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Twin MkIIIS Support Page

Shift Line Twin MkIIIS is a tube guitar preamplifier with a built-in cabinet simulator based on the Impulse Response Convolution technology.

This page contains extra info on the device's operation:

Standard mode

The device can utilize both stock and third-party impulses in WAV format. All the needed folders are automatically generated on the microSD card upon initial use (those folders are SD:\SL_IR\A\ and SD:\SL_IR\B\). In order to replace an impulse, simply delete the old one from one of the folders and place the new file into the same folder. For instance, to replace impulse A, go to SD:\SL_IR\A\ and replace SL_19A19.WAV with an impulse file of your choice (required format: 24bit 48kHZ WAVE PCM1, uncompressed). Next, insert the microSD card into the Twin MkIIIS and set the CAB switch to A in order to hear the new impulse. When no microSD card is inserted, the Twin MkIIIS uses built-in impulses. This way, you can extend your impulse pool to four or pair a stock impulse with a third-party one on the microSD card.

In this mode, the Twin MkIIIS will apply the built-in neutral power amp simulation to any impulses you upload.

Advanced mode

To simulate a different power amp, use the patch generator or create your own patch in SigmaStudio. Then, create an SL_HEX folder in the root directory of your microSD card. In the SL_HEX folder, create folders A and B (corresponding with the CAB switch positions on the device). Place the HEX file into any of the two folders (for example, SD:\SL_HEX\A\drive.hex). Each of the two folders can contain one HEX file. Make sure to observe folder hierarchy. Note that each HEX file's name should only consist of numbers and Latin letters.

If the microSD card has an SL_HEX folder in its root, the device will ignore the SL_IR folder and use alternative patches instead of impulses. The original firmware and impulses are still available for use: just eject the microSD card from the device.

You can download an archive with correct folder hierarchy below and extract it to a blank microSD card. The archive contains two power amp simulations with an impulse of a Fender Twin cabinet with two JBL D120F speakers. After that, you can simply replace the patch files with your own.
You can also download the archive containing all power amp simulations created for the Twin MkIIIS so far.
WARNING: HEX files created for the CabZone LE/CabZone X will NOT function properly with the Twin MkIIIS/Olympic MkIIIS because of level mismatch. We strongly advise against using CabZone LE/X patches in our preamps.

The same patches can be used both in the Twin MkIIIS and in the Olympic MkIIIS. Either device can utilize guitar and bass cabinet impulses.

Online patch generator for Twin MkIIIS

The Twin MkIIIS has only one power amp simulator (neutral) in stock. In most cases, it is enough — but you can also simulate other power amps if you wish. To do that, you need to create a user program (patch) containing the cabinet impulse and the power amp impulse of your choice (this can be done with our online HEX file generator). Once the patches have been uploaded to the device, the CAB switch will select between "power amp + cabinet" combos, which means you can create a pair of presets tailored to your needs.

This tool allows you to create a HEX file, which is an alternative control program / patch for use with the Twin MkIIIS's digital cabinet simulator.

To create and download a HEX file containing a "power amp + cabinet" combination, follow 3 simple steps:
  1. Select an impulse from the list:
    or upload your own (wav pcm, mono, 24 bit, 48 kHz, uncompressed):
  2. Select power amp:
    Select power amp set:
Description of power amp types
Neutral. The cleanest and loudest neutral power amp we could muster. It features a characteristic mild rolloff at the extremes of the range (-1dB in the highs and -2dB in the lows) resulting from a design limitation of a real output transformer. The dynamic range is interpreted in a way that doesn't make the signal sound compressed but instead saturates and livens it up. This power amp is practically impossible to overload with input volume. It should be your top pick if you want the cleanest sound for your guitar or bass.

6V6SE. The Class A power amp with 6V6 tubes is one of the most sought after — and rightfully so. Design imperfections introduce asymmetry into amplification and highlights even harmonics across the whole guitar range, which is a nice feature for booster users. The higher the input signal amplitude, the more characteristic overdrive there is. Our preset isn't a fully overdriven singletact amplifier but more on the verge of mild breakup. The compact transformers in such amps provide a mild rolloff below 80Hz and often make the highs stand out a little more. This virtual power amp goes into overdrive very tenderly; the dynamic range is interpreted in a way that only the loudest sounds get distorted, so it is not always clear if the distortion comes from the amp or the speaker.

6L6PP Classic. The American amp classic which all the various modern solutions stem from: a Class AB virtual push-pull amplifier which we just couldn't leave out. Almost as direct across the whole range as the Neutral one but with its own character. This amp cannot remain crystal clean at all volumes, but this imperfection makes it a substantial element of the signal chain. The incoming signal gets saturated by odd and even harmonics; this highlights guitar mids and highs without adding any nonsense in the lows. The dynamic range of such amps is peculiar: even quiet sounds showcase their nuances. We have attempted to reflect this in our preset, which will probably suit those who want to "round out" their guitar sound without introducing considerable distortion.

