# What is FX loop ??



## Verne (Dec 29, 2018)

I am still pretty new to heads and higher end amps. I see the FX loop on them and I don't fully get what it does. From reading an owners manual, it sounds like it does the same as putting the pedals in front of the amp. I have 5 pedals I run in front of my amps and always have. I am layman in many amp and electronic terms, so could somebody explain to me what this does, and will any of my pedals really need it? 
Distortion/OD pedal
Flanger
Chorus
Tech 21 California clone.

I just link each pedal to the next and run into the input. This is all I've ever known. FX loop is something new and wondering if I should be, or should have always have been, using it.


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## KapnKrunch (Jul 13, 2016)

Effects Loop Truths 

EDIT: skip the section where Kevin talks about the amps that he doesn't even make anymore (Scorcerer, Sustainor, Aurora). Update yer site, KO!


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## sulphur (Jun 2, 2011)

Usually, when using the O/D from the amp, the EL allows you to add the pedals after that dirt in the chain.

Same thing as organizing your pedals out front when using the amp clean and a dirt pedal.

Of course, it boils down to the user and what sounds best to you.


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## Dorian2 (Jun 9, 2015)

Always a good topic IMO. This is how I like to do it :

Tuner > Compression > Phaser > OD > Distortion/Heavy OD > Amp Input > *(FX Loop) Send* > Delay > Reverb > EQ > *FX Loop Return
*
Lots of variations depending on Amp, sound you want, blah blah....

As far as the FX loop itself, it's basically a stage between the Pre and Power amps. Someone else can explain that because I have to go do some stir fry now..


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## mhammer (Nov 30, 2007)

Verne said:


> I am still pretty new to heads and higher end amps. I see the FX loop on them and I don't fully get what it does. From reading an owners manual, it sounds like it does the same as putting the pedals in front of the amp. I have 5 pedals I run in front of my amps and always have. I am layman in many amp and electronic terms, so could somebody explain to me what this does, and will any of my pedals really need it?
> Distortion/OD pedal
> Flanger
> Chorus
> ...


There is much I could go into, but very little of what you use really requires use of an amplifier effects loop.

Having said that, effects loops in amplifiers are very similar to the "monitor" function on stereo amplifiers. Traditionally, selecting "monitor" would mean that your stereo sends out whatever you're listening to out to a tape deck of some sort, and the output of the tape deck is then what feeds your amplifier's power stage. So, for example...
in-from-CD-player --> to amplifier's preamp --> to cassette-deck --> from cassette-deck ---> amplifier tone controls --> to power-amplifier.
This arrangement lets you record whatever you're listening to, and play back the recording, or simply listen to it live, but with whatever tonal changes the cassette deck's electronics provide. In some instances, an expensive tape machine would let you hear (and amplify) what was laid down on tape in real time.

People will use effect loops for a variety of purposes:

To provide a preamp send to another amplifier
To insert a noise-control device to cure noise accumulated from pedals and the amp's preamp stage
 To attenuate the signal in an amp that lacks a master volume
To feed an outboard effect/device that requires, or simply works better with, a line-level signal (which is hotter than normal guitar signal)
 To insert an effect (typically time-based or reverb) which is normally applied as a post-production effect
There are other uses beyond this, but it gives you some idea of what folks do with it.


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## tonenut (Mar 1, 2019)

If you know anything about reading amplifier circuit schematics, you can look up the schematic for your amp and see where the FX loop fits into the chain.


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## mhammer (Nov 30, 2007)

tonenut said:


> If you know anything about reading amplifier circuit schematics, you can look up the schematic for your amp and see where the FX loop fits into the chain.


Absolutely correct. It will also identify whether the loop is buffered, what the approximate signal level will be, and whether the send/return path is "normalized".

I don't know that the term "normalized" _comes_ from modular synths, but it is a traditional term for describing things in that realm. If a connection is "normalized" it means that, unless a plug is inserted into one or both jacks, their path is "normally" connected.

Having said that, there are different varieties of normalized connections in an effects loop. For example, it could be that the Send is always connected to the Return, unless something is plugged into the Send. Take a feed from the preamp to send somewhere else, and the Return goes silent. OR, it could be that the Send is always available, to feed multiple destinations, _unless _something is plugged into the Return. Any of these, and other, combinations make use of so-called "switching jacks" that lift some connections and make others when a phone plug is inserted. 

