Marchand Electronics Inc.

Assembly Manual

XM26 Tube Electronic Crossover

XM26 Tube Electronic Crossover.Assembly of Cabinet

General

The XM26 cabinet contains 2 XM26 tube crossovernetworks and a PS227 power supply. Additionally thecabinet has 4 level controls, power switch, sum switchand 3 indicator lights on the front panel. The rearpanel has the 6 RCA signal connectors, line cord andfuse.The XM26-KK kit contains the following parts:

Parts List

1 Cabinet front panel XM261 Cabinet adapter panel1 Cabinet Rear Panel1 Cabinet Shell1 Cabinet Top4 Rubber feet + scews4 86 x ½” Button head cap screw1 PS227 Power supply Kit2 XM26 Xover board Kit4 XM26-FM Frequency Modules1 Line Cord1 T1 Toroidal Power Transformer

with mounting hardware1 Hex wrench 1/16”1 Hex wrench 5/64”

A bag with the following parts:3 RCA connector RED3 RCA connector BLACK1 Fuse Holder1 Fuse, 1A 250V1 Power entry connector1 Voltage selector switch17 1/2" Threaded Standoff5 #6 x ½” button head cap screw5 #6 x ½” machine screw17 6/32 * 3/8” Machine Screw21 6/32 * ¼” Machine Screw Black1 #6 Solder Lug2 Nylon cable clamp.4 4-40x3/8” Machine Screw4 #4 Locknut4 AT12 Level Control Attenuator 50K3 Red or Amber LED3 Holder for LED2 DPDT Rocker Switch Black4 Black Aluminum Knob2' 1/8" Heat Shrink Tubing2' Black #22 hookup wire8' Brown #22 hookup wire8' Red #22 hookup wire8' Orange #22 hookup wire2' Green #22 hookup wire2' Blue #22 hookup wire

Assembly Instructions

The front panel, rear panel and shell will beassembled separately and joined together at the end.First assemble the PS227-K power supply and the twoXM26-K crossover boards according to theinstructions provided.

Assembly of Rear Panel

The rear panel holds the RCA connectors and thepower cord and the fuse holder.Install the 6 RCA connectors in the holes input, highpass, low pass. The left channel has the connectorswith the BLACK insulators. The right channel gets theRED insulators. Each connector has two insulators,one with a shoulder and the other is flat. Make surethe shoulder is inserted in the hole of the panel. Installthe flat insulator on the other side of the panel. Installthe solder lug and the nut. Tighten the nut well.Install the fuse holder in the panel. The white washeris installed on the outward side. Gently tighten the nut.Too much force will crack the housing.Install the Power entry connector using two 4/40 x3/8” screws and #4 locknuts.Install the voltage selector switch using two 4/40 x3/8” screws and #4 locknuts. Orient the selectorswitch so that when the selector is switched towardsthe fuse holder it shows 115V.Attach wires to the RCA connectors. Prepare 4 pairsof wire by taking an 18" length of red and brown wireand twisting together. Slip a 3/4" length of heat shrinktubing over the end of each wire at one side of thepair. Strip 1/4" of insulation off each wire. Solder thebrown wire onto the solder lug of the connector.Solder the red wire into the center pin of theconnector. Slip the heat shrink tubing over the solderjoints. Shrink the tubing with a heat gun. If no heat gunis available use the heat of a soldering iron. Repeat this for all RCA connectors.The assembly of the rear panel is now complete. Put itaside until later.

Assembly of Front Panel

Install the 4 50K attenuators in the positions labeledlevel. Tighten the nuts carefully. One DPDT switchmounts in the position marked power and the otherDPDT switch mounts in the position marked sum.There are 3 holes left for the indicator LEDs. Do notinstall these LEDs yet at this time.Install wires to attenuators. Prepare 3 10" lengths ofred, orange and brown wire. Strip 1/4" of insulationfrom each end. Solder one end of each wire to anattenuator. T=brown, W=red, B=orange. Twist the wires to form a 3-wire cable. repeat above step for all four attenuators.Install two blue 9" wires to the sum mode switch.One wire goes to the bottom terminal of the switchand the other goes to the center terminal. The topterminal remains unused. Cover the solder joints witha 1/2" length of heat shrink tubing and shrink with heatgun.

