While trying to fix a family members dead sub my Presonus Eris Sub 8 has decided to mimic gale force winds for some reason. I checked everything from trying a different wall socket, removed inputs and outputs, and checked to see if the volume has any effect (it doesn't)
I have read that the cause is likely a leaky DC filter capacitor which would make sense, but I don't have a schematic for this power supply and don't know my way around them well enough yet to know which might be the likely culprit.
I did also notice a few dry solder joints but would they cause the issue?
I have read that the cause is likely a leaky DC filter capacitor which would make sense, but I don't have a schematic for this power supply and don't know my way around them well enough yet to know which might be the likely culprit.
I did also notice a few dry solder joints but would they cause the issue?
Is this noise an acoustic sound through the port, etc, or an electronic sound directly from the driver?
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It is through the driver itself. I did check if it was through the port first in case there was a breeze getting in somewhere and being amplified.
Ports often have wind noises because of the high Mach numbers at resonance, when playing hard.
If it is through the driver itself, try to find out if it is electronic noise or wind noise.
Can you describe the noise character? Rustling of leaves type or hum type?
Jan
If it is through the driver itself, try to find out if it is electronic noise or wind noise.
Can you describe the noise character? Rustling of leaves type or hum type?
Jan
I will add that the sound is variable and not consistent, which is why I checked proximity to my PC and other electrical cables and wall sockets. I legitimately thought it was the wind outside initially until I realised it was still.
No matter what I do with the volume and low pass filter knobs, nor the HPF and 180 phase switches it is constant.
As for the character, it is like wind blowing down a chimney, so a whooshing sound that varies in intensity.
No matter what I do with the volume and low pass filter knobs, nor the HPF and 180 phase switches it is constant.
As for the character, it is like wind blowing down a chimney, so a whooshing sound that varies in intensity.
I can put it back together and do that if preferred, but I found this video with the exact same sound -
I know there is always a noise floor as the satellites for my 5.1 system are amplifying it, but this has only started this past week after a couple of years of having it.
Usual way (if the electrolytics look ok) is to tap around on the pcb with an insulated tool, listening for noise,
looking for sensitive areas and bad connections. Then try spraying parts with circuit cooler if that does not help.
looking for sensitive areas and bad connections. Then try spraying parts with circuit cooler if that does not help.
I will give that a go. It is a studio monitor sub and is unusable for purpose as it is now, so something has definitely changed. I am wondering if the standby is gone, which would normally turn on when it is receiving no audio signal. Before it was totally silent even when turned up loud on the unit and source and has subsonic filtering and RF protection.
It seems a lot more of the signal is getting to the speaker than is supposed to - it isn't just the frequencies selected (ie under 80hz) It is making me wonder if the issue is actually on the other board and is not the power supply at all.
If somehow the gain has shot up, that would also increase the noise, so it could be something like that.
Good thinking.
Is there a volume control on the sub or preamp, does the noise change with the level setting?
Jan
Good thinking.
Is there a volume control on the sub or preamp, does the noise change with the level setting?
Jan
Yeah, there is a volume on the back but it has no effect on the noise. The Low Pass control does have an effect on the audio, but nowhere near as it should be. It is almost like I'm getting a signal bleed so the LPF is acting as though it is in parallel.
I did actually manage to get recordings of both a quiet period and a noisy one on my phone but no idea how to post them here.
I have an ESR meter on the way as it is going to make life a lot more simple seeing as all the caps on the SMPS are glued down and together.
I did actually manage to get recordings of both a quiet period and a noisy one on my phone but no idea how to post them here.
I have an ESR meter on the way as it is going to make life a lot more simple seeing as all the caps on the SMPS are glued down and together.
Yeah, I meant more a case of just 100% ruling it out really.
Will post a picture of the other board to see if there is anything immediately obvious.
I just checked the frequency response and it is acting like a normal speaker instead of filtering and sending the pass-through to the monitors. Something has definitely shorted.
Will post a picture of the other board to see if there is anything immediately obvious.
I just checked the frequency response and it is acting like a normal speaker instead of filtering and sending the pass-through to the monitors. Something has definitely shorted.
Are you sure there's an SMPS? The amp PCB has a bridge rectifier on it... and a typical 3-pin AC in connector for a transformer. I do not see the reason for an SMPS.
The whooshing sound reminds me of a bad capacitor or a failing bridge rectifier. Tricky to find exactly what's causing it... The above suggestions regarding tapping and using a freeze spray stand. I think you'll need to use both, in this case.
The PCB you've shown above looks good, the soldering looks really good.
The whooshing sound reminds me of a bad capacitor or a failing bridge rectifier. Tricky to find exactly what's causing it... The above suggestions regarding tapping and using a freeze spray stand. I think you'll need to use both, in this case.
The PCB you've shown above looks good, the soldering looks really good.
No, the only switches on it are HPF for speak pass-through, and phase. Then just the volume and LPF which seems to be working in parallel with the full signal. It is definitely not just putting through low frequencies but working like a normal speaker.
No, you are right, it is a tranformer into the rectifier. I am working on another sub which does have an SMPS so just typing error on my part.
You are the second person to mention the bridge rectifier so will definitely look at that and ESR meter has arrived today so going to check all caps. Freeze spray is on it's way. Would that also cause the full signal coming through the speaker instead of just the <120hz it should be doing?
There were a few joints with bubbles in the solder and the speaker cone wires were a bit loose, but sorted those out anyway.