Effects pedals in effects loop?

Len Amaral · From: Rehoboth,MA 02769

Reverb, delay and chorus pedals in an effects loop? Rack gear has a line level out, pedals have a preset level. Anyone use these pedals in the effects loop or just go to the input of the amp?

Godfrey Arthur · From: 3rd Rock

You can experiment. If your loop has a load setting work with those. Not all pedals are set so the impedances are right for every input/output. You might find that you need to put one pedal in front of the other in certain situations. Use your ear in the end. But going through loops puts the effect in between you amp's preamp and power amp, usually, rather than loading your amp's input. The effect is cleaner in most situations going through a loop. But you might like the sound going straight into the amp.

So experiment.
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Richard Sinkler · From: aka: Rusty Strings -- Missoula, Montana

I run a reverb and a delay through my effects loop. It works great. I use them in both my NV400 and a MarKBass bass amp.
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Steve Spitz · From: New Orleans, LA, USA

I like to run my effects through the loop. I like to send as direct a signal to my amp as possible. No tuners , or other gizmos to go through.

Are you asking for use with a particular set up, or just as a general preference ?

Len Amaral · From: Rehoboth,MA 02769

Recently got a DR. Z Surgical Steel head with a tube powered effects loop. I have my pedals near me and if I used the effects loop I would have a 10 foot cable from volume pedal to amp input then two 10 foot cables from send/return to the pedals. I guess I'll have to try it to see if I detect any signal loss.

Lane Gray · From: Topeka, KS

I doubt you'd hear much loss, but some stomp boxen don't like line level signals. I don't know if it's the level or the impedance, but every chorus box I've ever owned has only been happy before the amp.
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More amps than guitars, and not many effects

Steve Spitz · From: New Orleans, LA, USA

That effects loop is really attractive to me in a tube amp. I'd love to try one of those.

I like the idea of a tube amp seeing my direct signal .

I can see the thought of running long cables to the loop as a problem. could you keep the head and effects by your side, and just run a single speaker wire to your cabinet ?

I always wondered why more of the pricey tube rigs didn't have an effects loop. Maybe someone will chime in and set me straight.

ajm · From: Los Angeles

Effects loops are a tricky and touchy subject.
I will agree that each player needs to try it first and see if it works in their application. If not, then you need to find out why.

IMO effects loops in many amps are just something that is thrown in, without much real design thought, as an added feature to sell the amp.

There are two basic culprits that can come into play with effects loops: Signal level, and input/output impedance matching with your effects. Note that "effects" can be either rack gear or pedals or both, so manufacturers need to be cut some slack with their design. After all, they can't possibly account for every single effects and combination that we can come up with.

One quick tip: You might hook everything up in your practice room and it works great. When you haul it out to a gig, it sounds distorted. When you turn up the volume at the gig, you are probably increasing the signal level going to the effects in the loop, and are now overdriving them with a hotter signal.

Some amps have controls or switches to vary the signal send and/or return levels. My old old Carvin XV112E from 1984 or so has this, but it still wasn't designed perfectly to be used with pedals. I did some investigation and came up with a way to modify it to use it with my pedals. Even after all of that, I found that one of my pedals (an old Boss PN2 Trem/Pan) still degraded the signal in the loop. I fixed that by using it with a true bypass box in the loop. I swear, it never ends with this stuff.

Your concern about adding extra cable length with the effects loop send/return lines is valid. However, if the loop is designed fairly well this should not be an issue.

One thing that I seldom see mentioned is a device that goes into the effects loop that allows you to match impedances and signal levels. Dumble Amps calls it a Dumbleator. Ceria or Ceriatone has their own version of it that is reasonably priced. I think that Bludo Amps also makes one, but theirs is very pricey.

Whew. In a nutshell that is a brief tutorial of what I know about effects loops, or at least what I think I know ;>)).

Like I said, the first thing is to try it and see, and go from there.

Ken Fox · From: Nashville GA USA

From some older post I did:

I posted this a while back about the loops on the N112 amp and overlap they cause (N400 is similar):

As you can see both the effect loops on the N112 provide too much signal for optimum headroom and signal to noise ratio. The best choice would be the Pre EQ for the least amount of gain overlap (40 mv of overlap). This mean you cannot drive the amp to full power without clipping the reverb unit first!!

The post EQ is worse with 121mv of gain overlap.

