Feedback can be the annoying nemesis of all guitar players.
The painful sound of “screeching” and “wailing” can quickly derail recording sessions and embarrassing during live performances.
Although players love the ‘mellow’ and ‘acoustic’ tones from their semi-hollow or hollow body guitar.
Nevertheless, feedback is the more common and frustrating issue compared to their solid-body guitar cousins.
With my experience of feedback problems in the past. My post will deliver my best methods to tame pesky feedback with your hollow chambered guitar once and for good.
But first, let’s dive in with the short answer
How do you prevent hollow body guitar feedback? To prevent hollow and semi-hollow feedback you can have your pickups potted or placing foam or a cushion inside the body, or plug the f-holes. This prevents pickups from excessively vibrating. Alternatively, you can add a noise gate, stand further away from the amp, or decrease the amount of distortion.
Obviously, feedback in hollow chambered guitars isn’t exactly a new issue.
When the hollow body and semi-hollow body were born. They were predominantly used by jazz and blues players in the 50s and 60s. Obviously, these guitars are ideal for ‘mellow’ clean tones or mildly overdriven blues licks.
However, during the ‘rock revolution,’ guitar players started cranking their amps to new levels creating the iconic sound of dirty rock n roll distortion.
This opened the door for the sound of gristly distortion for guitar players which was a new and innovative sound. However, players noticed that archtop guitars are bad at taming feedback when paired with fuzzy distortion.
Secondly, during the 60s and 70s, high-wattage valve amps were ear-bustling loud.
Meaning hollow chambered guitars were not ideal for handling high wattage tube amps soaked in distortion.
Hence why the solid-body guitar was favoured and paved the way for the evolving heavier genres of music.
What is Guitar Feedback – How Is It Caused?
To put it simply, feedback is created when sound from the amplifier causes the guitar’s strings or pickups to vibrate.
When vibrations make it back into the guitar’s pickups. The signal gets trapped in a loop that grows in strength and this growing signal is sent back to the amplifier, creating the ear-piercing sound of guitar feedback.
Undoubtedly, hollow and semi-hollow body guitars are more prone to feedback. The reason is when soundwaves get trapped inside the hollow chamber, it promotes more string and pickup vibration.
These vibrations are sent back to the amp and back to the hollow chamber, and the process repeats. On each cycle, the signal gets stronger, which radiates from the amplifier, completing the process.
In comparison, solid-body guitars are more immune to feedback. The reason? A guitar comprised of a solid body completely dampens vibrations that do not reach the pickup, resulting in an effective ‘feedback buster.’
Hence, solid-body guitars are historically better suited for distortion-drenched genres such as metal, hard rock and punk.
Preventing Feedback in Hollow and Semi-Hollow Guitars
Now we have discussed the anatomy of feedback and why hollow-body guitars are so ‘feedback prone.‘ Let’s dive into the top solutions preventing this nuisance once and for all.
1. Have your Pickups ‘Wax Potted’
As mentioned above, pesky feedback is caused by excessive pickup vibration.
Therefore, ‘pickup potting’ is the method of dipping pickups into a container of hot wax, although other substances are applied, such as epoxy resin or nitrocellulose lacquer.
The substance is designed to encapsulate all of the pickup components tightly into place, significantly reducing vibrations, thus presenting feedback emission. The wax is effective at ‘smothering’ the components and setting them all in place.
As a result, those long turns of wire will stay fixed in place and the pickup will experience no unwanted microphonic feedback.
There will, however, be some “natural” feedback occurring, with your strings vibrating if the guitar gets too close to the amp. But this is easily controlled and causes no trouble.
Pickup potting shouldn’t be too complicated. However, we’d advise you to take your guitar to a professional instead of doing it yourself. Any average guitar tech, luthier, or guitar shop will be able to provide this service.
The best part is that proper potting is very effective at eliminating feedback.
The only downside is that your pickup tone can change, ultimately losing some of its potentials to sustain longer.
Additionally, the improper potting process can irreversibly damage the pickups, especially if wax, or any other material, is heated up too much.
How Much Does Pickup Potting Cost?
Depending on the company, wax potting can cost anywhere in the range of $50-$100.
Although doing it yourself can be cheaper, it does come with the risks of potentially damaging your pickups mentioned above.
If you are not an experienced guitar tech I would recommend having it done professionally.
2. Plug the F-Holes with Custom Silicone Plugs
The hollow-body design of electric guitars is most commonly accompanied by those stylish-looking “F”-shaped holes. This is what enables the guitar body to resonate properly.
However, we have a potential “weak spot” that enables unwanted feedback to occur with this kind of design. This is exactly the problem that semi-hollow-body guitars suffer from.
One of the ways to deal with it is to literally plug these “F”-shaped holes.
Standard round-shaped soundhole plugs are pretty common among those who play acoustic guitars with integrated preamps and piezo pickups.
By fitting snuggly over the edges, these silicone plugs manage to keep all the vibration from coming in or out of the body. As a result, the feedback is effectively eliminated.
Additionally, your guitar’s tone remains pretty much the same. There might be some differences, but there’s hardly any chance that it will be noticeable in live settings.
Of course, this only happens if these plugs are well-made. Luckily, manufacturers are usually pretty precise with them, and they can even make these plugs according to your custom measures.
What’s more, they’re designed in such a way to keep the main aesthetic qualities of your guitar unchanged. You’ll put them in your instrument, and it will still seem as if there are no plugs in there.
Both sonically and visually, these “F”-shaped plugs are one of the most effective ways of keeping your guitar tone safe from any unwanted microphonic feedback.
Where to Buy Silicone F-hole plugs?
