MI Amplification
Owner’s Manual
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1. Welcome .......................................................................................................................................4 2. Precautions...................................................................................................................................5 3. Amp Overview ..............................................................................................................................6
3.1. Preamp.............................................................................................................................................. 6 3.2. Power Amp....................................................................................................................................... 6 3.3. FX Loops .......................................................................................................................................... 7 3.4. Operating Modes ............................................................................................................................. 7
4. Getting Started .............................................................................................................................8 5. The Channels...............................................................................................................................9
5.1. Introduction ..................................................................................................................................... 9 5.2. Channel 1.......................................................................................................................................... 9
Overview....................................................................................................................................................................9 Channel 1: Low Gain............................................................................................................................................... 10 Channel 1: Mid Gain................................................................................................................................................ 10 Channel 1: High Gain .............................................................................................................................................. 10
5.3. Channel 2........................................................................................................................................ 10
Overview.................................................................................................................................................................. 10 Channel 2: Low Gain............................................................................................................................................... 10 Channel 2: Mid Gain................................................................................................................................................ 11 Channel 2: High Gain .............................................................................................................................................. 11
5.4. Channel 3........................................................................................................................................ 11
Overview.................................................................................................................................................................. 11 Channel 3: Low Gain............................................................................................................................................... 11 Channel 3: Mid Gain................................................................................................................................................ 12 Channel 3: High Gain .............................................................................................................................................. 12
5.5. Channel 4........................................................................................................................................ 12
Overview.................................................................................................................................................................. 12 Channel 4: Low Gain............................................................................................................................................... 12 Channel 4: Mid Gain................................................................................................................................................ 13 Channel 4: High Gain .............................................................................................................................................. 13
6. Other Preamp/FX Features.......................................................................................................14
6.1. Gain Trim....................................................................................................................................... 14 6.2. Dual Master Volumes.................................................................................................................... 14 6.3. FX Loops ........................................................................................................................................ 15
Standard Loops ........................................................................................................................................................ 15 Pro Loops (Optional) ............................................................................................................................................... 16 To assign and activate an FX Loop (Standard or Pro) ............................................................................................. 17 To connect an external preamp into the power amp of the Revelation .................................................................... 17
7. Power Amp.................................................................................................................................18
7.1. Introduction ................................................................................................................................... 18 7.2. Presence, Depth and Feedback Level (F.B)................................................................................. 18 7.3. Output Power................................................................................................................................. 19
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7.4. Screen Config................................................................................................................................. 21 7.5. Bias Config. (optional)................................................................................................................... 21 7.6. Power Tubes................................................................................................................................... 21 7.7. Discussion about Large Size Tubes.............................................................................................. 23
KT88........................................................................................................................................................................ 23 KT90........................................................................................................................................................................ 23 KT100...................................................................................................................................................................... 23 6550-A ..................................................................................................................................................................... 23
7.8. Discussion about Medium Size Tubes.......................................................................................... 23
6550 ......................................................................................................................................................................... 23 EL34......................................................................................................................................................................... 24 6L6GC ..................................................................................................................................................................... 24 6CA7........................................................................................................................................................................ 24 KT77........................................................................................................................................................................ 24 KT66........................................................................................................................................................................ 24 5881WXT ................................................................................................................................................................ 25
7.9. Discussion about Small Size Tubes .............................................................................................. 25
KT66........................................................................................................................................................................ 25 5881 ......................................................................................................................................................................... 25 6L6/G/GA/CB.......................................................................................................................................................... 25 6V6 .......................................................................................................................................................................... 25 6K6 .......................................................................................................................................................................... 26
8. Speaker outputs, Slave Output ..................................................................................................27 9. Configuring and Programming the Revelation........................................................................28
9.1. Standard Mode .............................................................................................................................. 28 9.2. MIDI Mode..................................................................................................................................... 28
Setting the MIDI Receive Channel .......................................................................................................................... 29 Editing and Storing a Program................................................................................................................................. 29
10.
10.1. 10.2.
For your Amp Tech - Changing and Biasing Power Tubes.................................................30
Preparing the Amplifier............................................................................................................ 30 Selecting Tubes and setting the “Tube Size” Switch .............................................................. 30
What other Tubes can be used?................................................................................................................................ 30 A note on NOS tubes. .............................................................................................................................................. 31 A note on Modern tubes........................................................................................................................................... 31
- 10.3.
- Biasing the Tubes....................................................................................................................... 31
Bias Setting Range for different tubes ..................................................................................................................... 32 How we bias in the Workshop ................................................................................................................................. 38
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1. Welcome
Hi there! I’d like to take this opportunity to thank you for purchasing the MI Amplification Revelation vacuum tube guitar amplifier. I’m very proud of my baby, and I hope you like her too! Well over 4 years of development have now gone into the Revelation. In releasing a vacuum tube amplifier, I didn’t want to just add another amp onto the market, simply because I could. Rather, I wanted to make a serious contribution to the continued evolution of this art form.
It seems to me that valve amp design is currently polarised into two distinct camps. The first of these are the elite boutique amps, offering amazing tone, wonderful workmanship, but with a limited set of features at typically ‘challenging’ prices. The second of these are the mass produced, assembly line amps. These offer great ‘value’, with (typically) many more features, but with very ordinary workmanship (since most consumer electronics are only engineered to have a life expectancy of 5 years), ‘budget’ components, and most importantly, generic tone. Looming in the background of this tussle is the ascent of digital modelling. This digital revolution has shown guitarists that they need no longer settle for one or two sounds. Now they can have as many as they want.
