Whether you're brand new to vinyl and turntables, or you've been around the block a few times, you've probably faced this problem. It's a phenomenon that has been an issue with turntables since their creation -- feedback!
When you are playing an album at low volume, everything sounds fine. However, as you turn up the volume, you get a howl through your speakers that gets louder and worse when you turn it up.
What is feedback, and why doesn’t it happen with my other sources?
Every other source in your system is totally different than your turntable. Your CD player is reading the disc with a laser, having no physical contact with the disc. Your other sources typically don’t have any moving parts other than maybe a hard drive; they just play a stream or read from the drive. Your turntable, however, is a different animal.
Sitting on the end of your tonearm is a cartridge with a cantilever that has a diamond on the end of it. The cantilever is that tiny little rod sticking out from your cartridge body. Basically, the diamond is tracing out small movements in the record groove, which causes the cantilever to move around. These movements of the cantilever are what create the sound from your records.
If you have ever heard someone talk on a microphone that was too close to a speaker, you have experienced feedback. It’s when the sound coming out of the speakers gets fed back into them from the microphone, continuing to amplify itself, and creating a loop that quickly turns into that classic loud howling sound. The same thing can happen with your turntable.
Your speakers are moving air to create sound. Your cantilever is moving ever so slightly to also create sound. It’s following the very tiny vibrations it’s getting from the record. Well, what do you think would happen if somehow your entire turntable started vibrating? The cantilever on the end of your cartridge picks up those small vibrations and sends them to your speakers. This is what creates the feedback loop.
When you turn things up pretty loud, you may find this really easy to hear. The bad news is, even at low volumes, you may not notice it, but extraneous vibrations may be entering your turntable and making the sound muddier than it should be.
What is causing the feedback, and how can I fix it?
Before you can fix the problem, the first thing you need to do is diagnose it -- you need to determine where the feedback is coming from.
Not Enough Isolation
Turntables vary in their ability to isolate themselves from external vibrations. If yours is a heavier turntable (say, 30+ lbs.) or has a spring suspension system, it will typically do a very good job on the isolation front. However, most modestly priced turntables do not have these features, which can lead to feedback.
Proximity to Speakers
This is probably the most common cause of feedback. If your table is on the same surface as your speakers and in close proximity to them (together on a tabletop, for example), there is a decent chance you’ll get feedback from two places. First, the airborne movements coming from the speakers may get into your table. Second, the vibrations from them make cause the tabletop to vibrate and then transmit those vibrations up into the turntable.
If you must set up your system this way, you’ll have to experiment a bit. Some simple rubber feet under your speakers may help out. Placing your table on a heavy piece of granite may also change the way your tabletop vibrates and fix the problem. The best solution, however, would be to just get your turntable off the same surface as your speakers and if you can, move it further away from them.
Wood Floors with Strong Subwoofers
Many of you may have a nice subwoofer as a part of your system. If you have wood flooring in your home, this combination can also cause a feedback issue. This situation is a little trickier but start by unplugging the sub. Does the feedback disappear? If so, you will probably need to mount your turntable on the wall with a wall mount bracket.
Many of the better phono preamps are prepared for feedback. Since feedback in a turntable is created from very deep bass notes, the better ones have a low-frequency filter built in. This will allow you to cut off the very deepest bass notes to prevent a feedback loop from occurring.
Feedback can ruin the enjoyment you get from a great vinyl system, but with a little persistence, you can typically get rid of it. We hope these tips have started you down the right path. As always, feel free to contact or chat with us if you have any questions.