Module DHCP-2 - Piratelogicmfb.piratelogic.nl/data/docs/DHCP-2.usermanual.en.pdf · • All filter components (R’s, C’s and opamps) are thru-hole components supporting the use

User manual Module DHCP-2 integrated 2 way motional feedback amplifier

DRAFT

made in holland

http://mfb.piratelogic.nl/data/docs/DHCP-2.usermanual.en.pdf – update 06/03/2014@13:15:30 Page 1 of 23

http://mfb.piratelogic.nl/data/docs/DHCP-2.usermanual.en.pdf

ContentsIntroduction...................................................................................................................................................................................................3

History............................................................................................................................................................................................................................................... 3DHCP Team........................................................................................................................................................................................................................................ 3Revisions.......................................................................................................................................................................................................................................... 3Erratum.............................................................................................................................................................................................................................................. 3Discussion Forum........................................................................................................................................................................................................................ 3

Module description.....................................................................................................................................................................................4Kit versions..................................................................................................................................................................................................................................... 4Electrical Characteristics..................................................................................................................................................................................................... 5Chipset datasheets..................................................................................................................................................................................................................... 5Pricing ............................................................................................................................................................................................................................................... 5

Circuit Description.....................................................................................................................................................................................6Truhole components.................................................................................................................................................................................................................. 7Signal input..................................................................................................................................................................................................................................... 8Rumble Filter................................................................................................................................................................................................................................... 8Xover - Low Pass .......................................................................................................................................................................................................................... 9Xover - High Pass.......................................................................................................................................................................................................................... 9High note amplifier.................................................................................................................................................................................................................. 10Low note amplifier.................................................................................................................................................................................................................... 10Bridge / Single ended amplifier operation............................................................................................................................................................... 11MFB Correction logic.............................................................................................................................................................................................................. 11Protection - Output Limiter................................................................................................................................................................................................ 12Protection – DC Detector..................................................................................................................................................................................................... 13

Formula ...........................................................................................................................................................................................................14Assembly wizzard...................................................................................................................................................................................................................... 14Calculation wizzard................................................................................................................................................................................................................. 14

Assembly instructions...........................................................................................................................................................................15LM3886 mounting .................................................................................................................................................................................................................... 15TDA 8950 mounting ................................................................................................................................................................................................................. 16Board measurements............................................................................................................................................................................................................. 17Off board connections........................................................................................................................................................................................................... 18Level adjustments.................................................................................................................................................................................................................... 19Bill of materials (bom)............................................................................................................................................................................................................ 19

Prototypes....................................................................................................................................................................................................20541..................................................................................................................................................................................................................................................... 20541/DHCP....................................................................................................................................................................................................................................... 20

Acceleration Sensors.............................................................................................................................................................................21The original Philips Sensor................................................................................................................................................................................................. 21The Pirate Sensor..................................................................................................................................................................................................................... 21Pirate sensor measurements............................................................................................................................................................................................ 22

Before you start........................................................................................................................................................................................23Required skill set...................................................................................................................................................................................................................... 23Responsibility............................................................................................................................................................................................................................. 23Warranty........................................................................................................................................................................................................................................ 23Copyright....................................................................................................................................................................................................................................... 23Support........................................................................................................................................................................................................................................... 23Thanks.............................................................................................................................................................................................................................................. 23



Introduction.Thank you for purchasing the DHCP-2 amplifier module. Using it in conjunction with modern drivers will allow you to build a first class motional feedback system.

HistoryAfter the successful reproduction of modernized working copies of the vintage 22AH587 mfb enclosures using the 2012.01, 2012.02 and last years 2013.01 modules the time has come for the next step. With it's class D amplification, modern op-amp based filter and correction logic design and professional SMD build quality the DHCP module represents another major step in our quest to bring MFB back into production.

DHCP TeamWhat started off as a one man show has rapidly grown into a team effort consisting of 4 members. The common denominator is MFB, we are all hooked on its low frequencies. The name DHCP is an aggregation of the team members name first letter and although some of us have a history in IT it has nothing to do with the dynamic host configuration protocol whatsoever: David Roozendaal, Hans Mons, Chris Camphuisen and Peter Helleward. As we speak the team has grown into a group of 5 with Bert Miermans being the latest addition.

