Page 1

drip seven

designed by gregory lomayesva

THIS DESIGN USES HIGH VOLTAGE - USE CAUTION client copy not for pulblic release

SPECIFICATIONS INSTRUCTIONS BILL OF MATERIALS NOTES AND COMMENTS SCHEMATICS ERRATA WARNINGS rev 1 : 3/6/2018

U73b COPYRIGHT 2018 GREGORY LOMAYESVA


U73b tube compliment per channel e88cc e99f (6bj6) e99f (6bj6) e80cf (6bl8) 5ar4 (psu) or us 2x 1n4007 diodes (use only one in psu) total heater current per channel 1 amp @ 6.3v total high voltage current per channel 20mA (max) @ 215V transformer compliment per channel sowter 1505e (input/interstage/control amplifier output) sowter 9375e (output amplifier plate choke) sowter 1275e (signal amplifier output transformer (10:1)

x3 x1 x1

power transformer recommended ratings : for 2 channels 250-0-250 @ 60ma (500V) 6.3V @ 2.5 AMPS 5V @ 2 AMPS (IF USING 5AR4 RECTIFIER TUBE) HAMMOND 370BX INTERNATIONAL (a better transformer in general) HAMMOND 270BX NORTH AMERICA


U73b OUTPUT amplifier

ZERO ADJUST 200uA

+

OPTIONAL 600T ATTENUATOR XLR IN

OUT

160V plate

31 10K

sowter 1505e 1:1 orange

1/2 E88CC

U73b INPUT amplifier

10K

E99F

01

yellow

secondary HI

SUPPRESSOR

1:1

GRID

10K 32

brown

VARIABLE INPUT PAD

6.3V

SYMETRY

INTERSTAGE

blue

cathode GRID

red

SUPPRESSOR

blue

CONTROL VOLTAGE (NEGATIVE)

plate

50R 28

160V

40V

ATTACK 10K 80

COPYRIGHT 2018 GREGORY LOMAYESVA PIN1

MAY BE VARIABLE PCB IS FIXED @ 10K OMIT RESISTOR ADD POT (100K)

PIN2 to E80CF grid

sowter 1505e

E99F

02

time (control line) PIN3

red

SCREEN

secondary LO

INPUT TX

U73b CONTROL amplifier

white

HEATER

to control amplifier

64

green brown

250R

6.3V

tertiary

THRESHOLD 100K POTENTIOMETER

40 10K

cathode balance

white CT

TO OUTPUT AMPLIFIER GRID

09

61

HEATER

notes : R61 is cathode balance use this trimmer to balance out artifacts during compression and limiting the tubes must be balanced before calibration begins

CT

COM

cathode

SCREEN

XLR3

CONTROL VOLTAGE

39

65

100K

5K

B+ 170v

170V

50 500K

70V

215V

PLATE

110V

SUPPRESSOR SCREEN GRID CATHODE HEATER

22 1 UF 200V

LIMITER

E80CF +

78

LIM COMP SWITCH

PIN 2 PIN 1

79 5K

79

COMPRESSION CATHODE BIAS

CALIBRATE ME

1:1

CATHODE

80V 300K 54

21 100UF 53 1M

CONNECT TO VARICOM PCB

GRID

HEATER

PIN 3

23 25UF

+

04

49 3K

COMPRESSOR

PLATE

notes :

when the unit is in comp mode ,the E80CF pentode is fix biased with a 3k resistor that is bypassed with a 100uf capacitor and the cathode is adjustable via R79 (5k) when in limt mode - the bias is fixed to 3k/100uf

100K orange 52

84

red

blue NEGATIVE BIAS FROM R63

sowter 1505e CONTROL OUTPUT TX

1.6K 44

PIN 1

notes :

1M 46

CATHODE

1.8V HEATER

500R 47

PIN 2 PIN 1

10:1

IN

1K 63

OUTPUT FIRST STAGE CATHODE BIAS

V72 OUTPUT SOWTER

215V

COPYRIGHT 2018 GREGORY LOMAYESVA

COM

XLR OUT

OUTPUT TX

10 UF 450V

10 UF 450V 170V

B+ 170v

ADJUST FILTERING TO 100UF@450V FOR OPTIMAL PERFORMANCE

10 UF 450V

XLR 1

XLR 3

sowter out

CALIBRATE ME

80K 170V 83 BZX79 5V

pos 63 pre biases the limiter essentially trimming the output volume when the unit is in limit mode

OUT

XLR 2

PLATE CHOKE V72 SOWTER

100UF 18

43

63 85

78

11 .025 @400V

10 UF 450V

PIN 2

limit 78 white

14

PIN 3

600 T ATTENUATOR

20

B+ 215v

TIME CONSTANT

PIN 3

brown

500PF

67 10K

GRID

LIMIT

LIMITING BIAS

comp

green

2K 42

1/2 E88CC

HEATER

COMPRESSOR

4UF/400V

2 UF/400V 19

PLATE

CALIBRATE ME

NEGATIVE BIAS FROM R63

yellow

170V

TIME

REFRENCE TIME CONSTANT DATA SHEET TIME CONSTANT MAY BE WHAT EVER YOU DESIRE ORIGINAL OR CUSTOM

215V VARICOM Z

notes : R67 adjusts the cathode of the output amplifier first gain stage. when the unit is in compression the cathode is biased with R67 and bypassed with a 100UF capacitor when in limit mode - the cathode is not bypassed with the 100uf capacitor

CATHODE

67

10 UF 450V

B+ 215v 51 200K

300K 41

OUTPUT AMPLIFIER GRID

62 FBK 100K PIN 3

IN

4K 33 primary green

10 50PF @400V

62 PIN 2

yellow

GRID

XLR2

81 25K PLATE

PIN 1

orange

SCREEN

0.1 @ 400V

CALIBRATE ME

notes : the feed back structure of the u73 has similarities to the V72 line amp. pos 62 will adjust the final makeup gain of the output amplifier.

