I know these are dirt cheap speakers and in all likelihood, they're toast, but I am going to see if I can give repairing them or doing something with them...
Cut a long story short, I ran them both too hot once about 12 months and they've both never been right since and both took a turn for the worst yesterday. After around 20 minutes, the sound went extremely hollow as if only the highs were coming through and most of the bass and mids were completely lost. The singer did an absolutely wonderful job of carrying us considering we had absolutely nothing coming through.
I backed the them off significantly and while one of them made it through just about (at about 70% volume), the other was really struggling and by the end was at around 30% and was still struggling to run for a few mins without losing all of the mids and bottom end.
I spent some time today and stripped them apart expecting to find a nailed preamp, but there's really nothing to indicate any damage. I read a couple of forum posts about the zener diodes going but they look fine. I've dug out the power amp on one.... again, it looks fairly normal. There's nothing to indicate it's toasted or any damage.
My gut feeling was the preamp at first but then it feels like the 20 minute delay might be something heat related.... which would be more likely the power amp right?
I have Googled.... and asked ChatGPT.,... in case anyone thinks I haven't tried yet 🙂
Cut a long story short, I ran them both too hot once about 12 months and they've both never been right since and both took a turn for the worst yesterday. After around 20 minutes, the sound went extremely hollow as if only the highs were coming through and most of the bass and mids were completely lost. The singer did an absolutely wonderful job of carrying us considering we had absolutely nothing coming through.
I backed the them off significantly and while one of them made it through just about (at about 70% volume), the other was really struggling and by the end was at around 30% and was still struggling to run for a few mins without losing all of the mids and bottom end.
I spent some time today and stripped them apart expecting to find a nailed preamp, but there's really nothing to indicate any damage. I read a couple of forum posts about the zener diodes going but they look fine. I've dug out the power amp on one.... again, it looks fairly normal. There's nothing to indicate it's toasted or any damage.
My gut feeling was the preamp at first but then it feels like the 20 minute delay might be something heat related.... which would be more likely the power amp right?
I have Googled.... and asked ChatGPT.,... in case anyone thinks I haven't tried yet 🙂
You have to do electrical testing, not just look at the parts.
If the problem only happens after 20 minutes, even at idle, there is a serious defect.
If it happens only after loud playing, it couldm be built-in thermal protection. Ask the mfr.
On the other hand, they are so cheap that they may not be worth repairing.
Clearly you need something more capable of higher volumes.
If the problem only happens after 20 minutes, even at idle, there is a serious defect.
If it happens only after loud playing, it couldm be built-in thermal protection. Ask the mfr.
On the other hand, they are so cheap that they may not be worth repairing.
Clearly you need something more capable of higher volumes.
Indeed, I was hoping for an easy win. Not so.
I don't believe it is occurring at idle. It's only occurring at loud playing. The sound goes hollow. It's like all the bass disappears. I'm wondering if I've blown the woofer.
I've got a couple of TS112s, I could whip the module out of one and hook it up to the woofer.
I'll have to run it for a good 20 mins at loud volume .... Fun.
Measure the DC resistance of the woofer out of the cabinet in question. I've seen a number of Alto cabinets, where the woofer "partially shorted"- it still worked, but its DC resistance (and therefore the impedance) would be lower than nominal, due to part of the coil shorting together.
It it's a 4 ohm driver- the DC resistance should be about 3 ohms. If it's less than 2 ohms, DC resistance- it's probably bad.
If it's an 8 ohm driver- the DC resistance should be somewhere near 6 ohms. If it's significantly lower than 4 ohms DC resistance, it's probably bad.
I've seen cases, where the damaged speaker measured at or less than ONE ohm. That will definitely make an amp cut out!
That type of woofer failure (too low impedance due to shorting) would make an amp overheat and/or go into protection, in many cases. Fortunately, a replacement or rebuilt/reconed speaker, should be much less expensive and easier to source, than other possible problems. I've personally reconed quite a few Alto woofers- and the cabinet worked fine afterward, in most cases. A few cases, the internal amp also had to be repaired- but in the vast majority- just fixing the woofer, fixed the issue.
Regards,
Gordon.
It it's a 4 ohm driver- the DC resistance should be about 3 ohms. If it's less than 2 ohms, DC resistance- it's probably bad.
If it's an 8 ohm driver- the DC resistance should be somewhere near 6 ohms. If it's significantly lower than 4 ohms DC resistance, it's probably bad.
I've seen cases, where the damaged speaker measured at or less than ONE ohm. That will definitely make an amp cut out!
That type of woofer failure (too low impedance due to shorting) would make an amp overheat and/or go into protection, in many cases. Fortunately, a replacement or rebuilt/reconed speaker, should be much less expensive and easier to source, than other possible problems. I've personally reconed quite a few Alto woofers- and the cabinet worked fine afterward, in most cases. A few cases, the internal amp also had to be repaired- but in the vast majority- just fixing the woofer, fixed the issue.
Regards,
Gordon.