Publishers of technology books, eBooks, and videos for creative people

Home > Articles > Apple > Audio & Video

Create Your Own Impulse Responses with Apple's Space Designer and Impulse Response Utility

Creative sound mixing can improve even the dullest recording. You're probably familiar with Space Designer's built-in impulse responses, but did you know you can create your own? David Dvorin, author of Apple Pro Training Series: Logic Pro X Advanced Audio Production: Composing and Producing Professional Audio, shows how to add custom IRs that you can apply anytime, for any sort of sound design you have in mind.
Like this article? We recommend

When doing sound design and mixing, I almost exclusively reach for Logic's Space Designer plug-in for my reverberation and signal processing needs. Its utilization of convolution technology to map the characteristics of recorded acoustic spaces and loudspeakers (called impulse responses, or IRs) onto any audio signal adds a special organic ingredient, giving sounds character and complexity.

In fact, the more I delved into Space Designer, the more interested I became in creating and using my own IRs. While I frequently continue to turn to Logic's excellent library for its pristine recordings of concert halls and rooms, I've found that my own IR recordings of spaces and loudspeakers make excellent fodder for compositions, sound design projects, and post-production work. The right IR can make tracks sound real or even downright mysterious!

While most advanced users are knowledgeable about Space Designer's capabilities, few are aware of how to go about creating their own IRs. In this article, we'll explore how to go beyond Space Designer's stock library by rolling your own IRs with Apple's Impulse Response Utility.

Accessing the Impulse Response Utility

Let's get started by launching the Impulse Response Utility. Unlike normal installed apps, the software is part of Logic's package contents, in a folder hidden away within Logic's support files. The quickest and by far the most convenient way to open the Impulse Response Utility is from within Space Designer itself. In the Input side of the plug-in window, click the disclosure arrow immediately to the right of IR Sample (see Figure 1) and select Open IR Utility.

Creating a Speaker Impulse Response

A great way to get your feet wet is by creating an IR of an available amplified loudspeaker. The more interesting the speaker, the better, as we're looking for something that transforms and colors sound signals. (Studio monitors and home stereo speakers aren't useful for this task, as they're designed to be transparent.) My favorites are tiny, cheap, battery-powered portable speakers that distort and color the sound in interesting ways. If you get ambitious, speakers in toys can also be rigged up with a home stereo amplifier to achieve nice results.

Start by cabling the output of your audio interface (or 1/8" audio out of your MacBook or Mac Pro) to the speaker, and cabling a microphone to an available input preamp. Choice of mic will greatly affect the sound of the recorded IR, as you're capturing not only the speaker/amp, but also the entire signal chain (preamp and audio interface included). Don't worry about it too much, however, as the result we're going for is pretty lo-fi. I usually use a common dynamic mic for this application, and I like to think I'm micing up a little guitar cabinet when I'm doing this, placing the mic in close to the speaker to capture its character, as shown in Figure 2. Again, don't sweat the details of placement—remember, you're after creative results, not traditional ones!

Setting Up Impulse Response Utility

When your speaker/mic setup is complete, it's time to set up Impulse Response Utility to capture the recording. Unless you've used it before, the software will launch with a prompt asking you to select the track layout for your recording, as shown in Figure 3. (You can also access this option by selecting New Project from the File menu.)

The choices in this dialog support mono, stereo, and surround recording of IRs, whose format is dictated by the number of mics (recording) and speakers (playback) utilized. For the speaker/mic setup I've described here, Mono configuration is perfect.

After choosing the IR recording format, you need to set the appropriate audio hardware used by the software, working at the top of the window in the Hardware I/O Assignment area. Figure 4 shows my selections for this example.

Generating the Sweep

The process of creating an IR entails both exciting the source (speaker, room, device, and so on), and recording its response. I find that using a sine sweep works best for the excitation task, because you more accurately capture how the source reacts to all frequencies over time. Impulse Response Utility will both generate and remove the sine sweep signal for you (more on removal later), which is really convenient. Within the Sweep Channel flip menu, located on the left side of the interface within the Monitor and Sweep Generator section, choose the channel on your audio interface that will output the sweep signal (see Figure 5). This setting should correspond to the physical output where you have the speaker connected.