Assembly of Shell

Place the shell on a flat surface with the bottom down.The front of the shell is labeled as such. Place thefront of the shell towards you. The 2 XM26 crossoverboards will be mounted in the holes marked at theright hand side of the chassis. Each board uses 6 1/2"standoffs and 12 # 6-32x1/4" screws. Install thestandoffs in the holes using flathead 6-32 screws.Now mount the XM26 crossover boards on thestandoffs.Install the PS227 at the holes marked, using four 1/2"standoffs. The side with the terminal blocks faces thetransformer. Use star locking washers under thescrews in the bottom shell. This is important. Thestarwashers will insure that the power supply isproperly grouned.Mount the TO5 voltage regulator on the rear panel ofthe cabinet. Use a mica insulator between theregulator rear panel. The mica insulator should becoated with heat sink compound on both sides.Install the toroidal transformer to the left of the PS227board with the mounting hardware included with thetransformer. The wiring of the transformer to the PS227 board isshown in the manual that comes with the PS227-K.The power wiring between the PS227 power supplyboard and the two XM26 crossover boards is shownin table 1. Prepare wire lengths of the proper lengthand color, strip 1/4" of insulation from each end, insertinto the terminal block and fasten the screw. Thepower wires typically run from the PS227 to the leftXM26 with one wire and then from the left XM26 tothe right XM26 with another wire. Twisting the wirestogether will make for a nice appearance.

Putting it all together

The Signal Wiring for the rear panel connectors isshown in table 2. A good way to do this is to place therear panel right next to the rear of the shell, but do notscrew it on. This way it is easier to insert the wires intothe terminal blocks. Note that the input signals arehooked up to both IN1 and IN2 of the XM26 crossovernetworks. Use a 1" piece of red wire to make thisjumper connection. When all 6 connectors are wiredup the rear panel can be fastened to the shell with the5 black 6-32 x 1/4" screws.The wiring for the front panel controls is shown intable 3. After connecting all four potentiometers andthe sum switch the front panel can be screwed on.Installation of the 3 LED indicators.Identify which end of each LED is the cathode(negative) lead. The LED has a flat on its side next tothis lead. Trim both leads to about 1/4". Using 1/2" of heat shrink tubing, connect one end of a6" green wire to the cathode of each LED. slide thetubing over the solder joint, against the LED andshrink with a heat gun.Using 1/2" of heat shrink tubing, solder one end of a2" red wire to the remaining lead of each LED(anode). Twist the 3 free ends of the red wirestogether and solder to a 4 " red wire. Use 1/2" of heat

shrink tubing to cover this 3-way split.Install the other end of the red wire to the terminalmarked 12.6 on the PS227 board. Connect the 3green wires to the PS227 as shown in table 4.Install the LED indicators into the front panel. Firstinsert the black grommet through the hole in the frontpanel from the outside. Then insert the LED into thegrommet from the inside. The grommet snaps aroundthe base of the LED and holds it in place.Now the AC power wiring will be installed.Install the fuse holder, line voltage switch and powerentry connector on the rear panel and install a DPDTswitch for the power on the front panel. Refer to theline power interconnect diagram for the wiringbetween these and the power transformer. Make surethe transformer wiring follows the colors indicated inthe diagram. Use heat shrink tubing over the solderedconnections where possible. Make sure to install thegrounding wire from the power entry connector to thechassis. Use a solder lug and a short wire for thispurpose. The solder lug can be installed under one ofthe screws that mounts the PS227 power supplyboard. Double check that the screws fastening thestandoffs for the PS227 to the bottom shell havestarwashers. This will insure proper grounding of thepower supply and line cord.Install a 1A slow blow fuse in the fuse holder.We will now test the power supply. Double checkproper grounding of the line cord by testing forcontinuity between the ground prong of the powercord and the shell of the XM26. Make sure all 8 12AX7 tube are REMOVED from theXM26 crossover boards. Plug the cord in and turn onthe power switch. The "Filament" indicator on the frontpanel should light up. After about 10 seconds the"Plate" indicator will light up and after another 2seconds the "Out" indicator will light up.Check the filament voltage by hooking up a voltmeterbetween the G and 12.6 terminals. The voltage shouldbe between 12 and 13 volts.

Check the positive and negative HV outputs on thepower supply. The voltahe should be about 170-190Volt.UNPLUG the power cord before proceeding.Install the 8 12AX7 tubes into the XM26 boards. Installthe frequency modules into the XM26 Boards. TheLow pass modules plug into the left side connector ofeach XM26 board. The High pass modules plug intothe right side connector of each XM26 board.

Installation.

The XM26-AA is now ready for use. See the UsersGuide for details on how to hook it up in your soundsystem.

Line power interconnect T1

Brown

Grey

Blue

Violet

Front PanelDPDT switch

Rear PanelFuse Holder

Rear PanelPower entry

Rear PanelVoltage selectorWire to

Case N

L

XM26 Tube Electronic CrossoverBoard.

Assembly Instructions.General

The XM26 is an electronic crossover for use in highquality audio equipment. The basic board has twofourth order filters, one for the high pass and one forthe low pass. The cutoff frequency is set with onefrequency module for each channel. The wiring of thefrequency module sets if it is highpass or low passand the frequency.

