M612 — Audio Distribution Amplifier

The M612 audio distribution amplifier is an ac operated, plug-in unit designed to bridge a single source ad provide twelve uniform, highly isolated outputs for distribution throughout an audio system. FEATURES: Integral bi-polar power supply for maximum reliability. This ultra-reliable design utilizes a bi-polar power supply to operate balanced differential, operational amplifiers. The absence of conventional transformers and coupling capacitors results in exceptionally high performance characteristics particularly with respect to isolation between outputs ad system noise and distortion_ IC balanced circuits Selectable gain Twelve 600 ohm balanced outputs are provided directly at the module output connector, exhibiting 7Odb of isolation between circuits across the entire audio spectrum_ External resistive splitter networks are eliminated.

Wiring is made directly to the MF6 frame receptacle 7Odb isolated between outputs 20hz 20Khz A preset front panel gain selector switch and t6db vernier potentiometer adapt the M612 to operate from unity gain to +38db, sufficient gain to bridge a -3Odbm audio source and provide twelve +8dbm outputs_ Balanced test jacks permit examination of both the input and output signals.

Other front panel facilities include a power switch, neon power indicator, ac primary ad dc fuses. 20K bridging input The modest size of 3.4W X 3.4H X 13.7D allows five M612 distribution amplifiers to be accommodated in one standard rack mounting (19W X 3.5H) MF6 equipment frame_ Low absolute output noise Trim 25ASB" OFF WBSt M6iz

The M612 audio distribution amplifier is an ac operated, plug-in unit designed to bridge a single source and provide twelve uniform, highly isolated outputs for distribution throughout an audio system_ FEATURES: Integral bi-polar power supply for maximum reliability. This ultra-reliable design utilizes a bi-polar power supply to operate balanced differential, operational amplifiers. The absence of conventional transformers and coupling capacitors results in exceptionally high performance characteristics particularly with respect to isolation between outputs and system noise and distortion.

IC balanced circuits Selectable gain Twelve 600 ohm balanced outputs are provided directly at the module output connector, exhibiting 7Odb of isolation between circuits across the entire audio spectrum External resistive splitter networks are eliminated. Wiring is made directly to the MF6 frame receptacle 70db isolated between outputs 20hz 20Khz A preset front panel gain selector switch and a #6db vernier potentiometer adapt the M612 to operate from unity gain to +38db, sufficient gain to bridge 30dbm audio source and provide twelve +8dbm outputs_ Balanced test jacks permit examination of both the input and output signals_ Other front panel facilities include a power switch, neon power indicator, ac primary and dc fuses 20K bridging input The modest size of 3.4W X 3.4H X 13.7D allows five M612 distribution amplifiers to be accommodated in one standard rack mounting (19W X 3.5H) MF6 equipment frame.

Low absolute output noise Trim 25AS8 OFF WBSE M6iz

The M612 audio distribution amplifier operated; plug-in unit designed bridge sincle squi ce anu provide twelve unitorm highly isolated outputs for distribution throughoul audio system; FEATURES: Integrae bi-polar power supply tOr maximum reliability. This ultra reliable design utilizes hi-polar power supply Qucrule Dalanced differential onerjuiona amplifiers; Uhe#oeence CCnona transformers coupling capacitors results in exceptionally high perforiance characteristics particularly with Fesn eCT Ksolation butwuen uulpuls und system noise and distortion IC balanced circuits Selectable gain Twelve 600 ahm balanced outputs are provided directly the matule oulpul connecidn exhibiting ZOdb otisolation between circuits across entire audio spectrum Extera rbsistan splitter networks are eliminated Wiring made directly t0 the MF6 frame receptacle 70db isolated between outnuts 20hz 20Khz presct ITOMI panel gain lector switch anc #Bub vernier potentiometer adapt the M612 operate from unity gain t0 !

J8db sufficient gain hridge 3Odhm audio source and provide twelve +8dbm outputs Balanced test jacks nermit examination bath Ine input and output signals, Otha front pancl facilities Include Dowut Switch, neon power indicator, &c primnary and dc Juser, Z0K bridging input Thc modest size of AW X 34HX 13.70 allows Iwve M612 distribution amplifiers accommodated one standard rack mounting (19W" X 3.5H) MF6 equipment frame Low ahsalute outpul naise TAA

M612 DISTRIBUTION AMPLIfIER

A ~b1e n t Te llpe r l t ur e : 0 to 60 degr e es Cels ius . D l~e nsi ons: 3 . 4 - wide X 3 .4 - h f gh X 13. 7- deep. ( 8 6 . . X 86Ii. X 34 8 • • ) .