You can also change the length of time the sweep will play (10 or 50 seconds), although I've found that 10 seconds does the job nicely for speakers. The Reverb setting governs how much reverberation "tail" to allow in your recording. Since we're recording a speaker and not an acoustic space, it makes sense to capture only a minimum amount of reverberation (1 second).

Next, set the input channel for recording within the Inputs/Tracks section of the interface under the Input column for the channel (there should only be one in a mono recording), as shown in Figure 6. Your setting should correspond to the physical input where your mic is plugged into your audio interface.

Impulse Response Utility will generate test tones to aid in setting the preamp gain on your mic channel. Do this by clicking the checkbox next to "on" within the Monitor and Sweep Generator section, which will cause the speaker to output at the selected frequency (1 kHz by default). Ideally, the signal should be pretty hot, and you can gauge this result by observing the Level meter for the channel. You can also try setting the Test Tone output to 100 Hz, 5 kHz, and 10 kHz via the flip menu, to ensure that clipping won't occur at different frequencies of the sine sweep.

Recording the Impulse Response

Now that levels are set, you're ready to record the IR. In the Inputs/Track section, click the R (record) button in the same channel row where you chose the input channel and set the levels, record-enabling the channel. You'll notice that the Sweep button in the Monitor and Sweep Generator section will no longer be grayed out, so go ahead and click it!

The sweep will play back while recording the results, stopping automatically after the elapsed time you designated in the Reverb menu. After the process is finished, you'll be prompted to save the project, and you should see a waveform of your recording displayed in the Editing area of the interface. Figure 7 shows the Impulse Response as recorded, sine sweep and all.

Deconvolution

Here's where the magic takes place. If you were to use the audio as is, you would hear the sine sweep loud and clear. (Click the play button at the top right to verify this.) In order to use it as an IR, you need to deconvolve the recording, taking out the sine sweep signal from the recording, and leaving only the speaker's response. Do this by clicking the Deconvolve button under the Process area within the Monitor and Sweep Generator section (see Figure 8).

After deconvolution, the audio waveform will look and sound drastically different, consisting of a short transient or "pop," as shown in Figure 9. (Try playing this to verify.)

Once the IR has been deconvolved, you can perform simple editing tasks to optimize its use in Space Designer. This often entails trimming "tops and tails," which you can do by selecting the area and clicking the Cut or Fade buttons shown in Figure 10. Considering that we're creating a speaker IR, it's a good idea to trim any silence at the beginning of the recording, which could produce a tiny but significant delay. (This silence might be desirable if you're working with an IR of an acoustic space.)

Using the IR Within Space Designer

Now comes the fun part: Using your newly created IR within Space Designer. Impulse Response Utility's Create Space Designer Setting feature makes this process a snap. Click this button at the bottom left of the interface to save a copy of the IR to Logic's default location (~/Music/Audio Music Apps/Impulse Responses), as shown in Figure 11. In the process, Impulse Response Utility also automatically creates a Space Designer preset for easy access from within the plug-in window.

Now you can access your work via any Space Designer plug-in preset menu (see Figure 12). When using a speaker emulation, it makes sense to do this on a Space Designer plug-in instantiated as a channel insert instead of a send effect (series instead of parallel processing). To hear the result of the entire signal sent through your "speaker," turn the Dry control to 0, adjusting the Wet control to get the appropriate gain level.

Try listening to results on an available audio track with recorded material, and observe the interesting timbral characteristics the speaker IR imparts. You can even rock out with your speaker replacing the cabinet in Amp Designer. Do this by inserting an Amp Designer plug-in first in the channel, followed by a mono Space Designer plug-in with the speaker IR loaded (again, 100% wet). Within Amp Designer, select your amp as normal through the plug-in settings menu, and defeat the matched cabinet by selecting Direct within the Cabinet flip menu (see Figure 13).