Parts List

R1 180K 1/2W,1% Metal FilmR2 180K 1/2W,1% Metal FilmR3 180K 1/2W,1% Metal FilmR4 180K 1/2W,1% Metal FilmR5 180K 1/2W,1% Metal FilmR6 180K 1/2W,1% Metal FilmR7 180K 1/2W,1% Metal FilmR8 180K 1/2W,1% Metal FilmR9 1.00M 1% Metal FilmR10 1.00M 1% Metal FilmR11 not usedR12 not usedR13 10.0K 1% Metal FilmR14 10.0K 1% Metal FilmR15 1.00M 1% Metal FilmR16 1.00M 1% Metal FilmC1 0.22 uF,250V Polypropylene FilmC2 0.22 uF,250V Polypropylene FilmC3 0.22 uF,250V Polypropylene FilmC4 0.22 uF,250V Polypropylene FilmC5 0.22 uF,250V Polypropylene FilmC6 1.5 uF, 250V Polyester FilmC7 1.5 uF, 250V Polyester FilmC8 0.22 uF,250V Polypropylene FilmC9 1.5 uF, 250V Polyester FilmC10 1.5 uF, 250V Polyester FilmC11 1.5 uF, 250V Polyester FilmC12 1.5 uF, 250V Polyester FilmC13 0.22 uF,250V Polypropylene FilmRLY DPDT Relay, 12V coilV1 12AX7A Dual TriodeV2 12AX7A Dual TriodeV3 12AX7A Dual TriodeV4 12AX7A Dual TriodeP1 Connector 10 positionP2 Connector 10 position

The following parts are supplied with each board kit:

Quantity Description

8 180K 1/2W,1% Metal Film2 10.0K 1% Metal Film4 1.00M 1% Metal Film7 0.22 uF,250V Polypropylene Film6 1.5 uF, 250V Polyester Film1 DPDT Relay, 12V coil4 12AX7A Dual Triode2 Connector 10 position40 Pin-socket2 2 Pos terminal block7 3 Pos terminal block1 XM26 Circuit board

Assembly Instructions

Most parts are installed in the usual way. Insert thepart at the location on the circuit board as indicated bythe silk screen identification and solder on the solderside of the board.Tube pin sockets: First install the pin-sockets for thefour 12AX7A vacuum tubes. These pin-scockets areinserted into the circuit board from the top (side withlettering) and soldered from the bottom. Make surethat all pin-sockets are inserted fully before soldering.A good way to insure this is use a tube as a guide.Insert the tube into the socket pins before soldering.This will hold the socket pins exactly where theyshould be. Make sure all pin-sockets are fully seated.Then solder the pin-sockets into the circuit board. Becareful not to get any solder inside the socket pins.Resistors: Insert the 8 1/2W resistors R1..R8(marked Brown-Grey-Black-Yellow--Brown), the 41.00M resistors (marked Brown-Black-Black-Yellow--Brown) R9,R10,R15,R16 and the 2 10.0K (markedBrown-Black-Black-Red--Brown) resistors R13, R14into the board and solder.Edge connectors: Install the 2 10 position edgeconnectors at location P1 and P2. These connectorshold the frequency modules.Terminal Blocks: The terminal blocks are supplied inunits of two and three. Make up a 10 position unit byjoining two 2-pos units and two 3-pos units. Make uptwo 6 position units by joining pairs of 3 position units.Install a 3 position terminal block at the input (IN1...),the 10 position terminal block at the output(OUT2.......) and the two 6 position units next to R11and R12 (GND.....).Relay: Install the relay at location RLY1.Capacitors: Install the 7 0.22 uF polypropylenecapacitors (marked .22K) at locations C1..C5, C8 andC13. Install the 6 1.5uF (marked 155K) at locationsC6,C7,C9..C12.Tubes: Insert the 4 12AX7A tubes in the sockets.

Assembly is now complete. Please double check allparts for proper insertion and soldering. Insertfrequency modules now or later.

Installation.

The XM26 needs a dual +/- 150V power supply for theplate/cathode and a 12.6V power supply for thefilaments. A 12.6 V voltage is needed to activate theoutput relays. Inputs: Signal inputs are connected to the inputs IN1and IN2 and the GND input located at the input side ofthe board.Outputs: The outputs are taken at OUT1 and OUT2.Level controls: Level controls need to be connectedalso. There is one control for each channel. The levelcontrol should have a value of 50K. for bestperformance. Controls with a linear taper arepreferred. Values up to 100K are satisfactory. Thereare two trimpots located on the XM26 circuit board.These can be used as level controls, or off-boardcontrols can be used. If the on-board controls areused use contacts marked PT for the input of thecontrol and contact marked PW as the wiper. Theground is already connected.Sum switch: The output of two channels can besummed (averaged) by using a SPST switch. Connectthe switch between the two terminals marked SM ofthe channels to be summed. This is useful whenusing a common subwoofer. The switch is connectedbetween the SM terminals of the low pass channels.Filament power: A 12.6 volt power supply should beconnected between the F1 and F2 terminals. Best is aregulated DC supply, in order to avoid hum, but an ACsupply can be used also. The supply should be nearground potential. For a DC supply this can beachieved by grounding one of the sides. For an ACsupply it is best to use a center grounding scheme, inorder to minimize hum. The current drawn is 600 mA.High Voltage Supply: A dual (regulated) supply of+150V and -150V should be connected to the ++ and- - terminals and ground. The current drawn is 12mA.Relay Power: A voltage of 12V should be connectedbetween the relay coil terminals RL1 and PL2. Thevoltage can be taken from the filament power supply.

