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What is the Mad Professor guitar amplifier about?
What is the Mad Professor guitar amplifier about?
Dynamics
Much attention has been paid to reduce the compression normally found in tube amplifiers as while compression is often very nice it is hard to remove once in the circuit. The Mad Professor amp was designed to be extremely dynamic as that is a very important feature in a tube amplifier. The MP therefore has a very big power supply for an amp in this power range and the reserve power allows 40 W defined as clean output, while producing 75 W full power distorted output, square wave at high slew rate.
You can get natural tube compression from MP by turning up the Master Volume to about two o'clock or more, and if you need to lower the volume use the Powersuck . Higher settings on the Boost control also increase power-amp compression.
One can also use compression pedals to get more compression if ever needed.
Part of the Powersuck circuit
Definition
The Mad Professor amplifier is capable of producing high definition, high density distortion at extreme power levels. The amplifier was designed backwards from full power output to low levels, thereby defining full power output distortion to let the other sounds fall from that as a consequence as in 'get the distortion right and the clean sound will be defined'.
The amplifier is capable of classic guitar sounds as defined by recordings and sound memories but they are done differently, avoiding as far as possible typical topologies. This means that the soul of this amplifier lays in definition more than a signature tone.
Definition means here that as far as possible all limitations to sound have been eliminated
The power amp alone would have 7 distortion mechanisms that most of them stem from limitations in peripheral circuitry and throughout amplifier measures have been taken to reduce the influence of peripheral circuitry and give as fast response as possible
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Clean work all through the amp
No Compromise
The reason to choose a one channel format for this amplifier was to allow no compromises to that one channel, and if one would need more sounds available the amp would accept every possible effects pedal.
Another reason for choosing a one channel format is the full power output and the definition wanted there. There are aspects such as artificial gain at the expense of bandwidth that would lead to uncontrollable instability in a multi channel set up or at any rate make half of the control panel unusable with the current topology at full power output while in its format the controls of the amplifier are always active and useful regardless of setting.
When amp runs at its own distortion the exact composition of treble and distortion can be set to complement most guitars and speaker cabinets.
The soul of this amplifier is total control, definition of tone and flexibility to stand through changes of sound preferences
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Totally handcrafted
Recording
One lesson the designer Mr. Bjorn Juhl has learned both in recording situations and in live performance is that what emanates from the speakers may not be the same as what the musician hears. In fact distortions of amplifier may produce acoustical distortion in front of the speaker dome, forming a low energy cloud upsetting other waves that have to pass through the cloud, while this can be believed to be mostly a function of the speaker it is also of utter importance what the amplifier produces at the output and this is the purpose of reducing the compression and peripheral distortions of the amplifier.
Mr. Bjorn Juhl has spent numerous hours listening close to the speaker dome both with ear and with different microphones recording at various levels to analyze the components of sound that creates disturbances and what causes this in amplifiers.
This has bearing on sound at all levels and control of this allows casual mic placement in recording and public address and ensures that what sound is set from amplifier is also recorded or broadcasted to audience and at ease controlled by sound men.
Lots of details
Versatility
The amplifier is best viewed as a one channel amplifier with lot of variety.
There are five controls and two inputs addressing gain and power levels and seven controls setting EQ.
Flexibility includes the use of several different tube types and ample bias range to allow this.
Very interesting things happen if output tubes are changed from standard EL34 to 6L6, 6550, 5881, KT88 or other types of tube of different brands. Amp is built to accept this and the qualities of the tubes used can clearly be heard over the circuit of the power amp, so the sound of the tube is dominating and not the circuit limitations.
There is an effect loop with two levels for various effects from vintage echo's to modern pedals.
The amp has total of 5 speaker outputs for all possible speaker cabinets
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Controls for the Tone
For the gain:
You can choose between two inputs: Normal and Abnormal . Normal gives sensitivity enough to drive full power at low distortion, whereas Abnormal gives a choice of two modes, Fet and Tube to access heavier gain.
Normal channel is designed for clean tones or for organic, not that tight old school distortion.
Abnormal input is equalized to allow definition at high preamp gain, but can be used also for the brighter less distorted sounds.
Tube/Fet selector at Abnormal input sets the texture of distortion and optimizing in Fet mode for high level distortion and in tube for standard tube response. For high level distortion the grid space of each tube is exposed to overload and to obtain definition at these distortion levels the function of rectifier distortion as is the effect of an overloaded grid, when current flows into tube or more precisely when grid takes on the function on the anode, has been controlled by the Fet so that high level distortion is well defined.
You can footswitch between the Tube and Fet position when you plug into Abnormal input and place the Tube/Fet switch in the amp front panel to Fet .
For the EQ:
Amplifier is equipped with a standard tone control net as in Bass, Middle, Tone Balance , while in addition to this it has a Treble control that set the treble (and nothing but the treble) of the tone balance and a Focus switch.
Tone Balance sets the upper midrange emphasis and the balance of treble and bass, while the Treble and Bass controls the outskirts and Middle controls the depth of the network.
Focus selector that has four modes sets the way the tone control works and allows to the left a two different hollow midrange tones and to the right, a denser midrange with or without treble emphasis. The use of this control is to set response for desired distortion level and speaker array.
There is also a Presence control, voiced a bit apart from the range of Treble, Tone Balance, Focus treble emphasis. This control is a part of power amp and sets the brilliance of amplifier.
The two most important elements of a guitar sound is the kind of treble and the texture of distortion as even in what would be recognized as a clean sound distortion creates shimmer that is not heard as distortion and much attention has been paid to this to allow settings that are e.g. bright but not piercing and the texture desired for sound and this is why extensive control has been given over treble and distortion.
