Saturday, August 15, 2015

Symetrix ZM760 loudspeaker manager

Symetrix DSP minidsp - grizzlyaudio

Are you looking for an active DSP crossover & equalisation solution for around the $300 dollar mark?  Let me introduce the superseded Symetrix zone mix 760...

Setting the scene 

If your reading this blogpost, you are likely contemplating building a set of active speakers, or in need of a decent sounding loudspeaker manager which doesn't break the bank..... Sure you have seen miniDSP and its implementation as a cost effective loudspeaker DSP while scouring the web, but are you questioning whether miniDSP is the right solution to provide a quality render/playback? I asked myself these very questions..... this quick blogpost is all about saving you sometime and money..... helping steer you in the right DSP direction.
Symetrix DSP minidsp - grizzlyaudioI trialed miniDSP's balanced 2x4 processor for my active DSP crossover duties. To cut a long story short the miniDSP product was unsuccessful in my active application.... The long and the short of it was the miniDSP balanced I/O's were just too noisy to be taken seriously in my HiFi application. Very prominent signal idle hiss was present with its utilisation in my system, ultimately ensuring it was not suitable for my critical active DSP crossover application.

Understanding the end goal for any DSP loudspeaker management implementation is excellent sound quality, ultra low noise and feature rich DSP functionality, I decided it was time I turned to pro level DSP products for a capable solution..... and so I introduce to you Symetrix's superseded zone mix 760 (ZM760), hot from eBay!

Why Symetrix?

Throughout my career in the AV industry I have used many pro level DSP units for front of house PA and conferencing solutions. One brand in particular I have been very impressed with is Symetrix. So I thought instead of mucking around with all-sorts of entry level consumer grade DSP options, to 'hopefully' find something that was 'quiet', DSP rich and had great sound quality. I decide a secondhand Symetrix DSP would be a great place to start for pro grade specs at second hand prices, as a new Symetrix radius or jupiter was just not feasible.
Symetrix DSP minidsp - grizzlyaudio
So off to eBAY I went, eventually managing to track down two superseded Symetrix ZM760's on ebay ranging from $250-300 a unit.... an absolute bargain for any DIY speaker builder.

The Symetrix zone mix 760 is essentially a 12input, 6output closed architecture DSP and loudspeaker manager. The ZM760 doesn't offer the vast open architecture and customisation seen in more expensive pro level DSP units; I.e Symetrix Solus or Radius for example. Instead the ZM760 favours a more basic fixed DSP offering and graphical user interface which provides a good mix of user-ability and functionality.

Symetrix market the ZM760 as "a complete paging and music management solution designed to save you time and money. Built upon proven and reliable technology, it is perfect for restaurants, hospitality, night clubs and more." my application it also appears the ZM760 is an excellent DIY loudspeaker manager with an adequate assortment of DSP tools to accurately tune and time align your DIY speaker setup in their environment. More on the ZM760's DSP features in a bit.

Symetrix DSP minidsp - grizzlyaudio
To diverge quickly, the Symetrix DSP units I purchased both had 'very' noisy power supply units. So I cracked open the cases and inspected the switch mode power supplies for any easy to see issues. It was obvious both main capacitors had prominent bulges, so I replaced the caps with new 450w 47uf units. While I was under the hood, I also replaced the single 50v 47uf cap at position 6 plus the four 35v 220uf caps at positions 1,2,3,4.... with brand new high quality panasonic caps. Once completed, and the power supplies were recalibrated to deliver 23.7vdc, I promptly powered the DSP units and observed, "power supply silence" just what I was after...... we were now ready to make music! ;)
Symetrix DSP minidsp - grizzlyaudio

Operational noise: Symetrix 

I must point out, once I had the ZM760's connected in my system; it took all of 2 seconds to appreciate the signal idle noise of the Symetrix was markedly less than the miniDSP 2x4 balanced processors they had replaced in my system. Infact the ZM760's could be considered 'quiet' with the right high quality electrical stable source. A welcomed outcome, but still not silent mind you.

The ZM760's performance mimicked my positive experience with the Extron DMP44, which I had previously used to benchmark the miniDSP against. The DMP44 performed flawlessly in the DSP idle hiss/noise department (again not silent but very good), which easily shamed the miniDSP 2x4 balanced highlighting its excessive output idle noise.

Symetrix DSP minidsp - grizzlyaudio

Subjectively I believe the ZM760's represent some of the best value & sounding processing I have heard for DIY'ers looking for similar low cost solutions.


Lets quickly review some of the DSP's rich feature list.

Symetrix DSP minidsp - grizzlyaudio


Symetrix DSP minidsp - grizzlyaudio
The unit is loaded with 12 analog inputs
4 balanced mic/line (either balanced/unbalanced)
8 unbalanced (great for native RCA equipment connection)

Each input provides the following functionality 

Signal inversion on mic/line balanced inputs
White noise generator (inputs 1-3)
Pink noise generator (inputs 1-3)
Symetrix DSP minidsp - grizzlyaudioDiscrete channel digital trim
Discrete input fader control
Discrete channel compression
Mic / Line level settings
Input EQ - 5 band parametric equalisation on all inputs
Channel mute
Equalisation bypass
Selectable 'freq' for rumble filter
Signal routing and matrix control
Discrete input auto gain control
Discrete and accurate meter monitoring
Symetrix DSP minidsp - grizzlyaudio

The unit is loaded with 6 balanced outputs, which can be terminated in either balanced or unbalanaced configuration

Each output provides the following functionality 

8 bands of parametric equalisation
Discrete channel delay up to 341ms!!! I think delay is covered! lol
Signal inversion on all output channels
Symetrix DSP minidsp - grizzlyaudioButterworth / Bessel / Linkwitz Crossovers are selectable at 6,12,18,24,30,36,42,48db
Crossovers can be high and low pass
Discrete and accurate meter monitoring
Discrete output channel limiters
Equalisation bypass
Output mute


No FIR equalisation is provided
No Biquad filtering is provided
For me this is not an issue, the Symetrix provides more than enough parametric equalisation for my builds & room.

Plus signal inversion is provided on both inputs and outputs.


Click here for the quick start guide.


Programming is via a fixed architecture interface. Connection to the unit is via Ethernet. Which is a big bonus feature over any hardwired USB programmable DSP.

This enables DSP files to be complete, uploaded and downloaded via a wireless Ethernet connection once the unit is connected to your wireless home router!!. a very convenient feature (Welcome to pro level gear!!) Software is found here: 

Symetrix DSP minidsp - grizzlyaudio
If you have any questions, send a message! cheers 

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