TO TUBE HEATERS PILOT LAMP METER LAMP

drip seven U73b DOCUMENT MY NOT BE PUBLISHED WITHOUT WRITTEN CONSENT FROM GREGORY LOMAYESVA (info@dripelectronics.com)

6.3VDC

56 3K

@ aprox 20ma B+ 215v TO POWER SUPPLY PCB

6.3VDC TO POWER SUPPLY PCB

@ aprox 1 amp

(per channel)


ultra psu schematic

ADJ ADJ

PIN 2 PIN 1

79 5K

HIGH VOLTAGE TRIM

1N4738

FILM 10 UF 600V

100 UF 450V

GND

INPUT ENABLE

1K

OUTPUT

REGULATED 6.3VDC +

470K STPS5L40 (5AMP)

5AR4 47K

953R

.1/100V

IN

1K2W

470K

1K2W 100 UF 450V

FILM 10 UF 600V

100 UF 450V 5 VAC 2 AMPS 10H 400V OPTIONAL

COPYRIGHT 2018 GREGORY LOMAYESVA

10K TO 15K UF @ 10V

ADJUST

MJE3439

OUT

PIN 3

240R

FOR ADJUSTABLE VOLTAGE : OMIT 1K RESISTOR PLACE 953R RESISTOR AND 100R TRIMMER

10K TO 15K UF @ 10V

ADJ

ECB

HIGH VOLTAGE TRIM

10K TO 15K UF @ 10V

REGULATED HIGH VOLTAGE OUT

LM317HV

100R

adjust values

240R OUT

PIN 1 PIN 2 PIN 3

10K TO 15K UF @ 10V

41K = 215V 57.3K = 300V 52.56K = 275V

1N4007

GND

10K TO 15K UF @ 10V

41K = 215V 57.3K = 300V 52.56K = 275V

100 UF 450V

DRIP HEATER

MIC29502WWT : 5AMP 470K

DRIP HIGH VOLTAGE

1N4007 PLACE ADJUST RESISTOR TO EQUAL NEAR THE DESIRED VOLTAGEUSE ADJ TRIMMER TO ADJUST TO FINAL VOLTAGE

FOR FIXED VOLTAGE: PLACE 1K FOR FIXED VOLTAGE OMIT TRIMMER AND 953R RESISTOR

MIC29752WWT : 7AMP

DOCUMENT MY NOT BE PUBLISHED WITHOUT WRITTEN CONSENT FROM GREGORY LOMAYESVA (info@dripelectronics.com)

1N4007 PROTECTION DIODES 550 VAC

6VAC 2.5 AMPS

dripseven

DOCUMENT MY NOT BE PUBLISHED WITHOUT WRITTEN CONSENT FROM GREGORY LOMAYESVA (info@dripelectronics.com)

COPYRIGHT 2018 GREGORY LOMAYESVA


section notes : contained in this area is the high voltage solid-state voltage regulator circuit - good up to 400v beneath the regulator is the AC mains hook up and power switch connections SS high voltage regulator

mains/power switch hookup

drip psu

the drip LDO heater regulator is a 7.5 amp (optionally 5 amps) a super low noise design with 1% regulation and adjustable fine tune trimmer

250mA tube rectifier

power transformer hookup a 5ar4 tube is utilized as the main high voltage rectifier. protection diodes and optional diode footprints have been added to bypass the tube and use diodes only. a choke hookup has been added , however may be bypassed and skipped.

regulated LDO heater supply

sma power to main board

xlr socket pcb with bypass

chan 1/2 xlr i/o/main board signal connections the xlr pcb uses pcb mount xlr sockets or may be hard wired to xlr sockets. two (hard) bypass relays are used per channel additionally a mute relay has been added grounding the output of the pcb while in bypass mode. connections may be sma or 10 pos cable.

an output attenuator (600 ohms) has been added for adjustment of the output signal post transformer. the original design does not have this control

threshold controls the amount of compression (signal to the control amplifier )

drip control

an input attenuator has been added to allow adjustment of the incoming audio signal (essentially an adjustable input pad)

time constant : you may adjust the time constant to the original specifications , however the release times in the original may be outdated for modern applications. the above configuration is the time constant of the fairchild 670 , a lovely set of time constants . this section is adjustable to what ever you desire)


instructions use pcb a template to mark holes on enclosure if it is not pre-drilled

connect signal source / calibrate close lid enjoy your new u73b

place parts as indicated on the pcb set silkscreen legend solder parts as indicated mount/solder wires of transformers as indicated mount boards in case connect sma cables / ribbon cables fire up - test voltages

ERRATA : 3/6/2018 R33 designator MISLABELED AS R43value on silk is correct R33 designator IS DUPLICATED TWICE value on silk is correct CONTROL TRIMMER designator IS LABELED TWICE WITH 78 AND 79 (IS 78 NOT 79) value is correct E88CC LABEL ALSO HAS 6JD8 TUBE IS ECC88 R180 AND R107 ARE THE SHUNTS FOR THE PLATE CURRENT MONITORING - THIS WILL NOT BE USED AND THESE (R107/180) SHOULD BE JUMPED ftc time constant needs 220k across + and -


drip U73b overview : front panel pcb

the drip u73b pcb set is a dual mono compressor limiter design based on the historic German u73b feed forward design. shown is one channel of the main pcb board . the design is duplicated and v-scored (this allows you to snap the board in half to create two separate boards) included in the pcb set : 1 main board with two u73b pcbs (arrayed and v-scored) 1 dual channel tube rectified / ss high voltage regulator and dc regulated heater board with xlr in/out bypass control.

powersupply and xlr pcb

2 front panel control pcb’s (this pcb holds the input/output attenuators / threshold / time constant) this new design is a straightforward buid. all connections are made with SMA cables or ribbon cables (you may use 2 ribbon cables per channel or for the highest degree of signal integrity you may use sma cables for the critical signal connections) intended for use with Sowter transformers it is possible to use different brands of transformers ( if mounted off board or adapted to the pcb transformer footprint.

drip U73b 1/2 main pcb


front panel hook up instructions

26 position 2.54 ribbon cable (polarity must match up to designators indicated)

connect sma cables match names

ribbon estimated hookup time : 10 sec

or use sma estimated hookup time : 1 min

sma

estimated hookup time : 60 seconds


10 position 2.54 ribbon cable (polarity must match up to designators indicated) two sma cables are used to connect power to the pcb 6.3v@1AMP 215V@20mA use rated sma cable

3 cables power supply hook up instructions estimated hookup time : 2 minutes

audio cable (in and out ) channel 1


hook up to power pcb

get to know me map

control amplifier

output attenuator

varicom hook up

limiting and bypass hook up

reduction threshold

ribbon cable front panel i/o

xlr input pad (attenuator)

time constant (fairchild 670 or traditional)

REDUCTION METER

sma front panel i/o output attenuator i/o

input amplifier

solid state high voltage regulator

i/o to xlr pcb and main pcb sma front panel i/o

meter hook up meter lamp

tube rectifier

super heater regulator

xlr in/out/bypass relays chan 1 and 2

ribbon cable front panel i/o

output attenuator i/o output amplifier xlr i/o/bypass trigger input amplifier plate current metering (optional)

signal transformer foot prints

mains hookup

secondary hookup

power to main board

signal i/o to main board and front panel


P2 max - + 8 dB is not exceeded at any point

set unit to compressor

take measurement @ input and output xlr across pin 2 and 3 meter set on ac (rms)

