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I worry that I may have blown my buddy's Denon
I mean, like, I don't THINK so, but when you hear hoofbeats, you think "horses", not "zebras", right?
Remember the Osprey? These guys?
Well, I borrowed them to a good friend & coworker last week. He's a good fellow when it comes to how he treats his & his friend's possessions. While I definitely don't think he had them dimed, tonight his receiver went bzzzt with a puff of smoke. Closer inspection revealed some burn marks on a part of the PCB that had FR-CH silk-screened. Ooof.
He said today at work that it had been acting kinda funny over the weekend--the receiver kept powering off. I never really thought of these speakers as a low impedance load to trigger amp protection, so we collectively wondered if the amp were dirty, and this was thermal protection. His cat DOES like to sit on top of it. But before he had a chance to open it up for cleaning, it gave up the ghost. Turns out it wasn't even that dusty inside.
He's got (or had) the Denon x3700. I've got the x3800--so the next revision, but with an amp section that Amir@ASR measured to behave a lot like the x3700. I can tell you that I have most certainly run these speakers in my living room at 95dB at the listening position for 10+ minutes at a time. Like a rented mule, I'm saying, and my Denon never batted an eye.
Here's the impedance sweep I took shortly before I tossed them in the car and headed to InDIYana last year. See anything that freaks you out?
Comments
No solid state amplifier worth it's salt should have a problem with that load. No amplifier should fail because it was driven hard (it should go into protection mode).
I find most amplifiers run at "max" just fine, they just sound meh (or bad) and don't get any louder. The days of an Ic failing or clipping and sending DC out should be problems engineering has solved. Chances are that amplifier met a natural fate caused by number of heat cycles and hours used. The impedance plot shows the the speaker does not have an internal failure that would cause concern.
It's sad to hear the amplifier died but I don't think there is anyone to blame.
Agree with @kenrhodes
Thanks Ken. That trace was from just after I had completed them. I still want to verify, in situ. I'm heading over to his house with a multimeter and the DATS this weekend. Because if I had overlooked something critical, well, I'd want to make amends and that means second guessing all my decisions so I'm not a shitty friend.
But I'm just not seeing it either. :-/
I don't see any issues with that impedance curve either. Based on experience, I will ask the question - Did you measure the impedance for both speakers?
Sehlin Sound Solutions
Sounds like the result of a slow heat death to me if the cat liked to lay on it. Elevated heat over the lifespan will shorten that lifespan.
I did! Here's the pair, overlayed.
Nope, I'm not seeing a bad load there at all.
InDIYana Event Website
I'd call that a match!
Sehlin Sound Solutions
I'm bored here at work, so I found the owners manual. It has a menu setting for output impedance? I've seen physical switches that change taps on the power transformer, but not sure what they are changing in software.
Smoke and burn marks on the PCB - If your really lucky a fusible resistor did what it's designed to do and there's no collateral damage. Looks like discrete outputs from the pics I found online, so that's good.
Update, stopped by this afternoon, and the impedance measurements looked safe & correlated. We're chalking it up to dumb luck.
We couldn't see anything amiss in the area that gave off the smoke, but the PCBs are vertical and we weren't going to disassemble any deeper than the cover. Turns out we have an authorized Denon repair shop in the area. He's taking it in tomorrow I think, and they quoted him $125 deposit for diagnosis & perhaps repair--they guessed, at worst, $250 all in. That's a far less than a new receiver of similar capabilities.
Anyway, he wants to know if I could be convinced to part with them. That's probably case closed.
Perfect!
I have the X3600H, and about a month ago, after some power outages happened, the receiver has gone randomly into protect mode when listening to any source.
I've had to "reboot" it to get it to work, and it would work for 2-8hours over the next week or two before going into protect mode again. Fast forward three weeks, and maybe 8 or 10 resets, and now it hasn't done this for a whole week of listening.
I imagine there is some electrical component that has started to fail. For reference, I never had the thing louder than 75-80db at my listening position, and It would do it with nothing playing at times.
Long story short (ha!), I suspect it's a known weakness in the model, and they know exactly what to do to fix this.
I'm keen to know what they replace when they do fix this as I might be a few months from the same adventure.
I'll report back. They said it could be up to 2 weeks if parts weren't on hand.
Soooo, the end of the saga. The technician repaired the bad output channel, but the digital board was still giving rando shutdown fits while it sat on the repair bench. My buddy decided $800 to replace THAT board was more than he was willing to spend to keep the 3700 alive.
Bummer!
Stupid electronics!
Did he try smacking it? Worked on old TVs..
InDIYana Event Website
That's too bad. It's unfortunate some gear has become so complex that repairs cost more than replacing the unit - most likely with something that has more or newer features.
It makes me wonder if there is a software/PC option for the HT crowd who wants the latest multi-channel technology. Add an audio interface & HDMI switcher and plug it in. Software could take care of everything. It might already exist - I'm ignorant when it comes to HT gear these days.
I hear you Tom. Sometimes I think we have taken it a bit too far.
I like HT. But I am not going ape sh!t over it. My family is blown away by the meger system I put together for them. They invite friends over because they think it is the best thing they ever heard. Probably true but, it is minimal to me.