Rupert Neve Designs Portico 500 Series User manual

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Operations Manual
Portico 543
500 Series Compressor-Limiter

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Portico 543: 500 Series Compressor-Limiter
Thank&you&for&your&purchase&of&the&543:&500&Series&Compressor-Limiter.&Everyone&at&Rupert&Neve&De-
signs&hope&you&enjoy&using&this&tool&as&much&as&we&have&enjoyed&designing&and&building&it.&Please&take&
note&of&the&following&list&of&safety&concerns&and&power&requirements&before&the&use&of&this&or&any&Portico&
Series&product.
&
Safety
It’s&usual&to&provide&a&list&of&“do’s&and&don’ts”&under&this&heading&but&mostly&these&amount&to&common&
sense&issues.&However&here&are&some&reminders:
Don’t&operate&your&Portico™&module&in&or&around&water!&Electronic&equipment&and&liquids&are&not&good&
friends.&If&any&liquid&is&spilled&such&as&soda,&coffee,&alcoholic&or&other&drink,&the&sugars&and&acids&will&
OH]LH]LY`KL[YPTLU[HSLMMLJ[:\NHYJY`Z[HSZHJ[SPRLSP[[SLYLJ[PÄLYZHUKJHUWYVK\JLUVPZLJYHJRSLZ
L[J:>0;*/6--044,+0(;,3@ILJH\ZLVUJLJ\YYLU[Z[HY[Z[VÅV^[OLTP_[\YLOHYKLUZJHUNL[]LY`
OV[I\YU[[VMMLLHUKJH\ZLWLYTHULU[HUKJVZ[S`KHTHNL7SLHZLJVU[HJ[Z\WWVY[HZZVVUHZWVZZPISL
at&[email protected]&for&resolution.
Don’t&be&tempted&to&operate&a&Portico&module&with&the&cover&removed.&The&cover&provides&magnetic&
ZJYLLUPUNMYVTO\THUK9-Z[YH`ÄLSKZ
Power Requirements
,HJO7VY[PJVPZÄ[[LKMVY\ZL^P[OZ[HUKHYK:LYPLZ9HJR4V\U[ZHUKYLX\PYLZT(TWZ
'=
Portico 543: Block Diagram

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Portico 543: Block Diagram
Portico 543: Front Panel
Portico 543:
Back Panel

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THE NEED FOR DYNAMIC CONTROL OF SOUND LEVELS
;OLK`UHTPJYHUNLVMZV\UKZ^LOLHYHYV\UK\ZPUUVYTHSSPMLNYLH[S`L_JLLKZ[OLJHWHIPSP[`VMV\Y
best&recording&and&processing&equipment&-&but&even&if&this&were&not&so,&the&scale&of&dynamic&range&
T\Z[ILHJJVTTVKH[LK[V[OL]LU\LPU^OPJOP[PZ[VILYLWYVK\JLK-VYL_HTWSLHJ[\HS]VS\TL
levels&of&the&dance&hall&would&be&deafening&in&a&students&bedroom.&In&the&same&way,&late&night&
listening&in&a&quiet&living&room&demands&careful&adjustment&of&dynamic&range.&In&the&constantly&
changing&background&noise&of&a&car,&drama&dialog&does&not&work&without&constant&attention&to&the&
SL]LSJVU[YVS0U[OLÄLSKVMJVTT\UPJH[PVUZP[PZVM[LUULJLZZHY`[VLUZ\YL[OH[[OLILZ[WVZZPISL
signal-to-noise&ratio&is&obtained,&in&the&interest&of&intelligibility,&within&the&limited&performance&of,&
say,&a&reporter’s&recording&device.&
Digital&recorders&are&unforgiving&when&overloaded.&Overload&can&be&avoided&with&careful&use&of&
high&ratio&compression&-&on&the&verge&of&limiting&-&with&careful&choice&of&time&constants.&A&
recording&that&still&sounds&“loud”&can&be&produced&without&non-musical&harmonic&distortion.&
A&compressor-limiter&is&one&of&the&most&powerful,&yet&subjective&items&in&the&sound&engineer’s&
armory.&&Compression&should&never&be&obvious&to&the&listener&and&this&needs&intuitive&and&effective&
controls&on&the&part&of&the&designer&together&with&considerable&skill&on&the&part&of&the&sound&
engineer.
