EVENT20/20bas: Overheat?

[etyrnal]

I have a pair of EVENT 20/20bas monitors.

They've worked great for my purposes for years.

One of them still works perfect.

The other works for a few hours, then...

I hear a POP! And the LED slowly fades out...

I turn it's power switch off.

If i wait a while (10-30 minutes), i can turn it back on and run it for a few more hours.

They sound identical.

I have above average soldering/desoldering skills... but am not an electronic engineer.

If i know what to replace, i can do it.

Can any one give me some idea of what this problem might be caused by?

Thanks

- L

[etyrnal]

did i not post this in the right area?

[ripple_fx1]

I'd venture to guess that the monitor amp is protecting itself via a thermal sensor - look for it on a heatsink, and then try and determine if it's an overheating problem by pointing a fan at the heatsink. If the unit stays operational, figure out which transistor(s) is/are overheating, and why - is there an inaudible parasitic signal on that particular channel, or does your amp need a tune-up? Put a short on the input of the amp and see if it still goes into protect...Cheers! JR

[Hardtoe]

I had a tweeter just stop working on one of mine after 10 years - the light still worked and the woofer, but no high end.

I just replaced them when I couldn't get a new pair - they actually have a very big dip in the upper mid-range which you dont realize until you compare them to a more evenly voiced speaker. I loved the way they sounded, but you might want to use this as a chance to upgrade to something more accurate. (I have krk vxt8's now which have much better freq response, but less of a sense of depth than the 20/20's - a better trade of for mixing IMO)

Using the one that still works for a little echo chamber.

[etyrnal]

Originally Posted by ripple_fx1

I'd venture to guess that the monitor amp is protecting itself via a thermal sensor - look for it on a heatsink, and then try and determine if it's an overheating problem by pointing a fan at the heatsink. If the unit stays operational, figure out which transistor(s) is/are overheating, and why - is there an inaudible parasitic signal on that particular channel, or does your amp need a tune-up? Put a short on the input of the amp and see if it still goes into protect...Cheers! JR

ripple_fx1, thanks for the reply. i actually bought a fan last year (like a little 6" one) that i have positioned to blow at a glancing upward angle across the back of the speaker/amp... seems to help a little. It doesn't feel any hotter than the other speaker/amp. would this be something that's potentially fixable? maybe a miscalibrated or too-sensitive temp-sensor? if i touch the woofer cone when the speaker is idle, i feel no movement whatsoever. if there were a subsonic signal, wouldn't i theoretically feel it trembling? and if the parasitic signal were above hearing, wouldn't it be filtered out by the crossover? Is it normal to thermally protect the power-supply section?

Also, part of the reason i have avoided disassembling it, was i was sort of worried about whether i'd be able to get it reassembled as snugly/tightly/sturdy as original factory seal... think that could be a cause for alarm? when re-assembling, is it smartest to try to follow old thread cuts? or to try to start new threads? i'm in the habit of following original threads, but if that would cause a potential for loosening up after vibrating for a while, i'd be tempted to cut the threads 90º off just to try to get a tight vibration-resistant seating of the screws. or is there something that can be applied to the threads the would be a removable/temporary "thread-lock" for those materials?

If i pass no program material through it (not the same as shorting the input - i know) i don't think it ever quits... which i though was weird because i figured that at least with some music flowing through there, the port vents would help mix/disburse the heated air near the internal components.

[etyrnal]

Originally Posted by Hardtoe

I had a tweeter just stop working on one of mine after 10 years - the light still worked and the woofer, but no high end.

I just replaced them when I couldn't get a new pair - they actually have a very big dip in the upper mid-range which you dont realize until you compare them to a more evenly voiced speaker. I loved the way they sounded, but you might want to use this as a chance to upgrade to something more accurate. (I have krk vxt8's now which have much better freq response, but less of a sense of depth than the 20/20's - a better trade of for mixing IMO)

Using the one that still works for a little echo chamber.

i know i've got a lot to learn about mixing, but i so far have gotten mixes that fool my ear at least. i seem to get the best mixes i know how to get with my experience, in my room, with my materials. I've decided on either a pair of Event Opals, or if i can't find a place to hear them nearby, i will go with Mackie HR824 mkII (are those 'unholy' to mix on?) -- i'm going to have to relearn my room ('9x9') yikes.

bass is very important to me, so i appreciate monitors than can reproduce the loudness necessary -- still looking for accuracy tho. When i write, i turn on a Mirage BP400 sub, because i need to know what the subs are doing to the little hairs on the body, to the t-shirt and jeans, the hair, and the skin... i mix with the sub OFF - and with monitors at various levels -- even checking balance with speakz turned down very low

end justifies the means i say (mostly)

[ripple_fx1]

Hi - it is typical for amps to protect themselves thermally...As far as the sub and supersonics, the speakers may not have sensitivity to those freqs, but the amp may. Swap L & R inputs to determine if it's amp or the source. The temp sensor may indeed be out of spec, and you can swap those around as part of your troubleshooting. It's also possible that one of the output devices is failing, either pulling too much current, or putting a bigger workload on the others - a cautious finger may tell you if that's the case.
If a wholesale swap of the output sections is possible, that could reveal quite a bit. Don't worry about pulling the drivers - it's not necessary or desirable to torque them down very tightly - evenly in a crossing pattern, but not overtight, as you may distort the basket. The port presents such a low impedance path compared to the seal that it not a concern. Most home improvement stores carry non-hardening press in place caulk rope or foam weatherseal products if you want to get slutty. Also wouldn't use a thread lock, as (assuming) pressboard won't tolerate it. If you do blow out a hole, be sure to seal all others with caulk before rotating, and drill a pilot hole that removes everything but the height of the threads first. Good practice to rotate your drivers 180 every so often to counteract the sag that gravity puts on them. Cheers! JR