Empirical Labs LIL FreQ Uživatelský manuál stáhnout pdf (Strana 7)

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SATURATION AND DISTORTION GENERATOR

The old, sought after vintage gear is not anywhere near as accurate (or linear) as devices made today, but certain “faults” or

non-linearities are exactly the reason some sell today at 10 times their original value. They color the sound with distortion

and frequency response shaping. Getting the frequency response ﬂat to 20kHz and having distortion below .5% used to be

an achievement. But even before 2000AD, there were 35 cent op amps that were ﬂat to 3 MHz, and produced distortion

below .002%. Getting things accurate in the digital age is relatively cheap and easy, but getting a piece of gear to be

“musical” and fun to use is whole different enchilada.

It is well known that the triode distortion in tube circuits produces lots of 2nd and 3rd harmonics, in some what varying

ratios. These lower order harmonics form “the octave” and “the octave and a ﬁfth” to the fundamental musical tones. They

are actually “musical” distortion. Harmonics above the 2nd and 3rd get increasingly harsh and unmusical, and therefore

should be lower in amplitude (<-60 dB) to keep with our line of thinking. Second harmonic is considered to be the warmest

and most “consonant”harmonic distortion. The 3rd harmonic is perceived more easily and often is the “BITE” that is added

to midrange and the “warmth” to the low freqs by tube gear. Analog tape also saturates in this manner. The 3rd harmonic is

induced in the FATSO by increasing level thru the distortion circuits. It is usually the result of ﬂattening the tops and bottoms

of waveforms. Second harmonic is also added especially while compressing in the FATSO. 10% of second harmonic can

be hard to perceive.

We have provided distortion indicator lights that indicate some reference operating levels. A “0VU” yellow LED light

indicates just under 1% THD and the red “Pinned” LED indicates 3% THD or more. These LED’s are an excellent guide to

where the user is in the “Grunge Department” and can help to avoid turning the music into a distorted mess. You will ﬁnd

that the harmonic distortion is generally more obvious on overall mixes and complex programs. On individual instruments,

sometimes 10% distortion sounds “fat” and “analog” and isn’t heard as distortion at all.

WARMTH PROCESSOR

The Warmth circuit is by far the most complex part of the FATSO. Basically it is a very strange high frequency (HF) dynamic

ﬁlter circuit, or High Frequency limiter. It operates very fast and should be very unobtrusive in operation since it gets in

and out of the way very quickly. The desired result is akin to the HF saturation that analog tape exhibits when the high

frequency amplitude interacts with the tape recorder bias to produce self-erasure of the higher frequencies. We provide

a very accurate display of the HF attenuation, with the upper FATSO bargraph showing the gain reduction at 20KHZ. The

nature of the ﬁlter allows the corner frequency to move as attenuation occurs.

We provide just one control for the warmth but there are other ways to control the overall action ofthis circuit. If you do

decide to use the compressor, set it up ﬁrst because it affects the operation of the warmth. There is heavy interaction

between the compressor and warmth settings. The warmth control is a step control with 8 ranges - no warmth action (no

LEDs lit), on up thru the highest setting of 7. Perhaps the best way to think of the settings is as compressor threshold, with 7

having the lowest threshold, and the most warmth, responding quickly and often to high frequency content. Just remember

that instead of controlling the overall level, this warmth “compressor” threshold only affects the high frequencies.

Hundreds of hours of experimentation were involved in developing the ﬁlter, to make it capable of large gain reduction at

20Khz without really dulling all the frequencies. Still, we remind you over and over in this manual to error on the side of

less WARMTH… and Compression. The temptation is to say “oh wow that’s great, so fat and warm, let’s warm it more.”

Resist temptation. Trust the meters when indoubt.... 3 - 5 dB is quite a bit of warmth on most signals. There may be times

where over 10dB does the perfect job, but trust us that if you see all the LED’s light on the warmth bargraph - you really

better know what you’re doing.

You will ﬁnd the warmth to be useful all by itself many times without the compressor or TRANNY or much saturation.

It can take some of the irritating ping and clickiness out of many sources. Originally the FATSO was only going to have

the saturation and this warmth circuit, but as our research went on, we decided the extra circuitry of the TRANNY and

compressor would provide some of the other important nonlinear elements of tape compression, and “vintage” gear as well.

THE TRANNY

The TRANNY is short for transformer. In the old days, to interconnect between audio devices with low impedance cabling (i.e.

noise resistant), the audio engineer used transformers on the input and outputs. Transformers isolate two signals using wire

coils wound close to each other, but not actually touching. They were never that linear and often introduced saturation and

LF distortion as well as changing the frequency response. Transformer design and use was an art (as demonstrated by folks

like Rupert NEVE), and there were always tradeoffs. However, it has been widely known that a good audio transformer

circuit can do wonderful things to an audio signal. This was the goal of our TRANNY circuit. We have tried to emulate the

desirable characteristics of the good old input/output transformers in a consistent musical way, and in a selectable fashion.