As the amplifier was designed to accept any kind of pedals, attention to distortion functions and filtering that could upset this has been paid in that a base tone for most any kind of pedal can be set while giving a desired bypass sound, as there may be small differences in base tone that can havoc or compliment e.g. a fuzz sound.
For the output:
The Master Volume and Powersuck are meant to work in conjunction for setting compression and swiftness of amplifier response as well as output level.
One can view the Master Volume as a sensitivity control for the power amp while the Powersuck is the final output control.
The Powersuck not only affects power level but can be used to adjust compression of power-amp together with Mastervolume (the higher Mastervolume level, the more compression).
At lowest Powersuck level the power amp is overloaded and the controls will have less effect as the power amp distorts what is fed to it as it would if full power were to be fed to the speakers, though then the compression and distortion of the speakers would interact more.
In conjunction with the other controls on amp the feel of power distortion can be approximated and different types of power amp distortion can be set at reasonable levels
There is also a Boost control that has a dial on front panel and a switch on the pedal. The purpose of this Boost pedal is to allow setting of two power levels for lead versus rhythm while sound set would stay about the same. At near full output this boost will add only distortion as the power amp runs out of reserve power to raise output further. This is a power amp control and the Boost control is active even then the Boost pedal is not plugged in
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Powersuck with four different power levels
Safety, Reliability and Serviceability
All components used have been examined for appropriate rating to ensure very good margins exceeding requirements for overload protection, and space between components and protection against surge build up at high voltage points have been calculated.
All windings of power transformer are fuse protected and measures have been taken to protect amplifier from tube failure so as to ensure that in the event of breakdown as any amplifier would be exposed to sooner or later, a fuse and tube change should be all needed to have the amp up and running again.
The transformers have ratings to exceed power drawn to ensure stability and reliability under any circumstances.
Under tube failure some components such as the screen grid resistors may fuse and thereby prevent further damage and these are also mounted for easy access and the amp is laid out for easy access of any component - one must assume that no component will last forever.
As this amp was designed and is built by amp service technicians, (builder is Mr. Jukka T. Mönkkönen of Wahvarikellari) failure mechanisms in tube amplifiers have been examined and as far as possible been prevented in the design and ease of serviceability has been born in mind for swift service.
There are four extra fuses (besides the two at back panel) inside for your and your amplifiers ultimate safety
Signature Tone
Because the Mad Professor amp is capable for so many tones it might be confusing that what the signature tone of this amp is. Well, it is the feel of the amp; the MP has a signature feel when you play it. Also the definition and dynamics make the signature for this amp.
What sets the Mad Professor apart from most other amplifiers in that many of the distortion and compression mechanisms normally associated with tube amps have been reduced to allow the voice of the tubes and not the limitations of the circuit to be clearly heard.
This makes for unusual dynamics and definition. In comparison sounds can be dialled close to classic amps as those sounds are the basis of rock, but in comparison the voice of the Mad Professor amp is clearly heard and most importantly felt. This is evident in the treble response and the deep bass response, the compression or rather the low compression (not to be confused with sustain) and the clarity of distortion.
The sheer amount of sounds might seem confusing but that really is just icing on the cake as the goal of this amplifier is to rid it of limitations.
The Mad Professor is also extremely pedal friendly amp and it worked fine with every pedal we have tested it with.
This tube amp features three gain structure options, extensive tone control network, 40-70 watts of (clean) output power, series effects loop with level options, selectable level boost at foot switch control with a front panel knob to set desired boost.
Tuned "POWERSUCK" switch for great tone even at small clubs.
BJF designed custom-made huge transformer, best audio components and careful fine-tuning with wonderful hand work by Bukka M. are some of the secrets behind this amp.
The real beauty is in the amp circuit that is a piece of art.
Lot of special tuned circuits where the placement of components and length of wires makes a difference in tone.
Mad Professor has FOUR ways to control the critical treble response:
- FOCUS switch has two options with slight treble boost, then there is
- TONE BALANCE that you can adjust treble with, the
- TREBLE control of course adjust certain Treble frequency and the
- PRESENCE controls another Treble frequency.
You will find the optimal Treble response with any guitar and cabinet using these controls.
Second is the Distortion even the clean tone you hear on a guitar amp has distortion. You hear it as shimmer, sparkle, twang etc. To hear a totally clean guitar tone plug to your home stereo and enjoy (or try some of the early silverface Fender by CBS engineers).
You can get distortion from each input (NORMAL, ABNORMAL at tube setting and ABNORMAL at FET setting).
You can footswitch between the TUBE and FET setting when you are plugged into ABNORMAL input and the TUBE/FET switch is turned to FET position.
You can have distortion from Preamp or from Power-amp, you can have it at lower volume levels with the special POWERSUCK switch.
There are lot of different distorted tones from this amp: "clean", sweet, crunchy, fat, "On the edge", singing, dynamic, with powertube saturation or without.. You can tailor the distortion so that treble distorts earlier than the low-end etc....
The amp is LOUD but has also great tone at club-levels thanks to special BJF design "POWERSUCK" option.
FRONT PANEL CONTROLS
NORMAL INPUT used for clean sounds to light overdrive
ABNORMAL INPUT used for overdrive sounds
FET-TUBE SWITCH selects the type of distortion obtained from Abnormal input - where the FET option lets the input tube be driven without the rectifier action of an overloaded control grid resulting in a sound with a little less buzz, slightly cleaner tone than ordinary tube overdrive. TUBE is an all tube structure for a classic tone
You can footswitch between the TUBE and FET setting when you are plugged into ABNORMAL input and the TUBE/FET switch is turned to FET position.
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