}

1

output volume @ xlr out pin 2/3 vrms

3

sweep test tone on input from +6 to +16 output should not rise above +8 dB - if necessary adjust R64 (100k threshold on front panel)

calibration : limiter mode

output P2 (db) volume

2

set test tone to -4db level should be +2dB on output (p2)

2

1

2. adjust trim 62 (fbk) make output level -10db

Set trimpot 63 (-5v bias) to center position, input signal 1kHz +16 dB adjust trimpot 79 (limit idle) for an output level of +7dB

output volume

calibration : compressor mode

set 1k test tone to -10 dB on input adjust output with trimpot 62 (fbk) so output measurement is -10 dB (fbk : feedback)

1. input level test tone 1khz -20db

-20dB

0dB P1 (db)

input volume

input volume measured @ xlr input socket pins 2/3 RMS

U 73, operating mode “compressor” (The adjustment of the U 73 basically starts in this mode!) Operating mode switch to “Compr.” input level p I = - 20 dB, Measuring frequency f = I kHz. Adjust output level with controller pos. 62 Jen on p2 = - 10 dB. Input level pl = - 4 dB, level should be P2> + 2 dB. Measuring frequency f= I kHz. The output Increase input level steadily in the range Pl=+ 6 ... + 16 dB, MeB frequency f = 1 kHz. The output level may be the highest P2 max - + 8 dB is not exceeded at any point. If necessary, Set the maximum value with controller Pos. 64 . This is the adjustment of the U 73, operating mode “compressor”, be ends. Items 62 and 64 must be checked during the subsequent adjustment work can not be adjusted anymore.

4

input volume repeat step 3 adjust trimpot 63 and 79 until its right (63 and 79 influence each other)

3

1kHz +16 dB adjust trimpot 63 so output is +6dB plus or minus (-0.5/+1.5 dB) and doesn’t rise above it by increasing the input tone replace e99f tubes if step 3 can not be achieved


if tx has one

green / yellow

green

green

red / yellow

red

red

yellow

yellow

white USA

black USA

ground to chassis (earth)

to main pcb 6.3V

hammond 270/370bx

TO CHANNEL 1 and 2

to main pcb 215V

isolate grey (USA) to power switch

PSU TRANSFORMER CONNECTIONS

ground to chasis (earth)


SIGNALTRANSFORMER CONNECTIONS

SOWTER TRANSFORMER 1:1

orange

INSERT FROM TOP SIDE OF BOARD SECURE WITH NUT ON BOTTOM SIDE

green

1:1 orange

yellow

yellow

green brown

white

red

blue sowter 1505e

NOTE : PCB HAS TWO WHITE PADS YOU WILL ONLY USE ONE

brown

white

red

blue sowter 1505e

wire plate choke here control amplifier output sowter 1505e

signal interstage sowter 1505e

COLOR CODED LEADS

place sowter E type transformer 3/8 post into hole and bolt on to the pcb - do not use excessive force when tightening bolt.

plate choke sowter 9375e

note the transformer type to be inserted not in use

pad to solder to color code

} strip tin and solder color coded leads to their appropriate pad with the labeled color next to it

not in use

input transformer sowter 1505e

output transformer sowter 1275e


red

blue

red

blue

red

blue sowter 1505e

SOWTER TRANSFORMER brown

red sowter 9375e

OUTPUT TRANSFORMER SOWTER TRANSFORMER 10:1

white

red

grey

pink sowter 1275e

hammond 300x series transformer 240V COLOR CODE DIAGRAM PRIMARY WINDING blue

240V isolate(connect to nothing)

blue/yellow brown/yellow brown

hammond 270bx

JOIN AND ISOLATE

isolate(connect to nothing)

black

black/red

white/black

NEUTRAL

USE FOR NORTH AMERICA 120V

this side of the power transformer is intended to receive the mains voltage of your house (the power company) this side of connections will include the IEC power inlet socket (i.e. the plug where you insert the power cord) and the power switch. all unused wires will be live when the transformer is energized use care and caution when installing and wiring.

white

GREY (ground this) isolate GREY HOT 115V

PLATE CHOKE

POWER TRANSFORMER COLOR CODES

SIGNAL TRANSFORMER COLOR CODES

yellow

sowter 1505e

red

sowter 1505e

if tx has one

white

green / yellow

brown

WHITE NEUTRAL

white

6.3VAC

brown

green

white

green

brown

red / yellow (ALWAYSGROUND)

green

green

BLACK HOT 120V

yellow

5VAC

green

orange

yellow

yellow

orange

yellow

550VAC

1:1

1:1

red

SOWTER TRANSFORMER

SOWTER TRANSFORMER

1:1

}

SOWTER TRANSFORMER orange

CONTROL OUTPUT TRANSFORMER

INTERSTAGE TRANSFORMER

}

INPUT TRANSFORMER

NOTE : NEVER NEVER GROUND THE 6.3V CENTER TAP LEAD (GREEN-YELLOW) IF YOU USE AN ALTERNATE STANSFORMER THAT HAS A 6.3V CENTER TAP TO 270 /370BX DOES NOT HAVE ONE ISOLATE - DO NOT GROUND

NOTE : USE ABSOLUTE CAUTION WHEN WORKING IN THIS AREA . NEVER HAVE THE UNIT POWERED OR PLUGGED IN MAINS VOLTAGE : USE CAUTION

note : the gray wire on the 300x series hammond transformer is the electro static shield - it is intended to be GROUNDED to the chassis . on the 200x series hammond transformers THIS IS LIVE part of the primary winding and NOT the electrostatic shield.


1

2

input level test tone 1khz -20db

set unit to compressor

output (y-axis)

cal step 1 compressor mode

COPYRIGHT 2018 GREGORY LOMAYESVA

output xlr measurment -10db

adjust trim 62 (fbk) make output level -10db

input tone -20db

input (x axis)

input xlr

-20dB

1

u73b

-10dB

2 external signal generator 600 ohms

1khz sine set to AC volts ~

output xlr

1 2

3 take measurement @ input and output xlr across pin 2 and 3 meter set on ac (rms)

0.077 Volts -20.000 dBu -24.000 VU

1khz sine

3

600 ohms 0.245 Volts -10.000 dBu -14.000 VU


output (y-axis)

COPYRIGHT 2018 GREGORY LOMAYESVA

cal step 2 compressor mode

1

2

input level test tone 1khz -4dB

output xlr measurment +2dB

if output is not +2dB adjust 62

input tone -4dB

input (x axis)

input xlr -4dB

1

u73b

+2dB

2 external signal generator 600 ohms

1khz sine set to AC volts ~

output xlr

1 2

3 take measurement @ input and output xlr across pin 2 and 3 meter set on ac (rms)

