Hafler TRM12S manual TRM10S/12S Functional Block Diagrams, Input circuit

Page 26

TRM10S/12S FUNCTIONAL BLOCK DIAGRAMS

Input circuit

The stereo input signals are connected to the amplifier through balanced XLR connectors J8 and J1, or unbalanced RCA connector TP2. Unbalanced operation can be selected with switch DS1, which grounds the RCA shell through R37. Input buffers U1 and U10 provide a stable input impedance, dominated by R10, R4, R42, and R32. The left and right balanced summing amplifiers U4A and U3A sum the inverting and non-inverting signals to form unbalanced right and left channel outputs RCH and LCH. The Common Mode Rejection Ratio (CMRR) of each channel is optimized with trimpots R8 and R58.

 

 

! Qualified Service Personnel Only

 

 

 

INPUT CIRCUIT

 

 

RCH

 

NON-INV

 

 

 

INPUT

 

 

 

 

 

BUFFER

 

RCH

 

J8

 

 

 

 

U1A

 

BAL

 

TP2

 

 

 

 

 

 

SUMMING

 

R10

 

 

 

 

 

BAL / UNBAL

AMP

 

R4

DS1

 

U4A

RCH

 

R37

 

 

 

 

 

R109, R110,

 

 

 

INV

 

 

 

 

CMRR

R111,R112

 

 

 

BUFFER

 

 

 

 

R8

 

 

 

 

U1B

 

 

 

 

 

 

 

LCH

 

NON-INV

 

LCH

LCH

 

BUFFER

 

BAL

INPUT

 

 

 

 

U1OA

 

SUM

 

J1

 

 

 

AMP

 

TP2

 

 

 

U3A

 

R42

 

 

 

R64 , R61

 

R32

 

 

 

R104 , R62

 

 

 

INV

CMRR

 

 

 

 

R58

 

 

 

 

BUFFER

 

 

 

 

 

 

 

 

 

U1OB

 

 

 

Mono Sum/Gain Circuit

Left and right input signals LCH and RCH are summed to mono through R49 and R51. The mono signal is then attenuated in two stages with dual potentiometer RV1 which is accessible from the rear panel heatsink and serves as the gain control. R56 and R83 determine the maximum achievable attenuation level. R59 and R66 help to reduce the tracking errors of RV1 due to absolute resistance. Buffer U3B unloads the attenuators and provides 6dB of gain with R25 and R73.

 

MONO SUM / GAIN CIRCUIT

 

 

 

SUB ATTN

GAIN

 

 

R59, R56

RCH

L/R SUM

U3B

RV1B

LCH

R49, R51

R25

R66, R83

 

 

R73

 

 

RV1A

 

 

 

Phase Control Circuit

The output signal of U3B goes directly to U4B if DS2 is left open

(0 degrees phase shift). If only DS2 is closed, the signal goes through 2 cascaded phase shift stages built around U6A and U6B, and experiences a 270 degree phase shift. Additionally closing DS3 causes the phase shift to be 180 degrees. Adding another closed switch DS4 results in only 90 degrees of phase shift. DS2, DS3, and DS4 are labeled 2,3, and 4 respectively on the rear panel heatsink.

Buffer/Gain Trim Circuit

U4B works as a buffer, and as a factory gain trim using trimpot R136. The voltage gain of the stage is (R74+R136)/R137.

Filter Circuits

TU112A and U112B form two cascaded 2nd order variable low pass crossover filters, for an overall 4th order 24dB/octave Linkwitz-Riley response. The quad potentiometer R29 is accessible from the rear panel heatsink and indicates the 40Hz to 140Hz range of the variable Low-Pass crossover. Following these circuits is a 2nd order subsonic High-Pass filter at U2A. The signal then connects to the Class-G amplifier.

PHASE CONTROL CIRCUIT

 

BUFFER / GAIN TRIM

 

 

 

CIRCUIT

-180º PHASE

-90º PHASE

DS2

BUFFER/

 

SHIFT

SHIFT

 

GAIN TRIM

U6A

U6B, R113, R120,

 

U4B, R137,

R100, R107,

R114, R123,

 

R74, R136

R101, R132,

C89, C74,

 

 

C86, C73,

 

 

 

D53

D54

 

 

FILTER CIRCUITS

2ND ORDER VARIABLE LP

2ND ORDER VARIABLE LP

U112B

U112A

R29A, R85

R29C, R164

R29B, R98

R29D, R130

C64, C48

C46, C45

2ND ORDER

 

SUBSONIC HP

CLASS G AMPLIFIER

U2A

 

C36, C42

 

R44, R82

 

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Image 26
Contents TRM10s TRM12s Declaration of Conformity Cmrr Damage Requiring Service Power SourcesCleaning Power Cord ProtectionCuadros DE Advertencias LEA LAS InstruccionesConserve EL Manual DEL Propietario Siga LAS InstruccionesConserver LE Guide DE Lutilisateur Suivre LE Mode EemploiLire LES Instructions Considérations DE Mise EN GardeInstruktionen Lesen Erforderlicher ReparaturserviceService Betriebsanleitung AufbewahrenAvvertenze Leggete LE IstruzioniConservate IL Manuale Seguire LE IstruzioniOperation InstallationService Reference Technical Design Features IntroductionMehsa Subsonic Filter TRM10s H E M a T I C D I a G R a M Page Removable Center Spread Qualified Service Personnel Only Output Circuitry Location Studio InstallationsHome Theater Installations Input From Source Input SwitchXLR Wiring Configurations Inputfrom SourceLOW-PASS Crossover Auto TURN-ON / Sleep ModeInput Sensitivity Electrical Crossover ResponsePhase Control Setup ProcedureAC Line LED IndicatorCleaning & Maintenance BREAK-IN and WARM-UPPC Board Layout CR2R T S L I S T Designator ValueQuavec des composants identiques TRM10S/12S Functional Block Diagrams Input circuitClass-G Transana Amplifier Power On/Off Circuit Circuit Calibration Amplifier Replacement Woofer ReplacementHow to obtain service or technical support Length of WarrantyWhat is Covered R V I C E P O L I C Y a N D L I M I T E D W a R R a N T YMade in the USA

TRM12S, TRM10S specifications

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