Strange noise from midrange

[kemmler3D]

So, I sort of fixed the issue and it was by dumb luck that I stumbled across this.

Somehow I had switched the outputs on my MINIDSP to play both L/R in both speakers. In essence, it was playing dual mono. It completely fixed the issue. That makes me think there is some weird cancellation that is happening. Literally, the system sounds 100x better. I, obviously lose stereo effects, but half the time I can't tell if they are by design or because of room issues that it's panning one way or the other. Now everything is in the middle where it belongs and the transients are crazy. The sacrifice is well worth it to me.

Taking summed measurements, even though dual mono is 6dB higher, the waterfall is significantly better and there are some difference (for the better) in the frequency response, especially from about 150hz to about 500hz.

So you're saying you accidentally started playing dual summed mono and 1) this fixed the weird resonance and 2) you prefer it to normal stereo?

If so, this just gets weirder and weirder...

 

[ozzy9832001]

So you're saying you accidentally started playing dual summed mono and 1) this fixed the weird resonance and 2) you prefer it to normal stereo?

If so, this just gets weirder and weirder...

Yeah. That's what I'm saying.

And yes, it just gets weirder and weirder. Obviously, there is something wrong with the speakers.

 

[kemmler3D]

Yeah. That's what I'm saying.

And yes, it just gets weirder and weirder. Obviously, there is something wrong with the speakers.

I think we are getting somewhere. Something is definitely wrong with the amp. I didn't realize there is only one amp for two speakers.

I'm out of my depth here, but it seems like having to drive two different signals is causing some kind of oscillation or interference or something with the amp.

I would probably send a summary of this thread to Edifier and ask for a replacement.

 

[ozzy9832001]

I think we are getting somewhere. Something is definitely wrong with the amp. I didn't realize there is only one amp for two speakers.

I'm out of my depth here, but it seems like having to drive two different signals is causing some kind of oscillation or interference or something with the amp.

I would probably send a summary of this thread to Edifier and ask for a replacement.

Filled out a support ticket and all for them this morning when I had that moment of clarity.

It's a shame too because they sound amazing when playing dual mono. It's ridiculous how good they sound. If they'd sound like that in Stereo, I'd say Edifier should charge more for them. Maybe they got knocked around in shipping or I just got a bad pair, but it's really frustrating.

 

[ozzy9832001]

Figured I'd give a quick update -- I got a response from Edifier and it was a bit disappointing, but I guess it was to be expected.

To summarize, they basically said that the speakers are 3 weeks out of warranty that unfortunately there isn't much they can do to fix them and the cost of repair + shipping probably wouldn't be worth it for a COD repair. So, I'll see what I can do with them on my own.

I did have time today to really delve into the left speaker, which is the "passive" one.

I removed the midrange and noticed there was a ton of damping behind it. Forgive my lack of technical terms, it's the while felty like stuff, I'm guessing poly fill or something similar. It was really crammed in there. Went all the way back to the end of the "chamber" (dunno what the technical term is for it). Removing it didn't really seem to make a difference one way or the other, so I replaced it with rockwool. That actually did make a difference both in the frequency response and a few of the stubborn resonances that were lingering.

Figured I'd do the same with the woofer. There were 3 pieces of polly on the 2 sides and 1 on the bottom. Removed and replaced with rockwool.

Not a huge difference measurement wise, little bit around 200hz but it sounds much cleaner from that low mid range area and I didn't seem to lose any aptitude. Less boxy sound overall.

Lastly, I plugged the port with some rockwool and it actually removed a hump I had from 50-60hz. I'm assuming it's tuning is somewhere in that range.

Unfortunately, it's a pain because the drivers are soldered onto the posts on the speakers so I can't actually remove them. My hands aren't stable enough these days to handle a soldering iron.

Tomorrow I'll work on the active unit and make the same same modifications and then take a look at the circuitry and see if there is anything that looks off. If I can get it out of the cabinet then I'll see about snapping some pictures.