0.489 Volts -4.000 dBu -8.000 VU

1khz sine

3 600 ohms

0.975 Volts 2.000 dBu -2.000 VU


output xlr measurement should not rise above +8dB if it does - adjust threshold on front panel (64)

64

until this is achieved

input level test tone 1khz sweep from +6 to +16 dB (slowly)

input tone sweep from +6 to +16 dB

external signal generator 600 ohms

1khz sine set to AC volts ~

1.546 Volts 6.000 dBu 2.000 VU to 4.887 Volts 16.000 dBu 12.000 VU

input (x axis)

input xlr

+16dB +6dB

output (y-axis)

cal step 3 compressor mode

COPYRIGHT 2018 GREGORY LOMAYESVA

1

u73b

output xlr

+8dB

2

1 2

3

take measurement @ input and output xlr across pin 2 and 3 meter set on ac (rms)

1khz sine

3 600 ohms

1.946 Volts 8.000 dBu 4.000 VU


output should read -10dB if not adjust 62 so that the output reading is -10

output (y-axis)

cal step 4 limiter mode

COPYRIGHT 2018 GREGORY LOMAYESVA

set unit to limter mode input level test tone 1khz -10dB

0.245 Volts -10.000 dBu -14.000 VU

input tone -10dB

input (x axis)

input xlr

-10dB

1

u73b

+8dB

2 external signal generator 600 ohms

1khz sine set to AC volts ~

output xlr

1 2

3

take measurement @ input and output xlr across pin 2 and 3 meter set on ac (rms)

1khz sine

3 600 ohms

0.245 Volts -10.000 dBu -14.000 VU


cal step 4 limiter mode

COPYRIGHT 2018 GREGORY LOMAYESVA

output (y-axis)

output should read +7dB

set unit to limter mode Set trimpot 63 (-5v bias) to center position, input signal 1kHz +16 dB adjust trimpot 79 (e80cf cathode adjust) for an output level of +7dB

input level test tone 1khz +16dB

4.887 Volts 16.000 dBu 12.000 VU

input tone -10dB

input (x axis)

input xlr

+16dB

1

u73b

+7dB

2 external signal generator 600 ohms

1khz sine set to AC volts ~

output xlr

1 2

3

take measurement @ input and output xlr across pin 2 and 3 meter set on ac (rms)

1khz sine

3 600 ohms

1.734 Volts 7.000 dBu 3.000 VU


COPYRIGHT 2018 GREGORY LOMAYESVA

cal step 6 limiter mode

+6dB plus or minus (-0.5/+1.5 dB) and doesn’t rise above it by increasing the input tone adjust trimpot 63 so output is +6dB plus or minus (-0.5/+1.5 dB) and doesn’t rise above it by increasing the input tone

input level test tone 1khz +16dB

repeat step adjust trimpot 63 and 79 until its right (63 and 79 influence each other)

4.887 Volts 16.000 dBu 12.000 VU

replace e99f tubes if this cannot be not be achieved

output (y-axis)

set unit to limter mode

the end your unit is calibrated

input tone -10dB

input (x axis)

input xlr

+16dB

1

u73b

+6dB

2 external signal generator 600 ohms

1khz sine set to AC volts ~

output xlr

1 2

3

take measurement @ input and output xlr across pin 2 and 3 meter set on ac (rms)

1khz sine

3 600 ohms

1.546 Volts 6.000 dBu 2.000 VU


TOP SILKSCEEN

IDC2

C18

B

JMP3

SW78A

TIME

out cat

THRESH PIN3

JMP10

R1ZERO

R40 JMP14

BLANK2

R28

V2

JMP18

JMP17

V3

GR METER

R79 TVS2 JMP20

GRID LO

D60

C21

D84

R49

PILOT LAMP

C

GRID HI

SW78B

JMP22

JMP23

D85

THRESH PIN2

R61 JMP37

JMP16

JMP13 JMP21

JMP12

E

JMP11

JMP9

NONAME3

JMP8

JMP30

R47

V1

R67

D61

R39 JMP28

R62

C11

C19

C9

JMP7

JMP33

R30

R41 R42

C14

JMP19 R90

LOW 170V

R78

JMP2

R81

R43 D83 R44

JMP25

JMP27

R33

C10

R46

R60

JMP36

R31

HI-170V

R45

VR1

C80

R32

B+

D

R65 JMP1

C81

SMA1

R107

CE1

JMP34

SMA2

R180

COMPONENT LEGEND

NONAME2

IDC1

SMA3

C20

LIM LAMP

LIM/COM

JMP24

V4

R51

R53

R54

R52

C23

6.3V

215V

BYPASS

JMP26

C22

R50

BLANK1

F

CE2

CE3

CE4

CE5

CE6

CE7

JMP29

R80

JMP35

JMP31

JMP32

R56

NONAME1

VARICOM

SMA3

R180

SMA2

SMA1

COMPONE

NONAME2

D

C20


front panel pcb bill of materials (single channel)

front panel bill of materials (single channel)

2 bourns 600-t attenuators (with pc pins) 1 bourns 91 100k lin potentiometer 1 grayhill 1 deck 2 poles series 71 rotary switch 1 26 pin 2.54 idc box header 11 sma pcb connectors (vertical) 2 10 pin 2.54 idc box headers 6 .7� violet jumpers preformed 1 1.0� brown jumpers preformed 3 1n4007 diodes if using the fairchild 670 time constant : reference (tradition time constant set up sheet) 1 8uf axial capacitor 150v (may use panasonic radial film) (8.2uf) 1 4uf axial capacitor 150v (may use panasonic radial film) (3.9uf or 4.7 uf) 1 20uf axial capacitor 150c electrolytic (22uf) 2 film 2uf 200v radial capacitors (panasonic) (2.2uf) 2 100k 2w resistors 1 68k 1w resistors 1 470k 1w resistors 1 220k 1w resistor (errata)

note - before soldering the attenuators you will need to elevate them to the correct height - then solder to the pcb use the front panel as a template - so all switches are aligned and to the correct height so the pcb does not flex upon insertion of the controls into the front panel holes. the bourns 91 and grayhill switch may be placed and soldered for they are at the correct height.

vu meter 3� illuminated 200uAdc meter model simpson 27 (instrument meter specialties) 4 PN-9C (PN21M) 33.5MM Bakelite knobs with screw lock (ebay) 2 chicken head knobs if using rotary switches for bypass and limit/comp additional front panel parts : 3 carling 110 toggle switches (power-bypass-limit/comp) 432-1216-ND

external locking pots for calibration zero adj 10k locking sym 61 : 250 ohm locking fbk 62 : 100k lin locking bias 63 (5v) : 1k ohm locking limit 79 : 5k locking cathode 67 :10k locking