We i ght : 5 pounds (2. 2 7 kg ) ne t .

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GENERAL DESCRIPTlDN 1'16 12 DISTRIBUTIDN AMP LIFIER

The 1'1 6 12 .. udio dist ribution IlIp l1fie r is I n ac o pe ra te d , plug-In unit des1g ned to bridge I si ngle a ue te s ource u d provide Illul tipleo f t s ct e ted , uni fo rllo utputs for distr ibu tio n throughout I television stud io o r s i . l1 a r audfo systell COlipleX. DUll differe ntia l ope rationll ul pliffe rs Ire ut il i ze d to produce b.. hnced o r unblhnced input operatio n and to provide twelve blhnced Ind isollted a ud io lines It t he output. The Ibsence of ccev ene ten e t a ud io t r u s f o r ller s Ind output coupl fng ee pa et tcr-s results i n e xce pti oni ll y high perfor ll.. nce chlrlcteristic s while t he self -contlined power supply ensures lndhldUil relh bfl1ty and fnedoll f rOIl the dependency of . ln y a llpltf1e rs upon a sing le ce ntrll i zed power supply . The twelve 6DD ohll ballnced outputs a r e I'Il ihble directly It the 1I0 dul e connecto rs. 60 d B of iso latio n i s prese nted between all outputs , lIe as ur e d a c r os s t he entire audio spectrull troll 20 Hz to 20 kHz. [lt t erna l s pl itte r resisto r net worts a nd attendant prolife ration of w1ring a r e eli llinlted; wiri ng is " Ide di rec tl y to th e KF6 f r i lle receptacle. A front pInel gl ln selecto r swttch an d a :!:6 dB ver nie r po t e nt i ollle t e r I da pt the 1'1 612 to opera te f r OIl unity gl ln to +38 d8, sufficten t gain to br idge a - 3D dBII a ud i o so ur c e a nd t o p rovide twelve +S dBII ou tputs. Sa l a nced test jlcks perllit en lllnitio n of bo th th e inp ut a nd o utpu t si gna ls. Othe r tron t pinel facilities include a c power switch and neo n indicator , prfllary I C f use a nd se co nda r y dc f use. All a c t t ve c i rcuit er eeenrs are assem ble d on II plug-tn PC card t o s implify t r oubl e - sh oo ti ng u d to perliit ra pi d unit inte rc hlnge. The e xce p t t e nel l y eff i c ie nt ci rc ui t configuration r e s ult s In l ow heat gen era t ion a nd e e e vt e perfora tions assu re e deque te ve ntila tion by na t ural a ir a .c

convectio n throug h the equipmen t r a c k sys te ll , ps

The JIIodest she of 3.4W X 3. 4H X 13.7D in ch es l110ws f h e BS

1'4612 ul plifle rs to be ac commodat e d i n o ne s t e nde t-d r a ck W

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WA R D - B EC K S YSTE MS LTD .

~ M612 DISTRIBUTION AMPLIFIER

The M612 pl ugs di r e ct l y into th e MF6 moun t i ng f r a me which may be i ns tall e d in a s ta nda r d EI A 19-in ch e qui pment rack. The MF6 fra me 101 11 1 acco mmo date a ma xi mum of fi ve H612 a mplifiers or a ny co mbi na t i on of s i ngle , doub le or multip le width modules not exce eding ten s i ngl e width modules. If the moun ting f ra me has been procured le ss re ceptacl es, t hese mus t be inst a lled i n the a ppr opr iate mod ule posit i ons. The M612 modu l e re q uires two t ype MFR6 fr ame r ec epta cles. Note that the re cep ta cle c ontll ini ng t heac line vo l tll ge ( PI) 15 i nve rted t o pr ovi de keyi ng i n or de r to prevent i na d ve r t ent ins e r t ion of other c ompa ni o n mod ul es whi c h do no t o pe rat e f rom the e c line. Whe re verti c a l rack space permits and whe r e the ult i mate i n noise a nd c r oss t alk is des i red, i t is rec ommended to a lloca t e on ly mod ul es of the s a me t ype t o e a c h individu a l MF6 mount ing frame. Alte r na t iv e ly , i t is pos s i ble t o afx mo dules of different t y pes by e xe rc i sing ex treme ca r e to separa t e c a bl es of differe nt l ev e ls a nd functi ons. Pla ce power s up plies a nd se lf- powe r e d un it s to t he rig ht of the fra me (n ormal prac t i c e viewed fr om rack front) . I ns t e t I i ns ula t i ng s l e ev es ov e r all ac sol de red te rmi nal conne cti o ns . All e x te r na l c onn e ctions a r e made t o th e fra me ee cep te cl e s . Refer to d r awing L861 2-0 9- 00 1. Jumpe r te r minal 8 ( c ha ss is g r ound ) o f al l ampli fiers on a c ommon fra me together and con ne c t a 118 AWG wi re from eac h f ra me of ampl t t r e r s t o the rack gr ou nd bus. The r ack g r ou nd bus is i n turn bond e d t o t he centa l sys te m g r o und.

