Friday, August 21, 2015

MiniDSP 2x4 (Analog to Analog) Crossover Implementation

An unbiased user review..... 

I purchased 2 x miniDSP 2x4 balanced DSP's...and a 4way advanced crossover plugin....  to simplify crossover design and implementation for my active speaker build.

minidsp review - grizzlyaudio - DSP

So why did I select the balanced miniDSP processors, over the unbalanced units? Well, I needed a digital crossover which had enough I/O signal voltage to adequately drive a mix of both residential & pro amplifiers.

MiniDSP 2x4 balanced fit the bill nicely, with its ability to accept & output up to +2v signals, a must when connecting the units to pro equipment, such as amplifiers, DAC equipment, which have much higher signal voltage swing capabilities V's HiFi equivalents. 

Early in the piece miniDSP felt like a solid decision, especially considering that throughout my pre-purchase research, it was evident there was alot of user/forum support detailing success with miniDSP units. Many of these users reported there was no audible difference with miniDSP in the chain. Ultimately, this was not my experience with the product. 

What proves frustrating is miniDSP has positioned itself as the DIY "audiophile" DSP solution. A product range which provides excellent transparency and an "uncanny" ability to slip right into your signal chain without any degradation to sound quality, modifications to your system, or introduction of hard to solve idle hiss and/or gain issues. I won't harp on here except to say tread carefully.... 

Don't necessarily believe everything you read. Yes the product has many excellent positives, like price point, convenience, accessibility and forum user support.... however.... yes I did find a but! (especially in my application) it became clear miniDSP also has some considerable shortcomings which may impact its suitability for many HiFi applications. So its worth treading with some caution.

I learnt first hand that miniDSP balanced was not suitable for my HiFi crossover setup. When I dug a little deeper with my online research. I found many users experiencing and struggling with similar application suitability and product issues. 

Before you click on that "BUY NOW" button take the time to google miniDSP hiss, miniDSP sound quality, miniDSP gain issues and you will find real miniDSP adopters struggling with their miniDSP Hifi & 5.1 applications. 

So with the much acclaimed miniDSP units tried and tested in my system, I give you the following unbiased and honest "abridged" account of my time with miniDSP balanced 2x4 4 way advanced crossover solution.


The miniDSP (Balanced 2x4) has a very noticeable idle noise floor. 

Let me explain.....  I connected the miniDSP 2x4 units between my balanced preamp and various balanced/unbalanced multi-channel amplification stages. I utilised 2 x brand name passive bookshelf speakers (circa 87db efficiency rating) and 2 x high end digital servo controlled subwoofers for testing... both balanced and unbalanced connection tests were conducted - utilising both residential and commercial amplification products. PM me for these details, if you are interested. 

Now if you are like me and run similar pre-amplifier / amplifier equipment and wish to use a single volume control before your miniDSP for attenuation (Your preamp) - you may need to think again. 

Testing various system setups/connections (utilising a pre amp/bypassing preamp), I found DSP idle hiss present on both mid and high frequency speaker drivers. The DSP idle hiss levels were far from acceptable. I have never had high frequency and mid driver system hiss before. I tried several different power supply units, connected at various different wall sockets, however the idle hiss remained constant and present. Power supply changes made no difference to the pitch, loudness or presence of noise. The idle hiss was audible from my seated position some 2.5 meters from my speakers. 

My exclusion tests later confirmed the MiniDSP as the source of the hiss. Why do I say this, because when I tested with no source connected to the miniDSP input.... I.e. miniDSP directly connected to my amplifier (various pro and residential units) signal hiss was unchanged and still present.

These tests clearly prove (at least in my system) miniDSP was the cause/originator of the signal hiss. Removing the miniDSP from the input of both amplifier setups restores dead quite systems. If this is not proof enough that miniDSP balanced is noisy I don't know what is..

minidsp review - grizzlyaudio - DSPIn fact I was so shocked I tried a comparable Extron DMP44LC a commercial grade 4x4 basic DSP which offers a SNR of 100db or greater. This unit demonstrated vastly lower DSP idle noise in comparison to the miniDSP, even when connected utilising the same balanced terminations and leads that just previously connected the miniDSP. Additionally I also experimented with a Symetrix zone mix 760 which also displayed a much reduced DSP idle hiss V's the miniDSP 2x4 in my system. 

minidsp review - grizzlyaudio - DSP

To provide a little background, I tested both 0.9v and 2v input sensitivities with unbalanced and balanced connections. The idle hiss was present with either input sensitivity selection. High end Pro and consumer amplifiers were also tested in the signal chain, which offer varying degrees of input gain (4db-32db). Tests were also conducted with and without a preampliier/source in the system (Direct miniDSP to amplifier connection). 

In all tests the DSP induced idle hiss was present. 

Bypassing the miniDSP (removing it completely from the signal chain) restored my systems fidelity and performance. 

So for me its no secret that miniDSP 2x4 falls short of cutting the mustard as a great sounding DSP/crossover product. In my system miniDSP simply could not perform to acceptable noise free HiFi SNR expectations.

I would argue just because miniDSP 2x4 is convenient (for equalisation/crossover duties), one should not automatically assume it is fit for permanent casual or even critical HiFi crossover applications. The amount of DSP induced signal hiss noise present at idle should be concerning for any potential user looking at analog to analog implementation.  

Look I am a realist so maybe different incarnations of miniDSP do perform to higher quality levels. Or maybe improvements/rationalisation elsewhere in my system could make up for miniDSP 2x4's shortcomings. 

Just beware its never the product that has an issue, its the implementation.  
At the end of my dealings with MiniDSP I managed to get a refund on my boards, but I had to push very hard. However it was easier to resell the units locally, as return freight overseas was an expense I did not want to incur.  

It appears the miniDSP 2x4 applies some gain attenuation between input to output at synergy.  

On a positive note, once ordered the miniDSP units arrived in 5 days!. 
I order them on a Saturday and the miniDSP package was on my doorstep that Friday!! straight from Hong Kong. That's is seriously quick. All items were very well packaged and arrived in pristine condition. 

Previous installation & programming experience with DSP's include:
Clearone, Symetrix, Biamp, Extron, EAW


  1. Sir
    Well constructed and informative....miniDSP seemed too good to be true. love to have a chat about pro-audio and DSP. I have Little Dot CD transport & DAC, Aphex, dBx eq, dBx electronic X-over, 2 ART SLA 1 Studio amps all XLR... -

  2. I am curently using the MiniDSP opendrc di (only digital inputs and outputs) and it works great for me to apply room correction.

    The nano digi 2x8 appears to work great as well if one needs a digital xover.

    It seems that the analogue sections of the Minidsp product are of really low quality.

    If one is willing to apply an all digital solution for xover or room correction and then use a quality dac, MiniDSP appears to work a lot better.