RV4L103C-ND RV4L251C-ND RV4L104C-ND RV4L102C-ND RV4L502C-ND RV4L103C-ND


BACK PANEL COMPONENT LAYOUT inside enclosure view

QUANTITY

IEC POWER INLET (FUSED) 1 PCS POWER INLET MODUAL WITH FUSE DRAWER 2 PCS 4-40 SCREWS 2 PCS 4-40 KEPS NUT 2 PCS 5X20 SLO BLO GLASS FUSE @1AMP 250VAC (4 EXTRA FOR REPLACEMNT)

G

GROUND PIN IS FLOATING (OPTIONALLY GROUND) PIN ONE IS GROUNDED TO CHASIS

DIMENSIONS FROM OTHER SIDE OF BACK PANEL

1

2

PIN THREE IS LOW (NEGATIVE)

3 G

PIN 2 IS HOT (HIGH) POSITIVE

duplicate holes for stereo

3

PLACMENT OF POWER GROUND HOLE 6/32 HOLE FOR CHASIS GROUND SOLDER TAGS 1 PCS 6/32 1/2 INCH SCREW 1PCS 6/32 KEPS NUT (LOCKING)

XLR SOCKETS MALE/FEMALE

DOUBLE ROW TERMINAL BLOCK 4 PCS 4-40 3/4 SCREWS 4 PCS 4-40 KEPS NUTS

POWER TRANSFORMER 270BX USA (120V) 370BX INTERNATIONAL UNIVERSAL PRIMARY

POWER TRANSFORMER MOUNTING BOLTS AND NUTS 4PCS 10-32 1/2 INCH 4PCS 10-32 KEPS NUTS (LOCKING)

6/32 HOLE FOR CHASIS GROUND SOLDER TAGS

4-40 KEPS NUT

6

6-32 SCREW

6

6-32 KEPS NUT

4

10-32 SCREW

4

10-32 KEPS NUT

6

6-32 LOCKING SOLDER TAG CARLING 110 TOGGLE SWITCH - POWER SW IEC FUSED POWER INLET 9 POS 2 ROW BARRIER STRIP (INSULATED) 18 GAUGE WIRE 3 COLORS SOLID CORE PREFFERED 5X20 SLO BLO FUSE 1 AMP GLASS HEAT SHRINK TUBE

1 1

1

BACK PANEL MOUNTING SCREWS AND NUTS

G

1

3 PCS SOLDERING TAGS 1 3

OUTPUT XLR CONNECTOR 1

1 PCS 6/32 1/2 INCH SCREW 1PCS 6/32 KEPS NUT (LOCKING)

INPUT XLR CONNECTOR

EXTERIOR VIEW

4 PCS 6/32 SCREWS 4 PCS 6/32 KEPS NUT

2

3 PCS SOLDERING TAGS

10

4

4 PCS 4-40 SCREWS 4 PCS 4-40 KEPS NUT

PLACEMENT OF AUDIO GROUND HOLE

4-40 SCREW

1

INPUT XLR HAS RELEASE TAB

if using pcb mount xlr sockets referance psu mounting template and hole pattern sheet

10

1

1

2

DESCRIPTION

1

OUTPUT XLR SOCKET WITH SOLDER CUPS INPUT XLR SOCKET WITH SOLDER CUPS HAMMOND 270BX (USA) 370BX INTERNATIONAL POWER TRANSFORMER


this is an example of a very secure and professional way of wiring the mains /transformer and power switch

ISOLATE

MANUAL HARD WIRING OF TRANSFORMER united states (north america 120v) isolate(connect to nothing) isolate(connect to nothing) isolate(connect to nothing)

otherwise the pcb has the mains and power switch wiring on board (use that) you may cut and individually shrink tube the unused wire then bundle and zip tie if you do not have a barrier strip to isolate them however , keep in mind ALL UNUSED WIRES WILL BE LIVE WHEN THE TRANSFORMER IS ENERGIZED ISOLATE DO NOT JOIN WIRES INSULATE THEM INDIVIDUALY !

yellow yellow grey

isolate(connect to nothing)

}

power transformer black

CONECT TO PCB 6.3VAC

CONECT TO PCB 500V

isolate(connect to nothing)

CONECT TO PCB 500V

connect to POWER SWITCH POS 1 connect to POWER SWITCH POS 2

connect to iec socket LIVE

power transformer white

connect to iec socket NEUTRAL

GND TO CASE

red/ with yellow stripe

CONECT CHASIS GROUND ground with solder tags SOLID GROUND TO CASE

CARLING 110 SERIES TOGGLE SWITCH


hammond 300x series transformer 240V COLOR CODE DIAGRAM PRIMARY WINDING

USE CAUTION

barrier strip will always be live if unit is plugged in / all positions will be live when transformer is energized hammond universal primary 240V hardwiring

isolate(connect to nothing) isolate(connect to nothing)

JOIN BROWN AND BLACK power transformer BLUE

place shrink tube to wire before soldering - cover exposed tabs

white/black black/red blue/yellow brown/yellow

isolate(connect to nothing)

connect to POWER SWITCH POS 1 connect to POWER SWITCH POS 2

GND TO CASE

brown/yellow brown

isolate brown and black once joined

connect to iec socket LIVE connect to iec socket NEUTRAL

blue/yellow

JOIN AND ISOLATE

power transformer WHITE red/ with yellow stripe GROUND GREY wire

}

ground with solder tags SOLID GROUND TO CASE CONECT CHASIS GROUND

240V WIRING DIAGRAM

isolate(connect to nothing)

}

isolate(connect to nothing)

power switch is always LIVE use caution !

}

isolate(connect to nothing)

blue

240V

black

black/red

white/black

CARLING 110 SERIES TOGGLE SWITCH

pos 1

pos 2

NEUTRAL

this side of the power transformer is intended to receive the mains voltage of your house (the power company) this side of conncetions will include the IEC power inlet socket (i.e. the plug where you insert the power cord) and the power switch. all unused wires will be live when the transformer is energized use care and caution when installing and wiring.

white

GREY (ground this) note : the gray wire on the 300x series hammond transformer is the electro static shield - it is intended to be GROUNDED to the chasis . on the 200x series hammond transformers THIS IS LIVE part of the primary winding and NOT the electrostatic shield.


solid state high voltage regulator

high voltage SS regulator

high voltage rectifier

6.3v regulated heater

xlr audio i/o

4 100uf@450v 16mm diameter electrolytic capacitors 7 :pos pcb barrier strip w/pins 2 :1n4007 diodes 1 :1n4738 zenner diode 1 :47k resistor .5w 2 :1k resistors 2 w 2 :470k resistors 2w (bleeder) 1 :240 ohm resistor .5w 2 :adjust resistors u73b=215v (41k total resistance) 2x 20k r resistors 1 : 5k trimmer .5w trimmer triangle pattern leads (not in line) 1 : 10uf film capacitor 500v 27.5 lead spacing(dc link) 1 MJE34339 transistor 1 lm317hv voltage regulator 2 1.5 inch heatsinks 2 mounting kits with thermalsil pads 1 : 8pos barrier strip with pcb pins 1 : .7� violet jumper to bypass choke