So out of this seeming disparity arose my own personal design challenge. Can a hand built boutique amp offer the same kind of features as a production line amp? Can a flexible amp be built with the best components, utilising an uncompromising build technique? And finally, can a pure vacuum tube amplifier be created with features and flexibility that pushes the limits of these traditional paradigms, even challenging the flexibility of digital modelling amps, but with pure valve integrity?
My response to these questions is the Revelation. It’s been a long time coming, but I hope you enjoy your new instrument as much as I have enjoyed creating it for you.
Michael Ibrahim MI Amplification
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2. Precautions
In order to get the most out of the Revelation, please make sure that you follow the points:
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Make sure that the power outlet is the correct rating as stated on the amplifier
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Make sure that if a fuse blows, you replace it with the same type and rating only. Do not substitute. Do not change any fuse while the amp is still plugged in. If your amp continues to blow fuses, get it checked out by a qualified technician.
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Make sure that the amplifier is properly ventilated, both from front and rear. Do not get the amp wet. Do not expose the amp to rain, moisture, or any water or liquid.
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Keep the amp away from any flammable objects, as the amplifier can generate quite a bit of heat.
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Do not expose the amplifier to direct sunlight or extreme heat. Make sure that you leave the amplifier standby in “Warm” for at least one minute after turning the power on in order to allow the power tubes to warm up properly before turning on the high voltage.
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Do not touch the tubes! They are VERY hot. Always make sure that the amplifier is connected to the correct load before operating.
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Always make sure that the amplifier is properly grounded by using a three-pin mains plug. Do not use a modified two-pin plug.
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Unplug the amplifier when it is not in use. Do not remove the back grill. Do not open the amplifier, as there are no user serviceable parts inside. Do not adjust the bias of the amplifier. This is for qualified technicians only. Always replace the power tubes with a good quality matched pair. Use hearing protection at all times if exposed to high sound pressure levels.
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3. Amp Overview
Figure 3-1 Front Panel Figure 3-2 Rear Panel
- 3.1.
- Preamp
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The Revelation features 4 completely independent channels, featuring GAIN, BASS,
MIDDLE, TREBLE and VOLUME. Each channel is independently voiced with unique
design architecture, in order to capture the sonic DNA of iconic guitar tones. What this means is that when you change channels, it feels like you’re changing amps, not simply adding more or less gain to the same basic sound.
Not only is each channel independently voiced, but they also feature 3 gain modes, namely low, mid and high gain. This revolutionary approach means that for the first time, the idea of a ‘clean’ or an ‘OD’ channel is done away with. Any channel can be assigned to operate as a clean, crunch, or high gain channel. You can, for the first time, set up 4 distinct clean tones. Alternatively, all 4 channels can be variations of dirty. It’s completely up to you.
GAIN TRIM, for a further ‘hot-rod’ of the high gain modes on all 4 channels. This rear panel control allows you to further increase the gain in the high gain mode for all 4 channels.
MI: Personally, I leave this control all the way down, as I feel that the amplifier has more than enough gain (especially in Channels 3 and 4). But if you want more gain, it’s in there!
- 3.2.
- Power Amp
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The Revelation features a push-pull power amp design, designed to take virtually any octal base power tube, including KT100, KT90, KT88, KT77, KT66, 6550, EL34, 6CA7, 6L6, 6L6G, 6L6GA, 6L6GB, 6L6GC, 5881, 6V6 and 6K6 power tubes.
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The Revelation’s power amp is configurable to match any of the tube types listed above. This ensures optimal performance for each tube type.
Dual master volumes MAST. A and MAST. B, give you the option of setting up two stage levels.
PRESENCE and DEPTH controls, allow you to control the frequency response and feel of the power amplifier. This is particularly useful for matching the sound of the Revelation to different guitar cabs or rooms.
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Selectable power amp feedback level (low/off/high) for controlling the feel and response of the power amp. This includes completely disabling the PRESENCE and DEPTH controls (off position) for unfettered power amp response.
The power amplifier features 3 selectable power levels, “High” “Mid” and “Low” Variations in output power are achieved in the most natural way possible, namely by varying the internal
6high voltage of the amplifier. This leaves all other supplies operating at their correct voltages, so that the operation of the amplifier is not compromised.
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Triode/Pentode configuration for further variation of the power amp’s feel and headroom. This is more than just power variation, but also affects the way that the power amplifier responds, with a much smoother transition between clean and clipping.
OPTIONAL: The Bias configuration option adds a further 2 operating modes on top of the standard fixed bias, namely Cathode Biased and Cathode Dynamic modes. These not only change the maximum output power of the power amp, but also have a dramatic impact on the tone and feel of the Revelation, making it much spongier and more ‘vintage’ sounding.
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Slave output with Level control.
- 3.3.
- FX Loops
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4 independent assignable FX loops. Each loop is assignable to any channel or program. For the first time ever, an integrated programmable FX switcher has been included in a guitar amplifier, allowing you to automatically switch your effects with each channel or each patch.
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OPTIONAL: Any or all of the loops can be upgraded to Pro Loops. Each pro loop features low noise buffered circuitry for the ultimate in performance. Each Pro Loop can operate as either series or parallel (instead of the standard series loop). They also features level selection (line or guitar), send level and mix control.
- 3.4.
- Operating Modes