A NOTE ON DISTORTION
;OLO\THUOLHYPUNZ`Z[LTPZHYLTHYRHIS`JVTWSL_TLJOHUPZTHUK^LZLLT[VILSLHYUPUNTVYL
KL[HPSZHIV\[P[Z^VYRPUNZHSS[OL[PTL-VYL_HTWSL6VOHZOPKLTVUZ[YH[LK[OH[HYIP[YHYPS`ÄS[LYPUNV\[
ultrasonic&information&that&is&generally&considered&above&our&hearing&range&had&a&measurable&effect&on&
listener’s&electroencephalo-grams.&Kunchur&describes&several&demonstrations&that&have&shown&that&our&
OLHYPUNPZJHWHISLVMHWWYV_PTH[LS`[^PJL[OL[PTPUNYLZVS\[PVU[OHUHSPTP[VMR/aTPNO[PTWS`
-$;VY;$-/PZWLLYYL]PL^LKWHWLYZKLTVUZ[YH[LK[OH[^LJHUOLHY[PTPUNYLZVS\[PVUH[
HWWYV_PTH[LS`^P[OTPJYVZLJVUKYLZVS\[PVUR/aPTWSPLZH TPJYVZLJVUK[LTWVYHSYLZVS\[PVU
^OPSLH*+H[RZHTWSLYH[LOHZHILZ[JHZL[LTWVYHSYLZVS\[PVUVMTPJYVZLJVUKZ
0[PZHSZV^LSS\UKLYZ[VVK[OH[^LJHUWLYJLP]LZ[LHK`[VULZL]LU^OLUI\YPLK\UKLY[VK)VM
UVPZL(UK^LRUV^[OH[TVZ[NHPUZ[HNLZL_OPIP[YPZPUNKPZ[VY[PVUH[OPNOLYMYLX\LUJPLZPUJS\KPUN
TVYL04KPZ[VY[PVU6ULJVTTVU04[LZ[PZ[VTP_ R/aHUKR/aZPUL^H]LZZLUK[OLT[OYV\NO
HKL]PJLHUK[OLUTLHZ\YLOV^T\JOR/aPZNLULYH[LK $(SS[OPZOPU[ZH[[OLPTWVY[HUJL
VMTHPU[HPUPUNHZ\MÄJPLU[IHUK^PK[O^P[OTPUPTHSWOHZLZOPM[^OPSLH[[OLZHTL[PTLTPUPTPaPUN
OPNOMYLX\LUJ`HY[PMHJ[ZHUKKPZ[VY[PVUZ(SSVM[OLHIV]LHUKV\YL_WLYPLUJLSPZ[LUPUNHUKKLZPNUPUN
suggest&that&there&are&many&subtle&aspects&to&hearing&that&are&beyond&the&realm&of&simple&traditional&
TLHZ\YLTLU[JOHYHJ[LYPaH[PVUZ
;OL^H`PU^OPJOHUHUHSVNHTWSPÄLYOHUKSLZ]LY`ZTHSSZPNUHSZPZHZPTWVY[HU[HZ[OL^H`P[ILOH]LZ
H[OPNOSL]LSZ-VYSV^KPZ[VY[PVUHUHUHSVNHTWSPÄLYT\Z[OH]LHSPULHY[YHUZMLYJOHYHJ[LYPZ[PJPUV[OLY
^VYKZ[OLV\[W\[ZPNUHST\Z[ILHUL_HJ[YLWSPJHVM[OLPUW\[ZPNUHSKPMMLYPUNVUS`PUTHNUP[\KL;OL
THNUP[\KLJHUILJVU[YVSSLKI`HNHPUJVU[YVSVYMHKLYJVUZPZ[PUNVMHOPNOX\HSP[`]HYPHISLYLZPZ[VY
[OH[I`KLÄUP[PVUOHZHSPULHY[YHUZMLYJOHYHJ[LYPZ[PJ(K`UHTPJZJVU[YVSSLYPLHJVTWYLZZVY
SPTP[LYVYL_WHUKLYPZHNHPUJVU[YVS[OH[JHUHKQ\Z[NHPUVM[OLHTWSPÄLY]LY`YHWPKS`PUYLZWVUZL[V
[OLÅ\J[\H[PUNH\KPVZPNUHSPKLHSS`^P[OV\[PU[YVK\JPUNZPNUPÄJHU[KPZ[VY[PVUPLP[T\Z[OH]LHSPULHY
[YHUZMLYJOHYHJ[LYPZ[PJ)\[I`KLÄUP[PVUYHWPKS`JOHUNPUNNHPUTLHUZ[OH[HZPNUHS¸Z[HY[PUNV\[¹[VIL
linear&and,&therefore&without&distortion,&gets&changed&on&the&way&to&produce&a&different&amplitude.