RevisionsPrior to starting work please check if the date stamp at the footer of this page corresponds with the one in the on line version at http://mfb.piratelogic.nl/data/docs/DHCP-2.usermanual.en.pdf

02/07/14 initial version by CC

ErratumAny bug fixes will be announced here.

Discussion ForumAll Piratelogic modules are discussed in the Piratlogic discussion forum, to visit this forum please navigate to:

http://forum.piratelogic.nlPlease note that in order for you to become a member of this forum you MUST send an email to [email protected] with a small introduction who you are and why you like to become a member. This is only to avoid spammers from polluting our forum. If you are for real access will be granted within 2 business days.



http://forum.piratelogic.nl/

http://doc.piratelogic.nl/usermanual.en.2013.01.pdf

Module descriptionThe DHCP-2 contains all electronics needed to make an audiophile active 2-way Motional Feedback loudspeaker system. It is a high quality double sided 1-Oz copper clad FR-4 PCB, measuring 80 by 100mm boasting the following features:

• Excellent PCB layout, offering dedicated ground planes, power rails and decoupling

• A new and revolutionary two way 12dB/Octave (2nd order) subtractive crossover. Built around operational amplifiers it offers superior distortion and linearity figures as compared to its discrete predecessors

• Typically, subtractive filters suffer from a 6dB/octave slope on the output due to phase differences in the subtractor. Here, an all-pass filter eliminates the phase difference, yielding a perfect 12dB/Octave slope. As added bonus the calculations for the filter values are very easy

• All filter components (R’s, C’s and opamps) are thru-hole components supporting the use of your choice of gourmet components

• The rest of the board is fabricated in Surface Mounted Technology (SMT)

• The audio path is completely free of electrolytic capacitors. The largest coupling capacitors are 470nF, and the boardspace is sufficient to facilitate PP or PE capacitors for all (thru hole) capacitors carrying audio signals

• A noise and distortion-free LED-LDR or OptoMOS based limiter to safeguard the drivers against overloading

• Low noise pre-amp/filter regulators

• MFB correction circuitry supporting both the original Philips MFB drivers as well as drivers equipped with the Measurements Specialities ACH01 acceleration sensor. Ready-to-use prepared woofers are available upon request

• One LM3886 Overture based amplifier for mid/high reproduction, delivering up to 68W RMS in 4Ohms, up to 38W RMS in 8Ohms and up to 135W instantaneous peak output power. Included are thermal protection, clipping protection and DC protection, and noise free startup and shutdown

• One TDA8950 based class-D amplifier for bass reproduction, delivering up to 170W RMS in 4Ohms in single ended mode, and up to 300W RMS into 8Ohms in BTL mode, both with an efficiency of typically 88%. Included are thermal protection, short circuit protection, DC protection, and noise free startup and shutdown

• Up to 27486uF on-board buffer capacity using 6800uF electrolytes

• Under-board (for cooling) rectifier bridge, offering direct transformer input, reducing the external electronic components count to zero

Kit versionsThe DHCP-2 comes in 3 flavors depending on your budget and skill set:

• Pre-mounted PCB including all smd components.

• PCB module completely build and tested

• PCB module completely build and tested and mounted as a plate amp complete with toroid, heat sink and XLR inputs.



Electrical Characteristics

DHCP-2 module

Pin[s] Parameter Conditions Min Stock Max Unit

~10~2

SymmetricalAC input

Stock values refer to the standard DHCP-2 equipped with onboard Panasonic lowesr 35V caps. For the Max values these need to be replaced by 40V/63V models.

2 * 12 2 * 22 2 * 26 ACV

2 * 15 2 * 30 2 * 37 DCV

LM3886 Highnote amplifier

Symbol Parameter Conditions Min Typ Max Unit

VP supply voltage

Tj = 85 °C; ± 9 ± 35 ± 40 V V

Po @ Tj

= 85 °Coutput power THD + N = 0.1% (max)