2 : 10000uf 16mm electrolytic capacitors 10v 4 : 1n4007 diodes (use only two for protection diodes if using tube) 1 octal socket gold plated 1 5ar4 tube 1 10uf 27.5mm lead spacing film dc link capacitor 500v 4 shottkey diodes 5amps (stps5l40) 1 10pos barrier strip with pins

6 sma vertical connectors 2 : 470k resistor 1 : 240r resistor 1 : 1k resistor if using fixed 2 : .1/100v film capacitor 1 : 953ohm resistor if using variable 1 : 100ohm trimmer .5w (triangle lead pattern) 3 : 10000uf capacitors 16mm 10v 1 : LDO voltage regulator mic29502 wt 1 : 2 inch heatsink 1 : mounting kit with thermalsil pad

6 g5v relays (6v) 6 milmax relay sockets 6 sma connectors vertical 2 10pin 2.54 box idc header 4 pcs .7 inch violet jumpers 2 xlr male socket 2 xlr female socket 2 12 inch 10 pos idc cables

aditional hardware: 6 locking 6-32 solder tags 1 fused iec socket (power inlet) 4 2amp slo blo 5x20 fuses

standoffs must be long enough to clear Iec socket if mounting psu board on back panel 10 pcs 4-40 1.25� standoffs (ss or aluminium) 10 pcs 4-40 keps nuts 10 pcs 4-40 .25� screws

mains hookup

tube rectifier

secondary hookup

super heater regulator

power to main board

xlr in/out/bypass relays chan 1 and 2

signal i/o to main board and front panel


operational controls distribution (front-panel pcb connections or hard wire connections)

signal amplifier/output amplifier/ control amplifier section

transformer / signal i/o section

drip main board


main board components the main board component list is shown on the right with designators and quantities following this page is a print out of the digikey main board part cart - the xls for this section is available Online.

main board transformers sowter 1505e (input/interstage/control amplifier output) sowter 9375e (output amplifier plate choke) sowter 1275e (signal amplifier output transformer (10:1)

x3 x1 x1

main board tubes

HAMMOND 370BX INTERNATIONAL HAMMOND 270BX NORTH AMERICA

SINGLE CHANNEL ORDER X2 IF BUILDING 2 CHANNELS

(AMAZON OR DIGIKEY)

1/2 inch 4-40 stand offs X10 4-40 keps nets for locking pcb to standoffs X10 1/4 inch 44-40 screws for mounting to case X10 .7” preformed jumpers / 1” jumpers (you can get a cheap kit on amazon or 20$ a bag for 3m jumpers on digikey)

main board amazon parts

tube sockets 2 pcs (ceramic) 9 pin sockets (gold plating preferred) 2 pcs (ceramic) 7 pin sockets (gold plating preferred) 1 pcs (ceramic) 8 pin sockets (gold plating preferred)

vu meter

E88CC (OUTPUT AMPLIFIER) X1 E99F (6BJ6) (INPUT AMPLIFIER) X2 E80CF (GOLD PINS) 6BL8 (NO GOLD PINS) X1

main board misc parts

power transformer

amazon is the best place to purchase some parts like the sma pcb connectors and 12” sma cable assemblies (otherwise you can pay up to 5$ apiece on digikey )

SMA PCB CONNECTORS X24 (UXCELL 20PCS BAG X2 ($8.22 per bag)) SMA CABLE (12”) OR 20” (SMA MALE TO MALE) X12 (DHT ELECTRONICS 20” 6$ EACH (EBAY is best price) ENCLOSURE BUD RM-14212 (17” DEEP) X1 ENCLOSURE LID TBC-14262 (VENTILATED) (TOP) X1 ENCLOSURE LID TBC-14252 (SOLID) (BOTTOM) X1 OPTIONAL MOUNTING PLATE FOR SINGLE CHANNEL C-14245 X1

3” illuminated 200uAdc meter model simpson 27 (instrument meter specialties)

toggle switches power / limit-compress / bypass carling 110 series : 432-1216-ND

toggle switches power / limit-compress / bypass carling 110 series : 432-1216-ND


Comment 7805 6BL8-E80CF E99F E88CC RELAY-G5V-2 TVS DIODE FROM ATTN TO ATTN COM 330R 25K 5K 2.7K 100K 250R 30K 1M 500K 3K 500R 1M 200K 1.6K 4.3K 80K 2K 300K 100K 10K 220K 50R 10K

Description VOLTAGE REGULATOR 5V TUBE TUBE TUBE RELAY 5V TVS DIODE SMA PCB CONNECTOR SMA PCB CONNECTOR SMA PCB CONNECTOR RESISTOR RESISTOR TRIMMER RESISTOR TRIMMER TRIMMER RESISTOR RESISTOR RESISTOR RESISTOR RESISTOR RESISTOR RESISTOR RESISTOR RESISTOR RESISTOR RESISTOR RESISTOR RESISTOR RESISTOR RESISTOR RESISTOR TRIMMER

Designator VR1 V4 V2, V3 V1 SW78A, SW78B TVS SMA3 SMA2 SMA1 R107, R180 R81 R79 R65 R62 R61 R54 R53 R50 R49, R56 R47 R46 R45, R51 R44 R43 R43 R42 R41 R39, R52 R31, R32, R40, R80, R112 R30 R28 R0, R67

Quantity 1 1 2 1 2 2 1 1 1 2 1 2 1 1 1 1 2 1 2 1 1 2 1 1 1 1 1 2 5 2 1 2

JUMPER

JUMPER

JMP2, JMP8, JMP9, JMP13, JMP20

5

JUMPER

JUMPER

19

26 PIN IDC 10 POS IDC CONNECTOR SMA CON 1N4148 BZX79 1N4007 100UF/450V

IDC CONNECTOR IDC CONNECTOR

.1/100V 22UF/70V 1UF/400V 100UF/12V 4UF/400V FILM 2UF/350V 100UF 25V 500PF .022/400V 50PF .1/400V

CAPACITOR CAPACITOR CAPACITOR CAPACITOR CAPACITOR CAPACITOR CAPACITOR CAPACITOR CAPACITOR CAPACITOR CAPACITOR

JMP1, JMP3, JMP4, JMP5, JMP6, JMP7, JMP10, JMP11, JMP12, JMP14, JMP15, JMP16, JMP17, JMP18, JMP19, JMP21, JMP22, JMP23, JMP24 IDC2 IDC1 GRID HI, GRID LO D84, D85 D83 D60, D61 CE1, CE2, CE3, CE4, CE5, CE6, CE7 C80, C81 C23 C22 C21 C20 C19 C18 C14 C11 C10 C9