The designer/manufacturer will make choices about how connections are made/disabled in the Send/Return loop, based on how they intend for the amplifier's preamp to be used. It can also be for how they intend the _power_ amp to be used. I don't imagine it's all that common, but a user might have another amplifier with a front-end that they really like (e.g., great EQing) but with a power amp or combo speaker/cab that is too much or too little for their immediate needs. They could run a cable from that amplifier's Send to the preferred power amp's Return, using the preamp in one but the power amp and speakers in another. And so on.

I have a little Fender solid-state SK20 stereo chorus amp. It's a puny attempt to mimic a Roland JC120 in mini-form, with a pair of 8" speakers in a smaller cab, with independent power amps, wet on one side and dry on the other. One thing it has that I like is a stereo effects loop, that allows me to insert different effects on each side. So, for instance, I can use the modulated delay normally available on the one channel, and insert a slow phase shift on the other one. Or I could have the delay side be clean, and dirty up the "dry" side. Or add a second modulated delay to the unaffected side. The possibilities are endless. Too bad it's such a small amp, but it lets me try out interesting experiments.


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## Verne (Dec 29, 2018)

Wow guys, thanks for the explanations. I think I am starting to get it. I don't have a delay, but am starting to think I may get one just because I now have a better understanding how to use it correctly. I assume then that the FX loop means 2 more cables. Pedal out to FX return, and pedal in to FX send? Hence the loop part? These explanations, albeit a little technical for my understanding at this point still, are really awesome and do help me a lot. I really like how each expands on the other posts. I love this board. It seems that no matter how basic the information is for you, you help somebody learn when they ask.

I can't read a schematic to save my life.....but feel confident if I asked, this board would have me a tech graduate in no time.


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## sulphur (Jun 2, 2011)

Yes, two more cables for the EL and you have the layout right.
Send into the pedal input and output to the return.


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## Dorian2 (Jun 9, 2015)

Verne said:


> Wow guys, thanks for the explanations. I think I am starting to get it. I don't have a delay, but am starting to think I may get one just because I now have a better understanding how to use it correctly. I assume then that the FX loop means 2 more cables. *Pedal out to FX return, and pedal in to FX send?* Hence the loop part? These explanations, albeit a little technical for my understanding at this point still, are really awesome and do help me a lot. I really like how each expands on the other posts. I love this board. It seems that no matter how basic the information is for you, you help somebody learn when they ask.
> 
> I can't read a schematic to save my life.....but feel confident if I asked, this board would have me a tech graduate in no time.


Re: 2nd part of the bolded part, it's absolutely correct, but I personally prefer phrasing it "FX Send to pedal In" simply because it's the way I think. But correct nonetheless...guess it's the way you look at it or phrase it. Re: using the Delay correctly in the loop. Consider it another option. Many prefer delay right in front of the amp as well. Depends on taste and what you're looking for sound wise. These are guidelines not rules.


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## Verne (Dec 29, 2018)

I was more or less looking at it from the guitar standpoint. Out the jack and the trail to/from the amp. Either way, once I really start to use it, it'll all make sense and become "normal" for me.


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## reckless toboggan (Mar 9, 2019)

I had never thought of using the FX loop to send to another amp. Usually I put distortion, od, fuzz, in front of the amp, and run phase, flange, delay, etc in the FX loop.

But the thought of using an FX loop send to another amp lead me to this idea:



1) Let's pretend I bought a Marshall Origin 20c.

2) Could I buy the DSL 20hr and plug the Origin effects loop send into the DSL guitar in, and the DSL speaker out or DI out into the Origin FX return, so that I could run the DLS head through the Origin speaker?



Seems like a terrible idea, from what little I knew before,... but just a thought since I read in this thread that you can use the FX loop to send to other amps.

...

Also, as a general comment, this forum rules for learning. If I'd had this around in the 90s and 00s when I was gigging, my band(s) would have sounded much better. We still would have been terrible, but you really would have been able to hear it lot better.


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## KapnKrunch (Jul 13, 2016)

In this case a picture is *not* worth a thousand words, because some excellent explanation has been shared here. But these pic's kinda sum up the basics.

