Synthesis Technology E520 User manual

E520 Effects
V1.1 – Nov 15, 2020
Menu Organization
Main Page
At power-up the Main Page is active. All effects are accesse in this page which is ivi e in five
separate areas:
1. Hea er area – contains the page title an several in icators, inclu ing the In/Out Filter status,
patch name, Mute status (speaker-slash icon) an EEPROM status light (green means
EEPROM is up-to- ate, re means EEPROM will be up ate with parameter changes within a
few secon s).
2. Menu area – contains four items which can be selecte via the rotary enco er:
1. Exit – select this item an press the enco er button to leave the Main Page an enter the Top
Page which allows access to other menus that control the E520.
2. Algo – select this item an press the enco er button to select the active effect. Selection uses
a pop-up scrolling menu.
3. P2 – rops own into the algorithm-specific settings page where you can change parameter
routing options, In/Out filter settings an a itional per-algo settings (if any).
4. P3 – rops own into the algorithm-specific patch page where you can loa an save
patches for the currently selecte algorithm.
3. Effect area – where the active algorithm ren ers its status
4. VU meters – L/R input an output volume in icators which show real-time signal levels on
input an output channels. When the VU meters show re then there is a strong likelihoo of
clipping istortion.
5. In icators for Fee back an Mix settings – four small sli er wi gets that show the current state
of the Fee back an Mix controls. When these controls are centere the ‘thumb’ of the wi get is
a fille circle, otherwise it is an outline. When Fee back controls are centere the amount of
fee back is zero. When Mix controls are centere the output will be an equal proportion of wet
an ry signal.
6. Buttons – legen s an status of the four UI buttons appear in this area. The three left-most
buttons are e icate to effect parameters while the right-most button is always a bypass
function that isables the effect an passes au io thru the E520 without mo ification.
Pg2
Pg2 (Page Two) off the Main page provi es a list of algorithm-specific settings inclu ing:

Items 1-6 are internal routing matrix settings that allow assigning CV inputs an internal LFOs
to the various parameters of the algorithm.
HPF In – a high-pass filter applie to the au io inputs prior to the algorithm. Can be use to
shape the way the E520 algorithm “sits in the mix”.
LPF Out – a low-pass filter applie to the au io outputs after the algorithm. Also useful for
sculpting the soun of the E520 for mixing.
Some algorithms have a itional parameters on Pg2 an these are escribe in more etail with
each algorithm.
Pg3
Pg3 (Page Three) off the Main page provi es six “Algorithm Specific” patches which use just the
current algorithm. These can be save an loa e using either the four buttons, or the enco er. As
shippe from the factory, at least one of these six will alrea y be efine as a “factory preset”, create
by our own Robert Rich to help emonstrate some of the unique capabilities of the E520.
Top Page
The Top page is use to select other functional pages. It provi es a short list of other pages that can be
entere by scrolling with the enco er an pressing the button. At the bottom of the Top page the current
firmware revision is isplaye .
Prefs Page
The Prefs page provi es a list of e itable parameters which are store in system EEPROM an control
various aspects of operation that are not irectly relate to algorithms an patching.
1. Time Display – select Secon s or BPM for isplay of some time values on the Main page.
2. Frequency Display – select Hz or BPM for isplay of some frequency values on the Main page.
3. Parameter style – select Pie, Arc or Bar for the visual wi get in icator of CV parameters on the
Main Page.
4. Input Level – select Mo ular (12Vpp) or Line (+4 Bu typical, +9 Bu max) for the max input
level on the au io input jacks.
5. Output Level – select Mo ular (12Vpp) or Line (+4 Bu typical, +9 Bu max) for the max
output level on the au io output jacks.
6. Aux Output – select “Algorithm” for auxiliary output from algorithms, or LFO1-4 to rive the
Aux jack with the output of one of the 4 internal LFOs.
7. CV Patch Loa – when “On” the Right Mix CV input can be use to select the active patch
from the 24 Global patches on the Patch page. When “Off” ( efault) the patches must be
selecte manually. Note that when this mo e is active the Right Mix function is still active from
this CV input but may be reassigne to another CV or a fixe value using the assignments on Pg
2.