Many of the older transformers had certain low frequency characteristics that some of our newer and more linear circuits

and transformers have “overcome”. As frequency goes down, the audio signal gets more like DC (i.e. slower moving).

Transformers don’t pass DC current thru them, so strange things start happening as the audio goes deeper. The addition of

harmonics and peak saturation along with frequency and phase changes on the low frequencies occurs. We found that we

could capture the low frequency effects of large and now expensive older output transformers in a weird, internally

buffered switch-able design.

To sum up the musical results of our TRANNY circuit, there will be a little more edge in the midrange, and the super low

frequencies will have been harmonically altered in a way that allows them to sound louder, even though the peaks are less

than the original. Playback on small speakers will show an improved audibility of low end from the result of the psycho-

acoustically-pleasing distortion the TRANNY adds. Something really interesting we noticed... even though fundamentals

below 100Hz cannot show up on the little speakers... because of the natural way a transformer saturates, the harmonics give

your ears enough clues that your mind somehow ﬁlls in the fundamental. If you have the time, try this experiment... put 40 Hz

sine wave tone into the FATSO, and match the TRANNY level to the bypassed level, then put the output thru a small speaker.

A/B the processed TRANNY signal with the bypassed signal in the small speaker. You will probably smile.

Note the position of the Warmth (and TRANNY) circuits after the Compressor,

accounting for the large interaction between their controls.

Control Voltage

One of two channels

Detector Circuits

Main Audio Path

To Front Panel

Bargraph.

Output

Amp

1/4" Phone

Output

Gain

Stereo Link

Warmth

Filter

Soft

Clipper

Input

Drive

Balanced In

Envelope Gen

Warmth

VCA

Active Outputs

Master

Bypass

Tranny

Sidechain

Envelope Gen

Compressor

XLR

Bargraph.

To Front Panel

Dynamic

Digital

Controls Controls

Digital

(Normalled)

DC Link to other

channel and

shown

In/Out

Comp/Lim

External Link.

Amp

Dif.

EXAMPLE SETTINGS (part 3)

way of vocals because the upper, spiky, harmonics are flattened a bit. When you are dealing with an

occasional peaky guitar where certain chords or notes take your head off, the dynamic action of the

WARMTH control can be very useful. Don't overdue this though, especially while tracking.

To smooth out solos, try the Tracking compressor with TRANNY and warmth. REMEMBER TO SET

UP COMPRESSOR FIRST. The WARMTH heavly interacts with the compressor.

Plucked Instruments & Acoustic Guitar - Plucked instruments can benefit greatly from

the Fatso's processing. Back in 1998, a prototype Fatso was taken to Greece and used on many very

troublesome ethnic plucked instruments. At Grammys, a club in ATHENS, some bizarre FATSO behavior

was immediately noticed, when the extremely transient acoustic instruments "swamped" some internal

circuits. The compressor needed a heavier knee with more "sponge" in the attack. The Tracking

compressor (Red LED on) was tweaked first. The fast attack of the TRACK or ELEVEN Compressor can

help get a "glassy" full sound since the pick noise will be attenuated and the sustain lengthened. Also the

threshold of the warmth circuits were lowered so they could grab the transient picked edges easier. This

allowed a solo instrument to be louder without the sharp attacks hurting.

Sometimes you may want to keep the dynamic range of a plucked instrument but need to smooth out

just the hard front edge of the attack. Warmth processing is perfect here. Adjust the WARMTH until you

have a smoother, more natural sound - usually 3 - 10 dB of HF attenuation is enough. It’s important to

listen very softly, and very loudly to the adjusted track to make sure it isn't too dull, or still in need of

"softening".

Acoustic guitars can be so creamy. Many times you will have an acoustic part that is very even and

you can nicely brighten it up with a top end EQ (high frequencies).... except for that one part where he

really bangs it! Use the Warmth control to grab those clangy brash freqs. Usually 1 - 5 dB is enough but on

really brittle parts,10 - 15 dB on peaks may be ok on extreme peaks. Again don't over do it, especially

during tracking. Listen really softly and really loudly to test evenness. Its often best to roll off subs or low

frequencies to prevent mud before the Fatso. This keeps the compressor from reacting to them.

