Archtop Guitar Feedback and how to deal with it

[McJazzer]

Hi everyone - in full transparency, I'm crossposting this from my website as I thought it may be relevant to those just starting out. TL;DR - I bought an archtop nearly a decade ago after playing it at a very low volume in the store and loving it. Turns out it's a nightmare for feedback so here's is a list of different ways I've either directly tried or have heard from others of helping that issue. Experienced players please feel free to add to this list and offer advice / criticism to anything I've mentioned.

Here's the web page (same info, a bit more colorful): Archtop Guitar Feedback | Alex Price Musician

There's also this old thread which is worth reading: Fight Archtop Feedback With Cotton Or Plugs


1 - Guitar Construction


Although this is not something you can change if you already own an archtop, it is 100% the most important factor influencing how quickly your jazz guitar begins to feedback. I think it's necessary to understand why your hollow body guitar may be having these problems. From the type of material used (a solid wood vs. a laminate for example), to the size of the body (depth and width), and even the finish type, all of these play into the tendency for a particular guitar to ring acoustically. The easier it resonates, the faster it will pick up sympathetic vibrations from a nearby source (such as an amp) and create a feedback loop. The Eastman Guitars website has a fantastic page dedicated to going over various construction styles of archtop guitars - Archtop - Educational - Eastman Guitars


Here are a few points to keep in mind:
— Laminate construction: less acoustic tone, more resistant to feedback
— Solid wood w/ carved top: acoustically live, more prone to feedback
— Dimensions of the body: thicker sides and larger top, more prone to feedback
— Finish type: Polyurethane and nitrocellulose are heavier & more resistant than varnish


2 - Pickup Mounting Style

The method that the pickups and electronics are connected to your guitar also greatly affects the tendency to feedback. You'll notice that the next couple points on this guide relate to adding weight to the top of your instrument and that's also what is making the big difference here. Guitars with pickups that are mounted directly to the top of the guitar (such as the Gibson ES-175, Super 400, or many other models) are adding considerable weight to the instrument and will keep it from ringing so easily. Guitars with mounted pickups also typically have electronics like volume and tone controls mounted to the top as well. A floating pickup archtop (such as the Gibson Johnny Smith) will usually have the pickup attached to either the neck or pickguard in order to prevent it from weighing down the top. I like to think of these instruments more like an acoustic guitar with a magnetic pickup and the mounted pickup style instruments behaving more like an electric guitar.


Remember these three points:
— Set / Mounted pickups: pickups add weight to the top, more resistant to feedback
— Floating pickups: usually mounted to the neck or pickguard, will not dampen the top
— Number of pickups: archtops with a bridge pickup add even more weight on the top.


3 - Covering the F Holes


Covering the F holes of your archtop will prevent the air from moving in and out freely, just like a rubber feedback buster on a steel string flat top guitar would work. With archtops, the F hole dimensions are far less uniform though and I'm not aware of any commercially available products designed to just easily drop in like the feedback buster does. Here's a list of three common ways guitarists have been plugging the soundholes to help eliminate feedback.


— “Doug’s Plugs” or similar: a few years ago you used to be able to order custom foam plugs to fit your archtop, which would fit into your guitar similar to a circular feedback buster on an acoustic. Unlike a Martin or other flat top acoustic there is no universal dimension for F holes on an archtop, so you will have to get these custom cut. Doug has retired and I’m not aware of anyone making a similar product. Basically, his product was made out of foam and he just cut the material to fit your guitar. The plugs add a bit of weight to the top, but mostly the feedback resistance was provided by blocking air from moving in and out of the top of the guitar. Get a pair of dollar store sandals and a razor blade and try it out.


— Tape: be very careful here as depending on what you use, it may leave residue on your guitar or even damage the finish. A polyurethane or nitrocellulose finish will probably hold up fine but if your guitar has a varnish, I would not use tape at all. I’ve seen clear packing tape used as it is not so obvious from the audience’s perspective. My recommendation would be painter’s tape since it is very easy to remove and probably the least likely to damage your guitar’s finish. Try to find tape that is not overly adhesive as you’ll probably want to remove it at some point (always take great care here) and it doesn’t need to be airtight to be effective. Electrical tape could also be effective and non-damaging.


— Clear vinyl: I have been told that some players are using this vinyl sheeting to cover the F holes of their instrument. It’s naturally adhesive, but again take great care when removing. I would test a small piece before committing to using this.


4 - Additional Top Dampening

This next point deals with intentionally adding weight to your instrument in order to dampen the acoustic resonance and fight feedback from creeping up. The obvious downside is that you lose acoustic volume.


— I’ve wedged a wad of paper in between my floating pickup and the top of the guitar and another in between the pickguard and the top. I used a tightly folded piece of paper and then wrapped it in gaff tape until it was large enough to maintain a bit of pressure in between the pickup, pickguard, and the top of the guitar.


