Piratelogic EVE Instructions for use

EVE
construction manual
STARBASS MOTIONAL FEEDBACK LOOP
DRAFT
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Contents
Before you start ..........................................................................................................................................................................................3
Bill of materials............................................................................................................................................................................................................................. 3
Prerequisites................................................................................................................................................................................................................................. 4
arranty / Disclaimer.............................................................................................................................................................................................................. 4
Pricing ............................................................................................................................................................................................................................................... 4
Consultancy.................................................................................................................................................................................................................................... 4
Copyright......................................................................................................................................................................................................................................... 4
EVE Kit..................................................................................................................................................................................................................5
Schematic diagram..................................................................................................................................................................................................................... 5
Schematic description............................................................................................................................................................................................................. 5
Configuring the MFB loop.......................................................................................................................................................................6
Enclosure size, F3box and Qbox.......................................................................................................................................................................................... 6
Low Pass Filter.............................................................................................................................................................................................................................. 7
Crossover points......................................................................................................................................................................................................................... 8
Sensor gain...................................................................................................................................................................................................................................... 9
Sensor lowpass filter................................................................................................................................................................................................................ 9
MFB Loopgain................................................................................................................................................................................................................................. 9
Loop gain bandwidth............................................................................................................................................................................................................... 10
MFB Loopshaping...................................................................................................................................................................................................................... 10
Building EVE .................................................................................................................................................................................................10
Power requirements............................................................................................................................................................................................................... 10
Boardlayout – top layer........................................................................................................................................................................................................ 11
Boardlayout – bottom layer............................................................................................................................................................................................... 11
Connections................................................................................................................................................................................................................................. 12
Overall design considerations.......................................................................................................................................................................................... 12
Acceleration Sensors.............................................................................................................................................................................13
Philips sensors........................................................................................................................................................................................................................... 13
Measurement Specialities sensors............................................................................................................................................................................... 13
Piratelogic Little/One and StarBass sensors.......................................................................................................................................................... 13
Design considerations.......................................................................................................................................................................................................... 13
Errata................................................................................................................................................................................................................14
Document Revisions................................................................................................................................................................................15
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Before you start ....
Thank you for purchasing EVE, prior to assembly please verify the kit contains the below listed parts, incase
something is missing or damaged please contact us immediatly. Please note this manual is still draft so
expect grammar & spell checks, incorrect and or incomplete info.
Bill of materials
The components indicated in red are not included in the kit as they are to be individually calculated for each
specific enclosure as described in this document.
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C6 100n C0805K
C7 47uf 35V E2,5-5
C8 100n C0805K
C9 100n C0805K
C10 47uf 35V E2,5-5
C11 C050-030X075
C12 C050-030X075
C13 C050-030X075
C14 470n C050-030X075
C15 3n3 C0805K
IC1 78L12 SOT89 Voltage regulator
IC2 79L12 SOT89 Voltage regulator
IC3 TL084D SO14
LO 5K B25P POTENTIOMETER
MFB 5K B25P POTENTIOMETER
PXE-PHASE JP2 JUMPER
R1 R0805D
R2 R0805D
R3 R0805D
R4 R0805D
R5 10 R1210
R6 1001 R0805D
R7 102 R0805D
R8 1001 R0805D
R9 1002 R0805D
R10 10 R1210
R11 R0805D
R12 R0805D
R13 102 R0805D
R14 2202 R0805D
R15 2202 R0805D
R16 R0805D
R17 1002 R0805D
R18 2202 R0805D
R19 R0805D
R20 4702 R0805D
T1 BCV62 SOT143B
T2 BC849 SOT23 NPN transistor
X1 V+ 237-8P AGO SRE CLAMP
PCB EVE 2017.0
X7R 100V Ceramic Capacitor
Electrolytic Capacitor
X7R 100V Ceramic Capacitor
X7R 100V Ceramic Capacitor
Electrolytic Capacitor
see text Polypropylene Film Capacitor
see text Polypropylene Film Capacitor
see text Polypropylene Film Capacitor
Polypropylene Film Capacitor
X7R 100V Ceramic Capacitor
Quad OpAmp
see text Film resistor
see text Film resistor
see text Film resistor
see text Film resistor
Film resistor
Film resistor
Film resistor
Film resistor
Film resistor
Film resistor
see text Film resistor
see text Film resistor
Film resistor
Film resistor
Film resistor
see text Film resistor
Film resistor
Film resistor
see text Film resistor
Film resistor
Current Mirror
Eve printed circuit board

Prerequisites
In order to successfully assemble the kit the following prerequisites are needed.