Power Supply Sequencing

There should be a delay of 10 seconds betweenapplying power to the filaments and applying the +/-150 voltages. Then there should be another 2 seconddelay before applying power to the output relay.

Circuit description

The XM26 circuit board has two filters. Each filter canbe low-pass or high-pass, depending on the frequencymodule. The filters are 24 dB/octave with the standardfrequency modules, but other slopes can be realizedby modifying the frequency modules. There are 412AX7A dual triode tubes on the circuit board.Channel 1 uses sections B of each tube and channel2 uses sections A. Please refer the circuit diagram for the followingdescription. The input signal is applied at the terminalmarked IN. Tube V1 is a cathode follower. It acts as abuffer for the input signal. The tube current is set by

resistor R2 and the cathode supply voltage. For thevalues used, the tube current will be about 1.5 mA.The second and third stages (V2 and V3) are theactual filter sections. The filter components aremounted on plug-in frequency modules. Thefrequency module determines the slope of the filterand if it is low-pass or high-pass. Each section is asecond order Butterworth filter. The two sectionstogether make for a fourth order constant voltagefilter. The schematics show channel 1 with a high-pass frequency module and channel 2 with a low passfrequency module.The output of the second filter is taken from thecathode of V3 with a 1.5uF capacitor (C6) at terminalOT. This capacitor prevents any DC component of thesignal from appearing on the level control.An external level control can be connected betweenOT and GR, the input of the output buffer V4. A linearpotentiometer works best at this location. The outputof the crossover is taken from the cathode of V4 witha 3.2 uF capacitor. This capacitor is made up of two1.5uF polyester film capacitors and one .22uFpolypropylene capacitor. The output of the crossover is shorted to ground withrelay RLY when it is not in operation. A time delayactivates the relay after warm-up and removes theshort. This arrangement eliminates any turn-ontransients at the output. The power supply sequencing circuit also releases therelay instantly when the AC power is turned off, thuseliminating any turn-off transients.

See table 5 for connecting power and signals to theXM26

Frequency module

Two frequency modules are used on each XM26crossover board. The frequency module board ismarked with components 1 through 10. Table 6 liststhe components that need to be inserted at theselocations for High pass and for Low pass operation.The table also shows typical values for a crossoverfrequency of 1000 Hz. Values for other frequenciescan be calculated by scaling the resistor values.

The values for the resistors are given by:

Rx = Rtable / Frequency(KHz)

Use 1% resistors with values closest to the calculatedvalue.

The frequency module should normally be insertedwith the components facing outwards, away from thetubes. Insertion in the other orientation is electricallyOK, but there may not be enough clearance that way.

XM26FM Frequency module

The values shown in table 6 are for the standardfourth order, 24 dB/oct filter. For third order alignmentuse the values in table 7, for second order alignmentuse table 8 or 9, and for first order use table 10. The constant voltage (Linkwitz-Riley) alignment has afrequency response that is 6 dB down at thecrossover frequency. The other alignments are 3 dBdown at the crossover frequency. The constantvoltage alignment is generally preferred for the evenorder filters because the sum of the output voltage onthe high and low pass outputs is constant for allfrequencies.

PS227 Tube Power Supply.Assembly instructions for Circuit board.

General

The PS227 is a power supply for the XM26 electroniccrossover network. It has a dual +/- 180 VDC highvoltage supply and two 12.6VDC regulated filamentsupplies. The supply has a heavy duty toroidal powertransformer with a dual 120V/ 240V line input. Thesupply is specifically designed for powering the XM26electronic crossover network. A relay driver is includedfor driving a signal relay that enables the outputs ofthe XM26 to be powered. Drivers for Light EmittingDiodes are provided that can drive 3 LED Indicatorlights.

Power Supply Sequencing

The power supply sequencing has a dual purpose.The tubes are protected from power turn on and turnoff transients by delayed application of anode voltage.The time delay relay driver enables the delayed turn-on of the output. The output thus becomes active afterthe tubes are warmed up!After the power to the PS227 is turned on the 12.6Vfilament power will become active immediately, butthe HV plate supply is not active yet. This preventsdamage to the tube cathodes caused by hot spots.After a 10 S delay the HV power is turned on. Theinternal voltages in the tube circuits take some time tostabilize. After another 2 S delay the output relay willbe activated.At each stage in the sequence the LED indicators willindicate the state of the power supply.When the power supply is turned off the output relaywill be deactivated immediately and the HV supply willbe turned off.

