How to Tell If Your Speaker Is Blown
The sound of a blown speaker is pretty tell-tale - fuzzy, distorted crunchy sound that may be roughly reproducing the signal you are sending through it or making no sound at all.
There are a few scenarios that can cause a speaker to malfunction. A speaker can sustain physical damage to the cone or even the voice coil. Sometimes the damage is obvious. In other cases, the speaker may look fine, and the distortion may be so subtle that you could be wondering if your amplifier is actually at fault. In this article, we’ll share our tips on how to determine whether your speaker or your amp is to blame.
The term “blown” is used as a blanket term to describe a speaker that is not working right. It can mean that your speaker is reproducing scratchy signal at a lower volume, or no sound is passing through the speaker. You can determine if your speaker is blown by trying one or more of the below tests.
Tests for determining whether a speaker is blown
Replace the speaker with a known good one. This is a great, easy way to quickly determine if your amplifier is working, and your old speaker is not. If you have a known working replacement speaker simply replace your old speaker with the working one. If you are getting good clean sound, your old speaker is the problem.
This is a great test that will give you solid answers when you’re hearing odd sounds from your amp and aren’t sure whether your speaker is the problem. However, note that it is possible that it is possible for a speaker to blow due to an amplifier malfunction. For instance, in a solid state amplifier where the power transistors are connected directly to the speaker, malfunctioning transistors can pass excessive current to the speakers, blowing the voice coil. (This is also possible in a tube amp, but in this case the output transformer will probably blow first.) If you have reason to believe that the amp is malfunctioning — and particularly if it smells like it is burning — you should investigate that before trying another speaker. It is very possible that the new speaker will blow also.
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So, before trying a new speaker, think about what happened to the amplifier before you suspected that the speaker is blown. If the signal distortion was accompanied by a popping sound, a burnt smell, and smoke pouring from the amp, do not try a new speaker before addressing the obvious issues with the amplifier.
Do I need to perform this test with a speaker of the same impedance? Yes, it is a good idea to use a speaker of the same impedance if you have one available. However, a small impedance mismatch should be okay, particularly if you are just performing a brief test. More information on speaker impedance here, and speaker information specific to Wurlitzer electronic pianos here.
Test your suspect speaker with a known working amp. If you don’t have another good speaker (or if your amp is in questionable condition and you don’t feel comfortable connecting your known good speaker to it), you can hook up the speaker in question up with a working amplifier. If this setup is giving you the same poor speaker sound, you can safely say that the speaker is blown.
Visually inspect the speaker. A blown speaker can have physical damage that can be seen. To inspect your speaker, remove it from the amplifier or instrument and take a look at the cone. There should be no holes or tears. Damage to the cone will prevent it from reproducing your signal properly, and will often result in ugly distortion.
Physically inspect the speaker. A blown speaker can have damage that can be heard with some mechanical movement. If you gently tap on the cone of the speaker it should have a firm drum like sound. If you hear a rattling sound (like a loose snare drum), this is an indicator of a bad speaker. Also, if you gently exercise the speaker cone by pushing on it (being careful not to puncture the cone with your finger or push it much further than 5 millimeters), you should hear almost nothing. Blown speakers will make a scraping or crunching sound with any movement. This is an indicator of a bad voice coil and it will most definitely need replacing.
What should I do if I have a blown speaker?
Luckily most speakers are not too expensive, and blowing them is somewhat rare. We recommend replacing the speaker. If you have an expensive speaker, such as something that might be made by JBL or a vintage Jensen, it may be worthwhile to repair the speaker, but keep in mind that if you are enlisting the services of an experienced tech you will be paying for both the part and their time.
If you plan to replace your speaker make sure it is the correct impedance for the amplifier and is rated at or above the wattage of the amplifier. Amp manufacturers regularly specify a speaker that is almost double the wattage of the amplifier’s wattage. A 30 watt amplifier may come with 50 or higher wattage speaker in order to be sure that it can handle the power that the amp is sending through it.
A replacement is almost always a good idea, and you can hang on to your original until you decide to fix it or not. If you don’t want the speaker you could sell it on ebay for a small percentage of it’s “working” price, because someone may want it for parts. Be sure to specify that the speaker is blown, and price it accordingly.
My Wurlitzer 140B, 112, 120, 720 or 145 has a blown oval speaker!
Well, you’re in luck: we just happen to have a bunch of those. Check out our Wurlitzer 6x9 speaker listing here for information on those speakers.
Further Reading
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