◦ESD safe working environment : EVE contains ESD sensitive jFet devices, please adhere to guidelines for
safe handling of ESD sensitive components during assembly of the sensors.
◦SMD soldering station : the EVE design uses surface mount technology and requires handling and use of
an appropriate soldering station to avoid thermal damage to the used parts when soldered onto the PCB.
arranty / Disclaimer
Although this kit has been developed with lots of love, tenderness and devotion we can only guarantee 100%
operation for ready & assembled EVE.
Although EVE has been tested with numerous MFB enclosures it is subject to constant research and
development and as such no guarantees and/or warranties can be given for the correct / optimal/failure free
working of the module. No responsibility is taken for any damage resulting from the use of this module.
Pricing
Bare EVE printed circuit boards without components are available for 15 euro per set of 2. An EVE kit
containing the PCB and parts listed in black on the BOM on page 3 costs 35 euro for a set of 2. Pricing excludes
VAT and shipment.
Consultancy
Upon request a prebuild and tested EVE module can be ordered which has been tailored for use with a specific
StarBass / Driver / Enclosure setup. Please contact chris at piratelogic dot nl for more information.
Copyright
The EVE pcb design is a brainchild of Chris Camphuisen and will eventually be released to the public as Open
Source Hardware as described in https://en.wikipedia.org/wiki/Open-source_hardware.
MAY THE MUSIC PASSING THROUGH THIS DEVICE
SOMEHO HELP TO BRING JUST A LITTLE MORE PEACE
TO THIS TROUBLED ORLD
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EVE Kit
EVE was originally developed to add a motional feedback loop to an ADAM A7 monitor in conjunction with a
StarBass equipped woofer., it contains all logic to add MFB to existing active enclosures or newly build low
frequency systems.
Schematic diagram
Schematic description
The audio signal enters at X1-4 where it passes high pass filter (hpf) around IC3D to set the lower bandwitdh
pole, the following IC3C lowpass filter (lpf) sets the upper bandwidth pole. Both filters follow a standard 2nd
order Sallen Key setup. Refer to the Crossover points section for example values. It is advised to feed EVE at
X1-4 from a low output impedance to avoid it from negatively affecting the hpf around IC3D.
The StarBass accelerometer signal enters at X1-1 where it is buffered & copied by the current mirror T1 into
the phase switch around T3 to allow the usage of third party sensors with different output phase.
The output of the phase switch is amplified by IC3A to match the level of the incoming signal from IC3C, C11
and R11 set the upper pole for the accelerometer signal, C14 and R20 the lower pole, use R19 to adjust sensor
gain.
IC3B sums the outputs from IC3C and IC3A, C12 limits the upper bandwidth of the mfb loop, R12 and C13 allow
the feedback loop to be shaped to match specific enclosure Q values. The input to the power amplifier is taken
from X1-5. IC1 and IC2 are standard voltage regulators to allow EVE from being operated from the poweramp
rails (max +/- 35V). please see Powering EVE and the Errata at the end of this document.
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Configuring the MFB loop
Being designed as a generic mfb correction module EVE such supports a wide variety of driver, enclosure and
amplifier combinations. Because of this generic setup it is not possible to provide a common set of
component values which will work for all configurations. To assist the user in determining which values will
suit a particular setup best the following information is given.