— Stuffing the body of the guitar. Some players have been known to stuff their guitar with cotton balls (you will need a lot) or something similar. This works well, but is a pain to remove. This method will add considerable weight to your guitar, especially if the body is packed tightly.


— Dashboard sunglasses holder: this is a thin rubber or silicon sheet that is self adhesive, designed to stick to a car’s dashboard. Like tape, it will probably be fine on your polyurethane or nitrocellulose finish, but I would not use it on a thin varnish. Take care and remove it slowly when you’re done. Don’t leave it on for a very long time or in the sun. You could also custom cut this material to cover the F holes, kind of a 2-in-one solution. Again, test this in a small area before committing fully so as not to damage your guitar's finish.



5 - Equalization

Some amps, like my Henriksen Blu 10, have a comprehensive EQ section that allow you to make some changes in the specific frequency that is giving you feedback. Most amps with a simple 2 or 3-band EQ however won't help you too much when it comes to feedback. Any change drastic enough to help reduce the feedback will probably affect your tone in an unsatisfactory way. I think a great way to make changes to your EQ to eliminate feedback without greatly altering your tone is to do so with either a parametric or graphic EQ pedal.


— A pedal like the Empress Parametric EQ is your best bet as you are able to precisely locate the frequency that is giving you trouble and eliminate it without affecting surround frequencies. Very expensive.


— The MXR 10-band EQ is going to be slightly easier to use and considerably more affordable than the Empress as it has preset controls for 10 different frequencies.


— On the budget, the Sonicake Tone Group is a great option - $50.


6 - Amp Proximity

By and large, the best way I have found to fight feedback is to adjust the position of the amp relative to the guitar’s body. I always try to position the amp just off to the left of me (I am a right handed player, so the amp is on the opposite side of the body of the guitar) and angled in a way so that the speaker is not pointing directly at the instrument. Most times, this is enough to fix my feedback issues. In certain stage setups however, this is not always an option so having some options on hand that I've mentioned earlier in this post is a great idea.


My website post was initially put together to go along with this video:

[Old Nick]

I'll just chime in to add that I use the LR Baggs Align EQ pedal. With its notch filter and clean boost, it has 'multitool' capability. I don't use the 6-band eq atm but it's there if motivated. No affiliation.

[Danny W.]

I've found that the adjustable high-pass filter in my Acoustic Image amps does a good job of reducing feedback and works better than just rolling off the bass and/or low mid controls. My homemade f-hole plugs made of EVA foam are very helpful, albeit with some loss of highs.

Danny W.

[rpjazzguitar]

Does blowing up balloons inside the guitar actually work?

[pauln]

Proximity to the amp and the surface area of the speakers; with an old Ibanez AG75...
I have tried to use a Twin (two 12") and could not get far enough away on a small stage.
However, my Princeton (one 10") I can practically sit on it on a small stage without feedback.

[John A.]

BTW, "Dampen" means to make wet. Damp (as a verb) means to reduce vibrations.

[Little Jay]

I put a sound post in my ES-125. It’s directly under the bridge on the bass side. No more feedback!

I did lose a little bit of acoustic volume I think but otherwise I didn’t notice any change in sound, if not for the better!

[sgosnell]

I think that if you play so loudly that feedback is a real problem, the best long-term solution is to get a semi-solid or solid body guitar. That said, the best solution to anything isn't always practical or even possible for everyone. If a different guitar isn't possible or desirable, then turning down the volume is the best solution. If that's not possible or desirable, then you have to start trying other means.

[pingu]

stuffing with foam rubber

I half stuffed (top bout only) my Af120 with foam , it suppresses feedback and lessens the acoustic volume a chunk

also made the guitar a bit less bright
sounding (less overtones)

hardly added anything to the weight


I finished it off with a bit of black
upholstery vinyl as you can just about see

I’m very happy with the results ….

[Cunamara]

I think that if you play so loudly that feedback is a real problem, the best long-term solution is to get a semi-solid or solid body guitar. That said, the best solution to anything isn't always practical or even possible for everyone. If a different guitar isn't possible or desirable, then turning down the volume is the best solution. If that's not possible or desirable, then you have to start trying other means.

One of my archtops can literally start feeding back on bass notes at a conversational level, let alone anything appropriate for playing a gig. In particular, this effect tends to happen when using my tweed Deluxe style amplifier; the culprit there is the rather strong bass response of that amp. I've modified the amp to be able to dial down the bass (Mission Amps Humbucker 1&2 mods) which can control that. When gigging, however, it's best to use an amp with greater control over the EQ.

Amplifying an archtop guitar which is designed for acoustic response is sometimes a bit of a challenge. as you see, they may not be the best tool for the job on a gig. My ES-175 is much more resistant to feeding back as is my GB10. I have solid body guitars that I play because I like the tone and feel of them, not because of feedback issues (I don't ever play that loud, even on gigs).