How To Build A DIY Passive Effects Loop Volume Attenuator

One Knob Guitar Pedal

As guitar players, we can all agree that valve amplifiers have a tone and ‘feel’ to them that no digital or solid-state amplifier can emulate. However, to get those fabled tones at reasonable volumes is incredibly difficult.

That is where guitar amplifier attenuators come in.

What Types Of Guitar Amplifier Attenuators Are Available?

There are a couple of different types of attenuators that you can purchase at varying levels of price points.

The most expensive of which will sit between your power amplifier and your speaker cabinet. This type of attenuation will allow you to make use of both the preamp gain and power amp gain as you are essentially reducing the power to the speakers only. This means that your guitar tone will be completely unaffected and you get to make the most of that saturated sound.

The more affordable option is a passive attenuator that sits in the effects loop of your guitar amplifier. As it sits in the effects loop, it means you can only make use of your amplifier’s preamp gain whilst the power amp remains unaffected.

Why Do I Need A Guitar Amp Attenuator?

The main benefit of a volume attenuator is that you can turn your guitar amp up to get that valve saturation and high volume ‘feel’ at bedroom volume levels.

Another benefit to using an attenuator, and the reason I use one, is to help manage a sensitive logarithmic volume control. On a valve guitar amplifier like the Fender Hot Rod Deluxe, there is a very fine line between a usable volume and an ear-splitting volume. Having a passive attenuator in your guitar amp effects loop will help make this a little more manageable and give you greater control.

This is the exact type of DIY attenuator that I’ll show you how to make.

Items Needed

Here’s a list of the items we’ll need to build a DIY passive effects loop guitar attenuator:

2 ¼ Inch Mono Jack Input

1 100k Linear Potentiometer

1 Hammond 1590A Enclosure

4 Small Lengths of Wire

DIY Passive Attenuator Wiring Diagram

Building your own DIY passive attenuator is a very simple build and would make for a great first project. Here is a quick wiring diagram of how the above components fit together to create this utility and what it will look like once you’ve put it all together.

Passive Volume Attenuator

As you can see, this is a very simple build and you should definitely be able to get this up and running within an hour.


Please note: This is a passive device and will not accept a load, please do not plug this in between your amp and your cabinet. This device is to sit in your effects loop only.

To get started with this build, gather together all of your components and lay them out in front of you to make it easier to grab them whilst you’re building this device.

Switch your soldering iron on and leave this to heat up for a few minutes. While you wait for this to get to the correct temperature, let’s drill the case ready for all of the hardware we’ll need. As we have two jack inputs and one potentiometer, we only need three holes. The ¼ inch input jacks will each require a 10mm hole and the potentiometer will require an 8mm hole. A step drill bit will do the job but if you’re using a standard drill bit, you will probably need to run a file or some sandpaper over the holes to smooth out any jagged edges.

Once you’ve done this, your soldering iron should be up to the necessary temperature. We can now prepare all of our hardware components and tin the connections with a bit of solder to make soldering the wires to them much easier.

As this build only consists of wires between the inputs and potentiometer, it makes sense to build this straight into the enclosure. It will save quite a lot of cable management time and make things much easier to follow should you need to do any debugging.

Once you have added a bit of solder to all the connections of your hardware, mount them into the drilled enclosure and tighten all of the nuts. For the jack inputs, try to ensure that the connections are pointing up towards you as this will make it much easier to work with, in your enclosure.

Now that these are in place, add the potentiometer and tighten this up whilst ensuring the connections have plenty of room to manoeuvre.

With all of the hardware secured, let’s move onto the wiring.

I’d suggest starting with the grounding wires. As you can see from the wiring diagram, we need a single ground wire between the two sleeves of the input jacks. Then, from the sleeve of one of those ¼ inch jacks, add another wire to lug number 3 of the potentiometer (far right connection).

The next connection to make is between lug 1 of the potentiometer (far left connection) to the tip of your guitar input jack. This leaves the final connection between the tip of the output jack and the middle lug of the potentiometer.

With all of these wires in place, give everything a quick check over to make sure you’ve made solid connections with a little excess wire as possible.

Once you have all of this wiring in place, your device should be complete and ready to plug-in.

Please note: this is a passive device and will not accept a load, please do not plug this in between your amp and your cabinet. This device is to sit in your effects loop only.

As always, enjoy building this passive effects loop volume control but if you hit any snags along the way, please let me know and I’ll help out wherever I can.

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Hi, I'm Pete!

I have been a guitar and effects pedal enthusiast since 2005 and electronics tinkerer since 2017.

I’m here to help you begin your journey with building DIY guitar effects pedals. Get in touch with me if you have any questions.

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