5
0UL]P[HIS`V\YKH[HIHURVM¸UH[\YHS¹ZV\UKPZI\PS[\WVU[OLIHZPZVMV\YWLYZVUHSL_WLYPLUJLHUK
[OPZT\Z[Z\YLS`LTWOHZPaL[OLPTWVY[HUJLVMSPZ[LUPUN[V¸UH[\YHS¹ZV\UKHUKOPNOX\HSP[`T\ZPJHS
instruments&within&acoustic&environments&that&is&subjectively&pleasing&so&as&to&develop&keen&awareness&
[OH[^PSSJVU[YPI\[L[VHYLSPHISLKH[HIHUR/\THUZ^OVOH]LUV[L_WLYPLUJLKLUV\NO¸UH[\YHS¹
ZV\UKTH`^LSSOH]LHÅH^LKKH[HIHUR8\HSP[`YLJVYKPUNLX\PWTLU[ZOV\SKILJHWHISLVMYL[HPUPUN
“natural”&sound&and&this&is&indeed&the&traditional&measuring&stick.&And&“creative”&musical&equipment&
should&provide&the&tools&to&manipulate&the&sound&to&enhance&the&emotional&appeal&of&the&music&without&
destroying&it.&Memory&and&knowledge&of&real&acoustic&and&musical&events&may&be&the&biggest&tool&and&
advantage&any&recording&engineer&may&possess.
6ULULLKZ[VIL]LY`JHYLM\S^OLUVULOLHYZ[YHJLZVMKPZ[VY[PVUWYPVY[VYLJVYKPUNILJH\ZLZVTLÅH]VYZ
VMKPZ[VY[PVU[OH[TPNO[ZLLTHJJLW[HISLVYL]LUZ[`SPZOPUP[PHSS`TH`SH[LYWYV]L[VJH\ZLPYYLWHYHISL
KHTHNL[VWHY[ZVM[OLZV\UKMVYL_HTWSL¸^HYTSV^Z¹I\[¸OHYZOZPIPSHUJL¹VYPUSV\KLYVYX\PL[LY
ZLJ[PVUZVM[OLYLJVYKPUN,_WLYPLUJLZOV^Z[OH[TPJWYLHTWZHUKIHZPJJVUZVSLYV\[PUNWH[OZZOV\SK
VMMLYZ\WYLTLÄKLSP[`V[OLY^PZL[OLLUNPULLYOHZSP[[SLJVU[YVSVYJOVPJLVMYLJVYKLK¸JVSVY¹HUKSP[[SL
recourse&to&undo&after&the&fact.&Devices&or&circuits&that&can&easily&be&bypassed&are&usually&better&choices&
when&“color”&is&a&consideration&and&this&particularly&is&an&area&where&one&might&consider&comparing&
ZL]LYHSZ\JOKL]PJLZ)L^HYL[OH[\Z\HSS`KL]PH[PVUZMYVTSPULHYP[`JHYY`H[SLHZ[HZT\JOSVUN[LYT
penalty&as&initial&appeal,&and&that&one&should&always&be&listening&critically&when&recording&and&generally&
“playing&it&safe”&when&introducing&effects&that&cannot&be&removed.
1.##Tsutomu#Oohashi,#Emi#Nishina,#Norie#Kawai,#Yoshitaka#Fuwamoto,#and#Hishi#Imai.#National
Institute#of#Multimedia#Education,#Tokyo.#“High#Frequency#Sound#Above#the#Audible#Range,Affects#Brain#Electric#Activity#and#
Sound#Perception”#Paper#read#at#91st.#Convention#of#the#A.E.S.October#1991.#Section#7.#(1),#Conclusion.