Doug’s Plugs (US Service)
Doug’s Plugs are based in the US that creates awesome handmade silicone f-hole plugs designed to fit your hollow body guitar.
On their website, all you do is provide on their order form the guitar’s make and model, and they provide high-quality silicone plugs that will fit into your guitar’s specific f-hole dimensions.
If they do not include your guitar from their catalog, you can send them a stencil of your guitar’s f-holes on a piece of paper.
They will then manufacture the custom sizes that will fit snuggly into your guitar’s f-holes.
Feedback Blockers (UK Service)
F-its Feedback Blockers are a company based in the UK that provides a similar service to Dougs Plugs. They create high-quality handmade silicone plugs for f-holes for guitars and double bases.
The difference is they require you to make a stencil on a piece of paper of your f-holes and send this to them.
This is so they can manufacture an accurate silicone cutout of your guitar’s f-holes that fit snuggly into your prized guitar.
3. Place Foam or a Cushion Inside the Guitar
The advantages of a hollow or semi-hollow guitar body design are apparent.
The tone changes drastically, and such a design is very useful for blues and jazz music, or pretty much any setting where you need more “depth” in your tone, along with “smoothened-out” edges.
However, as we already know, the feedback can be a nuisance. One of the most effective methods to deal with it is to literally stuff the inside of the body with foam or any material that will dampen it.
As a result, the chances of getting any feedback are reduced but at the same time, you’ll keep most of the sonic qualities that hollow-body and semi-hollow-body guitars are known for.
The idea of a foam-type or cushion-like material is to absorb most of the vibration inside the instrument.
Even if your amplifier and PA system are loud and the sound vibrations from the speakers reach the instrument, chances of getting unwanted feedback are close to zero.
There is, however, one potential issue with this approach. Having a lot of dampening material inside of the guitar can change its tone. If you stuff it with foam, you’ll most likely experience a “dampened” tone with fewer higher-end frequencies.
After all, the instrument was designed with the hollow body principle in mind. right?
If you decide on going down this path, it will take time and effort to find the right amount of foam-like material to put inside your instrument.
There’s always an optimum that dampens the tone just enough to reduce feedback, but it still doesn’t take away from the instrument’s main sound qualities.
4. Add a Noise Gate Pedal to The Chain
A noise gate pedal can do wonders for stopping buzz and hum radiating in the background in any rig.
It also serves as a great feedback tamer by stopping signal waves from growing in strength and producing the sound of blaring feedback.
A solution for stopping feedback is for an engaged noise gate to eliminate the source of the vibrations before it has the chance to gain in strength and intensity.
This is until the sound waves grow and evolve into the ear-splitting sound of feedback.
The level of sensitivity of the noise gate is controlled depending on how aggressive you want to keep unwanted noise and harmonics at bay.
It also depends on how noisy your rig is depending on the amount of gain you use. Plus, whether how well your electronics are shielded and the level of volume you use, plus other variables.
The best thing of all, a noise gate pedal is a relatively inexpensive and simple addition to any pedalboard.
Ideal for silencing the noise and feedback from a hollow body guitar, especially with a tone that is frenched in distortion, such as the heavy genres of music.
5. Stand Further Away From Your Amp
Another simple solution is to provide distance between you and your amp on stage. Obviously, this is difficult on a cramped stage in a small venue.
With that said, make distance by placing your amp as far away as possible on stage. Remember, distance is your friend.
Ensure you are facing away from your amp and not towards it. Facing towards your amp can increase the likelihood of feedback as the pickups and amplifier have an ‘uninterrupted route’ to transmit sound waves.
Guitarists who desire feedback for atmospheric effect before a song intro do the opposite effect.
This is to stand directly in front of the amp and shake the guitar violently for most vibration, resulting in atmospheric feedback.
On the other hand, for the players who want a silent and so-called polished sound on stage. Then try to put as much distance from you and your amp as possible.
This will keep your semi or full hollow body as quiet as possible once you mute the strings and stop playing.
6. Reduce the Amount of Distortion
Now, here’s a tricky one. One of the best ways to avoid unwanted feedback with hollow-body or semi-hollow-body electric guitars is to simply control the distortion.
Simply dial down on the gain control, and you’ll easily sort out the feedback issues. Sounds simple, right?
Well, the biggest issue here is that some guitar players simply want that ‘high-gain tone.’
After all, playing a hollow-body guitar in a high-gain setting gives a pretty unique tone. So is there a way to find an optimal solution for this?
How to Reduce Distortion without losing ‘Aggression’
There are actually two different methods to go about this.
The simplest way is to maintain the same amount of gain in your tone, all while dialling in the right tone with your amp’s and pedal’s equalizer controls.
Of course, the more detailed controls, the easier it will be to keep things under control. The main idea here is to control the high and high-mid frequencies, which can potentially cause a lot of feedback.
The advantage of this approach is that you can keep the high-gain setting. The disadvantage is that you’ll need to change the tone depending on the venue you’re playing in.
It’s an excellent one-off last-minute solution for some settings. You can also create your preset with a “safely” altered EQ that will work anywhere, although your tone might sound too “smooth” or “dull.”
Play Around with the EQ
The other and arguably better method is to reduce the amount of gain, but achieve heaviness in your tone in a different way.
In fact, a lot of the heavy tones that you know about from famous metal songs aren’t achieved using high-gain settings, but rather proper EQ settings and specific types of amps and pedals.
If you want a heavy tone that goes through the mix and yet it avoids feedback, then keep your tone mid-heavy. Keep the mids up high, while the high-end and bottom end is around 50% of the maximum.
Of course, the result of this will differ between individual amps. But you’ll need to see what works for you. Finally, get your gain setting lower, usually somewhere at the 50% mark.