Son­ic­smith Squa­ver P1+ and Con­ver­tor+

Bruce Aisher plugs in two novel pitch­track­ing semi­mod­u­lar ana­logue synths from Son­ic­smith

Future Music - - CONTENTS - CON­TACT KEY FEA­TURES WHO: Son­ic­smith WEB: www.son­ic­smith.com IACO plays ana­logue sin­gle os­cil­la­tor (with sub) synth along with the in­put au­dio. Ex­tracts gate, pitch, en­ve­lope and trig­ger CV from in­put au­dio. Sidechain in­put ac­cesses the 2nd ENV fol­lower.

Son­ic­smith are laud­able for try­ing some­thing new

We took a look at the Son­ic­smith Mo­du­lor A1 synth in FM a few is­sues back. This diminu­tive synth mod­ule was re­stricted to a sim­ple com­bi­na­tion of VCO, VCA and LFO. So, although it pro­vided some patch­ing, it was quite lim­ited in func­tional terms. More im­por­tantly, it didn’t in­clude the cen­tre­piece tech­nol­ogy of the Son­ic­smith range – ACO. The so-called Au­dio Con­trolled Os­cil­la­tor (ACO) chip is de­signed to track the pitch of in­com­ing au­dio with very lit­tle pro­cess­ing lag, and use the re­sult­ing sig­nal to con­trol an ana­logue os­cil­la­tor. The Squa­ver P1+ and Con­ver­tor+ on re­view here com­bine the abil­i­ties of the ACO chip with an os­cil­la­tor sec­tion and VCA. The more elab­o­rate P1+ adds a VCF, more ex­pan­sive rout­ing, and stomp­box styling.

Be­fore putting the Squa­ver P1+ to work, let’s look at the over­all sig­nal flow. The 1/4” au­dio in­put on the back panel passes through a high-pass fil­ter and on to an ad­justable gain sec­tion. A sim­ple four-stage LED me­ter shows the post-gain level. An un­buffered (pre-gain) ‘Thru’ out­put is pro­vided for daisy-chain­ing ef­fects or par­al­lel record­ing of un-pro­cessed au­dio, though this can also be switched to ac­cess the out­put of the next sec­tion – an ‘auto-fil­ter’. This fil­ter is de­signed to aid fre­quency de­tec­tion, and as such is not used for au­di­ble sound-shap­ing. It can be switched be­tween 2-pole (12dB/oc­tave) and 4-pole (24dB/oc­tave) modes, with the for­mer in­tended to pro­vide a faster tran­sient re­sponse. In or­der to avoid low-level sig­nal el­e­ments caus­ing prob­lems, it ini­tially ap­pears that there is noise gate fed from the in­put amp. How­ever, this is, in fact, part of a more elab­o­rate en­ve­lope de­tec­tor/trig­ger sec­tion. The thresh­old is ad­justable, and set with the help of the Gate LED in the synth sec­tion.

The au­dio then passes to the all-im­por­tant ACO, which gen­er­ates si­mul­ta­ne­ous square and saw­tooth wave­forms, as well as a squared­erived sub-os­cil­la­tor sig­nals one or two oc­taves be­low. Next comes a VCA (with a Ring Mod­u­la­tor in­put) and on to the fil­ter sec­tion. This has vari­able cut­off and res­o­nance, and can be switched be­tween low, high and band-pass modes with a se­lectable slope of 12 or 24dB/ oc­tave. The fil­ter can be set to process both the dry in­put and synth sec­tion, or the synth alone. Given the abil­ity to mix con­tin­u­ously be­tween both, this is use­ful.

As well as the afore­men­tioned rout­ing, the P1+ has an en­ve­lope

fol­lower that gen­er­ates a CV sig­nal that can be fed to mod­u­late the VCA (Amount), VCF (Cut­off fre­quency) or PWM (width). This is nor­mally fed by the in­put sig­nal, though it can be over­rid­den by a side-chain in­put (with switch­able +15dB gain). An ex­pres­sion pedal can also be plugged-in to con­trol the Har­mony, Oc­tave or fil­ter cut­off.

This is all rounded-off with a nice com­ple­ment of mini-jack patch points for au­dio and CV rout­ing.

As you can see, there’s quite a lot to the P1+, but what does it sound like? I started by plug­ging an elec­tric guitar into the unit – after all, it does have three foot switches and large stomp­box styling. After ad­just­ing the in­put level, and by­pass­ing the VCF sec­tion, I plucked a few notes to get a sense of the pitch­track­ing. Notes were de­tected across the full fret range quickly, with the in­put auto-fil­ter set­ting only hav­ing a moderate ef­fect on the re­sult. How­ever, let­ting notes die away nat­u­rally re­sulted in un­usual leaps of the synth (usu­ally down­ward). I ad­justed the Gate thresh­old to cut out the prob­lem­atic note ‘squig­gles’ be­fore they kicked in, but this did not en­tirely fix it. There were also de­tec­tion prob­lems when moving be­tween notes. De­spite my best ef­forts at clean play­ing, this meant my guitar ex­per­i­ments were var­ied at best. Sub­sti­tut­ing guitar for voice gave fewer odd side-ef­fects. Choos­ing poly­phonic or source with non-spe­cific tun­ing, such as the out­put from a drum ma­chine, gave un­pre­dictable, in­ter­est­ing re­sults.

The man­ual sug­gests plac­ing a com­pres­sor be­tween the source sig­nal and P1+ in­put to get more con­trol­lable dy­nam­ics. It may have been use­ful to in­clude a very sim­ple dy­nam­ics sec­tion and ad­justable high-pass fil­ter/EQ di­rectly after the in­put amp, to min­imise th­ese is­sues. This would also have a bear­ing on the en­ve­lope fol­lower, which can be some­what un­ruly. The ad­di­tion of a re­lease time con­trol would have made this much more us­able, or a trig­gered ADSR and on­board LFO.

Over­all, the Squa­ver P1+ is in­trigu­ing (if pricey), and Son­ic­smith are laud­able for try­ing some­thing new. Their ACO chip and as­so­ci­ated tech has a lot to of­fer, but, like pre­vi­ous real-time pitch­track­ing sys­tems, some acom­mo­da­tion is needed. But em­brace the more ex­per­i­men­tal side and it opens up in­ter­est­ing sonic ground.

SideChain In­put The sidechain in­put al­lows for a sec­ondary sig­nal to be used as the en­ve­lope sourceIns and Outs The wide range makes the unit an ideal ac­com­pa­ni­ment to a large mod­u­lar sys­temACO The heart of the P1+ is the Au­dio Con­trolled Os­cil­la­tor chip, which is also present in the smaller Con­ver­tor+

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