Finally! Omni 12 Tall Boy build

[Seth]

Because I'm too lazy to dig back through 250 posts.......what is the mixer/amp configuration?

Dayton Audio KABD-4100 4 x 100W All-in-one Amplifier Board with DSP and Bluetooth 5.0 aptX HD

[CarterKraft]

Because I'm too lazy to dig back through 250 posts.......what is the mixer/amp configuration? You said receiver - is that what your using? I wouldn't go changing components in the cab until you rule out the signal getting hammered somewhere.

Almost every time a venue calls me because they say the speakers are distorted - it's because they are overdriving the input. I turn down the input, turn up the output and voila.....same volume with no distortion.

As Seth posted it is a tiny chip amp combo with on board DSP. There is no physical crossover and separate audio components outside of the amp board which is entirely new.
It's Bluetooth signal in or line via 3.5mm stereo jack.
I have tried 3 Bluetooth sources/devices and one line in.

As I explained this happened in one moment, post sweep.

I had the gain tuned so that on Spotify on my phone at max volume the cabinet was not in clipping. This was for simplicity sake and to prevent anyone that might grab my phone from damaging something or over running it.

The Dayton tweeter I ordered has a built in protection cap so I can swap the whole thing as a unit to test.

It is possible I was over driving the input but that didn't change during this demo. Post sweep all the previous songs I played now clipped when they hadn't minutes before.

I'll figure it out, lete get the new tweeter and I'll begin troubleshooting again, might arrive Friday, or Monday.

[Bruce Weldy]

Well, it's possible that you damaged the tweeter during the sweep. But, it's also possible that you damaged the amp. Face it, for 89 bucks, you ain't gettin' a workhorse. Whatever it ends up being.....no more sweeps at high volume.

[CarterKraft]

I totally expected PE to tell met to get bent but the tech guy didn't at all. He said if that's what happened then we need to replace it. I really thought it was damaged at the time but now I don't think it was, still not sure I guess.

I definitely won't be doing that anymore, I had abused this thing at high volumes plenty and sort of thought it was bullet proof.

[Seth]

...I am ready to just buy a new tweeter and cap but I don't like throwing parts at stuff.
Any ideas?...

I took the time to follow up on some of this. Looking at the ratings for the APT-80 tweeter you have, it's rated 45 watts when crossed over at 3.5 kHz, 18 dB/octave and 85 watts if crossed over at 5 kHz. Guessing the difference is due to displacement limits more so than thermal???

Ignoring the "why" and just assuming the limits are actually thermal limits, it does stand to reason you could have melted the coil, given you potentially have upwards of 75ish watts available to the tweeter. If the coil melted it creates a short and lowers the resistance value of the coil. Perhaps that's what occurred and your amplifier is limiting/protecting itself due to a really low impedance.

Just a thought and another urging to check the DC resistance across the tweeter terminals. If it measures much less than 6.4Ω, it's likely the cause and issue.

[Tom Smit]

Good thinking, Seth.

[Grant Bunter]

If the coil melted it creates a short and lowers the resistance value of the coil. Perhaps that's what occurred and your amplifier is limiting/protecting itself due to a really low impedance.

Just a thought and another urging to check the DC resistance across the tweeter terminals. If it measures much less than 6.4Ω, it's likely the cause and issue.

My experience is that a melted VC in pretty much any driver is rarely measurable because it doesn't conveniently melt itself back to the other part of the coil.
Test Continuity first. No Continuity, VC has a gap in it's turns.
You can only measure DC resistance if you have a complete coil.
Sometimes, you have a complete coil but DC resistance is not near zero, but is less than the lowest rated nominal load of the amplifier channel. In which case it will go to protect.
Rarely, you can measure a very low impedance, say 1 ohm, and many amps will identify that as a dead short and go to protect.

The other answer is much less palatable. Some amplifiers will indicate a blown output stage by showing protect mode.
You can wire in any working 8 ohm driver, turn amp on, and if it goes straight into protect mode, then that is the likely cause.

[Seth]

...Sometimes, you have a complete coil but DC resistance is not near zero, but is less than the lowest rated nominal load of the amplifier channel. In which case it will go to protect.
Rarely, you can measure a very low impedance, say 1 ohm, and many amps will identify that as a dead short and go to protect.

I completely agree. My money is on DCR measuring less than 3Ω but greater than an open circuit, due to either melted insulation or the rare melted coil that didn't create an open circuit. Seems the most likely situation given the supporting evidence.

[CarterKraft]

Holy smokes you guys are working on this without me!

New tweeter came in today, it's much smaller than the original and might be a waste of money if I am really pushing it with more than 40 watts...

But anyway I got it swapped out, it didn't have a protection cap but a resistor in series. I added the 10uf cap in series with that and got it screwed in to the horn.

I am totally unsure about the resistor or the cap if anyonr has anything to add I'm all ears.

The "clipping"is gone but the "tune" is off, mostly levels and the tweeter might be out of phase, I'll have to perform the Seth tuning regimen again to get it back to the correct output.
So success I think.

And as I was reading yalls replies I remembered I forgot to measure the resistance of the APT coil.
2.30 ohms is the response, I think Seth wins some sort of award for that extra bit of homework.

[Grant Bunter]

You should be able to find a D25D diahpragm for the APT-80 for $10 + shipping.

Then you wouldn't have to reconfigure the settings...

[CarterKraft]

Since this is the old(er) version of the APT do you think it takes the same diaphragm?

I'll look for one, it would be nice to have the right driver in it.

[Grant Bunter]

Since this is the old(er) version of the APT do you think it takes the same diaphragm?

I'll look for one, it would be nice to have the right driver in it.

I would think so...

[CarterKraft]

This is what I put in there to test.


https://www.parts-express.com/Dayton-Au ... quantity=1

[CarterKraft]

It looks like there is a D25D3 available for $30 I might just buy a whole nother tweeter instead of trying to repair this one.

[Grant Bunter]

https://www.greatguitareshop.com/sell-5 ... hragm.html