f = 1 kHz; f = 20 kHz|V+| = |V−| = 28V, RL = 4Ω

- 68 - W

|V+| = |V−| = 28V, RL = 8Ω - 38 - W

|V+| = |V−| = 35V, RL = 8Ω - 50 - W

SNR Signal-to-NoiseRatio

PO = 1W, A-Weighted, Measured at 1 kHz, RS = 25Ω

- 92.5 dB

PO = 60W, A-Weighted, Measured at 1 kHz, RS = 25Ω

110 dB

TDA8950 Lownote amplifier

Symbol Parameter Conditions Min Typ Max Unit

VP supply voltage

Tj = 85 °C; LLC = 22 mH; CLC = 680 nF ± 12.5 ±35 ± 40 V V

Po @ Tj

= 85 °Coutput power SE operation at 4 W

VP = ±37 VTHD + N = 0.5 %

- 100 - W

BTL operation at 8WVP = ±37 VTHD + N = 0.5 %

- 200 - W

Chipset datasheets

LM3886 http://www.ti.com/lit/ds/symlink/lm3886.pdf

LM3886 appnote http://www.ti.com/lit/an/snaa021b/snaa021b.pdf

TDA8950 www.nxp.com/documents/data_sheet/TDA8950.pdf

ICEPOWER output coil http://www.icecomponents.com/images/document/PDF/1D10A.pdf

Pricing DHCP-2 pricing details are available online, please visit our forum at http://forum.piratelogic.nl for more info.



http://forum.piratelogic.nl/

Circuit DescriptionOnline : http://mfb.piratelogic.nl/data/docs/DHCP-2 Schema v2.0.png



http://mfb.piratelogic.nl/data/docs/DHCP-2%20Schema%20v2.0.png

Truhole componentsThe DHCP was build using mainly SMD technology, however the components marked red are kept in troughhole versions to allow for easy modifications.

Online : http://mfb.piratelogic.nl/data/docs/DHCP2.15.12.2013.schematic.thruhole_red.jpg



http://mfb.piratelogic.nl/data/docs/DHCP2.15.12.2013.schematic.thruhole_red.jpg

Signal inputThe DHCP module was designed with a high level of flexibility in mind, as such it's filters and correction circuitry allow for extensive tuning to match the drivers of your choice.

Input connections.

The audio signal enters the DHCP module through pin IN+ and IN- where it passes a low pass filter (R4, C5) to avoid the DHCP from processing non audible hf material. Please note the DHCP input is unbalanced, so the IN- pin is ground referenced.

The P+, W and P- pins allow for usage of a potentiometer for volume control, if omitted please bridge the P+ and W pins.

The ON- and ON+ pins allow the DHCP to be equipped with an automatic power on/off circuit.

Rumble FilterInputbuffer and rumble filter

Diodes D3 and D4 protect the first op amp from high level input signals. IC1A acts as input buffer and limiter. The limiter function is discussed separately.

Leaving IC1A the signal enters a buffer IC4A and a high pass filter based around C21, C22 and IC4B. To allow for easy adjustments to the high pass (rumble // subsonic) filter the pins RMBL1, RMBL2 and RMBL3 may be connected to external ly switched capacitors .



Xover - Low Pass The low pass signal is obtained by subtracting the highpass signal from the signal coming from the allpass filter.

The signal from the rumble filter IC4B feeds into both the high pass filter around IC11B as well as the all-pass filter around IC6A.

The high pass filter signal is subtracted from the all pass filter output via respectively R46, R26 and IC6B.

Because of the subtractive nature of the Xover design there is only 1 Xover frequency which is both the lownote cut off as well as the high note start frequency

Xover - High Pass

The high pass filter is formed around C30, C35 and IC11B. Due to the substractive nature of the xover thisfilter determines both the woofer cut off pole aswell as the tweeter start pole.

For tuning purposes the optional circuitry around IC11A allows for extensive corrections.

The pins HM1, HM2 and HM3 allow the DHCP module to be extended with a separate high note amplifier.



High note amplifierThe DHCP highnote amplifier features a LM3886 which DC offset is corrected by the integrator around IC1B (not displayed). For tuning purposes R73 and C78 are thruhole components .

The PCB has been designed to accommodate the standard vertical version of the LM3886 which by means of an angular profile should be mounted to the base plate for cooling purposes.

Please refer to the chapter Mounting Instructions for further information on alternative mounting methods.

Low note amplifierThe DHCP low note amplifier features a TDA8950 high-efficiency Class D audio power amplifier in a HSOP24 package mounted to the PCB bottom copper side.

The TDA8950 contains a stereo power amp capable of driving both 4 and 8 W loudspeakers.