Going Further

Now that you're familiar with the technique, you can apply what you've learned to other sources for creative convolution. Try setting up a studio monitor in a garage, closet, open washing machine, or even a grand piano to output the sine sweep. Capture the results with whatever mics you have handy. Afterwards, try moving up to multiple speakers and multiple mics (all accessible under the Track Layout dialog when starting a new project). You'll soon find that you have your own unique library of IRs to impart that special "something" to your recordings.

Peachpit Promotional Mailings & Special Offers

I would like to receive exclusive offers and hear about products from Peachpit and its family of brands. I can unsubscribe at any time.

Overview


Pearson Education, Inc., 221 River Street, Hoboken, New Jersey 07030, (Pearson) presents this site to provide information about Peachpit products and services that can be purchased through this site.

This privacy notice provides an overview of our commitment to privacy and describes how we collect, protect, use and share personal information collected through this site. Please note that other Pearson websites and online products and services have their own separate privacy policies.

Collection and Use of Information


To conduct business and deliver products and services, Pearson collects and uses personal information in several ways in connection with this site, including:

Questions and Inquiries

For inquiries and questions, we collect the inquiry or question, together with name, contact details (email address, phone number and mailing address) and any other additional information voluntarily submitted to us through a Contact Us form or an email. We use this information to address the inquiry and respond to the question.

Online Store

For orders and purchases placed through our online store on this site, we collect order details, name, institution name and address (if applicable), email address, phone number, shipping and billing addresses, credit/debit card information, shipping options and any instructions. We use this information to complete transactions, fulfill orders, communicate with individuals placing orders or visiting the online store, and for related purposes.

Surveys

Pearson may offer opportunities to provide feedback or participate in surveys, including surveys evaluating Pearson products, services or sites. Participation is voluntary. Pearson collects information requested in the survey questions and uses the information to evaluate, support, maintain and improve products, services or sites; develop new products and services; conduct educational research; and for other purposes specified in the survey.

Contests and Drawings

Occasionally, we may sponsor a contest or drawing. Participation is optional. Pearson collects name, contact information and other information specified on the entry form for the contest or drawing to conduct the contest or drawing. Pearson may collect additional personal information from the winners of a contest or drawing in order to award the prize and for tax reporting purposes, as required by law.

Newsletters

If you have elected to receive email newsletters or promotional mailings and special offers but want to unsubscribe, simply email ask@peachpit.com.

Service Announcements

On rare occasions it is necessary to send out a strictly service related announcement. For instance, if our service is temporarily suspended for maintenance we might send users an email. Generally, users may not opt-out of these communications, though they can deactivate their account information. However, these communications are not promotional in nature.

Customer Service

We communicate with users on a regular basis to provide requested services and in regard to issues relating to their account we reply via email or phone in accordance with the users' wishes when a user submits their information through our Contact Us form.

Other Collection and Use of Information


Application and System Logs

Pearson automatically collects log data to help ensure the delivery, availability and security of this site. Log data may include technical information about how a user or visitor connected to this site, such as browser type, type of computer/device, operating system, internet service provider and IP address. We use this information for support purposes and to monitor the health of the site, identify problems, improve service, detect unauthorized access and fraudulent activity, prevent and respond to security incidents and appropriately scale computing resources.

Web Analytics

Pearson may use third party web trend analytical services, including Google Analytics, to collect visitor information, such as IP addresses, browser types, referring pages, pages visited and time spent on a particular site. While these analytical services collect and report information on an anonymous basis, they may use cookies to gather web trend information. The information gathered may enable Pearson (but not the third party web trend services) to link information with application and system log data. Pearson uses this information for system administration and to identify problems, improve service, detect unauthorized access and fraudulent activity, prevent and respond to security incidents, appropriately scale computing resources and otherwise support and deliver this site and its services.

