Strange noise from midrange

[ThatSoundsGood]

Bracing probably not, but as I already said, build is very solid and really far from vibrating like a cardboard box - you barely feel vibrations when touching the box even if blasting really bass heavy metal music. Plus as OP said, the issue is present even with midrange driver pulled from the box, prejudices aside, please. Crossover is purely electronic, DSP based. An amateurish try (not mine) to capture drivers in nearfield see below.

This is all very odd. The measurements don't look bad at all. It seems as though the mid-range has a pretty steep high pass filter to protect it. I'm stumped here.

 

[malone-m]

@ozzy9832001 You probably also did pink noise tests, right? By the way, just for info, the two RCA inputs have different input sensitivities - there is a 200 mV difference between them. This was confirmed by the manufacturer's support.

 

[ozzy9832001]

@ozzy9832001 You probably also did pink noise tests, right? By the way, just for info, the two RCA inputs have different input sensitivities - there is a 200 mV difference between them. This was confirmed by the manufacturer's support.

Yeah. I tested with both RCA connections. Though, to be honest, I know nothing about power, at all, so I don't know which is actually the better of the two to use. I'm assuming RCA 1 which I believe is the higher of the 2 voltages. One is like 700mV and the other 500mV I believe.

So, I did something I typically don't do because it drives the animals in my house nuts, but they were out with the wife and the house was super quiet. I ran a 4MB FFT, instead of my standard 512. It's weird, because it's the first time any graph has shown any ringing and it's in the problematic zone.

Both of these tests were taken one after the other and it shows this weird decay around 350hz. It's odd because there 0 decay on it, like something is making the noise, but there is literally nothing running. My computer is a 0 noise and no other fans, hvac or appliances near me.

Just very bizarre. There are 4 windows in the room and I'm wondering if they are resonating. But they are only 2'Wx4' high, so the math doesn't really work out for that problem frequency unless it's the glass itself or maybe the baseboard plumbing.

Or is this just some artifact of the longer test?

Very odd.

 

[dasdoing]

Yeah. I tested with both RCA connections. Though, to be honest, I know nothing about power, at all, so I don't know which is actually the better of the two to use. I'm assuming RCA 1 which I believe is the higher of the 2 voltages. One is like 700mV and the other 500mV I believe.

View attachment 378847
So, I did something I typically don't do because it drives the animals in my house nuts, but they were out with the wife and the house was super quiet. I ran a 4MB FFT, instead of my standard 512. It's weird, because it's the first time any graph has shown any ringing and it's in the problematic zone.

View attachment 378848
Both of these tests were taken one after the other and it shows this weird decay around 350hz. It's odd because there 0 decay on it, like something is making the noise, but there is literally nothing running. My computer is a 0 noise and no other fans, hvac or appliances near me.

View attachment 378850
Just very bizarre. There are 4 windows in the room and I'm wondering if they are resonating. But they are only 2'Wx4' high, so the math doesn't really work out for that problem frequency unless it's the glass itself or maybe the baseboard plumbing.

Or is this just some artifact of the longer test?

Very odd.

in the generator play that 380-ish frequency as a sine wave. while it is playing touch surfaces that could be vibrating. once you find the offending surface you will know right away

 

[raindance]

Maybe I missed this, but does the volume you are listening at affect it? I am thinking it is internal limiting in the speaker.

 

[ozzy9832001]

Maybe I missed this, but does the volume you are listening at affect it? I am thinking it is internal limiting in the speaker.

It plays about 10dB higher than whatever is playing.

 

[Avp1]

Hi all,

Having a strange issue with my Edifier 2850DBs. For the most part, I love the speakers, but after my latest round of room treatments one issue really, really stands out.

There is an awful sound that emits from the midrange on certain songs. The issue seems to center around 250hz, but extends down to about 175hz and up to about 350hz. Regardless of volume the noise is there and it's typically the same volume. It sounds like a chair being drug across a floor. It always happens during some songs. I think the issue was always there but I thought it would be correctly when I treated the room. Turns out its definitely something with the speakers, but maybe someone can give me a clue what I'm experiencing.

