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MiniDSP 2x4HD noise 5 years 5 days ago #28236

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I have received the new MiniDSP 2x4HD a few days ago. My speakers are 2 way bi-amplified with no passive crossovers, that is why I needed the 2x4HD ... after all connections are done and music paused, I have noticed the noise coming from both drivers: a hisss coming from the mid/high driver and a hummm coming from the bass driver. The noise is annoying, can be heard from far distance and is not acceptable by any music lover, in my opinion.

The hummm noise dissapears if I remove the USB connection with the PC , but the hisss continues. Even if I remove the power source (and the USB connection removed) from MiniDSP 2x4HD, still a noise persist in mid/high drivers!? Of course that I have checked and triple checked the source pre-amp, the cables, the power amp ... all the noises are from MiniDSP 2x4HD.

I have checked my AV Receiver pre-outs directly with the power amp and of course is dead quiet, also checked the RCA-RCA cables, are good sturdy quality cables. Could be a miss-match between AV receiver pre-out - minidsp 2x4hd - power amp?

What can be done with those noises? The hummm noise from USB might be due to my PC (even if my other devices connected on this USB does not "complain" about it) but the hisss noise is not anymore from my PC and what really amazed me is that this noise persist even if I power off the MiniDSP 2x4HD

The system is:
PC diy mediaplayer
AV Receiver Yamaha Aventage RX-A2040
MiniDSP 2x4HD
Anthem PVA-4
DIY 2 way OB bi-amped (bass Eminence Beta 15A and mid/high SICA 6D1CS) no passive crossovers ...

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MiniDSP 2x4HD noise 5 years 2 days ago #28280

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@ Biscu

Let's start step by step
a) Your HUM is a so called ground loop. Make sure that your PC + audio system is on the system ground. That's the issue here.
b) Please share your configuration file loaded inside the system. It will help investigate
c) Also note that in most cases, the noise issues are down to gain structure issues. www.minidsp.com/applications/dsp-basics/gain-structure-101 Can you please clarify the levels you're seeing on in/out RMS meters when you're live and connected?
Thanks.

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MiniDSP 2x4HD noise 5 years 2 days ago #28292

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Yes, the hummm noise was solved by moving from my desktop USB to my laptop USB.

Regarding the hisss noise, a bad story just follows. I have opened the minidsp 2x4hd case and removed the circuit so I can see it.

Surprise! As you can see in attached picture my minidsp was repaired, meaning re-soldered as you can see on one lateral of the XMOS chip. I cleaned well with a small tooth brush those pins as it was some dirt remained from re-solder operation! it was not even cleaned after solder!
And the hisss noise already is reduced a lot. I can still hear it but now is not annoying and almost can't be heard from 3 meters distance from the speakers. Maybe If I will clean better also with some solution I will manage to reduce the hisss even more ...

But, I have paid you for a brand new product and I have received a repaired/serviced product !!! probably was a returned one ... not to mention the quality of the re-solder operation, I think can do it better and cleaner in my house! amateur repair!?

That is the way you do sales? Selling repaired units as new ones?

End of story ... :(
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MiniDSP 2x4HD noise 5 years 2 days ago #28293

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@ Biscu

This is very peculiar and indeed odd. For a general statement, we don't sell "used" units at all (see how we don't have a return policy). All our units are brand new. On an assembly line, it's very possible there is a rework done with "no clean flux" which might leave a smudge (i.e. it's no clean.. ;-) , however our EMS is very careful..

With this said, following few exchange with the engineering and manufacturing team, nobody has ever seen this before so we'd certainly love to investigate what we're looking at here! (e.g. SN#, AP results from the line) Knowing it's a boxed product, something tell me we need more info.

anyway, by no means trying to justify "anything" here. We're as quizzed as you are. :-)
Please start a tech support ticket with our team. (support.minidsp.com) and let's solve this issue together. Sounds good?

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MiniDSP 2x4HD noise 1 month 3 weeks ago #56796

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Bonjour, J’ai également acquis récemment un minidsp 2x4 hd et j’entends un bruit haute fréquence sur la sortie tweeter. Pour le minimiser j’ai du diminuer le signal sortie tweeter de 10 dB et celle de mon ampli intégré de 10dB également, et donc la sortie woofer de 20dB.
J’ai essayé pas mal de solutions
potentielles sans amélioration : 1. j’ai changé les cables RCA (ce sont des HICON
ambience series initialement, j’ai essayé des bas de gamme et haut de gamme sans changement) 2. j’ai alimenté le dsp sur batterie sans changement
Auriez vous un conseil ou une solution à me proposer ?
Merci pour ce forum
ps : à part ce défaut le mini dsp est parfait pour un filtrage 2 voies

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MiniDSP 2x4HD noise 1 month 5 days ago #56987

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In case it helps anyone: I also was struggling with this. Specifically, I would get audible noise, but it was inconsistent (not always present). This drove me crazy for months. 

In my case, the audible buzz occurs only / primarily when I've connected the plugin to the minidsp 2x4hd...and I can her the noise audibly change when loading configs / fir filters etc. 

The only good news in this case, is that not staying connected to the dsp largely eliminates the issue

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