GAIN Selectable: unity, +8db, +16db, +24db, +32db with f6db adjust for each range. FREQUENCY RESPONSE #0.25db 20 hz to 20Khz NOISE 75dbm absolute output noise (unity gain) 6Odbm absolute output noise (32db gain) TOTAL HARMONIC DISTORTION Less than 0.25% from 2Ohz to 20Khz (measured at +18dbm output level with 12 simultaneous split outputs) SOURCE IMPEDANCE 600 ohms or less balanced or unbalanced INPUT IMPEDANCE Greater than 20K ohms INPUT LEVEL 30dbm for +8dbm output level, 18dbm max LOAD IMPEDANCE 600 ohms balanced X 12 OUTPUT IMPEDANCE 600 ohms resistive OUTPUT LEVEL +8dbm nominal, +24dbm max after 6 splits, +22dbm max after 12 splits_ OUTPUT ISOLATION Greater than 7Odb, 2Ohz to 20Khz PHASING The low terminal number of the input pair and the low terminal number of the output pair are in phase.

POWER REQUIREMENTS 105 to 125 volts ac 6Ohz, 1SVA AMBIENT TEMPERATURE 0 c to 60 DIMENSIONS 3.4W X 3.4H X 13.70 inches WEIGHT 5 Ibs. net ACCESSORIES: MF6 600 Series Mounting Frame. 19W x 3.5H x 14.5D (less rear cable tray and cover) Standard EIA rack mounti ting: Accommodates five M612 modules or any combination of single, double or quadruple units not exceeding ten single width modules.

MFR6 600 Series Frame Receptacle_ Two required per M612. WARD-BECK SYSTEMS LTD_ WARD-BECK SYSTEMS INC. 841 Progress Ave,Scarborough,Ont M1H 2x4 290 Larkin St;, Buffalo, New York 14210 Telephone: (416) 438-6550 Telex: 06-23469 WBS TP2

GAIN Selectable: unity, +8db, +16db, +24db, +32db with #6db adjust for each range: FREQUENCY RESPONSE #0.25db 20 hz to 20Khz NOISE -75dbm absolute output noise (unity gain) ~6Odbm absolute output noise (32db gain) TOTAL HARMONIC DISTORTION Less than 0.25% from 2Ohz to 20Khz (measured at +18dbm output level with 12 simultaneous split outputs) SOURCE IMPEDANCE 600 ohms or less balanced or unbalanced INPUT IMPEDANCE Greater than 20K ohms INPUT LEVEL -30dbm for +8dbm output level, +18dbm max: LOAD IMPEDANCE 600 ohms balanced X 12 OUTPUT IMPEDANCE 600 ohms resistive OUTPUT LEVEL +8dbm nominal, +24dbm max after 6 splits, +22dbm max after 12 splits.

OUTPUT ISOLATION Greater than 7Odb, 2Ohz to 20Khz PHASING The low terminal number of the input pair ad the low terminal number of the output pair are in phase. POWER REQUIREMENTS 105 to 125 volts ac 6Ohz, 15VA AMBIENT TEMPERATURE 0 c to 601 DIMENSIONS 3.4W X 3.4H X 13.7D inches WEIGHT 5 Ibs. net ACCESSORIES: MF6 600 Series Mounting Frame.

19W x 3.5H x 14.5D (less rear cable tray ad cover) Standard EIA rack mounting: Accommodates five M612 modules or any combination of single, double or quadruple units not exceeding ten single width modules MFR6 600 Series Frame Receptacle. Two required per M612. WARD-BECK SYSTEMs LTD_ WARD-BECK SYSTEMS INC_ 841 Progress Ave_Scarborough Ont_ M1H 2x4 290 Larkin St, Buffalo, New York 14210 Telephone: (416) 438-6550 Telex: 06-23469 WBS F0

