· 7 min čitanja
4 cable method: kako povezati multiefekat sa pojačalom
Imaš pojačalo čija ti se distorzija sviđa i multiefekat sa dobrim delay-om i reverb-om. Ako sve pedale uključiš u ulaz pojačala, delay i reverb prolaze kroz distorziju i pretvore se u kašu. 4 cable method (skraćeno 4CM) to rešava: deo efekata ide ispred pretpojačala, a deo posle njega, i sve to sa jednim uređajem i četiri kabla.
Zašto je redosled važan
Pojačalo nije jedan blok. Ima pretpojačalo (preamp), gde nastaju gain, distorzija i boja tona, i izlazni stepen (power amp), koji pokreće zvučnik. Efekti zvuče različito zavisno od toga gde u tom lancu stoje:
- Ispred pretpojačala želiš sve što oblikuje signal koji ulazi u distorziju: wah, kompresor, overdrive, fuzz, boost. Overdrive ispred pojačala koje već malo „gura“ upravo tako i treba da radi.
- Posle pretpojačala želiš efekte koji dodaju prostor i pokret: chorus, flanger, delay, reverb. Tu oni obrađuju već izobličen zvuk, kao kad se reverb dodaje snimku u studiju, pa svako ponavljanje delay-a ostaje jasno.
Kad delay stoji ispred distorzije, svako ponavljanje se izobliči zajedno sa notom koju sviraš i sve se stopi. Uz čist zvuk to nije problem, ali uz distorziju pojačala jeste.
Šta ti treba
- Pojačalo sa efekt petljom (FX loop): na zadnjoj strani ima utičnice
SENDiRETURN. Petlja se nalazi baš između pretpojačala i izlaznog stepena. Bez nje 4CM ne može. - Multiefekat ili procesor sa sopstvenom send/return petljom. Imaju je, na primer, Line 6 HX Stomp i Helix i Boss GT-1000. Petlja u uređaju je ono što ti dozvoljava da „izađeš“ iz njega u sred lanca efekata i vratiš se.
- Četiri instrumentalna kabla. Kablovi 2, 3 i 4 idu do pojačala, pa im dužina zavisi od toga gde stoji pedalbord. Kvalitetni kablovi su bitni, jer signal sada prelazi dug put.
Povezivanje, kabl po kabl
- Gitara → INPUT multiefekta. Kao i obično.
- SEND multiefekta → INPUT pojačala (prednji ulaz). Ovim kablom ide sve što je u lancu ispred petlje: drive, wah, kompresor.
- FX SEND pojačala → RETURN multiefekta. Sada se u multiefekat vraća signal koji je prošao kroz pretpojačalo, znači sa distorzijom pojačala.
- OUTPUT multiefekta → FX RETURN pojačala. Signal sa modulacijom, delay-om i reverb-om ide u izlazni stepen i zvučnik.
Najčešća greška je zamena kablova 3 i 4. Pravilo za pamćenje: SEND uvek ide u RETURN, i obrnuto. Ako se ništa ne čuje, prvo proveri to.
Podešavanje u multiefektu
- Postavi blok petlje (FX Loop, Send/Return) u lanac. Sve levo od njega ide u pretpojačalo, sve desno ide posle pretpojačala.
- Isključi simulaciju pojačala i zvučnika u tom presetu. Pravo pojačalo radi taj posao; simulacija preko njega zvuči mutno i preglasno.
- Podesi nivoe. Izlaz ka prednjem ulazu pojačala treba da bude na nivou gitare (instrument level), da drive pedale i pojačalo reaguju kao inače. Za petlju gledaj šta pojačalo očekuje: neke petlje rade na nivou instrumenta, a neke na višem, linijskom nivou. Ako je zvuk tih ili se „guši“, probaj drugi nivo na izlazu ili u bloku petlje.
- Štimer stavi na sam početak lanca, da dobija čist signal gitare.
Česti problemi
Brujanje
Multiefekat je sada sa pojačalom povezan na dva mesta, pa može da nastane uzemljenje u petlji (ground loop) i tiho brujanje. Pomaže prekidač za odvajanje mase (ground lift) ako ga uređaj ima, kraći kablovi, i da pojačalo i pedalbord budu priključeni u istu utičnicu. Nikad ne skidaj uzemljenje sa strujnog kabla pojačala: to je opasno po život.
Serijska ili paralelna petlja
U serijskoj petlji ceo signal prolazi kroz efekte. U paralelnoj pojačalo zadrži svoj čist („suv“) signal i pomeša ga sa onim što se vrati. Ako je petlja paralelna, efekti posle petlje treba da vraćaju samo efekat, bez suvog signala (opcija „kill dry“ ili mix na 100 %). U suprotnom se suvi signal duplira, a malo kašnjenje digitalnog uređaja daje šupalj, „fazni“ zvuk.
Noise gate
Gate ispred pretpojačala ne vidi šum koji pravi samo pojačalo, a gate posle petlje seče i rep reverb-a. Najbolje radi gate koji koristi oba mesta: meri signal na ulazu, a utišava posle pretpojačala. Neke pedale su napravljene baš za to, na primer Boss NS-2 sa sopstvenim send/return utičnicama, a i mnogi procesori imaju gate koji se tako postavlja.
Menjanje kanala pojačala
Ako pojačalo ima više kanala, neki procesori mogu da ih menjaju sa presetom, preko posebnog izlaza za kontrolu pojačala (na primer EXT AMP na Line 6 uređajima) ili preko MIDI-ja. Tako jedan pritisak menja i kanal i efekte.
