Muusiga dhexdiisa, saddex-geesoodku waa saddex qoraal oo saddex meelood loo qaybin karo. Erayga "triad harmonic" waxaa ku soo daray Johannes Lippius "Synopsis musicae novae" (1612).
Marka saddex meelood loo qaybiyo, xubnaha saddex-geesoodka, laga bilaabo codka ugu hooseeya ilaa kan ugu sarreeya, waxaa loo yaqaannaa: Xididka Saddexaad - bareeg Ka sarreeya xididka oo ah seddexaad oo yar (saddex semitones) ama seddexaad weyn (afar semitones) shanaad - inta u dhaxaysa ka sarreeya saddexaad waa seddexaad yar ama seddexaad weyn, markaa inta u dhaxaysa xididku waa shanaad (lix semitones) , shanaad kaamil ah (todoba semitones), ama shanaad la kordhiyay (sideed semitones).
Xargaha noocaan ah waxaa loo tixraacaa sida triadic. Qaar ka mid ah aragtiyaha qarniga XNUMX-aad, gaar ahaan Howard Hanson iyo Carlton Gamer, ayaa balaadhiyey ereyga si ay u tixraacaan isku darka saddex nooc oo kala duwan, iyada oo aan loo eegin inta u dhexaysa dhexdooda.
Erayga ay adeegsadaan aragtiyaha kale ee fikraddan guud waa "trichord".
Kuwo kale, gaar ahaan Allen Forte, waxay adeegsadaan ereyga si ay u tixraacaan isku-darka sida muuqata la soo ururiyey ee durayo kale, sida "saddex-geesood". 1973-0-300-02120 Dhammaadkii Renaissance, muusiga fanka reer galbeedku waxa uu ka bedelay hab ka hortimid ah "horizontal" oo ku wajahan horusocodka chord-horumarka u baahan hab "toos ah" oo dheeraad ah, sidaas awgeed aad ugu tiirsan saddex-geesoodka oo ah dhismaha aasaasiga ah ee wada noolaanshaha shaqeynta. .
Codka xididka saddex-geesoodka ah, oo ay weheliso heerka darajada miisaanka taas oo ay u dhiganto, ugu horrayn go'aamiso shaqada saddex-geesoodka ah ee la bixiyay.
Marka labaad, shaqada saddex-geesoodka waxaa lagu go'aamiyaa tayadooda: weyn, yar, yaraaday ama la kordhiyay. Saddex ka mid ah afartan nooc ee triads ayaa laga helaa miisaanka Major (ama diatonic).
Anigu waxaan ahay Joost Nusselder, aasaasaha Neaera iyo suuqgeyn ka kooban, aabe, waxaan jeclahay inaan tijaabiyo qalab cusub oo gitaar ku leh qalbiga xiisahayga, iyo kooxdayda, waxaan abuurayay maqaallo qotodheer oo blog ah ilaa 2020 si loogu caawiyo akhristayaasha daacadda ah talooyinka duubista iyo gitaarka.