Parts list for circuit board

R1 22.1 Ohm 1% Metal film resistorR2 100 Ohm 1% Metal film resistorR3 100 Ohm 1% Metal film resistorR4 not usedR5 2400 Ohm 1W power resistorR6 not usedR7 100K 1% Metal film resistorR8 1.00K 1% Metal film resistorR9 2.20M 1% Metal film resistorR10 100K 1% Metal film resistorR11 100K 1% Metal film resistor R12 1.00 M 1% Metal film resistorR13 100 K 1% Metal film resistorR14 1.00 M 1% Metal film resistor R15 1.00K 1% Metal FilmR16 1.00K 1% Metal FilmR17 1.00K 1% Metal FilmR18 100 Ohm 1W Power resistorR19 100 Ohm 1W Power resistorR20 not usedR21 not used

R22 180 K 1/2W,1% Metal FilmR23 180 K 1/2W,1% Metal FilmR24 180 K 1/2W,1% Metal FilmR25 180 K 1/2W,1% Metal Film

C1 10,000 uF,25V Aluminum ElectrolyticC2 10 uF,25V Non-Polar Al. ElectrolyticC3 not usedC4 10 uF,25V Non-Polar Al. ElectrolyticC5 .22 uF,100V Polyester FilmC6 220uF,250V Aluminum ElectrolyticC7 220uF,250V Aluminum ElectrolyticC8 220uF,250V Aluminum ElectrolyticC9 220uF,250V Aluminum ElectrolyticC10 220uF,250V Aluminum ElectrolyticC11 220uF,250V Aluminum Electrolytic

D1 HER604 Diode,6A D2 HER604 Diode,6AD3 HER604 Diode,6AD4 HER604 Diode,6AD5 1N4937 Diode,1AD6 1N5232 Zener Diode, 5.6VD7 180 K 1W Power resistor*D8 180 K 1W Power resistor*D9 1N4937 Diode,1AD10 1N4937 Diode,1A D11 1N4937 Diode,1AD12 1N4937 Diode,1AQ1 IRFI640 N-Channel MOSFETQ2 IRFI640 N-Channel MOSFET

IC1 LM323K TO3 RegulatorIC2 not usedIC3 LM339 ComparatorRLY1 DPDT 12V RelayL1 156M 3H inductorL2 156M 3H inductor

*NOTE: yes, these are indeed resisitors.

The following parts are supplied with each board kit:

1 22.1 Ohm 1% Metal film resistor4 180K 1/2W,1% Metal Film2 100 Ohm 1W Power Resistor1 2400 Ohm 1W Power Resistor2 100 Ohm 1% Metal film resistor4 1.00K 1% Metal film resistor4 100K 1% Metal film resistor2 1.00M 1% Metal film resistor1 2.20M 1% Metal film resistor1 .22 uF,100V Polyester Film6 220 uF,250V Aluminum Electrolytic1 10,000 uF,25V Aluminum Electrolytic2 10 uF,25V Non-Polar Al. Electrolytic4 HER604 Diode,6A 7 1N4937 Diode,1A 1 1N5232 Zener Diode, 5.6V2 IRFI640 N-Channel MOSFET2 156M 3H inductor1 LM323K TO3 Regulator1 LM339 Comparator1 DPDT 12V relay6" Bare Hookup wire1 14 pin DIP Socket3 2 Pos terminal block4 3 Pos terminal block1 TO3 mounting hardware

SocketMica washer2 each #6 x ½” Self tapping screwTube of heat sink compound

1 PS227 Circuit board4 6/32 x 1/4” machine screw4 6/32 kepsnut4 #6 flat washer

Most parts are installed in the usual way. Insert eachpart at the location on the circuit board as indicated bythe silk screen identification and solder on the solderside of the board.Jumpers: Two jumper wires need to be installed.They are indicated with a white line running betweentwo holes in the circuit board. One is located near R8and the other is near C7.Resistors: The resistors are mounted onto the circuitboard as indicated. The resistors are color coded asfollows:

