I just received a pair of BP102s for a set of Tuba24s I'm going to build. I have them hooked up in parallel, out of phase, and I'm playing a 31.5Hz sine wave, at about 3.5V, through them to break them in. I've seen a recommendation that people run a level more like 10V, but I'm worried...
You see, I'm hearing occasional "crackling" noises from the drivers. Sometimes they're very brief, sometimes they last a few seconds. It's what I would imagine it would sound like if some dragged a sharp object like a pin across the paper cone: a sharp, papery crackling sound.
I plugged a pair of headphones into the amplifier (end of the signal chain, in other words) and I am not hearing this noise through the headphones.
Is this a normal part of the break-in process or is there something wrong with my drivers? It seems to be coming from both of them.
Odd noises during break in?
Not sure if I can address the crackling noise. Normally they'll be whisper quiet at that frequency in open space (not cab mounted). Right now I'm breaking in a 3015LF at 30 Hz, 10 volts continuously for a week now. I noticed after a few days it making more sound so I dropped the frequency down to 25 hz, not that that was really necessary.
This driver is a replacement for another that was making a continuous crackling or mechanical rubbing sound when I was breaking it in. Physically pushing on the paper cone, I couldn't feel any rubbing though.
It's strange that both your drivers are doing the same thing. For lack of better advice, I would say keep running them at the reduced voltage and hope the sound goes away.
This driver is a replacement for another that was making a continuous crackling or mechanical rubbing sound when I was breaking it in. Physically pushing on the paper cone, I couldn't feel any rubbing though.
It's strange that both your drivers are doing the same thing. For lack of better advice, I would say keep running them at the reduced voltage and hope the sound goes away.
Tomorrow I'm going to stop procrastinating - WB
That was it - Thanks, Tim!Tim A wrote:That sounds like amp noise, which you wouldn't hear through headphones. They go through a little tiny amp. Full power would blow your eardrums. Plug in another speaker and listen.
I disconnected the drivers, plugged in a known good speaker and listened for a while. No noise! So I reconnected the drivers... and guess what - no noise!
It must have been a poor speaker cable connection at the amp. (I'm using my bargain amp with home-stereo type spring-clip terminals. That'll teach me!)
Thanks again. I feel much better now!