The StageHog distortion is in series from guitar to amp input, and built for that. It is switched on&off.

The VanAmp reverb is in the FX loop and was built expressly for that application. It is always on, but doesn't have be.

Very typical. Very simplified, because I don't use "effects". You just have figure out which effects belong where, as has been explained in this thread. Example, preceeding the Hog is a wah. Example, if I were to add a delay it might go in the FX loop.


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## Dorian2 (Jun 9, 2015)

You can also use the FX loop Return only (without plugging into front of amp) for some multi effects units or Pedals that act as a Preamp as well. To test this, you can assume your OD or Dirt is a pre amp and send it directly to the Return in the loop so that way you have Dirt pedal (Preamp) to Return (Power Amp). You won't be able to set the Volume on the amp unless it has a *Master Volume*, which is basically your Power Amp volume. You'd control volume via pedal if no Master. There are occasions when you have to put a 1/4" jack or plug (end of cable) into the send input of the amplifier. It depends on the Amp and how it's wired though.


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## bigboki (Apr 16, 2015)

reckless toboggan said:


> I had never thought of using the FX loop to send to another amp. Usually I put distortion, od, fuzz, in front of the amp, and run phase, flange, delay, etc in the FX loop.
> 
> But the thought of using an FX loop send to another amp lead me to this idea:
> 
> ...


UGH, you made complete mess there. What you want there - please do NOT do it that way.

First of all most important.
EVERY tube amp has to have "load" attached to it when is powered.
That means every tube amp - head or combo has to have speaker connected when powered out.

So if you have a combo, and a head, and you want to use head with the speaker from the combo (I am doing this all the time):
1. do NOT turn combo on - I disconnect power cable from power just in case
2. connect combo's speaker cable to your head
3. use your head with the speaker from the combo.
If the cable is not long enough, you will have to make extension speaker cable.

Now, you have either playing Combo, or head no mixing.


For the loop you have to consider the following:
every amp consist of two parts (pre amplifier and power amp):
1. weak guitar signal is being "pre amplified" and messed with the "tone" knobs to line level. That part is done by amp's preamplifier part.
2. this signal (or part of it for parallel loops) will be "exiting" the preamp through Loop's SEND, or TO EFECTS or whatever is named
3. this signal is now going into 2nd part - power amp. If no loop is used it goes directly from preamp into power amp. If serial loop is used, total of pre amp will go into send, and whatever is returned into RETURN (or FROM EFECTS or INTO POWER AMP or whatever is called in specific amp) will go to power amp. With the parallel effects loop you have part of the signal going straight from pre amp into power amp and part is making through the loop.

So now, if you want to "mix and match" your two amps (one combo one head) you have to imagine that there are 4 parts, each amp has its own pre amp and its own power amp.

So if you want to hear amp 1 preamp through amp2 power amp, you will take amp 1 SEND into amp 2 RETURN.
Issue here is that you have to provide speaker to both amps since both will be powered. 
There are small number of amps that on standby do not need load and still have pre amp working but I don't know if any of the two you mentioned are like that.

Hope this is clear. If not let mw know which part is not and I will clarify


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## reckless toboggan (Mar 9, 2019)




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## Verne (Dec 29, 2018)

@bigboki I have a Tubemeister 36 head. I am currently running it into 2 single cabs at 16ohm/ea. I have a Peavey with the send/return on it. I could be reading your set up wrong, but does this mean I could run a cable from the TM36 head send to the return on the Peavey and run 3 speakers at once? Would that change it to 4 ohm, or does that not come into play with effects loop? Just trying to understand everything.


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## bigboki (Apr 16, 2015)

Verne said:


> @bigboki I have a Tubemeister 36 head. I am currently running it into 2 single cabs at 16ohm/ea. I have a Peavey with the send/return on it. I could be reading your set up wrong, but does this mean I could run a cable from the TM36 head send to the return on the Peavey and run 3 speakers at once? Would that change it to 4 ohm, or does that not come into play with effects loop? Just trying to understand everything.


I see that TM has only one single speaker out. How are you managing to run it with 2 cabs? probably some parallel box (2 speakers at 16ohm in parallel are 8ohms).