100Ohm,1W brown black black gold180K,1/2W brown grey black yellow brown100 Ohm brown black black black brown237 Ohm red orange violet black brown1.00K brown black black brown brown10.0K brown black black red brown100K brown black black orange brown1.00M brown black black yellow brown2.20M red red black yellow brownDiodes: Install the 5 1N4937 rectifier diodes, 4HER604 rectifier diodes and the 1 1N5232 zenerdiode as indicated. Make sure the band on the diodethat indicates the cathode matches the white band onthe identification. Some diodes have a black body andwhite band (1N4937, HER604) and some have awhite body with black band (1N5232 usually). It is very

important that the orientation is done correctly.IMPORTANT NOTE: Mount D1, D2, D3 and D4 sothere is a 0.2" to 0.3" gap between the diodes thecircuit board. This will improve the cooling of thediodes.Note that D7 and D8 are not used.Small Capacitors: Install the 0.22uF stacked filmcapacitor (marked 224) at location C5. Install the10uF non-polar capacitors at location C2 and C4.These non-polar aluminum electrolytic capacitors canbe oriented either way. Just ignore the polaritymarkings on the circuit board. Terminal Blocks: The terminal blocks are supplied inunits of two and three. Make up a 8 position unit byjoining 1 2-pos units and 2 3-pos unit. Also make up a7 position unit using 2 2-pos units and one 3-pos unit.Install the terminal blocks as indicated at one of thelong sides of the circuit board. Orient so that the wireentry is at the edge of the board.Large Electrolytic Capacitors: Install the 7 largeelectrolytic capacitors C1,6,7,8,9,10,11 as indicatedon the circuit board. Make sure the plus and minusside are oriented correctly. The plus side is marked onthe circuit board (+). The white band on the capacitorsindicates the minus (-) side.IC socket: install a 14 pin IC socket at location IC3.Note the orientation. Pin 1 of the socket is nearestR10. Insert the LM339 voltage comparator into thesocket. Make sure the pin 1 orientation is correct.Relay: Install the relay RLY1Inductors: Install the two large 3H inductors using #6screw and locknut. Place a flat washer between theinductor and the circuit board on each mountingscrew. This will prevent warping of the circuit board.Trim and insert the leads into the solder pads near theinductors.IC1: Use a piece of 6” twisted 3 conductor wire toconnect the TO3 socket to the circuit board atlocation marked IC1. Note the markings B and E nearthe terminals on the socket. The C terminal is themounting screw. Use brown for C (case), red for Band orange for E. Insert the wires into the 3-positionterminal block marked with B, C and E