To minimize thermal losses, EMI radiation and switching noise the DHCP is equipped with industry standard ICE power Class D chokes.



Bridge / Single ended amplifier operationThe TDA8950 based low note amplifier features 2 separate channels which depending on your application and driver impedance may be configured in single-ended (SE) or bridge mode (BTL). The DHCP-2 is factory set to SE mode with thelf driver connected to the L+ and GND connection pins. If BTL operation is desired the BTL/SE selection resistors need to be moved from R29/32 to R30/31 and the lf driver connected between l+ and l-. Prior to changing from single ended to bridged mode please consult the TDA8950 data sheet to ensure safe operation.

Single Ended operation Bridge Tied Load operation

MFB Correction logicThe correction signal enters the DHCP-2 at the MFB+ and MFB- pins, note that the MFB- pin is not ground referenced. IC8a together with C41 and R47 act as an low pass filter to limit the area were the correction is active.

The correction signal is then summed with the xover lowpass output through respectively R42 and R33. R35and C34 are optional thruhole components allowing a high lift of the low note signal.

The summed low pass signal then enters IC8B which apart from lf correction can also be used to increase the overall low note gain as the low note amplifier has a fixed gain of 30 dB in SE and 36 dB in BTL applications.

TODO: explain C41/R47



Protection - Output LimiterTo avoid damage to the DHCP-2 connected drivers it has been equipped with a limiter.

The limiter senses both the high as lownote output thru respectively R1 and R2. The rectified signals are send to the schmiddt trigger IC3 which drives the optomos device.

The optomos mosfet shorts the input signal to IC4Aby pulling R13 to ground level.



Protection – DC DetectorAlthough both low and high note amplifiers have been fitted with extensive protection schemes the DHCP-2 module itself offers an additional safety measure by monitoring the speaker signals for DC failures.

R79, R72 and R76 together with C79 and C83 form a LPF filter which effectively block out any normal musicsignals.

If case of amplifier failure Q1 detects positive and Q2 negative DC signals (Q3 and Q5 perform a similar function when the TDA is operated in BTL mode) and pull down relay driver Q4.



Formula The DHCP-2 module is accompanied with an on line assembly & calculation wizard, to use this wizard you will need an internet connection. The wizard has been tested with Chrome, Safari and Firefox and may be found at the following adress: http://wizards.piratelogic.nl The wizard features 2 operation modes, assembly and calculation. On startup it defaults to assembly mode :

Assembly wizzardBy using your keyboard up & down arrowkeys you may navigate through the bill ofmaterials column on the right side of thescreen.

Each step takes you thru a particularcomponent whereby the wizardautomatically switches to thecorresponding layer showing you it's placeon the pcb.

Because the BOM is maintained online it hasbeen removed from this manual. The futureversion of the wizard will include a featureto download the BOM in CSV format. Themain advantage of this online approach isthat you are allways working with thelatest & greatest most up to date version.

Calculation wizzardThe second operation mode offers a set ofcalculators to fine tune your DHCP-2module to specific driver specs by allowingyou to choose custom values for

• Xover frequency

• SE/BTL mode

• Limiters

During calculation the wizard automaticallydisplays the corresponding filtercomponents for easy location &modification.



http://wizards.piratelogic.nl/

Assembly instructions

LM3886 mounting To minimize the amount of work involved with mounting the LM3886 and further bring down the need for mechanical parts the DHCP module prototypes were fitted with modified LM3886 packages.

By default the LM3886 TO-220 power-15 package comes with 15 vertical legs. Using a standard 5mm angular aluminum profile the LM3886 legs were bent 90 degrees to allow for direct horizontal mounting.

By aligning the odd and even legs tightly against the corresponding sides of the angular profile an easily reproducible and perfect fit is created allowing for horizontal mounting of the LM3886 amplifier.

Please note that due the /TF version higher Rth value the dissipation of the LM3886 is limited to 30 watts. If the DHCP is used in a FAST arrangement where the high note amplifier powers a full-range driver the usage of a /T non isolated package may be obligatory to maintain the chips safe operating area.



TDA 8950 mounting



Board measurements

Distance between horizontal mounting holes : 94.6

Distance between vertical mounting holes : 74.6



Off board connections

Audio signal input MFB signal input

High note output AC power supply inputs



Level adjustments

R16 : high note amplifier level R45: MFB correction level

R61: lownote amplifier level

The DHCP-2 potentiometers.