RV-5

Nominal Input Level
-20 dBu 77mv
Input Impedance
1 M ohms
Nominal Output Level
-20 dBu 77mv
Output Impedance
1 k ohms
Recommended Load Impedance
10 k ohms or greater

N=112

Pre EQ patch send:
Load impedance: 10k Ohms or greater
Nominal output level: -18.6 dBV, 117 mV RMS
Pre EQ patch return:
Impedance: High Z, 220 k Ohms
Designed Input Level: -18.6 dBV, 117 mV RMS

Post EQ patch send:
Load impedance: 10 k Ohms or greater
Nominal output level: -14.1 dBV, 198 mV RMS
Post EQ patch return:
Impedance: High Z, 1 m Ohms
Designed Input Level: -14.1 dBV, 198 mV RMS

This was an earlier reply on the N-400 amp itself:

After 30 years of experience and training with the design of audio systems I know a bit about overloading devices.

Let's take a Boss RV-5 pedal for example:

nominal input level rated for -20dbu (0.21 volts)

Nominal level is the normal operating signal that allows 10db of headroom in live music or 20db of headroom in recording application to allow for volume dynamics associated with playing or recording music. That from my old Yamaha manuals of years ago!!!

The preamp output of the N-400 is 1 volt nominal and can go as high as 8 volts! That is 5 times the nominal voltage the Boss RV-5 want to see for it normal operating range and best signal to noise ratio.

The RV-5's nominal output is also -20dbu, 5 times to weak to properly drive the power amp of the N-400 amp.

The patch output of the N-400 is amazingly a nominal of 0.2 volts, same as the effects pedal requires!

The patch input of the Nashville 400 is 0.2 volts, the same as the nominal output of the effects pedal.

There is no supporting argument for using the preamp to drive a common effects pedal. Those pedal are designed for unity gain and a guitar level signal at their input.

So in layman's terms. using the pre-amp out to feed a common effect pedal is like trying to shove 5 lbs of stuff in a 1 lbs bag.

Your choice, do it either way. I just believe in the things I learned while I studied and trained in the Pro Audio field to preserve proper signal to noise ration and prevent gain overlap (that leads to distortion)

I could go on further into gain overlap, impedance matching and a ream of other subject matter but I do not think it necessary for this application!!

A bit more from the net about operating levels:

Nominal level is the operating level at which an electronic signal processing device is designed to operate. The electronic circuits that make up such equipment are limited in the maximum signal they can output and the low-level internally-generated electronic noise they add to the signal. The difference between the internal noise and the maximum output level is the device's dynamic range. When a signal is chained improperly through many devices, the dynamic range of the signal is reduced. The nominal level is the level that these devices were designed to operate at, for best dynamic range.

In audio, a related measurement, signal-to-noise ratio, is usually defined as the difference between the nominal level and the noise floor, leaving the headroom as the difference between nominal and maximum output.[1][2] It is important to realize that the measured level is a time average, meaning that the peaks of audio signals regularly exceed the measured average level. The headroom measurement defines how far the peak levels can stray from the nominal measured level before clipping. The difference between the peaks and the average for a given signal is the crest factor.

There is some confusion over the use of the term "nominal", which is often used incorrectly to mean "average or typical". The relevant definition in this case is "as per design"; gain is applied to make the average signal level correspond to the designed, or nominal, level.
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Ian Rae · From: Redditch, England

ajm · From: Los Angeles

FWIW, here are the Ceriatone devices.
Both of them are made with the intent of giving you a buffer in your amp effects loop.

The C-lator is rack mount tube driven.
It's also kinda pricey at $300.
However, from what I recall that is still less than half of the Bludo which is about the same thing.

The Klein-ulator is solid state and is reasonably priced.
It lets you adjust the send level to your effect(s) so you don't overdrive them.
It also lets you adjust the return level back into the amp to make up for any losses.

There are various schematics and discussions on the internet about the Klein-ulator.
You could build your own if you were willing to sift through all of the discussions, and you had some electronics background.
But the price is reasonable for a unit that is already designed and built.

Steven Paris · From: Los Angeles

Len Amaral · From: Rehoboth,MA 02769

Just thought of this as I have a Mesa Boogie 5 band EQ with pre and post Levels. This might help to increase a line level loss in the effects loop. Not sure if the level controls work with the pedal in the off position. However, I could set the EQ flat with it to on position and see what happens. Very interesting thread and I appreciate the input.

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