Kad 4CM nema smisla
- Pojačalo nema efekt petlju. Tada sve ide ispred ulaza, sa dva kabla. Delay i reverb biće bolji uz čist kanal ili blagu distorziju.
- Distorziju dobijaš od pedala, a pojačalo je čisto. Pojačalo tada ne izobličava ništa, pa i delay i reverb mogu da stoje ispred njega.
- Koristiš simulacije pojačala iz procesora. Tada ti pretpojačalo pravog pojačala ne treba: procesor ide direktno u ozvučenje (FRFR) ili u RETURN pojačala, da koristiš samo njegov izlazni stepen i zvučnik.
Ukratko
Gitara u multiefekat, SEND u ulaz pojačala, FX SEND pojačala u RETURN multiefekta, OUTPUT u FX RETURN pojačala. Drive ispred petlje, modulacija, delay i reverb posle nje, simulacija pojačala isključena. Ako bruji, proveri masu; ako je zvuk šupalj, proveri da li je petlja paralelna.
You have an amp whose distortion you love and a multi-effects unit with great delay and reverb. Plug everything into the front of the amp and the delay and reverb go through the distortion and turn to mush. The 4 cable method (4CM for short) fixes that: some effects go before the preamp and some after it, all from one unit and with four cables.
Why the order matters
An amp is not one block. It has a preamp, where gain, distortion and tone colour happen, and a power amp, which drives the speaker. Effects sound different depending on where they sit in that chain:
- Before the preamp you want everything that shapes the signal going into the distortion: wah, compressor, overdrive, fuzz, boost. An overdrive pushing an amp that is already breaking up is exactly how it is meant to work.
- After the preamp you want effects that add space and movement: chorus, flanger, delay, reverb. There they process the already distorted sound, like reverb added to a recording in the studio, so every delay repeat stays clear.
When the delay sits before the distortion, every repeat gets distorted together with the note you are playing and everything blurs. With a clean sound that is fine, with amp distortion it is not.
What you need
- An amp with an effects loop (FX loop):
SENDandRETURNjacks on the back. The loop sits right between the preamp and the power amp. Without it, 4CM is not possible. - A multi-effects unit or processor with its own send/return loop. The Line 6 HX Stomp and Helix and the Boss GT-1000 have one, for example. The loop in the unit is what lets you “leave” it in the middle of the effects chain and come back.
- Four instrument cables. Cables 2, 3 and 4 run to the amp, so their length depends on where your pedalboard sits. Good cables matter, because the signal now travels a long way.
Wiring, cable by cable
- Guitar → multi-effects INPUT. As usual.
- Multi-effects SEND → amp INPUT (the front input). This cable carries everything in the chain before the loop: drive, wah, compressor.
- Amp FX SEND → multi-effects RETURN. What comes back into the unit now has been through the preamp, so it carries the amp’s distortion.
- Multi-effects OUTPUT → amp FX RETURN. The signal with modulation, delay and reverb goes into the power amp and the speaker.
The most common mistake is swapping cables 3 and 4. The rule to remember: a SEND always goes into a RETURN, and the other way round. If you hear nothing, check that first.
Setting up the multi-effects unit
- Place the loop block (FX Loop, Send/Return) in the chain. Everything to its left goes into the preamp, everything to its right comes after the preamp.
- Turn off the amp and cab simulation in that preset. The real amp does that job; a simulation on top of it sounds muddy and too loud.
- Set the levels. The output to the amp’s front input should be at guitar (instrument) level, so drive pedals and the amp respond as usual. For the loop, check what your amp expects: some loops run at instrument level and some at a hotter line level. If the sound is quiet or choked, try the other level on the output or in the loop block.
- Put the tuner at the very start of the chain, so it gets the clean guitar signal.
Common problems
Hum
The multi-effects unit is now connected to the amp in two places, which can create a ground loop and a low hum. A ground lift switch helps if the unit has one, as do shorter cables and plugging the amp and the pedalboard into the same outlet. Never remove the ground from the amp’s power cable: that can kill you.
Series or parallel loop
In a series loop the whole signal goes through the effects. In a parallel loop the amp keeps its own clean (“dry”) signal and blends it with what comes back. If the loop is parallel, the effects after the loop should return only the effect, without the dry signal (a “kill dry” option or 100 % mix). Otherwise the dry signal is doubled, and the small latency of a digital unit gives a hollow, “phasey” sound.
Noise gate
A gate before the preamp does not see the noise the amp itself makes, and a gate after the loop also cuts reverb tails. A gate that uses both places works best: it listens at the input and mutes after the preamp. Some pedals are built for exactly this, such as the Boss NS-2 with its own send/return jacks, and many processors have a gate that can be set up this way.
Switching amp channels
If your amp has several channels, some processors can switch them with a preset, through a dedicated amp-control output (EXT AMP on Line 6 units, for example) or over MIDI. One stomp then changes both the channel and the effects.
When 4CM makes no sense
- The amp has no effects loop. Everything goes into the front input, with two cables. Delay and reverb will work best with a clean channel or light breakup.
- Your distortion comes from pedals and the amp stays clean. The amp distorts nothing, so delay and reverb can sit in front of it too.
- You use the processor’s amp models. Then you do not need the real amp’s preamp: the processor goes straight into a PA (FRFR) or into the amp’s RETURN, so you only use its power amp and speaker.
In short
Guitar into the multi-effects unit, SEND into the amp input, amp FX SEND into the unit’s RETURN, OUTPUT into the amp FX RETURN. Drive before the loop, modulation, delay and reverb after it, amp simulation off. If it hums, check the ground; if it sounds hollow, check whether the loop is parallel.