8. Fee back Limiter – The fee back an filter resonance loops have an optional limiter to
prevent runaway overloa s (“explosions” or “screaming”). When the threshol lou ness is
excee e the gain in the fee back loop is iale own to prevent overloa signals. There are
four settings:
1. Soft. (Default) Threshol of -6 Bfs, 0.8s attack time, 1.6s release time.
2. Me ium. Threshol of -9 Bfs, 0.5s attack time, 1.0s release time.
3. Har . Threshol of -12 Bfs, 0.3s attack time, 0.6s release time.
4. Off. Limiter is isable . Allows irect control of fee back an can allow much longer tails.
Be very cautious with this setting as extremely lou outputs may occur if fee back or
resonance controls are iale up to the extremes.
9. Tempo Hysteresis – Sets the hysteresis win ow below which tap tempo jitter is ignore in some
elay-base algorithms. Values are 2, 5, 10 an 20ms. Use this setting if you’re riving the sync
input with a source that has significant jitter an you want to prevent the elay from constantly
rea justing. The “Tap” mo e of the Scope algo can be use to estimate the amount of jitter
present, then set the Tempo Hysteresis larger than that amount.
10. Wet/Dry mix type – selects the control curves for the Wet/Dry mix knobs:
1. Linear – curves are simple 0-100% ramps that cross at 50/50 in the center.
2. Const Pwr – curves are square-law that cross at 71/71 in the center.
3. Center Full – curves are flat to the center at 100/100 then linear.
11. Sync Rate – selects the sync input ivi er ratio:
1. Quarter – quarter note sync. 1:1 clock ratio.
2. Sixteenth – sixteenth note sync. 4:1 clock ratio.
3. 24PPQ – 24 pulses per quarter note. 24:1 clock ratio.
LFOs Page
The LFOs page provi es an overview of an access to four internal LFOs which can be use instea of
CV inputs to rive any one of the eight algorithm inputs. Each LFO allows control over:
1. Frequency from 100 sec / cycle to 10Hz.
2. Waveform – Sine, Triangle, Saw Up, Saw Down, Square, Slow Noise, Fast Noise, Triangle
Mo ulation, 5-cycle Sine, Full-Wave-Rectifie Sine, 10% pulse, Steppe Ran om an Slewe
Ran om.
3. Offset
4. Depth

A parameter wi get an a waveform isplay are provi e to help visualize the effects of the various
settings.
Patch Page
The Patch page provi es access to twenty four user- efine patches which can use any one of the
available algorithms. Quick access buttons provi e instant loa ing of any one of the first four patches
on the page. These patches can also be loa e via the CV Patch mo e escribe above.
To loa an existing patch, use the enco er to select it an then hit the “Loa Sel” button.
To save a current configuration as a patch, use the enco er to select the esire patch number, then hit
the enco er button to enter the patch naming process. Up to 8 characters may be use to name the patch
using the enco er an buttons to navigate an select letters. When the name is complete, use the Save
button to store the patch.
File Page
The File page provi es access to File Input / Output functions using the SD car slot. Several
operations are possible:
1. Directory – shows a irectory of all visible files on the SD car . If there are more files &
irectories than fit on the screen then scrolling is possible. Use the Top / Bottom buttons to
instantly jump to the beginning or en of the list. One level of irectory epth is allowe , so
clicking on a Directory in the top level (highlighte in a unique color) will rop own. While in
a irectory, one of the buttons becomes the “Dir Up” which leaves the irectory. A “Delete”
button is also available that will elete files an irectories.
2. Sys Save – saves the contents of the system EEPROM to a file on the SD car . Up to 8 letter
names are allowe . The file type is always “.EEP”.
3. Sys Loa – loa s the contents of a “.EEP” file into system EEPROM to restore previous state.
This allows the user to keep an infinite number of unique patch arrangements in separate .EEP
files.
4. Loop Save – Only visible if the current algorithm is Spectral Time Machine or Looper, an the
algorithm is in PAUSE mo e. When these con itions are met then the contents of the au io
buffer can be save on SD car as a stan ar 16-bit 2 channel (stereo) PCM .WAV file. The file
name can be user efine but the file type is always “.WAV”.
5. Loop Loa – Only visible if the current algorithm is Spectral Time Machine or Looper, an the
algorithm is in PAUSE mo e. Allows loa ing the looper buffer with previously recor e
material on the SD car .
Note that while in the File page the E520 au io processing will be mute an the “Speaker-Slash” icon
will be isplaye in the upper right.

