Minidsp 2x4 hum (FWIW)

[RDoc]

I'm using a Minidsp 2x4 (not HD) as part of my patio system and have long been annoyed by hum which I traced to the Minidsp. It was only audible when a couple of feet from the speakers and not an issue at all when music was playing, but it annoyed me, so I chased it a bit. Purely by accident I noticed some popping when I moved the unit and eventually isolated that to the power connector which was flexing.
I switched from the "official" barrel type power connector to the USB port normally used for programming, but which also can supply power, and the hum dropped to near inaudible!
Bottom line is that if you're getting an annoying hum, try switching to the USB port for power. It's the old USB B mini connector type and I just used an old USB power block I had lying around.

 

[suttondesign]

that is a great tip. i have had issues with the minidsp units and hum over the years.

 

[Bergarth]

Wait what- you used the USB port you would connect to PC for tuning to power it? I thought that was for "programming" only.

 

[Deleted member 4708]

MiniDSP - company making products so bad you feel lucky to get "near inaudible hum". Wait until you need service from them. You will study Kafka. Sold my SHD and will never buy anything from miniDSP

 

[RDoc]

I've had very good experiences with miniDSP, but YYMV.
Hum seems to be a general issue with DSP products within a reasonable price range.

 

[sejarzo]

I had a DDRC-24 that was extremely susceptible to hum from the new LED light dimmers I recently had to install. No other components connected to the same circuits (several DAC and power amp or AVR combinations) suffered the same problem. There was always some level of hum, but it varied depending on the point at which I set the sliders for the two sets of in-ceiling lights in the room. I noted that in a private thread with another member who said he noted the same problem and tried different wall warts until he found one that didn't cause the problem. Each set of lights has its own breaker, while the receptacles powering the audio gear are on another. Depending on a wall wart to reject interference in your product doesn't seem like proper engineering to me.

 

[hwest]

I'm using a Minidsp 2x4 (not HD) as part of my patio system and have long been annoyed by hum which I traced to the Minidsp. It was only audible when a couple of feet from the speakers and not an issue at all when music was playing, but it annoyed me, so I chased it a bit. Purely by accident I noticed some popping when I moved the unit and eventually isolated that to the power connector which was flexing.
I switched from the "official" barrel type power connector to the USB port normally used for programming, but which also can supply power, and the hum dropped to near inaudible!
Bottom line is that if you're getting an annoying hum, try switching to the USB port for power. It's the old USB B mini connector type and I just used an old USB power block I had lying around.

This was a concern for me as I'm thinking about adding a 2x4 MiniDsp to my setup and wondering what that will do to my Total distortion levels.

 

[sejarzo]

I remain confused as to why this works. The maximum voltage that a USB B mini cable should supply is 5VDC, but the wall wart and the connector on the 2x4HD show that it should be supplied with 12VDC.

 

[SuicideSquid]

I remain confused as to why this works. The maximum voltage that a USB B mini cable should supply is 5VDC, but the wall wart and the connector on the 2x4HD show that it should be supplied with 12VDC.

Perhaps it's running natively at 5V and stepping down the voltage of the DC input.

 

[sejarzo]

Perhaps it's running natively at 5V and stepping down the voltage of the DC input.

Then I wonder why they opted to use 12VDC as the standard supply. I'm not an EE but I believe that regulators typically entail a 2VDC or so drop. Feeding it with 12VDC would simply waste more than half the input wattage as heat.

 

[Hov]

Perhaps it's running natively at 5V and stepping down the voltage of the DC input.

This seems likely for sure.

Great to know and thanks for sharing, I'm considering a MiniDSP (HD) 2x4 for my subwoofers and will definitely note this.

 

[sejarzo]

The spec for the output is 2Vrms max. 2.0Vrms would require a minimum of 5.66 VDC peak-to-peak.

If the unit is powered by 5VDC, it cannot generate a 2.0 Vrms max output at 0 dBFS input. I don't know if that creates compression on peaks or if it impacts the entire waveform equally.

 

[SuicideSquid]

The spec for the output is 2Vrms max. 2.0Vrms would require a minimum of 5.66 VDC peak-to-peak.

If the unit is powered by 5VDC, it cannot generate a 2.0 Vrms max output at 0 dBFS input. I don't know if that creates compression on peaks or if it impacts the entire waveform equally.

I wonder if it's just reducing the output level on USB power and that's reducing the hum.

 

[jaudio]

Unfortunately powering via USB is not possible with the HD version of the 2x4:

miniDSP 2x4 HD powered through USB?

Any way of powering the miniDSP 2x4 HD through USB like the 2x4? Trying to cut down on the number of outlets required in my setup.

www.minidsp.com

 

[sejarzo]

Unfortunately powering via USB is not possible with the HD version of the 2x4:

miniDSP 2x4 HD powered through USB?

Any way of powering the miniDSP 2x4 HD through USB like the 2x4? Trying to cut down on the number of outlets required in my setup.

www.minidsp.com

Thanks for that. When I read @hwest reply about adding one, I immediately thought of the HD as the original is no longer available new.

 

[hwest]

I've had very good experiences with miniDSP, but YYMV.
Hum seems to be a general issue with DSP products within a reasonable price range.

Well is there another product that can be used to level out multiple subs that's of better quality?

 

[RDoc]

There is this one: https://www.audiosciencereview.com/...ds/thomann-t-racks-dsp-4x4-mini-review.33306/
From the review it sounds pretty good for the price. I've no personal experience with it though.

 

[hwest]

There is this one: https://www.audiosciencereview.com/...ds/thomann-t-racks-dsp-4x4-mini-review.33306/
From the review it sounds pretty good for the price. I've no personal experience with it though.

I don't see that Thomann is supported in REW, that's an issue. I may have to stick with the MinisDSP 2x4 and take my chances.