Broken Amp?

[anikun07]

I've been using a Dayton SA240 for the last year and a week. It is now one week out of warranty so I don't know if PE will work with me or not but I've sent them an email. In the middle of the night we woke up to a strange noise that my S.O. described as someone jumping up and down and it sounded like it came from the attic or basement. So we looked around, and of course, didn't find anything. This morning when we woke up the furnace kicked on and simultaneously, pure coincidence I think, the subwoofer starting making the noise again. So at first we though the furnace wasn't igniting properly almost like there were mini explosions in the chimney - scary! Then is stopped for a moment and then started again. Hot air was coming out of the vent, so obviously the furnace was igniting just fine. I walked closer to the subwoofer, Tuba HT, and it sounded like the subwoofer was connected to a microphone and someone was running their finger directly on the mic element. It was an odd static sound that seemed to get louder. I unplugged the inputs going to the amp and the noise didn't stop. I set the power switch to "off" and it still persisted. Only when I unplugged the power cord from the surge protector strip did the noise stop. I though maybe it was the new SLA speaker I placed near the amp that was causing the problem so I disconnected it and moved it away, but the amp was still sending the noise to the sub.

Does anyone have any idea what might cause this or if it's even fixable? My amp sits on top of my THT but this has never been a problem for the past few months I've had this set up. Before I had the amp about 6 feet away from the sub, but with the new set up the sub is closer to the AVR so the subwoofer cable is long enough to reach the subwoofer. Does this sound like magnetic interference?

[anikun07]

I sent the amp back to PE yesterday. They were kind enough to accept it under warranty, even though one year from purchase was 3/11 and one year from delivery was 3/14. I'll post back after I hear from them about either fixing it or if they decide to replace it.

I'll note that it seemed like the power button was an issue because when I would actually switch it to "On" it got a lot quieter, but in "Off" or "Auto" it got loud.

[anikun07]

I wanted to post pictures of my workflow in connecting the woofers and drivers. Once I got a pattern started it went pretty quick. I started by tinning all the driver terminals first. Then I prepared the connecting wires. I separated + and - wires to make running them easier.

First I pull the wires long enough to reach the driver. This also makes it easier if I ever have to replace a driver in the future without having to open the cab.


Second, use wire strippers to cut the sheath in two places about 1/2" - 5/8" apart.


Third, using an X-Acto knife of box cutter cut a line between the wire stripper cuts and pull off the sheath.


Fourth, bend the exposed wires in half. This is only necessary for terminals that are in the daisy chain.


Fifth, use pliers to flatted then wire, it makes it easier to solder to the terminal.


Sixth, flux the wires.


Seventh, tin the wires.


Eighth, solder the wires to the terminals and make sure it has a strong joint.


Repeat for the rest of the drivers. For end terminals I just clip the wire and flatten it, just like the steps above. This worked very well for my speakers.

[bmf]

On the odd chance PE tells you that they find nothing wrong there is one other possibility.
More years ago than I care to mention I was running sound for a band that spent the summer opening for various national acts when they came to the area. During our soundcheck for one of these shows the entire system started to make a strange thumping noise. It sounded like someone punching a pillow except it grew incredibly loud then slowly faded away. It had a constant tempo as it faded up then away. The head of the soundcrew just sat there and waited for it to end then looked at me and said "Have you ever heard frequency pulse from the power source before?". The look on my face must have gave away that I hadn't. He explained (and I probably will not correctly) that main lines can have frequency pulses when something connected to them has been damaged or is out of sorts. We are talking large scale here. And this can cause the power in entire areas to create pulses that can be heard in audio equipment. They usually only last a few seconds and are not noticed but sometimes can be severe. They also can hit one building and not the next and come and go for weeks before the problem is discovered. He went into the technical specifics of it but I would most likely get them completely wrong so I won't try.
Probably has nothing to do with your issue but your description reminded me of the occurrence. Apologies for a long story to make a simple point.

[anikun07]

Thanks for the post, that's actually really fascinating. I never even would have thought of something like that. It's really good to know in the odd case where something like that could happen. For me, this seemed like it could go on for minutes or longer if left plugged in. But if it were more like seconds, as you said, I might not be standing around scratching my head wondering what the heck is going on. Again, thanks for the post.