Drums - Without any processing activated, the saturator which is always inline, will pack those peaks

down smoothly giving you 2 - 6 dB more average level. Distortion indicator LEDs, the O VU and the

Pinned red LED give you a good idea of what's going on. On percussion, peaks can light up the Red

Pinned LED without any nasty distortion, if they are short enough. Analog tape can not handle all the top

end and will round out the sound... as will the FATSO's warmth processor and saturator. Don't use more

than 5 - 10 dB of WARMTH on drums though.... or you are probably asking for a dull sound! Try

putting digitally recorded tambourines etc through the Fatso and listen to the difference. That clacky front

edge will become warm and easy to listen to - like the old analog tape and vinyl.

Snares/Kicks/Toms - If you don't want to lose the basic sound, try setting the compressor to BUSS

compressor first. This is a very gentle slow compressor that will leave the transients untouched. If there

are areas with over eq'd highs or unnatural transients, get into the WARMTH processing. On snares that

have had 8 - 10K added and have some really overly dynamic hits, 5 - 10 dB of WARMTH may fold the

highs back (attenuate them) and smooth out the tonality. Use the High Frequency saturation that the

WARMTH control provides on Kick drums that have the occasional clacky hit. The TRANNY will be useful

also. If the Kick drum is too boomy or too thumpy without enough clarity, the TRANNY will add some upper

harmonics to the low freqs, while rolling off some of the subsonics that could rumble in a mix.

Overhead Mics - Also for over dynamic and brash cymbals, the WARMTH processing can be a real

sweetener. To soften the edge of cymbals try WARMTH on 4 or 5 setting and turn the input up to

control the amount of warmth. Watch anything over 5 dB of WARMTH as this is really attenuating a lot

of high end. But if it is just the front edge of the cymbals, it can be very pleasing. Of course

compression may be used but if it is, set it up first.

Room mics - Again, the most gentle compressor for the room mics will be the BUSS compressor.

However, radical room compression is currently in style. The TRACK or ELEVEN compressor will be

useful over a wide range from 1 dB of GR to 20 dB depending on what you are going for, and what the

tracks will allow. But for over the top treatment, try SPANK! The SPANK is not the NUKE of the Distressor

yet it can add some of the same sustain and intense size to it. The bargraph can be run right offscale with

the SPANK type compressor, and still be a very useful sound. Fifteen to twenty dB of compression is

starting to have that John Bonham thing that the Distressor can do. Watch over-heating the tracks though.

Also, any loud cymbal playing will become annoying with lots of compression on the room mic. Sometimes

it may help to feed a compressed room signal back to the drummer while tracking to give him a feel for

balancing his cymbals and drums.

The TRANNY

The TRANNY is short for transformer. In the old days, to interconnect between audio devices with

low impedance cabling (i.e. noise resistant), the audio engineer used transformers on the input and

outputs. Transformers isolate two signals using wire coils wound close to each other, but not actually

touching. They were never that linear and often introduced saturation and LF distortion as well as

changing the frequency response. Transformer design and use was an art (as demonstrated by folks

like Rupert NEVE), and there were always tradeoffs. However, it has been widely known that a good

audio transformer circuit can do wonderful things to an audio signal. This was the goal of our TRANNY

circuit. We have tried to emulate the desirable characteristics of the good old input/output transformers

in a consistent musical way, and in a selectable fashion.

Many of the older transformers had certain low frequency characteristics that some of our newer

and more linear circuits and transformers have "overcome". As frequency goes down, the audio signal

gets more like DC (i.e. slower moving). Transformers don't pass DC current thru them, so strange

things start happening as the audio goes deeper. The addition of harmonics and peak saturation along

with frequency and phase changes on the low frequencies occurs. We found that we could capture the

low frequency effects of large and now expensive older output transformers in a weird, internally

buffered switch-able design.

To sum up the musical results of our TRANNY circuit, there will be a little more edge in the

midrange, and the super low frequencies will have been harmonically altered in a way that allows them

to sound louder, even though the peaks are less than the original. Playback on small speakers will

show an improved audibility of low end from the result of the psycho-acoustically-pleasing distortion the

TRANNY adds. Something really interesting we noticed... even though fundamentals below 100Hz

cannot show up on the little speakers... because of the natural way a transformer saturates, the

harmonics give your ears enough clues that your mind somehow fills in the fundamental. If you have

the time, try this experiment... put 40 Hz sine wave tone into the Fatso, and match the TRANNY level to

the bypassed level, then put the output thru a small speaker. A/B the processed TRANNY signal with

the bypassed signal in the small speaker. You will probably smile.

Fatso Block Diagram

Note the position of the Warmth (and TRANNY) circuits after the Compressor, accounting

for the large interaction between their controls.

FATSO BLOCK DIAGRAM

1 2 3 4 5 6 7 8 9

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