What I've tried:

1. I removed the midrange from the speaker cabinet and held it in my hand and played offending song(s) -- issue still present. Slightly reduced and not quite as offensive.
2. Inspected driver. Nothing seems out of place or damaged -- looking at the surround and cone under a microscope doesn't seem to show any mini holes are malformations.
3. Plugged port.
4. Moved speaker outside where the only boundary was the ground for 100ft.
5. Reversed speakers and the right speaker also does it.
6. Lowered gain on MINIDSP and increased speakers and vise versa (increasing speaker volume does make it more offensive, but increasing gain on MINIDSP does not).
7. Changed power cable (worth a shot)

Investigating frequency range:

• If I use my minidsp and cross over at 400hz, 24db/butterworth, the issue goes away completely. Obviously I've gutted the frequency range, so that make sense.
• Placing a notch filter in PEACE at 250hz, quality 2, the issue goes away, but again the response is gutted.
• Placing a peak filter in MINIDSP @ 250hz, -8, 2.5Q softens it significantly.
• The odd thing is that if I do a sweep nothing shows out of the ordinary. Everything is very, very tight and the only EQ filters I use are the peak @ 250 and a few shelf filters.
• The weirdest part is it's like the 250hz region is out of whack, like it's louder than it should be but it doesn't show on any sweep or test tone. Lowering it by 8dB actually seems to put it "in line", perceived loudness with everything else.

The only way I can seem to get it to go away is with extremely specific positioning.

If I stand up and walk about 8' away from the speakers and stand off axis opposite the speaker it seems to dissipate. So this would be the equivalent of having the left speaker on the right side of me, 8' toed away from me.

I contacted Edifier but I'm SOL since it's been more than a year since I purchased them.

Any ideas?

I would say that drivers are defective. Since your speakers are out of warranty, you will likely have to buy new drivers. It is very much can be a defective batch which was used by manufacturer. Considering low price, manufacturer unlikely does QC of purchased parts or complete speaker after final assembly.

 

[KrayzIvan]

I believe the voice coil is mis aligned. I've had the same issue. Depending how severe it is you can lightly touch or push on the cone and feel the scratching. I tried turning the speaking hoping gravity might solve the issue but finally just got a new midrange.

 

[ozzy9832001]

After countless tests, I really think the issue on this set of speakers is the amp. I think for some reason the signal from about 200hz to roughly 400hz is being overdriven. If I eq that entire band down on the output side of the DSP the problem goes away and the entire system seems to open up.

When I have time I may remove the amp just to see if there is anything I can spot as being out of sorts.

I am convinced this is a problem they tried to fix with the 2800DBs, and while they corrected the FR, they ended up boosting it too much.

It's an issue that's difficult to describe because it's not like the midrange isn't playing. The frequencies it's responsible for sound fine, except for this noise or whatever.

 

[Avp1]

After countless tests, I really think the issue on this set of speakers is the amp. I think for some reason the signal from about 200hz to roughly 400hz is being overdriven. If I eq that entire band down on the output side of the DSP the problem goes away and the entire system seems to open up.

When I have time I may remove the amp just to see if there is anything I can spot as being out of sorts.

I am convinced this is a problem they tried to fix with the 2800DBs, and while they corrected the FR, they ended up boosting it too much.

It's an issue that's difficult to describe because it's not like the midrange isn't playing. The frequencies it's responsible for sound fine, except for this noise or whatever.

I cannot imagine what kind if failure in amplifier can cause this.

 

[dasdoing]

have you missed my post?
pretty sure it is a vibrating surface

in the generator play that 380-ish frequency as a sine wave. while it is playing touch surfaces that could be vibrating. once you find the offending surface you will know right away

 

[ozzy9832001]

have you missed my post?
pretty sure it is a vibrating surface

The only thing that could be vibrating is the box itself. It happens when I move them out of the room, off the stands, on the floor or heck, even if I remove the midrange and hold it in my hand. At the end of the day, I'm going to chalk it up as it's just a limitation of the speakers. Not a huge deal, considering their price, still a good set of speakers.