2.##Miland#Kunchur,Depart#of#Physics#and#Astronomy,#University#of#South#Carolina.#“Temporal#resolution#of#hearing#probed#
by#bandwidth#restriction”,#M.#N.#Kunchur,#Acta#Acustica#united#with#Acustica#94,#594–603#(2008)#(http://www.physics.
sc.edu/kunchur/Acoustics-papers.htm)
3.##Miland#Kunchur,Depart#of#Physics#and#Astronomy,#University#of#South#Carolina.Probing#the#temporal#resolution#and#
bandwidth#of#human#hearing#,#M.#N.#Kunchur,#Proc.#of#Meetings#on#Acoustics#(POMA)#2,#050006#(2008)#
543 DESCRIPTION
The&Portico&543&Mono&Compressor&delivers&the&unobtrusive,&musical-sounding&dynamic&control&and&
brick-wall&limiting&made&famous&in&the&Portico&5043&to&the&500&series&format.&The&543&features&a&fully&
controllable&compressor-limiter&with&feed-forward&/&feedback&modes,&Peak&/&RMS&detection&and&a&built&
PUZPKLJOHPUOPNOWHZZÄS[LY>P[OHU\UYP]HSLKOLYP[HNLHUKH[YLTLUKV\ZMLH[\YLZL[[OL`PLSKZH
JVTIPUH[PVUVMYPJO^HYT[OÅL_PIPSP[`HUKWYLJPZPVU[OH[HSSV^ZP[[VIL\ZLKLMMLJ[P]LS`VU]PY[\HSS`HU`
source&material.
THE WAY THE 543 WORKS&
(WHY[VM[OLH\KPVZPNUHSPZYLJ[PÄLKHUKZTVV[OLK[VWYVK\JLHZ\P[HISLJVU[YVS]VS[HNLMVY[OL=*(
which&has&to&respond&very&quickly&and&have&low&distortion.&If&the&response&is&too&fast,&low&frequency&
signals&will&themselves,&be&“gain&controlled”!&If&the&response&is&too&slow,&the&signal&will&overshoot&
HUK[OLÄYZ[ML^J`JSLZ^PSSUV[NL[JVTWYLZZLK;OLZWLLKHUKHJJ\YHJ`VM[OLYLZWVUZLRUV^UHZ
the&“attack”,&and&the&time&frame&that&gain&remains&under&the&initial&control,&known&as&“release”&or&
“recovery”,&&play&a&large&part&in&the&way&a&compressor&sounds.
;OL7VY[PJVTHRLZ\ZLVMH]LY`HJJ\YH[LSV^UVPZLSV^KPZ[VY[PVU=*(OH]PUNLZZLU[PHSS`UV

6
¸ZPNUH[\YL¹VMP[ZV^U;OPZSLH]LZ[OLKLZPNULYMYLL[V\ZLHTWSPÄLYHUK[YHUZMVYTLYJVTIPUH[PVUZ[OH[
are&well&proven&and&produce&the&desired&sonic&quality.&&
All&Portico™&modules&use&input&and&output&transformers&and&almost&entirely&discrete&component&
HTWSPÄLYZ[VWYVK\JL[OLT\ZPJHS¸ZPNUH[\YL¹MVY^OPJO[OL`HYLRUV^U;OLZLHYLMHJ[VYZ[OH[LUHISL
[OL7VY[PJV[V^VYR\UVI[Y\ZP]LS`^P[OPU[OLJVU[L_[VMH]LY`OPNOX\HSP[`H\KPVJOHPU
0M[OL=*(*VU[YVS]VS[HNLPZ[HRLUMYVT[OLPUW\[PLILMVYL[OL=*([OL=*(¸RUV^Z¹YPNO[
away&that&a&gain&change&is&required&and&there&is&almost&immediate&response.&&This&is&known,&logically,&
HZH¸-LLK-VY^HYK¹JVTWYLZZVY0M[OL=*(JVU[YVS]VS[HNLPZ[HRLUMYVT[OLV\[W\[PLHM[LY
[OL=*(P[JHUUV[HJ[PTTLKPH[LS`VU[OL=*(ILJH\ZLP[OHZHSYLHK`ILLUTVKPÄLKI`ZL[[PUNZ
VM[OL=*(HUKJPYJ\P[Z[OYV\NO^OPJOP[OHZWHZZLK;OPZPZRUV^UHZH¸-LLK)HJR¹JVTWYLZZVY
The&two&compression&characteristics&are&quite&different,&there&is&more&“overshoot”&and&both&the&attack&
and&recovery&ramps&are&changed,&providing&the&user&with&powerful&choices.&&&A&choice&between&“Feed-
-VY^HYK¹HUK¸-LLK)HJR¹JPYJ\P[Y`PZWYV]PKLK(STVZ[HSS4Y9\WLY[5L]L»ZLHYSPLYKLZPNUZ^LYL
¸-LLK)HJR¹;OL`^LYLTVYLT\ZPJHSHUKZ^LL[LY[OHU^P[O¸-LLK
Forward”&designs.