Enclosure size, F3box and Qbox
The first step is to choose the lower frequency pole for your mfb box, F3mfb. As a lower limit keep the drivers
physical resonance frequency Fc, i.e. don't choose 40hz when your drivers Fc is 60hz. Failure to comply will
result in an inefficient system with a driver trying to perform excursions beyond its physical limit possibly
resulting in permanent damage to the driver motor.
The second step is to choose enclosure dimensions using the selected driver T&S parameters and the
standard closed box design formulas – to ease down on the involved math one may choose to use a program
like inISD. As a starting point choose an enclosure Q of 0.7. MFB allows you to split F3box in half so if the
desired lower frequency pole of your finished box F3mfb is 60hz the chosen F3box should be 120hz or lower.
Example INISD response plot for a driver with a Fc of 60hz mounted in a sealed Q=0.7 enclosure with a
natural Fbox of 120hz which is moved down to Fmfb of 60hz.
Keep in mind that the higher Qbox is chosen (= smaller box) the harder the driver will need to work to reach the
required excursion, as such one is discouraged from using Qbox values above 1 as it will severely limit the
drivers efficiency and SPL.
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Low Pass Filter
The third step is to decide on a low pass filter frequency - Flpf - using the drivers datasheet as reference.
EVE's onboard lowpass filter follows a 2nd order Sallen Key setup, as such it is advised to choose Flpf at least 1
octave below the first occurrence of cone breakup. In the example below cone breakup happens in the red
region onwards 2500hz making 1250hz or lower a valid choice for Flpf
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Crossover points
Using F3mfb and Flpf and F3box the component values for the desired crossover points can be calculated. The
blue curve represents F3mfb and the green curve Flpf. These values were calculated using http://sim.okawa-
denshi.jp/en/OPstool.php for the lowpass and http://sim.okawa-denshi.jp/en/OPseikiHikeisan.htm for the
highpass filters.
Build and tested EVE modules are preconfigured for a Rumble filter frequency of 32hz and a lowpass filter
frequency of 493hz.
Incase the module is to be used with existing active enclosures it's buildin rumble and lowpass filters may
need disableing.
•Disabling the rumble filter : ommit R1, R4 and replace C2 ,C3 with wire bridges.
•Disabling the lowpass filter : ommit C1, C4 and replace R2, R3 with 0 ohm resistors.
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R1, R4 (K) R2,R3 (K)
100 15 106 2.2 47 100 1055 1n5
100 18 88 3.3 47 100 703 2n2
220 10 72 3.9 47 100 595 2n7
220 12 60 4.7 47 100 493 3n3
220 15 48 2.7 100 220 397 3n9
220 18 40 3.3 100 220 325 4n7
220 22 32 3.9 100 220 275 5n6
220 27 27 4.7 100 220 228 6n8
220 33 21 5.6 100 220 191 8n2
2n d o rd er R um b le filter I C3D Q= 0.5
2n d o rd er Lo wpass f il ter I C3 C Q= 0 .7 4
C2,C3 (nF) Frequency (hz) C4 (nF) C1(nF) Frequency (hz) C12 (nF)

Sensor gain.
The fourth step is to configure the MFB preamp IC3A. Acceleration sensor output is determined both by its
sensitivity in mV/G as well as the drivers linear cone excursion - to reproduce a certain SPL a small diameter
driver will need to perform larger excursions then a large diameter driver, as such the accelerometer output
is depended on the driver cone diameter. Small drivers with a high Xmax – so called longstroke subwoofers -
will exhibit a relative high signal output when compared to large drivers. To accommodate for this ajust R19
which sets the gain for the pxe element, lower values result in more sensor signal gain. Allowable values are
between 470R and 10K.
Sensor lowpass filter.
The fifth step is to limit the bandwidth of IC3A to avoid driver breakup from entering the summation signal at
IC3C. As a starting value half the low pass filter frequency (Flpf) should be used when calculating the C11. The
lower pole for the accelerometer signal is determined by C14 and R20 and already set to optimal values for
use with StarBass accelerometers.
