Celestion IRs (Impulse Responses) are highly accurate digital representations of a selection of our legendary speakers. They allow you to simulate the tone you would get from playing your guitar (or bass) through one of our physical speakers, but by digital means instead.

Our Impulse Responses were created with the help of multi-platinum Engineer/Producer Mike Spink at Decoy Studios, a world class live room which is the professional home of award-winning mixing engineer Cenzo Townshend.

For each guitar speaker we recorded a set of Impulse Responses for 5 different cabinet configurations: closed back 1×12, open back 1×12, closed back 2×12, open back 2×12 and closed back 4×12 (with the same configurations for 10” cabs, too.)

IR Microphones and Mix Information

Then, for each cabinet type we recorded using 3 different industry standard microphones, Royer R-121, Sennheiser MD421, Shure SM57. Each was placed in 6 different positions, corresponding to a range of different tones (balanced, dark, dark 2, bright, fat and thin) – making 18 recordings in all.

Additionally there are Impulse Responses recorded by separate room mics (two Neumann TLM 107s) that have captured the ambient response of the live room, there are three of these recordings: Left, Right and Stereo.

Open back guitar speaker cabinet options also include a single rear mic ‘SM57 Rear’. This is located in the SM57 folder and is also used on the mix using “all mics.” We suggest blending this with the front SM57 for a fuller sound.

Then we created several additional mixes based on different mic combinations, to give yet further tonal variety. To round off the package we’ve also included a “room mic only”, as well as providing two IR lengths, and a range of sample rates to choose from.

5 Microphone mixes:

  • R-121+SM57
  • MD421+SM57
  • MD421+ R-121
  • R-121+MD421+SM57All three mics together with room microphones added in both mono and stereo.

Each mix is included twice; tailored for lower and higher gain guitar sounds and with both 200 and 500 ms sample lengths to work with a wide range of hardware and software loaders..


For each bass speaker we have recorded a set of IRs featuring the most appropriate cabs for the speaker size. For bass speaker recording we used the following mics: AKG D112, Neumann FET47, Sennheiser MD421, each placed in the same positions relative to the speaker’s cone as out guitar cab IRs, to provide a range of different tones (balanced, dark, dark 2, bright, fat and thin).  Again, we created several additional mixes based on different mic combinations, to give yet further tonal variety.

To round off the package we’ve included the Neumann TLM 107  “room mic” option as well in L & R  mono and stereo, and a set of  IRs for an HF horn driver, recorded with a Neumann KM84 mic that can be mixed with the cone driver IRs to add some additional high frequency signal to the tone where required.

Then we created a range of different bass style mixes to get you up and running fast. These comprise: Finger Basic; Finger Warmth Detail; Slap; Plectrum Basic; Plectrum Aggressive. Of course, we also provide the same two IR lengths, and sample rates to choose from.


Included in the bass speaker collection bundle are the following mic mixes:

  • D112+KM84
  • FET47+KM84
  • MD421+KM84D112+MD421+KM84
  • FET47+MD421+KM84
  • FET47+D112+KM84
  • All mics
  • All mics plus Room Stereo
  • All mics plus Room Mono

IR File Formats

Our Impulse Responses are 24-bit digital downloads in five sample rates:

  • 44.1 kHz
  • 48.0 kHz
  • 88.2 kHz
  • 96.0 kHz

and in 2 lengths:

  • 200 ms
  • 500 ms

All Impulse Response Digital Downloads are in a non-proprietary, native uncompressed WAVE audio (.wav) format.

Some software or hardware may need the files to be converted to a different format before they can be used.

Other types of software/hardware may convert the files for you automatically when you load them. You’ll need to check the instructions for your particular hardware to find out which file formats are supported and what conversion may be necessary.

Once you have downloaded the IR library for the cabinet type you want (or all five cabinets together if you choose the Collection option) you can start adding them to your guitar sound. You can do this in two ways:

  • Via a convolution plugin in your DAW
  • Via your standalone amp/cab modelling hardware

IR Convolution

Each Celestion Impulse Response captures the essence of one of our guitar (or bass) speaker’s tone. In order to make use of an IR, it must undergo a process called convolution. This is a signal processing operation that has the effect of combining the IR with an input signal, thereby digitally applying the speaker’s tone to that signal.

The convolution process is already built in to the operation of standalone amp modelling hardware, so you don’t even need to be aware of it. If you’re using the Celestion Impulse Responses with a DAW, then the IR convolution process will be performed by a purpose-designed plugin which you will need to source if you don’t already have one check out SpeakerMix Pro.

High Quality, Professionally Mixed Celestion Tone

The result is incredibly high quality, professionally mixed Celestion tone that you can use time and time again.

But it doesn’t stop there. Because you have all the speakers in digital format you can mix them together to create your own unique sound, blending different mics, speakers, and cabinet types to find your perfect tone quickly and easily.

And, because your IR library is highly portable you can quickly recreate the tones anytime and anywhere you want – whether you’re working in the studio, practicing with a band or performing live in different venues.

Explore the rest of our Knowledge Base section for additional technical details, or listen to IR samples on our product pages.

Related Information:

  • IR Instructions– Detailed information about how to use the files.
  • FAQ – Find answers to Frequently Asked Questions.
  • Why We Did This– An interview with the Celestion IR development team.