&

7
The&way&in&which&these&modes&change&the&dynamic&performance&can&be&seen&in&the&above&graph&-&
I\[[OLTVYLPU[LYLZ[PUNLMMLJ[ZHYLUV[LKI`SPZ[LUPUN¸-LLK)HJR¹WYVK\JLZHZ^LL[LY^HYTLY
ZV\UKI\[PZUV[HZHJJ\YH[LPM`V\ULLK[VWYV[LJ[H[YHUZTP[[LYMVYL_HTWSL
543 FEATURES
THRESHOLD
:L[ZSL]LS^OLYL[OLJVTWYLZZVYTH`ILNPU[VYLHJ[MYVTK)[VK)4PUPTHSVYUVJVTWYLZZPVU
is&with&this&control&fully&clockwise&and&it&gets&more&sensitive&and&tends&to&cause&more&gain&reduction&as&
[OLRUVIPZYV[H[LKJV\U[LYJSVJR^PZL^OPJOTH`ILJV\U[LYPU[\P[P]L[VZVTL
RATIO
:L[Z[OL¸ZSVWL¹VM[OLJVTWYLZZPVUMYVT!TPUPTHS[V!3PTP[-VYL_HTWSLPM[OPZRUVIPZZL[
MVY![OLUPM[OLZPNUHSNVLZK)V]LY[OL[OYLZOVSK[OLUP[H[[LU\H[LZK)HUKHSSV^Z[OLV\[W\[[V
YPZLK)0UNLULYHSSV^YH[PVZJHUUV[KHTHNL[OLT\ZPJHZT\JOHZOPNOYH[PVZI\[OPNOYH[PVZTH`IL
TVYL\ZLM\S[VTPUPTPaLJSPWWPUNHUK63SPNO[ZPU[OLYLJVYKLY
,_J\ZL[OLMYVU[WHULSQ\TWHUKKPNYLZZPVUI\[P[PZHWWYVWYPH[L[VTLU[PVU[OL.(059,+<*;065
HUK6<;7<;TL[LYZUV^ILJH\ZLZVTHU`VM\ZSLHYULK[VZL[\WJVTWYLZZVYZI`^H[JOPUN[OLHSS
PTWVY[HU[.9TL[LY>OLUZL[[PUN[OL;OYLZOVSKHUK9H[PVP[KVLZOLSW[V\ZL[OLTL[LYZOV^L]LYHZ
HS^H`Z^LZOV\SKYLS`VUV\YLHYZHUK`LVSKL¸*64705¹)`WHZZ)\[[VUTVZ[VMHSS6ULTPNO[[Y`
[VPU[LYWYL[[OL6<;7<;TL[LYHZVULL_LYJPZLZ`LVSKL¸*64705¹I\[[VU[VVHZ[OPZTPNO[ILTVYL
HWWYVWYPH[L[V`V\YNVHSZ[OHUH[HYNL[VM?K)VYU\TILYVM3,+ZVMJVTWYLZZPVU0Z[OLNVHS[VTHRL
great&sounds&or&to&blink&LEDs&half&way&down&the&meter&because&you&read&it&somewhere?&
COMP IN
The&compressor&section&is&engaged&with&this&button&in.&This&may&be&the&most&useful&control&on&the&
JVTWYLZZVYILJH\ZLP[PZ[OLYLMVY¸JVUÄKLUJLJOLJRZ¹0UWHY[PJ\SHYL_LYJPZLP[PUIV[O[OLX\PL[LZ[
HUK[OLSV\KLZ[ZLJ[PVUZVM[OLZVUN>H[JOV\[MVY[OLJVTWYLZZVYL_HNNLYH[PUNUVPZLHUKYVVTZV\UK
in&the&quiet&sections&and&chopping&off&transients&and&consonants&in&the&loud&sections,&either&of&which&
suggest&maybe&too&much&compressor&“action”.&Conversely,&losing&quiet&phrases&or&inadvertent&clipping&
might&suggest&that&a&little&more&compression&is&warranted&keeping&in&mind&that&you&can&always&do&a&bit&