So if you want the same signal to go to Peavey's (I guess combo). You can try to just connect SEND from TM to RETURN of Peavey. But I think that is serial loop on TM and since loop is not closed I think you will get sound only from Peavey.

Both amps have to be connected to their corresponding speakers and both have to be powered on. Guitar is connected only to TM.
Try it the worst thing that can happen is you will get feedback somewhere which you can quickly eliminate by tuning volume off


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## Verne (Dec 29, 2018)

Awesome !! Thanks. I'll try it. I can power both easily. I was more worried about them running together would make it 4ohms. I have 2 single 12" cabs in parallel as my main. I literally just got this TM and plan on keeping it for a long time, so don't want to inadvertently blow it up.


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## bigboki (Apr 16, 2015)

Verne said:


> Awesome !! Thanks. I'll try it. I can power both easily. I was more worried about them running together would make it 4ohms. I have 2 single 12" cabs in parallel as my main. I literally just got this TM and plan on keeping it for a long time, so don't want to inadvertently blow it up.


as long as it has speaker connected all is good.
Yeah I just spotted your NAD. Congratulations. 
Also keep in mind - speaker out need speaker cable.
Loop out/in needs instrument cable.


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## Verne (Dec 29, 2018)

I have the speaker cable from out. I also did use a guitar cable to the Peavey (combo BTW). I only tried briefly, and will play around more later, but I did get a lot of hum from the 3 speakers. It's still new to me, so I'll either figure it all out, or just use it for what it is. Thanks for accolades. Loving this more than the TM5. It's what got me thinking about the FX loop. I researched a few brands to death before actually making any contact. I wasn't 100% sure on the FX loop, so before I jumped on this head, I asked so I would be more informed.


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## bigboki (Apr 16, 2015)

Verne said:


> I have the speaker cable from out. I also did use a guitar cable to the Peavey (combo BTW). I only tried briefly, and will play around more later, but I did get a lot of hum from the 3 speakers. It's still new to me, so I'll either figure it all out, or just use it for what it is. Thanks for accolades. Loving this more than the TM5. It's what got me thinking about the FX loop. I researched a few brands to death before actually making any contact. I wasn't 100% sure on the FX loop, so before I jumped on this head, I asked so I would be more informed.


Interesting that you get the sound from TM as well. That means, when the loop is not closed on TM it sends signal both to SEND and to power amp. Cool
The hum is ground loop. You have to play with power the amps from two different power outlets and similar


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## davetcan (Feb 27, 2006)

If you want to be completely safe just get yourself one of these.


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## High/Deaf (Aug 19, 2009)

The crux of the matter, when using one for effects, is with distorted tones.

If you plug a guitar straight into an amp that is set up to distort, you can hear how different the guitar sounds as you turn it's volume control down. That change affects the amount of distortion as much or more than it changes the volume level, when plugged into a dirty amp. Try it yourself just to hear the difference. Lots of guys play single channel amps and roam the tonal range from clean to crunchy just by adjusting their guitar's volume control(s).

Now consider that delay pedals produce an output that starts loud (maybe as loud as your straight guitar signal) and get quieter with each echo. As those repeats hit the input of the amp, it will be like playing notes while turning the guitar's volume down for each successive note. The actual level/volume won't change much (which we want in an echo) but the amount the note is distorted will be reduced for each successive repeat (not what we want in an echo).

By putting it after the preamp, where the distortion is coming from, it will receive a 'pre-distorted sound' and each repeat will have the same amount of distortion but will be successively quieter (which again is what you want with an echo).

If you don't play with distortion or use a pedal to get your distortion, effects loops don't matter as much (and as long as the delay is after the distortion pedal). 

Modulation and reverb effects also tend to sound better if fed a distorted signal (more harmonics to work with). But again, all of this is preference. For the price of a couple of guitar cables, it's fun to mess around with the stuff and see what you like and don't like. You're unlikely to hurt anything as long as you stay away from the power/speaker output of the amp. Just leave that plugged into a speaker at all times.


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## Dorian2 (Jun 9, 2015)

That's the best description that I've heard and is very applicable to my own sound and what I'm hearing as well. Thanks for putting it that way @High/Deaf !


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## bigboki (Apr 16, 2015)

High/Deaf said:


> By putting it after the preamp, where the distortion is coming from, it will receive a 'pre-distorted sound' and each repeat will have the same amount of distortion but will be successively quieter (which again is what you want with an echo).