DIODE DIODE ZENNER DIODE-, DIODE CAPACITOR

1 1 2 2 1 2 7 2 1 1 1 1 1 1 1 1 1 1

SINGLE CHANNEL parts list with description and designator


In1

Quan- Part Number tity 2 Z108-ND

Manufacturer Part Number G5V-2-H1 DC5

2

2

CMF55330R00FHEK

3

1

4

1

5

2

6

1

7

2

8

1

9

2

10

1

11

2

12

1

13

1

CMF330HA-ND CMF25.5KHFCT-ND BC4317CTND CMF100KHFCT-ND RC12JT30K0CT-ND CMF1.00MHFCT-ND PPCHF510KCT-ND CF12JT3K00CT-ND CMF500HY-ND CMF200KHFCT-ND RC12JT1K60CT-ND S4.3KHCT-ND

14

1

CF12JT82K0

15

1

16

1

CF12JT82K0CT-ND CMF2.00KHFCT-ND PPCHF300KCT-ND

CMF5525K500FHEB SFR16S0002701JA500 CMF55100K00FHEB RC12JT30K0 CMF551M0000FHEB HVR3700005103FR500 CF12JT3K00 CMF55500R00FEBF CMF55200K00FHEB RC12JT1K60 CFM12JT4K30

CMF552K0000FHEB HVR3700003003FR500

Description RELAY GENERAL PURPOSE DPDT 1A 5V RES 330 OHM 1/2W 1% AXIAL RES 25.5K OHM 1/2W 1% AXIAL RES 2.7K OHM 1/2W 5% AXIAL RES 100K OHM 1/2W 1% AXIAL RES 30K OHM 1/2W 5% AXIAL RES 1.00M OHM 1/2W 1% AXIAL RES 510K OHM 1/2W 1% AXIAL RES 3K OHM 1/2W 5% AXIAL RES 500 OHM 1/2W 1% AXIAL RES 200K OHM 1/2W 1% AXIAL RES 1.6K OHM 1/2W 5% AXIAL RES 4.3K OHM 1/2W 5% CF MINI RES 82K OHM 1/2W 5% AXIAL RES 2.00K OHM 1/2W 1% AXIAL RES 300K OHM 1/2W 1% AXIAL

digikey cart - main board

Customer Reference

Backorder 0

Unit Price 3.18

Extended Price $6.36

17

5

CMF10.0KHHCT-ND

CMF5510K000FKEA

18

2

0

0.56

$1.12

19

1

0

0.61

$0.61

20

2

0

0.13

$0.13

21

2

0

0.61

$1.22

22

1

SFR16S0002203FR500 541-4226-ND CMF5550R000FKEK70 3362P-103LF- 3362P-1-103LF ND 3362P-502LF- 3362P-1-502LF ND 3362H-1-104LF

0

0.62

$0.62

23

1

0

0.49

$0.49

24

2

0

0.54

$0.54

25

2

0

0.1

$0.20

26

0

0.72

$0.72

0

0.61

0

3362P-1-201LF

2

3362P-201LFND 1N4148FSND 1N4007-TPMSCT-ND 399-7672-ND

27

1

EF6105-ND

ECQ-E6105KF

$1.22

28

1

EF4225-ND

ECQ-E4225KF

0.62

$0.62

29

2

0

0.1

$0.10

30

1

493-14320-1- TVX1E101MAD1LS ND P15425-ND ECW-HA3C223J

0

0.1

$0.10

31

1

338-2827-ND CD15ED470GO3

0.61

$0.61

32

1

0.54

$0.54

33

2

493-16280ND 1175-1613ND

12V REGULATOR 0 ADJ 2K 0

SINGLE CHANNEL

1N4148 1N4007-TP R76TR3100SE30J

TVX2A220MAD 3020-26-0100-00

RES 10.0K OHM 1/2W 1% AXIAL RES 220K OHM 1/2W 1% AXIAL RES 50 OHM 1/2W 1% AXIAL

0

0.41

$2.05

0

0.2

$0.20

0

0.49

$0.49

TRIMMER 10K OHM 0.5W PC PIN TRIMMER 5K OHM 0.5W PC PIN TRIMMER 100K OHM 0.5W PC PIN TRIMMER 200 OHM 0.5W PC PIN DIODE GEN PURP 100V 200MA DO35 DIODE GEN PURP 1KV 1A BIAS REGULADO41 TOR DIODE CAP FILM 0.1UF 5% 1.6KVDC RADIAL CAP FILM 1UF 10% 630VDC RADIAL CAP FILM 2.2UF 10% 400VDC RADIAL CAP ALUM 100UF 20% 25V AXIAL CAP FILM 0.022UF 5% 1.6KVDC RAD CAP MICA 47PF 2% 500V RADIAL CAP ALUM 22UF 20% 100V AXIAL IDC BOX HEADER .100” 26POS

0

1.02

$2.04

0

1.02

$2.04

0

1.02

$1.02

0

1.02

$1.02

0

0.1

$0.20

0

0.11

$0.22

0

1.79

$3.58

0

1.21

$1.21

0

1.67

$1.67

0

0.95

$1.90

0

0.81

$0.81

0

2.11

$2.11

0

0.93

$0.93

0

0.78

$1.56


34

2

3020-10-0100-00

1

1175-1609ND P16728-ND

35 36

7

P5934-ND

EEU-EB2V470

37

2

GH7106-ND

71BDF30-01-2-AJN

38

1

1727-6149-1- BZX79-C5V1,133 ND

ECW-FD2W475J

IDC BOX HEADER .100” 10POS CAP FILM 4.7UF 5% 450VDC RADIAL CAP ALUM 47UF 20% 350V RADIAL SWITCH ROTARY 2-6POS FRONT PANEL 250MA 115V SWITCHES DIODE ZENER 5.1V 400MW ALF2

0

0.48

$0.96

0

1.23

$1.23

0

1.55

$10.85

0

15.72

$31.44

0

0.14

$0.14

Subtotal $82.87

digikey cart - main board

SINGLE CHANNEL


ZERO ADJUST 200uA OPTIONAL 600T ATTENUATOR XLR IN

OUT

+

U73b INPUT amplifier

10K 160V plate

31 10K

E99F

01

sowter 1505e yellow 1:1 secondary HI orange

SUPPRESSOR

orange

SCREEN

1:1 yellow

GRID

IN

XLR3 BYPASS

COM

10K

4K 33 primary green

32

brown

VARIABLE INPUT PAD

CONTROL VOLTAGE

cathode

6.3V

white CT

GRID

COPYRIGHT 2018 GREGORY LOMAYESVA

red

SCREEN

secondary LO

SUPPRESSOR

blue

02 50R 28

PIN3

PIN1

to control amplifier

green brown

white

blue

cathode

to control amplifier time (control line)

sowter 1505e

E99F

plate

160V

40V 64

40 10K

HEATER

INPUT TX THRESHOLD 100K POTENTIOMETER

09

250R

6.3V

to control amplifier XLR OUT

cathode balance SYMETRY

tertiary red

61

HEATER

notes : R61 is cathode balance use this trimmer to balance out artifacts during compression and limiting the tubes must be balanced before calibration begins

