibility requirement for iTunes at the moment. If you don’t feel comfortable turning it on, we recommend leaving it off until Apple provides a cut off date when it must be enabled.

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Podcast Publisher: Specify Publish Date And Time in Your Posts

Available today on our Podcast Publishing system, you can specify a publish date and time on posts. This was a requested feature and is something we wanted to get into v1 of the podcast publisher system but didn’t get to.

Customers requested this as it’s an expected feature in a CMS, but also because it’s handy when you migrate from other hosting services and need to re-create your posts and preserve the original publishing date and time.

Selecting a publish date and time

date and time fields

The new date picker

date picker

Updates to File Storage

Several months ago we increased the provisioned file storage from 250MB to 400MB for all customers. Today we made a tweak to File Storage to include a status that reflects whether or not that file is attached to a post. For example, if you have a draft post with an uploaded file, the file will say “Draft.” If you have a post that’s been published, the status of the file will reflect “Published.”

podcast file storage status


FeedPress podcast publisher updates: Specify a publishing date/time on posts.
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Publish your own podcast

You remember that feeling of delight you experienced when you first tried ice cream as a kid. That’s what podcasting on FeedPress feels like. Publish your own podcast today on a 14-day trial and experience delight once again.

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High-Pass Filtering: Getting Rid of Undesirable Low Frequencies

I care deeply about the level of production that goes into each podcast that I make. My production chain begins with using the best microphones I can afford and ends with carefully edited and mastered audio that is suitable for consumption by the listener. I enumerate my production chain below and how it flows to the final product:

  • Microphones
  • Outboard processing (compressors)
  • Mixer
  • Computer
  • Recording software
  • Editing
  • Mastering
  • Upload to the web

Disturbing frequencies you don’t want

A common problem in podcasts produced by the inexperienced is an abundance of undesirable low-end frequency. For example: excessive bottom end that’s audibly disturbing when people hit their microphones, slam their arms on a desk, or a car drives by with its subwoofer blaring. If you record in a noisy environment, this amplifies certain problematic frequencies. Short of recording in an acoustically treated room away from the noise of the outside world, you can’t completely get rid of all undesired frequencies. You can of course minimize the impact or “energy” of the problem.

If you have a dynamic or condenser microphone with an XLR connector, there’s a good chance you will find a switch on it that is a bass roll-off (sometimes referred to as HP or High-Pass). The characteristics of the bass roll-off implementation can vary from microphone to microphone. Consult the manual from the manufacturer to get the details on how they implemented a bass roll-off.

XLR cable

What frequencies should I filter?

A High-Pass filter, as the name suggests, allows high frequencies to pass through whilst unwanted low frequencies (below the threshold you specify) are removed.

For spoken word, I typically filter below 100Hz as you really don’t need frequencies below that. Most of the frequencies that live below 100Hz too easily creep into a recording, some are avoidable if you have poor microphone technique and bad habits, others may be out of your control (as described earlier). In the illustrated example below, the microphone I use is a Shure SM7B. At the rear, there are two switches: one provides a presence boost, the other a bass roll-off. Audio engineers will tell you filtering closest to the source is best. I would agree, but in some scenarios, you’ll find the bass roll-off too aggressive.

Shure SM7B

The SM7B is a fantastic microphone, but I don’t roll-off on the microphone because the filtering slope begins at around 200Hz. There are some lower frequencies in a male voice that I like to retain around 150Hz). Other dynamic microphones more commonly roll-off at around 100Hz or even 80z. There are other microphones that offer granular controls such as the Sennheiser MD-421 that have multiple bass roll-off options. If you don’t filter at the source, there are 3 other options: filter at the mixer level if you have the luxury of owning one, filter at the preamp/channel strip, or in software.

dbx 286s

Rolling off bass in software

My primary recording software is Adobe Audition. The example below applies to other popular software packages such as: Avid Pro Tools, Logic Pro X, GarageBand, or Audacity. Plugins are little software programs that can be inserted into an individual audio track to apply a particular desired effect such as: dynamic processing (compression), reverb, delays, equalization, and more. To filter out low frequencies, insert an EQ plugin into the problematic audio track.

Enable the HP button and specify a value for the filter. Note that I set mine to 100Hz.

Note: If you prefer, you can filter all tracks at once, and how you do that is by inserting the same EQ plugin on your “Master Bus” track. The Master Bus is a stereo bus that sums all of the individual audio tracks together.

Parametric EQ

You’ll notice in the screenshot below that below the “Frequency” option, there is “Gain” setting, which defaults to 24dB/Oct. This setting tells the filter by how much gain should it attenuate from the signal in db (decibel as the unit of measurement for the intensity of sound). In other words, how aggressively should it cut out the frequencies. The “Oct” stands for octave. In musical terms, an octave is described as follows:

A series of eight notes occupying the interval between (and including) two notes–one having twice or half the frequency of vibration of the other.

To put this all together, my High-Pass filter will filter out frequencies at 100Hz or lower and will cut them on a relatively aggressive slope of 24db per octave.

HP filter


Podcast tip: Remove undesirable low frequencies from your podcast audio with High-Pass filtering.
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Coda

You now have an understanding of problematic frequencies that you want to remove from your podcast audio, how to remove them, and what exactly is going on from a technical perspective behind the scenes.

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