electrostatic audio products SR-series ELECTROSTATIC EARSPEAKERS
SR-404 Signature SR-303 Classic
Revolutionary new diaphragm of only 1.35 in thickness The Stax SR-404 Signature utilizes a new super thin diaphragm of only 1.35 in thickness. This unique diaphragm has only been made possible by a revolutionary new material with a molecular structure previously unavailable. The improvement in sound quality and retrieval of inner detail is simply stunning. The Stax SR-404 comes complete with a low capacitance wide format PC-OCC cable.
Diaphragm material reduced to a thickness of Only 1.35 Featuring the same element material as the SR-404 Signature, the Stax SR-303 is a startling innovation in a more affordable earspeaker package. The sound is both refined yet powerful and the unit comes complete with a low capacitance standard PC-OCC cable to allow the Stax SR303 earspeaker to attain their full sonic potential.

SPECIFICATIONS

Description Type Frequency Range Capacitance (including cable ) Sound Pressure Level Cable Earpads Weight (without cable) Standard Bias Voltage SR-404 Signature Electrostatic Open back Push-pull driving 741,000Hz 110pF 100dB / 100V r.m.s Low Capacitance wide format 6-parallel core PC-OCC High quality artificial Leather 295g 580VDC Low Capacitance 6-parallel core PC-OCC 120pF SR-303 Classic
Specifications and design are subject to change without notice for improvements.
STAX LIMITED 293-1 Fujikubo, Miyoshi-cho, Iruma-gun, Saitama Prefecture Japan 354-0041
Copyright (C)1999 STAX Ltd. All rights reserved.
Tel :81-492-58-3988 Fax :81-492-58-2659
Home Page:http://www.stax.co.jp E-mail :info@stax.co.jp

Auridux

Stax SR-404 Electrostatic Headphone Amplifier OTL Differential Design

By Doede Douma

Version 2.2

Updated March 1st, 2004

http://www.dddac.de/

CNVB#1 CNVB#2 CNBF#1

VB-Right 420 Volt VB-Left 420 Volt
One Amplifier Channel Shown
415V C3 47uF Black Gate WKZ

Both Channel Shown

MP-1L/R CNBF#3 FIL 12.6 Volt FIL for TOP Tubes 800mA FIL

V1 Filament of ECC 99

Bias 580 Volt CNBF#2

Tube1 ECC99-a

Bias Uo+ UoP3 10k R14 1k

ECC99-b

CNBF#4 MP-2L/R

R17 180k

R2 100k

P1 R610k 1k

R16 100k 235V R15 3k9 / 2W C4 100n V1 Filament of ECC 99

C1 100n

R7 3k9 / 2W
These 2 resistors for both Channels

R8 10M R10 10M 180V

C5 2u2 / 450 Volt

To other Channel

Tube2 ECC99-a ECC99-b

R18 235k

CNBF#5
FIL 12.6 Volt FIL for BOTTOM Tubes 800mA FIL

CNVB#3GND

GND Right

CNBF#6

GND Left CNVB#4GND
CNVB#7 On / Off CNBF#7 CNVB#5 CNVB#6 VB Right -20 Volt
R5 2k2 S1 R4 15k C2 TLP2 200E R9 200E
R11 10E // 10E 1% R13 10k V1 Filament of ECC 99

Cooling 30K/W

2SK1058

R12 100E TL431

VB Left -20 Volt
With P1 and P3, adjust for minimum delta DC on amp output AND equal drop over all tubes With P2, adjust for 30mA: measured over R11 = 150mV. R11=5 Ohm

AuriDux Amplifier

Update: 23-02-2004 Rev: 2.2 Built: YES Author: Doede Douma Page: 1 # 8 Design ready: YES

Rotary Switch 2x6

R51 10M

U-tube-L

Chassis CN Sight

U-tube-R

LCD1 200mV R49 100k

Vout-DC-L

Vout-DC-R U-tube-L MP-3 No Connect U-tube-R

Cable CN Sight

BF = Bias & Filament VB = Power Supply VB Left and Right

Vout-DC-R

Chassis Solder View

No Connect

SR-404

R+ BIAS

Read out should always be as close as possible to ZERO Full reading is 20Volt
AuriDux Meter & Connectors
Update: 23-02-2004 Rev: 2.2 Built: YES Author: Doede Douma Page: 2 # 8 Design ready: YES

Tr / 75VA 375V / 50mA 0V

D1 BYW96E

Relay Delay

R5 110E / 2Watt R3 2M2 100/500V JJ C4

VB 480 Volt Left

C8 R9 560k

CNVB#2

100/500V JJ

GND IN OUT

CNVB#4

VB -24 Volt Left

-22V / 50mA

D2 BYW96E

CNVB#6

7924 VR1 10H

R6 110E / 2Watt R4 2M2 100/500V JJ C5

VB 480 Volt Right

C9 R10 560k

375V / 50mA 0V

CNVB#1

BYW96E

CNVB#3

VB -24 Volt Right

D4 BYW96E

CNVB#5

7924 VR2

D5 1n4005

CNVB#7 CNBF#7

4700uF

C112 Volt Rel1 AC

Relais A

AuriDux VB Power Supply
Update: 22-02-2004 Rev: 2.2 Built: YES Author: Doede Douma Page: 3 # 8 Design ready: YES

Tr / 75VA 610V / 1mA 0V 13V / 3A
R1 BYW96E 10k 470k 470k P3 5M R8 10M R6 10M R2 R5

Adjust at 1.56 Volt

CNBF#1

VB 580 Volt BIAS

C3 470n / 1000V

C4 470n / 1000V R7 27k

470n / 1000V

CNBF#2

All floating: do NOT ground !!

to next page

To Delay Circuit

Cooling 10K/W

1N4005

LM317 VR1 OUT

CNBF#3
FIL 12.6 Volt L & R TOP

C1 4.700 P1 2k2

Tr / 25VA 15V / 2A

CNBF#4

LM317 VR2 OUT
FIL 12.6 Volt L & R BOTTOM

C2 4.700 P2 2k2

AuriDux PS FIL & BIAS
Update: 08-02-2004 Rev: 2.2 Built: YES Author: Doede Douma Page: 4 # 8 Design ready: YES

Delay = 30 seconds

12V D1 1N8 IC1 LMR3 10k # MAX 100mA # 5 - 6 connected R4 10k R1 1M R2 10k
12 Volt from Filament Supply

C1 33uF GND

When Input becomes higher than + terminal, Output goes LOW

Supply Voltage Delay

Update: 08-02-2004 Rev: 2.2 Built: YES Author: Doede Douma Page: 5 # 8 Design ready: YES