GREAT explanation. Just one thing - I think you meant 
it will receive a 'POST-distorted sound'
correct?


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## High/Deaf (Aug 19, 2009)

bigboki said:


> GREAT explanation. Just one thing - I think you meant
> it will receive a 'POST-distorted sound'
> correct?


Yes. Or no. Semantics.

By 'pre-distorted sound' I mean 'already distorted' and not 'before the distortion happens'. Fricken English! LOL 

Regardless. Or would that be irregardless? At least it's not flammable. Or would that be inflammable. *#*(


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## bigboki (Apr 16, 2015)

High/Deaf said:


> Yes. Or no. Semantics.
> 
> By 'pre-distorted sound' I mean 'already distorted' and not 'before the distortion happens'. Fricken English! LOL
> 
> Regardless. Or would that be irregardless? At least it's not flammable. Or would that be inflammable. *#*(


Yes indeed. Now encounter me as non native english speaker, and you can have a whole lot of a mess


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## Verne (Dec 29, 2018)

High/Deaf said:


> Or would that be irregardless?


How DARE you !!!! Go to the corner so you can think about the wrongness of this question.


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## Granny Gremlin (Jun 3, 2016)

mhammer said:


> Absolutely correct. It will also identify whether the loop is buffered, what the approximate signal level will be, and whether the send/return path is "normalized".
> 
> I don't know that the term "normalized" _comes_ from modular synths, but it is a traditional term for describing things in that realm. If a connection is "normalized" it means that, unless a plug is inserted into one or both jacks, their path is "normally" connected.


"Normalized" is an adjective used to describe digital audio that has been batch processed to make it's peaks set to a given level (usually 0db but some algorythms allow the user to choose). This is a commeon thing with softsynth guys as well as digital audio recordists (the idea being that, especially since this isn't tape anymore and so therefore there is no imperative to maximise s/n ratio by getting the hottest signal possible to the medium, that some tracks might be very quiet, so you can normalise them all instead of going through and adjusting all the individual channel gains as per gain staging best practises before starting a mix). The term originated in IT referring to the degree of data redundancy or efficiency in the tables of a database (e.g. 3rd Normal form; is the data normalized etc) and was later applied to digital audio. Incidenatally, Data Normalization was a product of a time when a major factor was minimiseing storage requirements (storage was expensive). These days , since storage is cheap, it's gone the other way - less normalization allows for simpler and faster queries to the database and therefore improves system performance (though this may increase risk of data integrity issues, since multiple tables contain the same feilds).

"Normalled" is what you are talking about and it originated with patchbays, back when telephone operators were sitting in front of switchboards (aka a small wall full of 1/4" jack panels) and had to connect your call mechanically for you. The meaning is simply that the normal state of the jack (i.e. when nothing is plugged in) is that it is connected to X. E.g. The FX loop's send jack is normalled to the return jack.

It is possible that synth guys have collectively decided to use 'normalized' instead for this second meaning (I dunno; rarely talk shop with those weirdos ;P) - I have seen that sort of thing happen before, where in one particular niche they use terms differently.


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## mhammer (Nov 30, 2007)

Nah. You may be right about : "normalled" vs "normalized". The "-ized" suffix typically suggests a transformation of some sort, and what I was describing was not that, whereas the digital massaging you described IS. It's been a while since I plowed through my 40+ year-old issues of POLYPHONY to look at patching diagrams, so I may have misremembered the precise term. Appreciate the correction. I'm always in favour of language precision.


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## jb welder (Sep 14, 2010)

Just wanted to add that the most common configuration is with the 'disconnect' *only* in the 'FX Return' jack (sometimes called 'power amp in').
So if you plug into the 'send', you have a pre-amp out signal, but the amp carries on as normal. If you plug into 'return', the amp's preamp section is disconnected, and from the amp you will only hear the signal that is applied to the 'return' jack.

Attached is a great article that explains it, shows a diagram, and also tells how it is the most common cause of a few symptoms that amps suffer from (and the related fix).


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## Granny Gremlin (Jun 3, 2016)

Yeah i didnt even think about it but that totally would make more sense than normalling the send/ preamp out.


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