So i'll try to make this concise, but the detail will stretch this out a bit.
After working up to the tests on the Audyssey this week, I was going to do some with and without critical listening. Just happened to be on the main floor and played some music we hadn't heard in awhile which i thought I would like to hear in the media room for the Audyssey test.
Then what do i hear?
Some kind of distortion from the big Tannoys, right channel, bottom driver. Let's say it sounded like a reverberating buzzing with the polypropylene cone and not like the sound of a wire vibrating against a part.
I did take some video/audio of the sound.
Tannoy Speaker driver 1aTannoy Speaker driver 1bPick out which has the distortion sound.
For reference in the upcoming text, the song played was: La Goutte D'Or by St. Germain (it has a constant bass beat, starts after the first minute of the song, which runs the remainder of the song so very easy to replicate this distortion noise)
https://www.youtube.com/watch?v=QxCI05Vz4LUWhen i refer to a second test song, that one was from my standard test list: Calcium by Future Sound of London (same thing, it has a strong bass beat which makes it easy to reproduce the distortion sound)
https://www.youtube.com/watch?v=a4iyPMWOZkYHere's where i'm going to detail the list of things i did after:
- check the counterpart/left channel speaker for the same sound to eliminate song as source--> nothing, bass playback was fine, smooth
- swap the speaker cables to see if the sound followed the source channel to eliminate left vs. right from source song, or source equipment--> it did not, the sound remained with the suspect speaker driver
- listened to the song on another system, speaker set (Axioms) to further eliminate song as source or equipment--> the distortion was not reproduced, bass sounded fine on the Axioms
- gently pushed the suspect Tannoy driver down and back to see if i could hear any scraping--> nothing evident that the cone is rubbing against anything or that the voice coil sounds crackly
- pulled the Tannoy driver, checked ohms--> read 5.4 and the speakers are rated as 6ohm so all seems ok with the voice coil from that perspective
- swapped the suspect driver with the 'good' driver in the other speaker (to eliminate crossover as any problem)--> no change, the sound remained with the suspect driver
After all this, what is there to conclude except something is going on with this driver? Though it doesn't seem like the obvious things; no clear rubbing of the cone against anything, voice coil has electrical integrity, no apparent rips or tears on the inside, source sound/music and x-over eliminated as faults.
I have a local friend who is a long time stereophile that hopefully can help to figure this out, but in the meantime i decided to bring my old vintage Mission 737 speakers to the main floor to use as a replacement for now.
Here's where things get ridiculous.
I hook up the Missions to the gear that the Tannoys were hooked up to, play the song and the Missions produce a nearly identical/similar buzzy sound and only from one driver (coincidentally it also was on the right channel at the time).
I mean WTF??
I started to second guess myself that the issue had nothing to do with the Tannoys, but then what about the results of the other tests; how do they explain this?
So, i did some of the same tests on the Mission speakers as i did with the Tannoys.
- check the left channel Mission speaker for the same sound--> nothing, bass was playing fine, distortion still only in the right speaker driver
- swapped the speaker cables to see if the sound followed the source channel--> it did not, the sound remained with the suspect speaker (coincidentally same result i got with the Tannoys)
- instead of listening to the song on another system since i already did that with the Axioms, i brought the Missions from the main floor to the media room to play the song down there instead on all different equipment of course (cables, amp...the only thing that was the same was playing the song through Sonos but since the Axioms never played back the sound, and all other test results included, there is NO way it has anything to do with the source material)--> the distortion was reproduced on the suspect Mission speaker driver in the media room system as well
- gently pushed the suspect Mission driver down and back to see if i could hear any scraping--> nothing
- to eliminate the possibility that the Axiom speakers don't play back this sound the same way as the other two brands, i hooked up the new office Monitor Audio Golds to the media room system and played the song. No hint of distortion from either bass driver, same result as for the Axioms. I will mention again here that only ONE driver from each of the Tannoys or Mission speakers had this distortion sound while their counterpart driver in the second speaker did not.
- to further eliminate the song as somehow being the problem, i used my second test song for testing bass--> same result with the Mission speakers suspect driver (by this point i had unhooked the Tannoys so i never tested the 2nd song theory with them but again, with all other tests run, i don't think there is evidence to point to the source song as the problem).
From all that, looking for thoughts.
The only conclusion i have come to is that i have a problem with two woofer drivers; one on the Tannoys, one on the Missions.
Does this make sense?
There may be other things to test, but we're starting to get beyond my knowledge level of what else to look for and why let alone anything i can fix (loose wires, dust cone that isn't fully attached, sure, but broken voice coil or cone misalignment, not so much). I can add that we did find a small red truck inside the suspect driver's tower which apparently my daughter shoved in there probably 10 years ago, but even removing that didn't change anything. It was buried in the batting at the bottom anyway. Is it possible when that truck got pushed in though that it hit and damaged something in the driver that went undetected for all this time?
