What made my tweeters go bad?

J

jasoncorrie

Audioholic Intern
The tweeter in each of my PSB B2s has gone bad. They are still functional, but their output is quite low. I have a pair of B1s that have the same tweeters, so I swapped them out. What a difference. The ones that are messed up sound like you have your hand over them when you are listening to them. You can hear them, but you aren't getting most of the frequencies.

First of all, I need some replacement tweeter. Any suggestions where to get these. I can't find anything online. Or should I replace with different tweeters.

Second, what made them go bad? Now, I didn't buy the speakers brand-new, but they were in excellent shape when I got them 3 years ago or so. I moved one year ago, and immediately noticed the problem. I thought it might have been the room at first, but it was the tweeters. Of course, they could have been bad all along and I didn't notice since I had a great listening room before I moved.
I am wondering if UNDERPOWERING them would have messed them up. I have been running them with an Onkyo 601. It does an OK job. It has been pretty good to me, actually, but I don't have anything to compare to.

These are the specs on the Onkyo:
Stereo Mode Power: 110 Watt @ 6 ohm, 1 kHz, THD: 0.08%
Surround Mode Power: 85 Watt @ 8 ohm, 20 Hz - 20 kHz, THD: 0.08%

These are the specs on the speakers: Frequency response is rated by the company as going from 49Hz to 21kHz +/- 3dB (measured on-axis). Anechoic efficiency is rated as 89dB/W/m, and the impedance is said to be 6 ohms nominal, hitting a 4-ohm minimum. PSB recommends the use of amplifiers rated from 10 to 100Wpc.

So, did these tweeters fail due to faulty power? Should I upgrade my receiver for this reason, or were they bad to begin with? The rest of the speakers work fine.

Thanks for any help you can offer
 
croseiv

croseiv

Audioholic Samurai
What model is the receiver? And yes, if you are running at high volume with your receiver, it could be clipping and that would affect the tweets.
 
C

Chicagorep

Junior Audioholic
Under powering tweeters and playing them at high volume is usually the culprit
 
j_garcia

j_garcia

Audioholic Jedi
Did you notice when it happened? Were you playing something very loud? As Chicagorep notes, underpowering which will create clipping and distortion is what causes drivers to fail and tweeters tend to go first.
 
J

jasoncorrie

Audioholic Intern
The receiver is an Onkyo 601. The specs are listed in the title post.

I didn't notice it right away, apparently. It wasn't until I moved them into a different room that I noticed they sounded bad.

Is there an explanation for why they work a little, but are not all the way gone? They are not "distorted" but really muffled.

So, was it simply the volume, or underpowered volume? Would simply upgrading the receiver fix the problem? What kind of power specs do I need to look for in a receiver to avoid this happening again given my speaker specs listed above?

Thanks for all of your help guys. Any suggestions on finding replacement PSB tweets?
 
selden

selden

Audioholic
Underpowered volume causes clipping in the receiver. What goes in as a smooth sine wave comes out as a square wave which contains many more inaudible high frequency sounds. These high frequencies cook tweeters. The damaged tweeters have to be replaced.

You can upgrade to an AVR with a better power supply (not just increased per-channel wattage) and/or you can get external amps (if your the AVR has line-level preamp outputs) and/or you can invest in more efficient speakers.

For large rooms at high volume levels, you need to get efficient speakers with a sensitivity of greater than 90db (most are in the mid 80s). To get a 3db (barely noticeable) volume increase just from the amps, you need to *double* their power. It's much better to get increased volume by having more efficient speakers.
 
J

jasoncorrie

Audioholic Intern
Well, I talked to PSB and they will sell me a replacement tweeter for $61.95 + shipping. I need two of them.
They transferred me to tech support and he couldn't offer many reasons why they would have gone bad. "Playing at high levels or sending them a 'dirty' signal" is about all he could offer. I have never played higher than reference (around 80db) and that is never for long.
Is pink and white noise considered a "dirty" signal I did some of that at near reference levels for calibration purposes.

So, still wondering why they went bad and what I need to do to prevent that from happening again.
 
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