Guitar HD IR Pack 1

Rather than raw “cab + mic” snapshots, the impulses in the Guitar HD IR Pack 1 are instead multi-mic mixes with frequency correction applied. For this reason, we’ve opted not to elaborate which mics were used when recording individual impulses. For each cabinet, we picked a set of mics which captured the cab’s character the best to our ears. With this approach, detailing the mics and their balance in each case wouldn’t really make sense. With the Guitar HD IR Pack 1, our goal was to create an impulse pack that would make bass players’ lives easier on stage and at the studio, and we hope you find it useful in your work.

Any impulses from the Guitar HD IR Pack 1 with the same length and bitrate can be blended together with no frequency response issues (such as comb filtering or the lows disappearing). This is due to the fact that all impulses in the pack are in phase with each other.

Additionally, all impulses have been mastered to an almost identical subjective perceived volume (ITU-R BS.1770 LKFS standard). The volume of the longest (500ms) impulses is around -35 LUFS (-32 LUFS for stereo versions). Shorter impulse versions also have equal volume, except this time Total RMS is used (this allows to achieve minimal volume fluctuations when using hardware IR players). Please avoid normalizing the impulses to 0 dB as it can lead to significant differences in their perceived volume.

The collection includes impulses of different lengths — not just because certain impulse players can only process a particular length, but also because shorter impulses have less room reverb data. “The longer, the better” doesn’t apply to cabinet impulses; instead, it boils down to personal preference: some prefer impulses with more “volume” while others go for dry-sounding ones (and blend in some early reverb reflections if needed). The only objective difference is this: short impulse lengths (such as 20 ms) are less precise in the lows. It’s up to you to decide if you prefer that or not.

All impulses in the pack were recorded with a neutral power amp. EQ was later applied to achieve a more balanced final sound. If you feel that an impulse sounds too dark or too bright, feel free to use an EQ and/or adjust the rest of your signal chain to achieve the tonal balance you need.

This IR pack consists of 80 impulses recorded from 10 guitar cabinets. For each cab, there are 4 mono and 4 stereo versions. Each impulse has different length versions in 3 formats. 

The available formats are split into folders as follows:

• The 96k folder includes 96k@24bit WAV files. These are the max resolution versions (HD).
• The 48k folder includes 48k@24bit WAV files (the current industry standard). 
• The 44k folder includes 44.1k@16bit WAV files. This is the classic CD quality format. We recommend using those if your impulse player doesn’t support the 48k or 96k formats.

Each of the folders above has 4 subfolders for different impulse lengths:

• The 500 folder includes impulses with a length of 500 ms. Those are the most precise and “spacious” versions. 
• The 250 folder includes impulses with a length of 250 ms. Such impulses have high precision and medium “space”.
• The 125 folder includes impulses with a length of 125 ms. Those are highly precise but have the minimum amount of “space”.
• The 20 folder includes impulses with a length of 20 ms. Such impulses lack precision but offer the “driest” sound possible. These files can be used with the Shift Line CabZone X and Twin MkIIIS IR players. 

Once again, high precision doesn’t necessarily mean the best sound. Each of the lengths provided in the pack can produce great results, so try them all and see what works best for you.  

Each length folder has 3 subfolders:

• Mono: 40 mono files (PCM1).
• Stereo: 40 stereo files (PCM2). These files have slight differences in frequency response between the right and left channels. They also differ from the mono versions in how the mics were set next to the speakers and in the room.
• Stereo Split: 80 mono files (PCM1). These are separate channel files for the Stereo versions. You can use these files if your impulse player doesn’t allow channel selection. The Mono and Stereo versions sound very similar but still have some differences. In this folder, you can select the file you need for mono use. 

All files in the pack follow the same naming convention: SL_XXX_Cab_Name_Y (mono), SL_XXX_Cab_Name_Y_ST (stereo) and SL_XXX_Cab_Name_Y_L/R (separate stereo channel). XXX denotes cabinet type (the size and number of speakers). ST always means that the file has two channels, while the L and R postfixes are used for separate stereo channels.

The Y suffix denotes one of the four cab versions:

• A (Average): a well-balanced sound which is the closest to the cabinet’s real-life tone. 
• B (Bark): a mid-heavy, “barking” tone which is perfect for solo parts and punching through a busy mix.
• C (Crisp): a detailed, bright and shimmery tone with prominent highs. This is a great choice if you want attack and clarity, particularly on clean or light overdrive.
• D (Deep): a deep and massive tone with prominent lows achieved by mic balance in the mix. This isn’t the typical ribbon mic impulse response with overwhelming bass; instead, it’s a deeper and more spacious version of the impulse which is a perfect choice for wall-of-sound tones. 

Example: SL_410_Fender_BM_B_ST.wav is a stereo version of the impulse response recorded from Fender Bassman (a cab with 4 10-inch speakers) with boosted mids. It will work great for sustained low- to mid-gain solo parts.

Keep in mind that you can also blend each version with other impulses from the pack without any phasing issues.

You can download the free version to get a taste of the Guitar HD IR Pack 1. The free pack includes 4 500-millisecond impulses (2 mono and 2 stereo) along with a selection of 20-millisecond ones. The files are in the WAV 24bit 48kHz format and are compatible with the Shift Line CabZone X and Shift Line Twin MKIIIS hardware IR players.