EL84PP California. EL84s are very divisive tubes as many people tend to dislike the way they operate at high volumes. However, one cannot overestimate what those tubes add to the guitarist's sonic palette. Power amps with EL84s often have characteristic "torn-up" lows and slightly "whistling" highs; this is a result of uneven amplification of odd and even harmonics across the spectrum. In our model, the second and fifth harmonics are very prominent in the lower part of the range, which should appeal to blues lovers. The virtual power amp is set to "max volume" and has a great response to changes in input volume. The characteristic non-linear compression and mild low shelf at 160Hz mean that the amp takes fuzz and classic low-gain overdrives extremely well.

EL84PP England. The sound of the British invasion. In a different part of the world, the same old El84s gave birth to characterful Class AB power amps with super juicy mids. Trying to set the amp to a higher volume results in an entirely different sonic character: focused, round, and rich in harmonics. This amp's dynamics model highlights the characteristically "compressed" and "sharp" sound which gets along well with treble boosters but doesn't really suit high gain. The amp has a mild low shelf at 40Hz and cutting presence.

EL34PP England. The next step in the British effect on guitar music: push-pull amps based on EL34 tubes. Those were perhaps the most widespread amps in the 70s and 80s. Fully cranked, they provide substantial overdrive with boosted mids, a bit of harshness in the highs, and focused lows. Our virtual British guy works great for classic rock: all you have to do is put a mid-gain preamp or classic Tube Screamer in front. Additionally, the resonance at 80Hz results in a very characteristic palm-muted sound. To get a cleaner sound from this power amp, just roll back the volume on your guitar — that's the classic way to go.

6L6PP Modern. The development of push-pull amps based around 6L6s went in different ways. One of the results is the "Californian amp". Loud, cutting and with a pronounced "oomph" on palm mutes, it is the dream power amp of any metal guy from the 90s and early 2000s. Silicon diode PSU is emulated in this preset. A slightly "barking" character, pronounced low frequency detonation, harmonic saturation and considerable compression — all of these are fully present. This model works great with high-gain distortion pedals. Of course, the V-shaped EQ is more fitting than ever here!

EL34PP Modern. Another legendary branch of British amps tries to be modern but in a slightly different way. The secret is not in tolex color but in the approach to power amp overdrive. It's basically hot bias of the same EL34s, an emulation of a kenotron-based PSU with the characteristic bump in compression and distortion resulting from increased input level (just like the SAG knob on fuzzes) and great low frequency response. All of this results in highlighted third and fifth harmonics along with substantial compression and distortion; however, the sound remains "huge". This virtual amp's master volume is always set to max, and gain depends on input level. You can get a pretty wide gain range via your guitar's volume knob alone but overdriving this power amp won't hurt (particularly in the mids). Hard-hitting modern rock is where this power amp feels at home.

6L6PP Mississippi. The third remarkable variation of Class AB power amps based on 6L6 tubes. Unlike the previous two, this one has notable distortion in output tubes in cold bias. The distortion from the "underbiased" amp is audible even at lower gain and is characteristic of heavy genres. The preset features medium damping, which adds some room to low frequencies. The higher the volume, the more compressed and distorted the signal gets, which results in characteristic "crunch". This virtual amp is meant for high gain first and foremost, but it will also work great for classic rock. If you love palm muting and dive bombs, this is the power amp for you. It's also worth noting that the amp isn't set at max volume but has some headroom. This amp tends to feed back at high volumes, which is something to keep in mind.

6550PP Overloaded. Today, relatively few power amps feature 6550 tubes on board, so we couldn't pass up on modelling one. Imagine a monster with four of those tubes overdriven beyond any reasonable limit. This is where the fun starts! The sound starts to show some pretty weird features: a roar in the lows and lots of aggression in the highs. Add a classic Rat, and you can play doom metal using headphones which won't make your ears bleed. This might indeed be the least common power amp model out of the 10 but we just couldn't do without it. Surprisingly enough, this amp is pretty great with bass.

Additional info

  • The digital cabinet simulator used in the Twin MkIIIS is based on DSP ADAU1701 (input: ADC0, output: DAC0).
  • The built-in DSP chip sees the microcontroller as a ROM chip in selfboot mode.
  • SigmaStudio is the official programming environment for the DSP chip. SigmaStudio allows to download ROM files in HEX format for use in selfboot mode. This can be used to create custom patches. Create a program, compile it, give the resulting HEX file a name in Latin letters and place it into either folder on your microSD card (for instance, SD:/SL_HEX/A/twin_patch.hex).
  • The FIR block in SigmaStudio accepts mathematical impulse factors. To turn a WAV impulse into a list of factors, you can use the WAV2FIR online tool.

User guide

Impulse packs

We have released several impulse packs for guitar and bass, and we are going to keep adding more packs in the future. You can either use those impulses in our devices directly or generate complex patches with them.