PLEXIMANIA
It is generally considered that the late 60's Marshalls have one of the best amp sounds in the world.
What is the secret?
First all tube amps even a high end stereo amp where removing all distortion is a given ...distort. Well as a casual listener they do not seem to distort at all. So whats going on.
AMPS & OVERTONES
There are even overtones. These are ones that are quite literally related to the fundamental and odd overtones these are not.
What's the difference.
Well odd overtones are harsh because they are overtones not actually in tune with the key you are playing in. ( Note: A FUZZ Box is virtually all odd overtones so it is very harsh)
Even overtones are related to that key. Lets talk about the first and most predominant overtone . The second harmonic.
Simple.. the second harmonic for example of an A note is A.
Think of it this way ...it kind of like having an A octave pedal playing an A one or two octaves higher to your A note.
.
When talking about high end stereo the objective is to have the signal that goes into an amp be exactly the same as the signal that comes out. If it does not. It is a 'distortion' of the original signal.
So here is the deal. All tube amps no mater how clean ...take the even harmonics ...especially the second and exaggerate them. The second harmonic in effect becomes a second note playing along with the actual note. What is not to like? This means every note or chord is almost like 2 notes or 2 chords. Twice as fat sounding.
The late 60's Marshalls did 2 things. First they exaggerated the second harmonic to the extreme.
Secondly they made the lower mids louder then the upper mids. you could call the upper mids the 'treble mids' and the lower mids the bass mids. It is a no brainer. Lows sound fat...highs sound thin.
Exaggerated second harmonics almost create a doubling effect ..Two notes are fatter then one.
So in short you have two sources fattening the sound!!!
So why did they stop making them???
Well the trouble with lower mids is that the drums and bass guitar create a sh@t load of them. The guitar sound can get lost in a band context. Players were all using the Rangemaster Treble booster.
A misleading description because the Rangemaster boosted the highs..off course ...BUT they boosted the poop out a the upper mids too. Hendrix and others were using the Fuzz pedal for more sustain. The course sound of it became popular because it was aggressive. The second harmonic of the amp itself smoothed out enough of that harshness to sweeten the sound.
So Marshall redesigned the amp with high mids being the loudest. They put in a preamp volume/level control. This in effect was to replace the reliance of the Rangemaster and the Fuzz.
It also allowed the amp to be turn down below tinnitus levels. lol
One second thing that contribute to the Plexi. The transformers had inadequate headroom. This meant the louder you pushed them the less able that they could reproduce the peak levels of the input.
Think of a peak visually as the letter 'A'. It has a point on the top representing the peak.
If the transformer can not produce it ...it cuts the top off the 'A'.
The shape of a fuzz pedal signal is completely flat. No point at all. In fact the fuzz signal is a square shape ...not an 'A' shape.
In short the transformer turns the sound into a distortion box.
It also in effect turns the transformer into a limiter/compressor . Or to keep it simple the amp sounds like a pedal compressor pushing an overdrive pedal.
Ok one last thing. No tech here. The amp section of all tube amps reacts in a kind of pumping fashion. The louder it is the more it pumps When you hit your strings hard it pumps up. This not only exaggerates the dynamics but 'feels' really good to the player. It is why most players prefer tube amps.
The feel good factor affects all of us in a positive way. It gives you a feeling of power which makes you feel confident that you are empowered. So...you quite literally PLAY BETTER!
_______________________________________________________________________
NOTE: WANT A PLEXI ?
The new Thomas Blug Bluguitar Amp 1 has only one tube It is between the preamp and the solid state class D transistor amp. This section is called the 'Driver'
It is a tiny military spec tube. This tube has a lovely tendency to 'pump' beautifully! The transistor amp simply reproduces this. The result is a Plexi feel and sound to the unit.
The great thing is this amp does not have to be loud for the this tube to pump like a very loud Plexi.
I bought one! When I say it sounds AWESOME... I am not using the word as a figure of speech.
Many people have shied away from this amp.
...too good to be true?
...the preamp is transistor?
...the power Amp is transistor?
...it looks like a toy?
...a 2 pound amp can not put out any serious power?
THE TRUTH
...it only appears to be too good to be true
...everyone is using OD pedals...which are quite literally little transistor pre amps
...as explained above the preamp does not contribute to the 'amp sound'
...it photographs badly.
It looks like a plastic Boss drum machine painted with cheap metallic silver paint. If you get one in your hands and you can easily see it is a high tech thick but light alloy ...with an amazing heavily textured industrial finish. The controls are very firm..the knobs feel like the pots have ball bearings in them.
A good stage amp needs no more then 50 watts ...this has 100 watts. Anything louder then 3 or 4 on the master volume will blow your head off. This thing can be EXCRUCIATINGLY F__KING LOUD !!!.
Let me tell you a funny story.
It is a pedal. (although I just put on top of its cab...I do not need it on the floor)
So like all pedals ...to try it out I did the standard deal of putting all the knobs on 12 o'clock.
I turned it on and hit a chord.
"JESUS CHRIST !!! " I screamed.
My scream was heard in every apartment in the building.
I HAD THE MASTER AT 12 O'CLOCK ....on 5. LOL
It was painfully, painfully loud!!!
YOUR CHOICE ???
SO...the amp is $800.00 USD
A Celestion Neo Creambacker $169.00 USD
A 60watt speaker with a neodymium magnet that is very light weight.It sounds like the G12H 30's in the Marshall cabs that went with the late 60's Plexi.but with just a bit more punchy lows.
I built an open back very small and light cabinet out of pine the extra lows make up for not having a closed back Marshall cab.
.(I made it in an apartment dining room with hand tools. It was easy ..looks much more pro then you think ...you could do it)
The extra lows make up for the lows made by the Marshall 1960A ...4x12 ..30 watt sealed cabinet half stack.
Cabinet costs. About $100.00USD
BLUGUITAR AMP 1 & SPEAKER/CAB .........................Total $1069.00 USD .
MARSHALL 1959 SLP with a 1960a SPEAKER CAB ....Total $4000.00 USD
_________________________________________________________________________
The cab is about 10 lb.. the amp is 2 lb. that is about the same as a Les Paul in it's case. I have owned a real Plexi....it was an amazing amp ...since selling it I have never been happy with my sound until now!!!
