Re: DQ-10 Midrange Speaker Crackle - Part II
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John van Son -- I think you nailed the solution.? And thank you?to everyone who offered a solution, because if the problem comes back, I will be re-reading your advice!!
?First, my soldering iron is not the best (tiny end and the tip was nearing end of life) and then coupled with my crap soldering skills, when I replaced the old crossovers with Regnar rebuilt ones, I have had the perfect storm of loose solder connections on the speaker tabs AND I undoubtedly bent the tabs away from the speaker cones (and toward the magnets) on probably more than one speaker, to make the soldering easier and keep hot and potentially dripping solder away from the fragile speaker material, that then probably resulted in the speaker tab metal touching the top plates of the magnet structures -- and as you wisely said could create this problem.? Wiggling the speaker wires (or the right frequency vibration) was in turn wiggling things just enough to cause the vibration induced shorting.
So, for the moment until I do more testing, the crackle and sometimes lingering static and fuzziness is gone -- after I resoldered some loose speaker wire connections (still not great solder work) AND I pushed the speaker tabs back toward the front of the speakers -- as I must have bent them back to make soldering easier at some point (not realizing I was creating another problem).? ?
So, for all of you -- solder carefully, and be careful what you bend and twist when you monkey with the innards of your DQ-10s.? The electrical gremlins are ready to strike without a moment's notice!? Hats off to all of you!!!
Thank you so much John!!!
On Fri, Sep 25, 2020 at 12:28 PM John van Son < jpvanson@...> wrote: The tinsels for the midrange dome are mounted on the driver's front plate and accessible without disassembling the driver. You can see them from the front of the speaker, actually, without any undoing anything other than the grill. The tabs you see are just mounted to pass throughs that the tinsels are then attached to on the front. The screws you removed should be replaced. Disassembly of the driver for access to the soft parts involves the four screws on the front, but you shouldn't have need to do that just yet. It's best to hold off on that as long as possible as it's difficult to center the voice coil of a dome driver during reassembly to prevent rubbing if you've not done it before.
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I don't have an example at hand (my parts and DQ-10s are in storage), but what sounds like might be happening is you may have bent the tabs when soldering to touch the topplate of the magnet structure. This would cause a short if both are in contact. This could cause crackling with intermittent contact. With firmer contact as you are applying during testing, while the crossover should still be presenting resistance to the amplifier in that case, it might reduce the system's impedance enough to be triggering the amplifier's protect circuitry causing it to cut out.
Of course, the crackle may be unrelated to the tabs shorting when you push them and may be due to a rubbing voice coil with the midrange dome. This will happen if the driver has been damaged from excess power causing the coil to unwind partially when the glue let go, but not enough to completely blow the driver. There is another case in that it might be the woofer that's blown. Dahlquist's documents indicate the tweeter and possibly also this driver would create a buzzing (high frequency noise) if the woofer was suffering a short. If you have an ohm meter handy, it'd be worth measuring both these drivers and seeing what you get.
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