Color Page
The Color page allows users to customize the screen colors. There are 10 color types use throughout
the GUI, an each one may be set to any one of 512 colors (eight brightness values for each of R, G
an B components). There are also a number of color presets efine :
1. Default – A cool slate & cream colore scheme that is use on initial power-up.
2. Warm Mo e – a tan scheme with warmer “ esert” tones.
3. Dark Mo e – a cool, ark scheme for use when the lights are low.
4. Bright Mo e – the original color scheme, similar to that use in the E352 an E370 Uis.
Moses Page
A picture of Paul Schreiber’s cat.
About Page
The About page isplays various bits of information about the E520 firmware, inclu ing:
The current CPU loa ing (in the upper left of the isplay)
The time / ate & version of the firmware.
A scrolling marquee of the names of the usual suspects.
The measure Vref voltage. 2.5V is normal
The measure CPU temperature. 30-50C is normal.
A status listing of all the CV an button inputs for iagnosing hookup problems.
About O erloads
In a multi-effects processor like the E520 there are an infinite number of ways to generate overloa s –
situations where the output signal “blows up” an generates maximum lou ness soun s that can
potentially amage equipment an cause iscomfort to the listener. To help avoi this, fee back
limiting is inclu e (see the escription in the Preferences section) which efaults to provi ing some
protection against this an supports even stronger levels of protection. Despite this it’s still possible to
create lou an unexpecte soun s, but this can be minimize with some simple steps:
1. Be careful when switching between algorithms – make sure that the Fee back an Filter
Resonance controls (if any) are not set to extremes.
2. Use the limiter feature provi e on the Preferences page – this applies to almost all algorithms
that support fee back, as well as all algorithms that allow resonant filters. Use extra caution if
the limiter has been isable (“Off” setting).
3. Some algorithms are especially prone to overloa ing:

1. Clean Delay – with both taps active an 100/100 mixing the output signal can naturally be
quite lou . With resonant filtering an strong fee back it will overloa very easily even
when limiting is enable .
2. Dual Mono – in Chain mo e it is very easy to overloa when using fee back.
4. When esigning new patches or just experimenting, be wary of setting fee back an resonance
controls beyon 75%.
Emergency Mute
If the E520 (or an upstream source) happens to generate un esire soun s, an “Emergency Mute”
feature is provi e that will quickly mute the output. Simply press any 3 of the LCD buttons
simultaneously an output au io will cease an a small “Speaker-Slash” icon will appear in the upper
right of the isplay to in icate muting is enable . Pressing 3 buttons again will unmute.

Description of E520 Algorithms
The following are in ivi ual escriptions of each algorithm in the E520. The algorithms are groupe
into several types:
Time Domain Delay effects
Time Domain Shift effects
Looping effects
Spectral effects
Miscellaneous effects
Time Domain Delay Effects
Time omain effects in the E520 are processe without the use of time/frequency transforms an use a
buffer rate that provi es a goo compromise between overhea an latency.
Resampling Mini Delay
O er iew
This effect is base on the E580 Resampling Mini Delay an encompasses or exten s all of its
functions. Stereo inputs are mixe own to a single channel, resample (ie – the sampling rate may be
re uce by a variable amount through a ban -limite interpolation process), pass through a elay line
with a fixe an variable tap, an are then resample to two separate outputs. Separate L/R fee back
controls allow fine a justment of recirculation on both the fixe an variable elay. Three mo e
settings emulate various classical elay characteristics.
CV Inputs
Four CV input parameters are supporte :
1. Tap Offset – controls the position of the variable elay tap. Range is from 0% to 200% of the
fixe tap position. Varying this control in real-time will cause granular cross-fa ing effects as
the elay amount changes. The parameter rea out shows offset as a percentage of the fixe tap.
2. Delay Time – this controls sampling rate over a 1:8 (48kHz-6kHz) range, smoothly varying
elay without granular artifacts but intro ucing consi erable FM. The parameter rea out shows
the time multiplication factor.
3. InMix – The original E580 is a monophonic effect, so on the E520 which is stereo the two
inputs are mixe accor ing to this. Full CCW is 100% Left channel, full CW is 100% Right
channel an 12:00 position is 50/50 mix. The parameter rea out shows percent L & R.
4. Multifunction – varies epen ing on mo e selection:
1. Clean mo e – no functions

2. BBD mo e – re uces SNR by a ition of noise.
3. Tape mo e – controls ran om elay time variation. Similar to unstable tape spee warble.
Buttons
Three button functions are supporte :
1. Range – Four elay settings for the fixe tap: 1x, 16x, 256x, 4096x allow elays from 0.196s to
~10min.
2. Mo e – Similar to the E580, there are three operating mo es:
1. Clean mo e – Basic elay function with no istortion or filtering asi e from the normal
resampling process.
2. BBD mo e – Emulates ol -style bucket-briga e circuit with rolloff starting aroun 4kHz.
The fourth parameter controls a variable noise floor.
3. Tape mo e – Emulates ol -style tape loop, inclu ing saturation istortion, slight peaking
an rolloff aroun 2kHz. The fourth parameter controls tape warble.
3. Freeze – Au io in the elay line is “frozen” an no new au io overwrites it. Fee back controls
on’t have any effect an the contents repeats at the elay rate.
Readouts
In a ition to the parameter rea outs there are four in icators:
1. Range – the range button selection
2. Mo e – the mo e button selection
3. Fixe Delay – the time elay on the fixe tap
4. Tap Offset – the time elay on the variable tap
Page 2 Settings
There are two Page 2 settings:
▪Tape NL - controls the type of nonlinearity applie in Tape mo e. Settings are None, 2n , 3r , 4th –
the exponential or er of the nonlinearity.
▪Tempo Ratio – controls an a itional ratio between the Tap Tempo an timing. Values are 1/1, 3/2,
2/1, 3/1, 4/1, 8/1, 16/1,2/3, 1/2, 1/3, 1/4, 1/8, 1/16
Feedback
Both fee back knobs are active in this effect.
Tap Tempo
Tap Tempo is active an controls the amount of fixe elay. Use the range button to return to the fixe
ranges. Tap Tempo status is shown in the upper left of the effect area: No in icator means tap tempo is
inactive, “...” means that some taps are etecte an the algorithm is acquiring the tempo, while “TT”