TVYLPU[OLTP_I\[\UKVPUNV]LYJVTWYLZZPVUPZUV[M\UHUKVM[LUUV[L]LUWVZZPISL
FF/FB
;OLZLHYL[^V]LY`KPMMLYLU[JVTWYLZZVYTVKLZ-,,+)(*2HUK-,,+-69>(9+=PU[HNLJVTWYLZZVYZ
HSTVZ[HS^H`Z^LYL-,,+)(*2KLZPNUZ^OPJOTLHUZ[OL`SVVRLKH[[OLV\[W\[HM[LY[OL=*(=VS[HNL
*VU[YVSSLK(TWSPÄLYVYNHPUJOHUNPUNLSLTLU[HUK\ZLK[OH[ZPNUHS[VJVU[YVS[OLH[[LU\H[PVU-,,+
-69>(9+JVTWYLZZVYZILJHTLWVW\SHYPU[OL»ZHUKYLHK[OLZPNUHSILMVYL[OL=*(HUK[OYV\NO
more&elaborate&electronics&to&control&the&attenuation&because&this&has&some&advantages&in&regards&to&
[OLYH[PVHUKJVU[YVS[PTPUN7LYOHWZHTVYL\ZLM\SNLULYHSPaH[PVUPZ[OH[[OL-)TVKLI\[[VUPU[LUKZ
to&sound&smoother&and&often&more&natural&and&tends&to&be&quicker&to&set&up.&The&FF&mode&can&be&more&
useful&for&shaping&the&envelope&of&the&sound&and&introducing&more&bounce&and&pumping&in&time&with&
the&song,&when&that&is&the&goal.&FF&compressors&were&often&used&on&80’s&dance&tracks.&Some&engineers&
WYLMLY-)^P[OSV^LYYH[PVZHUK--^P[OOPNOLYYH[PVZ

8
GAIN
6M[LUYLMLYYLK[VHZ4HRL<W.HPU*VUZPKLYPUN[OLJVTWYLZZVY»Z=*(PZNLULYHSS`ILPUNMVYJLK[V
attenuate&louder&signals&some&method&of&returning&the&average&level&to&a&volume&comparable&with&the&
JVTWYLZZVYI`WHZZLKPZKLZPYHISL;OL.(05JVU[YVSPZTVZ[S`\ZLKMVY[OPZW\YWVZLLZWLJPHSS`MVY[OVZL
VM\Z[OH[KLWLUKVUJVTWHYPUNJVTWYLZZPVU[VI`WHZZ.(05PZVM[LUW\ZOLKMVYL]LUTVYLSL]LS[OHU
“bypass”&because&it&is&understood&that&the&compressor&should&be&providing&some&effective&headroom&
ILZPKLZ¸SV\KLYPZIL[[LY¹ILPUN[OLVSKLZ[[YPJRPU[OLIVVR
ATTACK
;OPZZL[ZOV^X\PJRS`[OLJVTWYLZZVYYLHJ[ZHUKZ[HY[ZH[[LU\H[PUN0MZL[MHZ[T:[OLJVTWYLZZVY
should&react&to&very&quick&transients&like&the&initial&stick&hit&of&a&snare&drum&and&can&attenuate&the&“hit”&
ZV[OL¸UV[L¹VM[OLKY\TZLLTZYLSH[P]LS`LTWOHZPaLK0MZL[ZSV^LY[OLJVTWYLZZVY^PSS[LUK[VPNUVYL
the&fastest&transients&and&react&more&to&the&drum&resonance&and&attenuate&the&“note”&of&the&drum&so&that&
[OLOP[ZLLTZTVYLLTWOHZPaLK:PTPSHYS`VUHTP_LK[YHJRPMHJVTWYLZZVYPZZL[[VVMHZ[P[^PSS[LUK[V
YLTV]LKY\TZ^OPJOTH`OLSW[VL_WSHPU^O`THZ[LYPUNLUNPULLYZ[LUK[V\ZLTLKP\T[VZSV^H[[HJR
times&and&lower&ratios.