 

[malone-m]

@ozzy9832001 One more question - if you feed any of the digital inputs (including bluetooth) with full level 0 dBFS signal and lower ONLY the internal amp output volume (on the speakers) to moderate/low level, is this "distortion" sound still present?

 

[ozzy9832001]

@ozzy9832001 One more question - if you feed any of the digital inputs (including bluetooth) with full level 0 dBFS signal and lower ONLY the internal amp output volume (on the speakers) to moderate/low level, is this "distortion" sound still present?

It's slightly less annoying when the speakers are turned down. I may pull the midrange again and test a multimeter to see how much power it's getting. It really does sound like an overdriven signal to me. Not sure why it would only affect that frequency range, but it does, unless the crossover is borked and it's not summing properly. It's also possible that the built in tone controls aren't working properly. Though the "bass" control doesn't go into that region, I believe it cuts off at 150hz.

It's slightly less annoying off axis...and in general, I actually prefer the tonal balance better when the speakers are pointed straight ahead rather than toed in. Seems to be a hump around 1khz with them toed in.

I actually thought to myself yesterday that maybe these speakers were really designed for distance listening, but the sound is present even at 8 feet away, so that's not it. They are advertised as nearfield speakers, but who really knows what they meant by that when they designed them.

For now, I'll just use EQ to solve the problem. It's a shame though, because the speakers really are impressive for the price, add in the Jamo 912C and the system is super solid.

 

[malone-m]

The reason why I'm asking is that I'm using them in exactly this way (I cannot push them too loud because of neighbors ), and I'm listening rock/metal too. My bet is rather some kind of defect than just "a feature", because I do not hear any strangeness coming out of the speakers in my case. Maybe capacitors damaged by temperature or PSU.

 

[ozzy9832001]

The reason why I'm asking is that I'm using them in exactly this way (I cannot push them too loud because of neighbors ), and I'm listening rock/metal too. My bet is rather some kind of defect than just "a feature", because I do not hear any strangeness coming out of the speakers in my case. Maybe capacitors damaged by temperature or PSU.

It's certainly possible. I've been messing around with them today, and I did find that I like it when my ears are between the woofer and midrange. Seems to open them up a bit more. They are a bit bright by default and seem to have fairly wide dispersion. I also found I like them pointing straight ahead rather than toe'd in. Gives a very nice soundstage. Much more 3D. Vocals from center but instruments seem to come from all around.

The other thing is no EQ really needed except for 3 filters on the subs. The minidsp allows me to control the subwoofers and speaker separately and I can just lower the speaker volume to get the best bass ratio at whatever volume I'm listening at, which is only about 75dB max. I listen in the nearfield, about 36" away.

 

[ThatSoundsGood]

have you missed my post?
pretty sure it is a vibrating surface

I still think you have a resonant box. Are you sure the resonance is not coming from the low woofer making the entire box resonate? try taking out the low woofer and unplugging it to see if the problem goes away.

 

[kemmler3D]

Could be a resonant box but the peak in the waterfall chart looks too narrow for that IMO.

I wonder if something went wrong with the tone controls and it ends up self-oscillating somehow.

 

[malone-m]

They are a bit bright by default and seem to have fairly wide dispersion. I also found I like them pointing straight ahead rather than toe'd in. Gives a very nice soundstage. Much more 3D. Vocals from center but instruments seem to come from all around.

What I noticed is that the grille frame reflects some amount of the tweeter radiation at an approx. 45° angle to the sides. Maybe it's on purpose. I asked Edifier if these speakers are tuned with or without grille and they replied that it's recommended to leave grille on, especially for protection...

 

[ozzy9832001]

What I noticed is that the grille frame reflects some amount of the tweeter radiation at an approx. 45° angle to the sides. Maybe it's on purpose. I asked Edifier if these speakers are tuned with or without grille and they replied that it's recommended to leave grille on, especially for protection...

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.