CT

XLR2

0.1 @ 400V

39

65

100K

5K

10 UF 450V

B+ 170v

TO OUTPUT AMPLIFIER GRID

INTERSTAGE


B

C

D

E

F

A TOP SILKSCEEN DETAIL A : CALIBRATION TRIMMERS

errata note this is trimmer 63 not r79 as labled on the pcb

1

U73b INPUT amplifier

160V plate

63 62

67

zeroadjust

E99F

01

61 79

SUPPRESSOR

orange

SCREEN GRID cathode

61

HEATER

6.3V

cathode balance SYMETRY

HEATER

R180 2 LO SHUNT

2.7K

SCREEN SUPPRESSOR

02

E99F

plate

160V

40V

calibration trimmers once the build has been finished and operational a series of calibration procedures must be performed. the use of a 1k test tone and multimeter will be necessary . calibration will bring the u73b to it’s historic operation characteristics.

3

yellow

green brown

B+ 170v

red

PLATE BALANCE the ability to monitor the plate balance has been added to the circuit - this feature would allow you to balance the cathodes visually on a 200ua microamp meter- sans the fairchild 670 metering circuit-

white

R65

cathode GRID

40 10K

250R

6.3V 2

HI SHUNT R107 1

1:1

blue sowter 1505e

for the most part this feature should be left unused since it carries 170vB+ and plate voltages it is intended for manufacturing calibration. optionally this can be used to monitor compression however the low voltage metering hook up performs the same function and is safer to use in the long run.


interstage transformer input pad

feedback adjust (output amplifier gain)

THINK V72 AMPLIFIER FEEDBACK ARRAINGMENT

341 OHMS WINDING (PRIMARY)

50PF (ADJUSTABLE)

signal amplifier 683 OHMS FOR SECONDARY WINDING

signal amplifier input winding

output amplifier 2nd stage

output amplifier 1st stage

62

optional frequency filter

61

mu line (control voltage)

control amplifier winding 341 OHMS WINDING (TERTIARY)

input frequency filter (optional)

170v

cathode balance

output amplifier 1st stage limiter gain (cathode adj)

500PF zero adj COMP MODE ADDS 100UF BYPASS CAPACITOR TO BIAS

+

R43/80K

5V 67 R67/10K

V72 TYPE OUTPUT TRANSFORMER

5v limiting dc bias adj

V72 TYPE PLATE CHOKE

meter

control frequecy filter (optional)

63

GND

GND

optional frequency filter

170v

GND

GND

R65 5K 170v mu line (control voltage)

control amplifier

to varicom COPYRIGHT 2018 GREGORYLOMAYESVA DRIP ELECTRONICS

64

GND

215V

LIMITING DC BIAS DIODES

attack

215V

control amplifier input (reduction threshold) control compressor “idle” similar to carburetor idle

voltage GND

79

controll amplifier limiting mode cathode adjust (controls the input gain) how deep limiting mode is GND

GND

time (release)


A

B

C

D

E

F

A TOP SILKSCEEN DETAIL A : CALIBRATION TRIMMERS

1

1

reference legend for the location of the calibration trimmers . the trimmers may be hard wired to the front panel using 3 pos 2.4mm wire assemblies description and purpose :

2

2

R63 LIMITING BIAS (5V+) feeds negative voltage to the top and bottom winding of the control output transformer loosely this controls pre bias of the control amplifier in limiting R61 SYM (SYMMETRY) essentially : cathode balance to dial out artifacts while compressing (thump/clicks etc) this balances the cathodes of the input tubes (top and bottom e99f (6bj6))

draft

R79 LIMIT (E80CF CATHODE BIAS ADJUST) control amplifier in limiting mode the control amplifier is biased with the r79 trimmer in compressor mode the trimmer is bypassed and a fix bias of 3k is used to bias the e80cf use this to adjust the ‘idle of the control amplifier’ meaning how the threshold of the control amplifier is set in limiting 3

3

R67 BIAS controls the first stage of the output amplifiers cathode resistance (gain) in Limiting mode - the cathode is only fed with the R67 TRIMMER R62 FBK (FEED BACK) output amplifier - output stage feedback controls the gain of the output amplifier final stage adjust this to set the (make up gain) 4

4 TITLE

=DocumentScale

A

B

C

D

E

F

R64 THRESHOLD ( FRONT PANEL THRESHOLD 100K POTENTIOMETER)


B

C

E

F

BLANK1

BYPASS

LIM/COM

LIM LAMP

JMP26

D60

GR METER

BLANK2

TVS2

SW78B

CE2

JMP24

C21

JMP22

JMP20

R61

R49

C22

JMP37

R1ZERO

R67

C14

R62

out cat

R79

LOW 170V

R78

HI-170V

1

R28

JMP3

B+

R107

JMP12

SW78A

C18

R180

JMP10

SMA3

SMA2

D61

SMA1

IDC2

THRESH PIN2

1

PILOT LAMP

COMPONENT LEGEND THRESH PIN3

TOP SILKSCEEN

D

TIME

A

R50

R41 R42

CE3 V1

CE1

V4 V2

JMP2 JMP18 R40

JMP14

CE6

INFO@DRIPELECTRONICS.COM

CE7

DRIPELECTRONICS.COM VARICOM

R56

6.3V

D84

215V

R39

JMP8

D85

JMP9 JMP19

JMP7

R43 D83 R44

C81

CE5

C23

JMP21

JMP13 JMP11

C80

R52

JMP16

C9

NONAME3

NONAME2

JMP28

JMP29 NONAME1

JMP30

JMP35

JMP34

JMP25 JMP27

JMP31 JMP32 R33

JMP36

R90

R31

JMP33

R30

R32

R60

IDC1

3

R80

3

4

4 TITLE

=DocumentScale

A

B

C

D

E

COPYRIGHT 2018 GREGORY LOMAYESVA

R54

GRID LO

C19

JMP1

2

R53

V3

VR1

R51

JMP17

R81

C11 C10

C20

R45

CE4

GRID HI

R47

2

JMP23

R65

R46

F

U73B  
U73B