RELEASE
;OPZZL[ZOV^MHZ[[OLJVTWYLZZVYYL[\YUZIHJR[VaLYVHM[LYH[[LU\H[PUN;`WPJHSS`LUNPULLYZOH]L\ZLK
X\P[LZSV^YLSLHZLZ^OLU[OLULLKPZ[VTPUPTPaLHU`VI]PV\ZJVTWYLZZVYHJ[PVUVYNHPUZJOHUNPUN-VY
TVKLYUWVWT\ZPJX\P[LVM[LU[OLNVHSPZ[VOH]L[OLJVTWYLZZVYJOHUNLNHPUZHWWYV_PTH[LS`PU[PTL
with&the&music&and&the&RELEASE&control&setting&becomes&important&for&this.&On&the&other&hand,&many&
of&us&were&trained&to&avoid&having&compressors&“pump”&and&sound&like&they&are&breathing.&Another&
TH`IL[VVJVTTVU\ZLVMJVTWYLZZVYZPZ[VTH_PTPaL[OLHWWHYLU[]VS\TLHUKMVY[OPZVULNLULYHSS`
^HU[Z]LY`MHZ[YLSLHZLZL[[PUNZZV[OH[HM[LYYLK\JPUNWLHRZ[OLJVTWYLZZVYYL[\YUZ[VTH_PT\TSL]LSZ
as&quickly&as&possible.&And&by&“as&possible”&there&is&a&practical&matter&regarding&the&tendency&of&
compressor/limiters&to&introduce&a&nasty&form&of&distortion&called&“modulation&distortion”&when&they&are&
set&for&a&combination&of&fast&attacks,&fast&releases&and&high&ratios.&
RMS/PEAK
This&changes&the&compressor&from&essentially&responding&to&the&RMS&level&of&the&audio&to&also&
YLZWVUKPUN[V[OL7,(2SL]LS94:YVV[TLHUZX\HYLKJPYJ\P[ZHYLJVUZPKLYLK[VIL[[LYTPTPJ[OL
way&the&ears&perceive&apparent&loudness,&while&Peak&circuits&tend&to&directly&respond&to&the&waveform&
]VS[HNL^OPJOTH`ILTVYLVMHJVUJLYUMVYWYL]LU[PVUVMJSPWWPUNHUKTH_PTPaPUNSL]LSZ0U[OPZJHZL
pushing&FAST&uses&a&combination&of&both&methods&to&get&the&best&of&both&worlds&and&avoidance&of&the&
drawbacks&of&each&method&on&its&own.