TO3 Socket Terminal blockE(orange) EC(brown) C

B(red) BConnections for IC1

PS227 XM26 Left XM26 Right Color signal

RLY RL1 RL1 Blue coil of 12V relay

12.6 RL2 RL2 Blue coil of 12V relay

12.6 F1 F1 Green tube filaments 12.6V DC

G F2 F2 Green tube filaments ,neutral

GND GND GND Brown ground for power supply

V+ ++ ++ Red plate voltage, +150V DC

V- - - - - Orange cathode voltage, -150V DC

Table 1: Connections for controls and power

Source XM26 Left XM26 Right Color signal

Left In, center IN1, IN2 Red Left input signal

Left In, Lug GND Brown Left input ground

Right In, Center IN1, IN2 Red Right input signal

Right In, Lug GND Brown Right input ground

Left Out Hi, Center OUT1 Red Left High Output signal

Left Out Hi, Lug GND Brown Left High Output ground

Right Out Hi, Center OUT 1 Red Right High Output signal

Right Out Hi, Lug GND Brown Right High Output ground

Left Out Lo, Center OUT2 Red Left Low Output signal

Left Out Lo, Lug GND Brown Left Low Output ground

Right Out Lo, Center OUT 2 Red Right Low Output signal

Right Out Lo, Lug GND Brown Right Low Output ground

Table 2: Connections for rear panel signals

Source XM26 Left XM26 Right Color signal

Left Low Level Control OT, Left side Brown connect to top of control

" GR, Left side Red connect to wiper of control

" GND,Left side Orange connect to ground of control

Left High Level Control OT, Right side Brown connect to top of control

" GR, Right side Red connect to wiper of control

" GND,Right side Orange connect to ground of control

Right Low Level Control OT, Left side Brown connect to top of control

" GR, Left side Red connect to wiper of control

" GND,Left side Orange connect to ground of control

Right High Level Control OT, Right side Brown connect to top of control

" GR, Right side Red connect to wiper of control

" GND,Right side Orange connect to ground of control

Sum Switch SM, Left Side Blue one wire of sum switch

" SM, Left Side Blue the other wire of sum switch

Table 3: Connections for front panel controls

Source PS227 Color signal

Filament LED LED 3 Green connect to cathode of LED

" 12.6 Red connect to anode of LED

Plate LED LED 2 Green connect to cathode of LED

" 12.6 Red connect to anode of LED

Out LED LED 1 Green connect to cathode of LED

" 12.6 Red connect to anode of LED

Table 4: Connections for front panel LED indicators

Location Terminal channel signal

input IN1 1 input1

" GND ground for input cable

" IN2 2 input2

near R12 PT 2 top of onboard control

" PW 2 wiper of onboard control

" GR 2 connect to wiper of control

" SM 2 connect to sum switch

" OT 2 connect to top of control

GND 2 connect to ground of control

near R11 PT 1 top of onboard control

" PW 1 wiper of onboard control

" GR 1 connect to wiper of control

" SM 1 connect to sum switch

" OT 1 connect to top of control

GND 1 connect to ground of control

output OUT2 2 output2

" GND ground for output cable

" RL1 coil of 12V relay

" RL2 coil of 12V relay

" F1 tube filaments 12.6V DC @ 600mA

" F2 tube filaments ,neutral

" OUT1 1 output1

" GND ground for power supply

" ++ plate voltage, +150V DC @12 mA

" - - cathode voltage, -150V DC @12 mA

Table 5: Connections for signals, controls and power onXM26 board

Location High Pass Typical Value for 1000Hz

Low Pass Typical Value for 1000Hz

1 C1 3300pF R1 34.0K

2 R2 68.1K C2 3300pF

3 R3 68.1K C3 3300pF

4 C4 3300pF R4 34.0K

5 R5 68.1K C5 3300pF

6 C6 3300pF R6 34.0K

7 R7 68.1K C7 3300pF

8 R8 68.1K C8 3300pF

9 C9 3300pF R9 34.0K

10 R10 68.1K C10 3300pF

Table 6: component selection for frequency module forstandard 24dB/oct,

Constant Voltage (Linkwitz-Riley) alignment.

Location High Pass Typical Value for 1000Hz

Low Pass Typical Value for 1000Hz

1 J1 Jumper Wire J1 Jumper Wire

2 not used not used

3 not used not used

4 C4 3300pF R4 47.5K

5 R5 47.5K C5 3300pF

6 C6 3300pF R6 23.7K

7 R7 47.5K C7 3300pF+3300pF

8 R8 47.5K C8 3300pF+3300pF

9 C9 3300pF R9 23.7K

10 R10 95.3K C10 3300pF

Table 7: component selection for frequency module for 18dB/oct, Butterworth

Location High Pass Typical Value for 1000Hz

Low Pass Typical Value for 1000Hz

1 J1 Jumper Wire J1 Jumper Wire

2 not used not used

3 not used not used

4 J4 Jumper Wire J4 Jumper Wire

5 not used not used

6 C6 3300pF R6 34.0K

7 R7 68.1K C7 3300pF

8 R8 68.1K C8 3300pF

9 C9 3300pF R9 34.0K

10 R10 68.1K C10 3300pF

Table 8: component selection for frequency module for 12dB/oct, Butterworth

Location High Pass Typical Value for 1000Hz

Low Pass Typical Value for 1000Hz

1 J1 Jumper Wire J1 Jumper Wire

2 not used not used

3 not used not used

4 C4 3300pF R4 47.5K

5 R5 47.5K C5 3300pF

6 J6 Jumper Wire J6 Jumper Wire

7 not used not used

8 not used not used

9 C9 3300pF R9 47.5K

10 R10 47.5K C10 3300pF

Table 9: component selection for frequency module for 12 dB/oct,Constant Voltage (Linkwitz-Riley) alignment.

Location High Pass Typical Valuefor 1000Hz

Low Pass Typical Value for1000Hz

1 J1 Jumper Wire J1 Jumper Wire

2 not used not used

3 not used not used

4 C4 3300pF R4 47.5K

5 R5 47.5K C5 3300pF

6 J6 Jumper Wire J6 Jumper Wire

7 not used not used

8 not used not used

9 J9 Jumper Wire J9 Jumper Wire

10 not used not used

Table 10: component selection for frequency module for 6 dB/oct

TerminalBlock

location

TerminalID

Xformer

CE5899

Xformer

CE6196/2

067546

signal

2 AC Black Orange 240 VAC transformer secondary, side 1

2 AC Yellow Green 240 VAC transformer secondary, side 2

2 COM Red, Orange Yellow, White

240 VAC transformer center tap

2 V-- +170 VDC output

2 GND HV ground

2 V++ +170 VDC output

1 L1 Cathode of LED, relay indicator light

1 L2 Cathode of LED, HV indicator light

1 L3 Cathode of LED1, power indicator light

1 FF green red 15 VAC transformer secondary, side 1

1 FF white black 15 VAC transformer secondary, side 2

1 12.6 12.6V DC @1A regulated filament supply,

Anode of LED1,2,3, relay coil 1

1 G Ground for filament supply

1 RELAY relay coil 2

Table 11: Terminal block signals for PS227 power supply board

V++

D7

PS127 Tube power supply(c) 1998 Marchand Electronics Inc.

V--

+-

+-

+-

relay

led 1

led 2

led 3

VAC

VAC

CT

FF

FF

D11

D12

C10

D9

D10

C6

C7 D8

D4

D3

D2

D1

C1 R8

D6

IC2

R12

R9

R10 R11

R13

R14

C4

R7C5

D5IC3

IC3

IC3

R16

R17

R15

Q1

Q2

L1

C8

R18

L2

C9

R19

1 in out g

3

2

+12.6V

R1C2

IC1

R3

ncno

ncno

RLY1

R23 R25

R22C11 R24

R2

T1 R5

L H

H H HH

H H

HHHHH H

L

L

L

L L

LL

L

L

H

XM26 tube electronic crossover(c) 1997 Marchand Electronics Inc.