M612 DISTRIBUTION AM PLIfiER

Capa cito rs CIa and Cll couple the ba la nc e d prU IlIpl1f1er s ig nal t o t he power amplffier . Z3 and Z4. in co nj unc t io n wfth power device s QI th r o ugh Q8. form a n ac tive ly balanced ope rationa l amplif i e r wfth a 3 watt output c apabi lity. The o utp ut config uratio n dr ives t he r e s i s t i ve t we l ve-way dividing networ k RS2 th r ough R75 . Re s is t o r s R5I and R76 prov ide is ola ti on to t he outp ut t est points . The bi polar power supply en a bles th e output cir cuit to f unc t i o n wi t hout t he pr esen ce of de a t the a udf o o ut put . Pot entiome ter R33 permits th e offset vol tage to be ad j us t e d t o ze r o. Differentia l bal ance co ntro ls R28 a nd CI5 compe nsa te t he out put amplif ier a nd estab lish t he o pt i mum longitud in a l bala nce for the ampl ifier acros s t he ent ire audio range . Trim control R35 shunt s t he f e edback app l ied to R30 and R3I to pro du ce a ±6 dB gaf n c ha nge . thus th e a mplifi er ga in adjusts froll - 6 to +38 d8 t hro ugh t he cOlllbined a djustment of SWI a nd R35. The ac tive . bala nc ed out put is ro uted vi a t e r minal s 16 a nd 17 of th e subs i diary PC c a rd . The re sistive div i d i ng ne two r k operates f r om a zero i mpe da nc e source wit h the a bs e nc e of r e a c t iv e co upling compon ents su c h as capacit o rs o r transforme rs. The system ex.hl blt s 60 dB of isolation betw ee n i nd iv id ual outputs . The l oad s operate f r om twe lve t rue 600 ohm ba la nc ed sou r ces. each wi t h an output l e ve l ca pab ility e xc e e d in g +18 dBm. The out pu t test poi nt s ar e via 300 o hm re s i sto rs . hen ce. when termi nated wfth a 600 o hm l oa d. the t est poi nt leve l i s representative of t he leve l at a ll ot her correc t ly te rminate d outpu t s . Pr i ma r y ac power 15 a ppli e d via recept acle PI, pi ns 7/1 6 . powe r switch SII2 and primar y f us e F2 . Ne on i ndic a t o r DSI provides a visual ind ic ation of a pplie d a c . Tr a ns f o r mer T1 s upp lies a .c

second ary ac t o br idge rect i f ie r CRII-I4 . wl'li ch. i n co njunct1 o n ps

with f i l t e r c a pac itors C24 a nd C25. ge nerate s ±26 volt s de fo r ampl i fier a nd r e g ul a t o r operation. Se co ndary de fuse FI moni to rs BS

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W A R D - B E CK S YSTEMS LT C .

CIRCUIT DESCRI PTIDIt

"'612 DISTRIBUTIDIt AMPLIFIE R

Tra ns istors Q9 , QI0 and Ql1 . Q12 fo r . a c o. ple llen t ar y voltag e regu lato r produc ing a !I S vol ts e e o utpu t to opera te Zl and Z2.

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MA INTENANC E M61 2 DISTRI8U TlO N AMPLI FI ER

The H612 is de s igned f o r depen dabl e . troub l e- free se rvi ce; however , as with all hfgh quality e lect roni c equ1plllent. a regular sche d ule of in s pe c t i on shou l d be es t ab l ishe d . Any a c c ulllu la t 10 n of d ust s ho uld be periodically r e moved with a soft br ush an d a YaCUUIl hose. Cautfon: r e pla ce fuses wft h the corr ec t t y pe a nd r atf ng. Unde r no cfrclllista nces s houl d substitutes of high e r current caplcHy o r l onge r fus ing du ration be used. The acti ve cfrcuitry . ' y be re lloved f or in spection by unp lugg ing the MI52 c frcuft boa rd. Do not in sert o r ee acve the cOllponent boa rd withthe unitene rg~If ilfault1ss usp ected . lIu su r i ng the dc voltage pr e s e nt at th e t ra ns fs t or a nd i nte g r a ted c i rc uit pins . ay assist .to dete r llin e the cause. YOLTAGE CHART

( li ne voltage adjusted to produce ±26 volts de withfn the unft ). Pi n ' 11 12 13 14 +11.5 +1l .5 0 0 ." ." . - 18 . 00 - 18 . 00 0.62 +0.55 - 17. 5 - 17 .5 +17 . 5 +11.5 - 26 .5 -2 6 .5 +12 . 0 +12.0 - 0. 1 - 0. 1

