Minidsp with high efficiency speakers; noise? - Page 2 - diyAudio
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miniDSP Low cost, modular Digital Signal Processor (DSP) kits for the DIYer from miniDSP.

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Old 14th June 2012, 09:04 AM   #11
diyAudio Member
Join Date: Nov 2002
Location: The Netherlands
Originally Posted by minidsp View Post
@ Leeuwarden,

One thing to remember is that the miniDSP balanced is twice the amount of output than the miniDSP unbalanced so you'd have to pay attention at your gain structure vs a miniDSP unbalanced. With this said, we're not aware of issues with the design..

Quick question: How is your amp/DSP setup when it comes to volume control for the outputs? (e.g. is attenuation done at the amplifier,i.e. using the volume control) or at the DSP using the digital attenuation).

Hi DevTeam,

My audio setup is as follows:

MacMini with M2Tech Hiface USB/SPDIF converter.
Relaixed II balanced pre-amp (with relay-attenuator)
UCD400AD balanced power-amps
My speakers: floorstander with Dynaudio D260 and Alcone AC8HE.

I use the volume-control on the pre-amp.

At the moment I use my speakers with passive filters so al the tests I do at this moment are with a passive filter in the chain.

Let me start by saying the noise/hiss is very low but it's there.

So what did I do:

I already tested the sensitivity jumpers same time ago with no effect. I switched pre amp in the mean time so I tested again without result.

I tested with all equipment turned on: there is noise.
I disconnected the pre-amp and turned on the MiniDSP Balanced and the power-amp: there is noise.

When I use my set-up totally passive there is no noise at all which leads me to the conclusion that somewhere in my balanced MiniDSP (I actually have two MiniDSP's and both do the same) something goes wrong.

So how does my MiniDSP look like:

Click the image to open in full size.
MiniDSP inside by jvdwal2008, on Flickr

The turn on/off protection with it's own powersupply is on top of the MiniDSP.
I tested the MiniDSP board also without the protection board: there was noise.

Power supply for the MiniDSP is in front of the MiniDSP.

Did I overlook something?

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Old 14th June 2012, 09:15 AM   #12
diyAudio Member
Join Date: Oct 2007
Location: melbourne
the noise is coming from the minidsp

i inserted mine into a setup ive had for years and know well

before the mini dsp it was dead silent
once the mini dsp is inserted it makes the dreaded hissing noise

you will have to either live with the noise or use it for bass only like i am

cheers sheafer
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Old 14th June 2012, 09:35 AM   #13
diyAudio Member
Join Date: Aug 2010
When dealing with such DSP boards like miniDSP (and others like GroundSound,...) with AD/DSP/DA one should really take great care of a proper gain structure. Attenuation should be done after the DSP (analog or digital) and input signal should ideally be close to FS (no attenuation before DSP).
A friend of mine uses groundsound modules with high efficiency speakers (>100dB) and uses 20dB attenuation (resistive network) at the output of the DSP to optimize the gain structure. With miniDSP he also has some hiss without this attenuation (no big difference between those DSPs with respect to noise/hiss).
In my implementation with digital input and digital attenuation noise is not an issue.
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Old 14th June 2012, 12:05 PM   #14
beeah is offline beeah  United States
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Join Date: Feb 2006
Location: Upstate NY
Keep in mind that you can switch from Rev A to Rev B (.9V vs. 2V input level) depending on whether you control volume upstream or downstream from the DSP.
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Old 17th June 2012, 09:57 AM   #15
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Join Date: Nov 2002
Location: The Netherlands
Pretty quiet over here .

Perhaps nome interesting info in this google-translated topic, it's only 4 pages:

Google Vertalen

Like to know DevTeams reaction on this topic.
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Old 17th June 2012, 10:30 AM   #16
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nome = some
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Old 17th June 2012, 08:16 PM   #17
sannax is offline sannax  Norway
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Very interesting all of this.
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Old 17th June 2012, 08:29 PM   #18
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Old 17th June 2012, 08:38 PM   #19
sjalloq is offline sjalloq  United Kingdom
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Just randomly saw this thread from the front page. I've just got a 2x4 up and running in an active config with Visaton B200's at 96dB and the noise is pretty bad. I get a loud hiss that I can hear over the music. I was hoping that this was due to the fact that I hadn't boxed the board yet but perhaps it's more fundamental.

I'm running a passive pre into the 2V input and MiniSDP driving my amps directly. The B200's are driven by a Linn LK85 which I've had no issues with before.
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Old 17th June 2012, 08:43 PM   #20
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Are you using a balanced MiniDSP?
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