Depending on the need to allow adjustment s to happen from outside the enclosure the potentiometers may be moved from the components to the copper side of the board.

Bill of materials (bom)Pressing the download button under the bill of materials section of the wizard will open a new browser tab containing the wizards database for the currently selected board.

The data displayed is an export from the eagle 6.5.0 bom.ulp user language program script, is semicolon delimited and uses the following field definitions:

2;10R0;R-EU_R1210;R1210;R103, R105;RESISTOR, European symbol;;;;

count value family package part # type description n.a.

2; 10R0 R-EU_R1210; R1210; R103, R105; RESISTOR European symbol; ;;;



Prototypes

541The original design philosophy and marketing pitch behindmfb was: small enclosures that produce a big sound. Thesmallest of the original series, the 541, measured a mere[todo :541 sizes].

It's successor, the 585 was the reason we started theDHCP-2 project after a very well received demo of amodified version during the 2013 mfb meeting where thedemo'ed 585 had it's rumble -3dB point lowered to 24hz.

It's outstanding sub bass performance combined with thedirectional behavior of this size of speakers made uschoose this form factor to be our DHCP starting point.

541/DHCPLike the 532 enclosure was used to test drive the 2012 modules a 541 enclosure was chosen to home the first DHCP prototypes. Displayed on the left are the 541 of team member Peter sporting a DHCP-2 module, a POS (power on signal) module all using the original transformer.



Acceleration Sensors

The original Philips SensorTo fast track development we started off using an original 541 enclosure equipped with a 7066/MFB woofer. Soon after we successfully made the DHCP-2work with this sensor we started looking for commercially available sensors.

The Pirate SensorThe high price , less than ideal form factor and relatively high weight of commercially available sensors forced us to do our own development.

By using a lowcost pxe element in combination with standard through hole components we were able to fabricate a transducer that mimicked the original seventies sensor.

An additional advantage of the new sensor over the original one was that due toits relatively high intrinsic capacitance the low frequency response was significantly improved.

Further development and the wish to bring down the sensor size & weight resulted in the first SMD based sensor making it better suited for use in fast (2 way) woofers by minimizing its addition to Mms.

By changing the way the pxe element is mounted to the base plate the sensor resonance frequency was doubled while maintaining it's output levels.

Because this sensor is still in beta availability is limited. The first production run is expected for Q4 2014.

For further information and or to obtain prototype sensors please contact [email protected].



mailto:[email protected]

Pirate sensor measurements

Proof of concept for recycling old Philips 22RH422 two way enclosures : this is what happens when you fit the latest Pirate sensor into a Philips AD7065/W4 woofer while maintaining the original 4 liter enclosure. Left correction off, right correction on.

The original MFB woofers are more then 40 years old, the more interesting it gets using the Pirate sensor with a modern studio chassis like the RCF L8S800. Blue = correction off, Black = correction on.



Before you start...

Required skill setThe DHCP-2 module like any mains connected apparatus will kill you if build / treated incorrectly, do not engage into using this kit (or any other DIY project for that matter) if you a) lack the necessary skill sets to safely build this thing b) see a, I'm not joking c) see b. Really.

ResponsibilityWe are not responsible for failures and or damages resulting from the use of this kit and will not replace any components once they have been used / soldered into the pcb.

WarrantyAlthough this kit has been developed with lots of love, tenderness and devotion we can only guarantee 100% operation for the ready & assembled versions. All kits are weighted & photographed before they leave our premises to make sure we don't forget anything. Might something be missing then contact us immediately within 1 week after receival.

The pre-assembled and tested kits come with a 1 year warranty, for INTL customers please note that this does not include transport costs.

CopyrightThe DHCP-2 is a brainchild of team DHCP.

SupportFor online support please visit our forum at forum.piratelogic.nl

ThanksTo all MFB lovers, engineers, salesmen, product managers, freaks and the douane. To Philips for the invention.

Chris Camphuisenteam lead

facebook.com/piratelogic



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Module DHCP-2 - Piratelogicmfb.piratelogic.nl/data/docs/DHCP-2.usermanual.en.pdf · • All filter components (R’s, C’s and opamps) are thru-hole components supporting the use

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