C11 Sensor cut-off frequency
2n2 7200 hz
3n3 4822 hz
3n9 4080 hz
4n7 3386 hz
5n6 2842 hz
6n8 2340 hz
8n2 1940 hz
10n 1591 hz
15n 1061 hz
22n 723 hz
33n 482 hz
47n 338 hz
MFB Loopgain
The sixth step is to configure the feedback loop. EVE has been designed for a loopgain between 12 and 20dB
and although higher values are possible one is discouraged from doing so as it requires extensive tuning
measures which are outside EVE's design scope.
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Loop gain bandwidth
C12 limits the upper bandwidth of the mfb loop and it's value should be set to match the lowpass filter setting
for IC3C. Please refer to 2nd order Lowpass filter IC3C table on page 8 for C12 values.
MFB Loopshaping
Use R12 and C13 to compensate for the natural roll-off below F3box.
Building EVE
Power requirements
The EVE currentdraw at +/- 12V is 20mA max. hen EVE is used to modify off the shelf active loudspeaker
enclosures the best and easiest way to power EVE is to feed it off existing stabilized opamp rails where EVE
supports rails between +/- 12 and 18V.
Incase no stabilized opamp rails exists the
onboard 78L12 and 79L12 regulators allow
EVE to be powered from a maximum rail
voltage of +/- 35V.
Do not use R5 and R10 as voltage droppers as
these are only allowed to dissipate 50m and
are used for filtering the incoming power only.
Incase of availability of regulated opamp rails
the onboard regulators may be omitted and
bypassed using 2 wire bridges:
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Boardlayout – top layer
Boardlayout – bottom layer
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Connections
Eve accepts standard asymmetric audio coming from either a mixer, preamp, phone or any other sound
source and should be hooked up as shown below.
Overall design considerations
•MFB does not work with Helmholtz resonator based enclosures such as bass reflex boxes.
•The StarBass sensors have been tested successfully with a maximum loopgain of 20dB.
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Acceleration Sensors
One of EVE's design criteria was to make it a Swiss Tool for building motional feedback loops. Next to a fully
configurable filter and power section EVE has also been provisioned to support a large number of
accelerometers ranging from the original Philips sensors to the latest StarBass models.
Exact component values cannot be given as they depend on (specimen) sensor sensitivity, frequency
response, enclosure Q factor, driver diameter etc and as such are only available for known – fixed – setups.
Philips sensors
EVE supports the original Philips MFB sensors, both the original 532, 541,544,567 and 545 10M sensor as well
as the 585, 586 and 587 33M sensors. As a starting point use a 3K3 resistor for R19 and a minimum of 3n3 for
C11.
Measurement Specialities sensors
EVE has not been tested with the ACH01 sensor but should have no problems processing it's input. . As a
starting point use a 3K3 resistor for R19 and a minimum of 3n3 for C11.
Piratelogic Little/One and StarBass sensors
EVE supports the modern Piratelogic accelerometers, both Little/One and StarBass. As a starting point use a
1K resistor for R19 and a minimum of 1n for C11. For further information about Piratelogic acceleration
sensors please refer to https://piratelogic.nl/?p=en.accelerometers.
Design considerations
An accelerometer output level is not fixed and depends on several factors such as driver cone excursion and
diameter, cabinet Q factor and driver sensitivity. As such EVE component values for a certain driver-
enclosure combination might need tweaking when either one is changed !
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Errata
Version 2017.0 of the EVE pcb contains an error
in the shape used for the negative voltage
regulator IC2, a temporary workaround is
shown here :.
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Document Revisions
Prior to starting work please check if the date & time stamp at the footer of this page corresponds with the
one in the online version at
https://piratelogic.nl/data/docs/products/eve/piratelogic.eve.2017.0.manual.en.pdf
01-08-18 initial version by CC
18-08-18 Added Design considerations, Using EVE with existing active enclosures.
04-09-18 Added Configuring the MFB loop section
07-09-18 Spelling / Gra ar
26-09-18 Disclai er / Pricing
05-10-18 Loopgain info added
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