Do&we&recommend&any&particular&compressor&settings&for&particular&instruments?&No,&but&we&will&
recommend&that&you&not&depend&on&hear-say&settings&and&that&you&always&listen&carefully&to&the&levels&
HUKTP_]HS\LZHZ`V\[^LHR@V\JHUNLULYHSS`YLNHYKHJVTWYLZZVYHZHZLTPH\[VTH[PJ]VS\TL
control&and&be&aware&of&the&kinds&of&artifacts&that&you&would&get&moving&a&fader&quickly.&You&can&also&
listen&for&changes&in&tone&that&are&probably&due&to&altering&the&relative&strength&of&transient&hits&and&
plosives&that&often&contain&more&high&mid&and&highs.&
Side Chain HPF
;OPZYV\[LZHOPNOWHZZÄS[LYZL[[V/aPU[V[OLJPYJ\P[[OH[[OLJVTWYLZZVY\ZLZ[VKL[LYTPULSL]LS
commonly&referred&to&as&“the&side-chain”.&Note&that&the&rest&of&the&circuit&and&output&will&not&have&those&
SV^ZÄS[LYLKV\[;OPZM\UJ[PVU[LUKZ[VIL]LY`\ZLM\SILJH\ZL[`WPJHSZV\UKZVM[LUOH]LTVYLLULYN`

9
PU[OLSV^VJ[H]LZHUKJHUJH\ZLL_JLZZP]LJVTWYLZZPVU6\YLHYZTH`[LUK[VHZZVJPH[LSV\KULZZ^P[O
mids&or&high&mids&for&some&sounds&and&one&may&be&wanting&the&compressor&to&regulate&and&smooth&
perceived&loudness.&Removing&some&amount&of&low&frequencies&that&the&compressor&“sees”&can&help&
LZWLJPHSS`PMVULPZJVTWYLZZPUNKLLWS`K)VYTVYL
Link
With&most&new&500&series&racks,&an&internal&link&buss&is&provided,&allowing&two&or&more&543’s&to&link&
[OLPY=*(»Z^OLU[OLSPURZ^P[JOPZ[VNNSLK0U[OPZJVUÄN\YH[PVU[OLZHTLSPURI\ZZPZZOHYLKI`HSSVM
[OLTVK\SLZPU[OLYHJRZVP[PZUV[WVZZPISL[V\ZLTVYL[OHUVULWHPYVM»ZVYV[OLYJVTWYLZZVYZ
using&the&link&buss)&in&the&same&rack&concurrently.
&
>OLUSPURI\ZZPZUV[WYV]PKLKVYP[PZUV[WVZZPISL[V\ZLP[JOLJR^P[O[OLYHJRTHU\MHJ[\YLYPM
\UJLY[HPUHQ\TWLY^PYLJHUIL\ZLK[VJVUULJ[HKQHJLU[TVK\SLZ>LOH]LWYV]PKLKHWPU
connector&on&the&back&of&the&543&for&a&jumper&cable&which&can&directly&connect&the&link&buss&on&the&
TVK\SLZ)V[OWPUZJHYY`[OLSPURZPNUHSZV[OH[ZPUNSL^PYLQ\TWLYZJHUIL\ZLK[VSPURT\S[PWSLTVK\SLZ
in&a&daisy&chain&fashion.
&&
If&you&need&to&purchase&one&or&more&jumper&wires,&please&contact&[email protected]&
SPECIFICATIONS
GainRange:&
*VU[PU\V\ZS`]HYPHISLMYVTK)[VK)
ThresholdRange:
*VU[PU\V\ZS`]HYPHISLMYVTK)[VK)
RatioRange:
*VU[PU\V\ZS`]HYPHISLMYVT![V3PTP[!
AttackRange:
*VU[PU\V\ZS`]HYPHISLMYVTT:[VT:
ReleaseRange:
*VU[PU\V\ZS`]HYPHISLMYVTT:[V:LJVUKZ
TotalHarmonicDistortionandNoise:&&
 'R/aK)\V\[W\[SL]LSUVSVHK
&&&& Main&Output,&compressor&bypassed
 )L[[LY[OHU
 'K)\IL[[LY[OHU
& Main&output,&compressor&engaged
 )L[[LY[OHU
Noise:&
 4LHZ\YLKH[4HPU6\[W\[\U^LPNO[LK/aR/a;LYTPUH[LK6OTZ
 >P[O.HPUH[<UP[`*VTWYLZZVYKPZLUNHNLK
 IL[[LY[OHU K)\

10
 >P[O.HPUH[<UP[`*VTWYLZZVYLUNHNLK!
 IL[[LY[OHU K)\
FrequencyResponse:&
 4HPU6\[W\[<UP[`.HPU
 'R/aK)
Crosstalk:
& Measured&channel&to&channel
 )L[[LY[OHU¶ K)'R/a
Meters:&
 4VUP[VYZ057<;3,=,3HUK.(059,+<*;065
LineInputImpedance
 6OTZ
Maximum Output Level:
 K)\MYVT/a[VR/a
Power requirements:
 :\WWSPLKI`ZLYPLZYHJR^P[OT('=