signifies that tempo is active an overri es the Range setting. Tap intervals longer than ~5 secon s
cause the tempo calculation to reset.
Auxiliary Output
This effect has no auxiliary output.
Clean Delay
O er iew
The Clean Delay is a non-resampling elay (ie – the sampling rate is constant throughout the
processing) which always runs at the full 48kHz rate an intro uces no interpolation artifacts into the
signal while the elay length is stable. This is a true stereo effect in that there are separate elay lines
for Left an Right channels but they are processe i entically (same elay length, same filtering, etc.).
A switchable resonant 4th-or er lowpass filter is available in the fee back path if esire . Ping-pong
fee back between the two channels may be enable .
CV Inputs
Three CV input parameters are supporte :
1. Dly Len – this controls the length of the elay line. Varying this control in real-time will cause
granular cross-fa es as the length changes. The parameter rea out is in percentage of the full
range from 0-99%.
2. Tap Offset – controls the position of the variable elay tap which is mixe with the main elay
accor ing to the proportions selecte on a Pg2 setting. Range is from 0% to 200% of the Delay
Length from parameter #1. Varying this control in real-time will cause granular cross-fa ing
effects as the elay amount changes. The parameter rea out shows offset as a percentage of the
Delay Length. When set to 0% this tap is isable .
3. Filter Cutoff Frequency (when filter enable ) – controls the lowpass filter cutoff frequency. The
parameter rea out is in kHz from 0-24kHz. When the filter is isable this parameter is graye
out.
4. Filter Resonance (when filter enable ) – controls the lowpass filter resonance. The parameter
rea out is in percentage from 0-99% where 0% is no resonance. When the filter is isable this
parameter is graye out. Be careful – the filter may self-oscillate when this parameter is near
99% an can cause overloa s in some situations.
Buttons
Three button functions are supporte :
1. Range – Four elay ranges: 1x, 16x, 256x, 4096x allow elays from 0s to ~6min.
2. Swap – swaps the fee back paths of the L & R channels so that au io “ping-pongs” between the
two channels.
3. Filt – enables the filters.

Feedback
Fee back is active for this effect.
Readouts
There are five rea outs for this effect:
1. Range – 1x thru 4096x
2. Swap – on/off
3. Filter – on/off
4. Time – main elay time in secon s
5. Offset – elay time of the tap in secon s
Page 2 Settings
There two a itional Page 2 settings:
▪Tap Mix - provi es several options for mixing the main an aux taps – either 100/100, 90/10, 50/50
or 10/90. Use caution with the 100/100 setting as this, couple with extreme fee back or resonance
settings can easily result in overloa s.
▪Tempo Ratio – controls an a itional ratio between the Tap Tempo an timing. Values are 1/1, 3/2,
2/1, 3/1, 4/1, 8/1, 16/1,2/3, 1/2, 1/3, 1/4, 1/8, 1/16
Tap Tempo
Tap Tempo is active an controls the Delay Length. Use the range button or Delay Length parameter to
resume knob/button control. Tap Tempo status is shown in the upper left of the effect area: No in icator
means tap tempo is inactive, “...” means that some taps are etecte an the algorithm is acquiring the
tempo, while “TT” signifies that tempo is active an overri es the Range setting. Tap intervals longer
than ~5 secon s cause the tempo calculation to reset.
Auxiliary Output
This effect has no auxiliary output.
Resampling Delay
O er iew
The Resampling Delay is a variable-rate interpolating elay which allows control of both the elay line
length (for granular cross-fa e effects) as well as sample rate (for smooth elay changes an FM
effects). This is a true stereo effect in that there are separate resamplers an elay lines for Left an
Right channels but they are processe i entically (same elay length, same filtering, etc.). A switchable
resonant 4th-or er lowpass filter is available in the fee back path if esire . Ping-pong fee back
between the two channels may be enable .