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M612 DISTRIBUTION AMPLIFIER The M612 directly into the MF6 mounting frame which In8ta?ie may be ed in standard EIA 19-inch equipment rack The MF6 frame wil) accommodate maximum 0 f ve M612 amp] ifiers or any combination 0 f Te , double or multiple {ng9 ? width modules not exceeding ten sing width modules . If the mount frame has been procured Iess receptacles these must Ain9nstalie be ed in the 'PPPrPRE' ate module positions The M612 modu ]e requires two type frame receptacles Note that the receptac]e containing the aC Tine voltage (P1) i$ inverted to provide keying in order to Prevent inadvertent insertion 0 f other companion modules which not operate from the ac Tine Where vertica] rack space permits and where the ultimate in noise and cross talk is desired recommended to a locate only modules 0 f the ame type to each individua] MF6 mounting frame Alternatively _ possible to mix modules 0 f fferent types by exercising extreme care to separate cables 0 f different levels and functions Place Power uPp] = ies and self-powered units to the ri ght 0 f the frame (norma Practice ewed from rack front )_ Instal] insulating s ]eeves over a / 1 ac s0 |dered termina ] connections A11 externa| connections are made to the frame receptacles Refer to drawing LB612-09-001 Jumper termina I (chassis ground ) 0 f a 11 amplifiers on common frame to ether and amp] {9tees connect 018 AwG wire from each frame to the rack ground bus The rack bus i$ in turn bonded to Xro"np_ the centa system ground _ input shield bus receives a]1 input cab ]e shields for each frame 0 f amp]ifiers and is connected separately to the rack ground bus as shown schematically and pictorially.

For optimum results use isulated, shielded twisted pairs for both input and output wiri Cables operating with {"96 Tevel differences should be Taced separately Frcredic? %51 and dressed apart from other and from power wi ring. Ground hields at one end onIy The preferred system schematic 15 shown In drawing LB612-09-001. 3 -1

M612 DISTRIBUTION AMPLIFIER When comparing the measurements Tisted in the Vo] tage.chart, cons deration" should be !i ven to the fact that, for direct ed sections cona fau] in one circuit may other cause abnorma itions circuit areas - ( | ? The preset adjustments associated with the M612 are factory set and hould not be varied by field personne| unless absolutely necessary In the event that it becomes necessary reestablish correct contro] settings_ the fo]lowing implified adjustment procedure may be followed a ) With no Toads connected to the amplifier insert microammeter between one 0f the output test nts and ground Adjust OFFSET contro] R33 for m89i= imum current typicaily Tess than uA): Transpose the meter to the other output test point and repeat the adjustment Equalize the tota o ffset current between the upper and Tower active sections 2-3 approximately uA per side) 4`^ ' ~'" - b ) Apply ba lanced 60 Hz s igna 1 source to: the amplifier and observe the autpvr . wa veform 45inga an osci]loscope directly or via Remove the lanced gna and short the two nput termina ] s P2-16 and P2-8 together Now apply the 60 Hz source between the shorted inputs and ground_ This Will produce difference s igna] at the output Adjust R28 for minimum output- Repeat the difference test a $ above with 15 kHz sTgna / Adjust C15 for min mum output. Repeat to optimize the settings .

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M612 DISTRIBUIION_AMPLIEIER The M612 is des igned for dependab]e trouble-free service; however, as with a11 high quality ectronic equipment, regular chedule 0 f inspection should be established _ Any accumulation 0 f dust should be periodica]ly removed with soft brush and vacuum hose Caution: replace fuses with the correct type and rating _ Under no circumstances should substitutes of higher current capacity or Tonger fusing duration be used The active circuitry may be removed for inspection by unplugging the M152 circuit board Do not insert remove the component board with the unit energized If fault is suspected, measuring the dc voltage present at the transistor and integrated circuit pins may a ssist to determine the cause VOLITAGE_CHARI (Line Vo | tage adjusted to produce +26 volts dc within the unit) Pin +11 +11 18 18 00 17 17.5 +17 +17 26 26 +12 +12 # 26 0 .

62 8.52 25 -26 +25 8 8 Q8 8 26 26 26 _ +26 .0 25 25 25 +25 +17 .5 +18 26 18 -18 -26 0 . 62 -18 Q12 -18 . 0

M6 1Z DI STRIBUTION AMP LI FIER

PART DESCRIPTIOH "FG MFGPART NUMBER

."'" R es 1 ~ t or 411 51 '" " Ph! lfps

". "3 R4S '" '" " ... '" R47

"0 Ru t:to r 1s11 51 '"10 10 10 10 Resistor .W 51 '" '" Res f ~tor 'til 51 300 JOO

". . R5 3 m 300 300 300

... ess m m 300 300 300

..,, 300 . .0 300 300

... R63 300 300

......65,, JOO 300

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JOO m 300 BS

R73 300 W

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PARTS LIS T 1'1612 DISTR IBUTION AMPLIFIE R

PART