Cookies and Related Technologies

This site uses cookies and similar technologies to personalize content, measure traffic patterns, control security, track use and access of information on this site, and provide interest-based messages and advertising. Users can manage and block the use of cookies through their browser. Disabling or blocking certain cookies may limit the functionality of this site.

Do Not Track

This site currently does not respond to Do Not Track signals.

Security


Pearson uses appropriate physical, administrative and technical security measures to protect personal information from unauthorized access, use and disclosure.

Children


This site is not directed to children under the age of 13.

Marketing


Pearson may send or direct marketing communications to users, provided that

  • Pearson will not use personal information collected or processed as a K-12 school service provider for the purpose of directed or targeted advertising.
  • Such marketing is consistent with applicable law and Pearson's legal obligations.
  • Pearson will not knowingly direct or send marketing communications to an individual who has expressed a preference not to receive marketing.
  • Where required by applicable law, express or implied consent to marketing exists and has not been withdrawn.

Pearson may provide personal information to a third party service provider on a restricted basis to provide marketing solely on behalf of Pearson or an affiliate or customer for whom Pearson is a service provider. Marketing preferences may be changed at any time.

Correcting/Updating Personal Information


If a user's personally identifiable information changes (such as your postal address or email address), we provide a way to correct or update that user's personal data provided to us. This can be done on the Account page. If a user no longer desires our service and desires to delete his or her account, please contact us at customer-service@informit.com and we will process the deletion of a user's account.

Choice/Opt-out


Users can always make an informed choice as to whether they should proceed with certain services offered by Adobe Press. If you choose to remove yourself from our mailing list(s) simply visit the following page and uncheck any communication you no longer want to receive: www.peachpit.com/u.aspx.

Sale of Personal Information


Pearson does not rent or sell personal information in exchange for any payment of money.

While Pearson does not sell personal information, as defined in Nevada law, Nevada residents may email a request for no sale of their personal information to NevadaDesignatedRequest@pearson.com.

Supplemental Privacy Statement for California Residents


California residents should read our Supplemental privacy statement for California residents in conjunction with this Privacy Notice. The Supplemental privacy statement for California residents explains Pearson's commitment to comply with California law and applies to personal information of California residents collected in connection with this site and the Services.

Sharing and Disclosure


Pearson may disclose personal information, as follows:

  • As required by law.
  • With the consent of the individual (or their parent, if the individual is a minor)
  • In response to a subpoena, court order or legal process, to the extent permitted or required by law
  • To protect the security and safety of individuals, data, assets and systems, consistent with applicable law
  • In connection the sale, joint venture or other transfer of some or all of its company or assets, subject to the provisions of this Privacy Notice
  • To investigate or address actual or suspected fraud or other illegal activities
  • To exercise its legal rights, including enforcement of the Terms of Use for this site or another contract
  • To affiliated Pearson companies and other companies and organizations who perform work for Pearson and are obligated to protect the privacy of personal information consistent with this Privacy Notice
  • To a school, organization, company or government agency, where Pearson collects or processes the personal information in a school setting or on behalf of such organization, company or government agency.

Links


This web site contains links to other sites. Please be aware that we are not responsible for the privacy practices of such other sites. We encourage our users to be aware when they leave our site and to read the privacy statements of each and every web site that collects Personal Information. This privacy statement applies solely to information collected by this web site.

Requests and Contact


Please contact us about this Privacy Notice or if you have any requests or questions relating to the privacy of your personal information.

Changes to this Privacy Notice


We may revise this Privacy Notice through an updated posting. We will identify the effective date of the revision in the posting. Often, updates are made to provide greater clarity or to comply with changes in regulatory requirements. If the updates involve material changes to the collection, protection, use or disclosure of Personal Information, Pearson will provide notice of the change through a conspicuous notice on this site or other appropriate way. Continued use of the site after the effective date of a posted revision evidences acceptance. Please contact us if you have questions or concerns about the Privacy Notice or any objection to any revisions.

Last Update: November 17, 2020