OT

IN1

C6

V1b

PT

PW GR

OUT1 R9

2

3 1 5

4

Rx Rx

Cx Cx

V--

R1 R6

8

9 7

106

Cx Cx

Rx Rx

V2b V3b V4b

R11

R13

R5 R15

C10

C9

C8

V++

OT

IN2

C7

V1a

PT

PW GR

OUT2 R10

2

3 1 5

4

Rx Rx

Cx Cx

V--

R4 R7

8

9 7

106

Cx Cx

Rx Rx

V2a V3a V4a

R12

R14

R8 R16

C11

C12

C13

V++

R2

R3

SM

SM

ncno

ncno

RL1

RL2

OUT1

OUT1

F1

F2

v1 v2 v3 v4

tube filaments

2 1 4 3 5 7 6 9 8 10

frequency module

1 2 3 4 5 6 7 8 9 10

C5C4C3C2C1

V++V--

Appendix 1Modifications for Balanced inputs and outputs

Component Changes:

R5 and R8 change to 22K, 2WR9 and R10 change to 10.0K 1%MFV4 changed to 12AT7

XM26 tube electronic crossoverOptional balanced inputs & outputs

XLR

12

3

YEL

Jensen JT-11-EMCF

ORGBRN

RED

Jensen JT-11P-1

YEL

ORGBRN

RED

BLKWHIcan XM26 board

IN1

GND

IN2

GND

OUT1

YEL

Jensen JT-11-EMCF

ORGBRN

REDGND

OUT2

Rt

Rt

Rt = 21.0K 1%MF

XLR

12

3

XLR

12

3

Module for 1000Hz 12dB LP filter + 300Hz notch filter

Location TypicalValue for1000Hz

1 R1 34K

2 R2 15K

3 not used

4 C4 5600pF

5 R5 475K

6 not used

7 C7 3300pF

8 C8 3300pF

9 R9 34K

10 C10 3300pF

11 C11 5600pF

component selection for notch filter

For different frequency, scale all capacitors inversely withfrequency.For example, C7=C8=C10=(1000/F)*3300pF; where F is new frequency

Spice simulator by Linear Technology www.linear.com

XM26 frequency moduleModification for notch filter

Rear of XM26

Cut trace here

Jumper wireC11

6 7 8 9 10 5 4 3 2 1

Module for 1000Hz 12dB HP filter + 3000Hz notch filter

Location TypicalValue for1000Hz

1 R1 10K

2 R2 4.99K

3 not used

4 C4 1800pF

5 R5 162K

6 not used

7 R7 41.2K

8 not used

9 C9 3300pF

10 R10 82.5K

11 C11 1800pF

12 C12 3300pF

component selection for notch filter

For different frequency, scale all capacitors inversely withfrequency.For example, C9=C12=(1000/F)*3300pF; where F is new frequencyC4 & C11 are for notch frequency; C9 & C12 are for xover frequency

Spice simulator by Linear Technology www.linear.com

XM26 frequency moduleModification for notch filter

Rear of XM26

Cut trace here

C11C12

6 7 8 9 10 5 4 3 2 1

Appendix 2Mono version

Parts List

1 Cabinet front panel XM26-MONO1 Cabinet Adapter Plate1 Cabinet Rear Panel1 Cabinet Shell1 Cabinet Top1 PS227 Power supply Kit1 XM26 Xover board Kit2 XM26-FM Frequency Modules1 Line Cord1 T1 Toroidal Power Transformer

with mounting hardware

A bag with the following parts:3 RCA connector RED1 Fuse Holder, D hole1 Fuse, 1A 250V1 Power entry connector1 Voltage selector switch10 1/2" Threaded Standoff11 6/32 * 1/4 Panhead Machine Screw 11 6/32 * 3/8 Flathead Machine Screw 5 6/32 * 1/2 Panhead Machine Screw 5 6/32 * 1/2 Black Buttonhead Machine Screw 1 #6 Solder Lug12 #6 Locknut4 4-40x3/8” Machine Screw4 #4 Locknut2 50K Level Control Potentiometer3 Red LED3 Holder for LED1 DPDT Toggle Switch2 Black Aluminum Knob2' 1/8" Heat Shrink Tubing4' Black #22 hookup wire 32224' White #22 hookup wire 32222' Black #22 hookup wire 11225' Brown #22 hookup wire 11225' Red #22 hookup wire 11225' Orange #22 hookup wire 11222' Green #22 hookup wire 11222' Blue #22 hookup wire 1122