I remember a while ago someone asking what the differences were...I
have all 3 of the following (including original boxes, owners manuals,
service manuals).

* note [.......] = writing on actual front of unit

SQD-2000 [SQ DECODER SQD-2000 SOLID STATE] built 1970-71, 2 single-
sided fully discrete (no ICs) 2 main printed circuit boards (each
approx A4 size). These were connected together at one end by simple
wiring loom. This version was made to match the 2000 series amp made at
the time eg rotary selector knobs.

It also had two 4-channel discret inputs (1 at front via 2 1/4"
sockets).

SYSTEM rotary switch - 2 CH, MTX (like QS?), SQ, 4 CH-1, 4 CH-2.
Mode rotarty switch - F/B REV, MONO, NORMAL, FRONT REV, BACK REV.
TONE (back) - BASS TREBLE seperate pots.
MONITOR - 4 CH, 2 CH seperate up/down selectors.
VOLUME controls - 4 individual types next to meters.
VOLUME control - master for all 4 channels at once.
POWER - on/off.

SQD-2010 [4 CHANNEL DECODER SQD-2010] build only early 1972, the 2 pcbs
from previous version are now combined into 1 single-sided printed
circuit board, this was achieved by removing most SQ decoder
transistors,diodes, resistors & some capacitors with custom build ICs,
also the rotary selector switches are removed to be in line with
recently released TA-1150 (and similar) new Sony gear with push-button
switches. The unit had the following other features -

SYSTEM push buttom switches - 2 CH, 2->4, SQ, R MTX, DISCRETE.
MODE push button - MONO / NORMAL.
TONE (back) - BASS TREBLE seperate pots.
MONITOR - 4 CH, MONITOR, 2 CH common up/down selectors.
VOLUME controls - 4 individual types next to meters.
VOLUME control - master for all 4 channels at once.
POWER - on/off.

SQD-2020 [SQ DECODER SQD-2020 SOLID STATE] build late 1972 to 1975, the
customs ICs are now removed (costly process) & the discrete transistors
& other components are now re-instated (as SQD-2000). The printed
circuit board is now a single A4 size double-sided (copper tracks both
sides) but not plated through the holes, Sony used rivets to achieve
contacts from one side to the other. This is the main problem with
these units - over time the rivets oxidise & units stated to fail,
cleaning the board & soldering both sides of all rivits normally fixes
the problem. The front & rear controls & inputs/outputs are the same as
the SQD-2010.

Note that all three versions were designed to be used in all overseas
countries - hence there is a small raised rectangular area on the rear
with 2 screws fixing it. Removing these screws will reveal the voltage
selector jumper. Most early 1970s Japanese companies did this as it
ment that they only needed 1 transformer & power supply design for a
world market? - pity they do not do it these days.....

I have the following quad gear if any of you require any other
information-

I have several equalizers in my systems at home & they work well, note
that the JDM had them labeled as Victor SEA-V7E but when exported they
were re-branded as JVC SEA-V7E – the setups that I have are as follows –


System 1 – mix of Sony & JVC & Toshiba & Eversonic

VT-700 (Tuner)
SEA-V7E (Equalizer)
SQD-2000 (Decoder)
4VN-880 (Amp)
KD-10 (Cassette)
HR-40 (4-Channel Headphones)
Eversonic (4 off) 50W 5-way

System 2 – mix of Sony & JVC & Philips

VT-700 (Tuner)
SEA-V7E (Equalizer) - front
SQD-2010 (Decoder)
SEA-V7E (Equalizer) - rear
4VN-880 (Amp)
5911 (4-Channel Remote)
5944 (4-Channel Headphones)
733K (CD)


System 3 – Sony & Technics & Magnat

ST-5150 (Tuner)
TA-1150 (Amp) – front
SQD-2020 (Decoder)
TA-1150 (Amp) – rear
D-5A (CD)
EAH-400 (4-Channel Headphones)
Magnat-6 Speakers (4 off) 160W 3-way

System 4 – PC system, to transfer LPs to CD

PC with sound blaster Live 5.1
Sound Forge software
Sound Laundry software
SL-10 (Turntable)
Terratec Phono Pre-Amp Studio
+ approx 250 Quad LPs


I also have the following other pieces in my collection.

Cosrad HS 4000 4-Channel Headphones
Hafler 101A Preamp
KD-10 Cassette – used for spare parts
JVC ECA-102 4-Channel Reverb.
Marantz ST-400 Tuner (modified to include AM Stereo PCB)
Pioneer QD-240 CD-4 Demodulator
Quad 405mkII Amp
Sony SQA-100 Decoder (3)
Sony SQA-200 Decoder
Sony SQA-2030 Decoder
Sony SQD-1000 Decoder (2)
Sony SQD-2020 Decoder
Sony SQD-2050 Decoder (2)
Sony SQD-2070 Decoder
Sony ST-80F Tuner (3)
Sony ST-88 Tuner (2)
Sony ST-2950 Tuner
Sony TA-88 Amp (3)
Sony TA-1055 Amp (3)
Sony TAH-10 Headphone adapter
Technics SH-400 CD-4 Demodulator
Technics SH-3433 Scope

Plus Service manuals for most of the above.
I am still searching for the following 2 elusive items JVC VT-900 tuner
& Sony ST-5555 tuner…..

regards

Steve (in New Zealand)