Arp Quartet

String processor (1979)

String paraphonic processor, a rebrand of Italian Siel orchestra, 100% the same


OVERVIEW  C-C 49 keys with full polyphony, the  Quartet a 4-part string processor synthesizer with 4 sounds presets: Brass, Strings, Organ and Piano,  of which up to two can sound at the same time.

 - Siel Orchestra: the same
Siel Orchestra II: upgrade with more sound control

Terminal connectors:
- audio out Hi/low
- footswitch for sustain
- 5-Dinfor volume pedal


OSCILLATORS Divide down tone generation , the 4 tone color families can be played individually or two can mixed. Some parameters can be changed.A 12-note TOS  Mostek 50242,  is used the main core then  TDA 1008 chip is used as a frequency divider -  amplification is provided by an LM 13600  OTA OpAmp. Chorus is generated by 3 BBD TDA1022 

EDIT some section have some tweaks:
-  Brass section with independent attack and sustain controls EG. 
 - String section  with independent attack and sustain controls EG.
-  Organ section is 2-voice and offers a Celeste sound  
-  Piano section has two variations:, traditional piano or Hony Tonk. .

LFO  a single Vibrato 

FILTER  only brilliance control for brass section

Arp Quartet Specifications

Polyphony - 49 notes
Oscillators - Brass, Strings, Organ and Piano

VCA - Yes, individual attack and decay sliders for strings, brass and piano sections.
Keyboard - 49 keys
Memory - None
Control - None
Date Produced - 1979-1982

S50242 TOS
TDA1008 dividers
 LM13600 dual ota
 TDA1022 Bucket brigade 

Weight: 22lbs / 10 kg
Dimensions:   80.5 cm in width, 35.5 cm in depth and 15 cm in height. 

Average price today: 300€

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