Keep it simple and keep it analog!

Finally we have put out the first MRA-4 in it's current design and hope you will like it.We think that a stereo unit and all accessories are still part of the furniture and part of your lifestyle. Not a cold metal block or a cheap and nasty looking plastic box. We remembered the good old fashioned 70's designs and have been inspired by them. The result is now here as the first MRA-4. A low cost small Multiroom Audio System in one ultra compact enclosure. This is a real power packet and like all Delta Audio Engineering products, fully analog and proudly made in New Zealand. And we made it easy to use, very easy.

The MRA-4 is Delta Audio Engineering's smallest Multiroom Audio System with a new push button select control and LED indication. Ultra Compact, will fit nicely in any environment.

4 x 15W at 8 Ohm or 4 x 20W at 4 Ohm (we have reduced the 4 Ohm power)
Frequency response according to DIN 45500 HiFi: 20Hz - 20kHz
Bass: +/- 12dB
Treble: +/- 12dB
THD: 0.01%
Weight: 4.6Kg
Dimensions: Width 270mm, Height 160 mm, Depth 185mm

4 Audio sources can be connected to the MRA-4, this can be anything like a CD player, a Tuner, a DVD player, iPod or a computer, anything that produces a sound, it's your choice.
For each room, you can choose your audio source by pushing the Select button until the LED for the Input of your choice lights up. Then you can adjust your Volume and your Tone Controls (Bass and Treble).
If you like a remote Volume Control in a room, you press the Remote active button and the Volume can be altered from a Volume panel on the wall. In this mode, the Volume Control on the unit is out of order.
Having now four different rooms with individual control over 4 different sound sources, giving users the possibility of listening to a CD in the bedroom, radio in the kitchen TV sports on the deck or just something else somewhere else at the same time. This system extends to as many rooms as you like.
And by the way, if you don't like people "playing" with your wall mount Volume Control, just turn the Remote active at the system OFF and you only can adjust the volume from the system itself.

Each room amplifier is limited to 15Watts in power to avoid overloading.
This system can be extended by a second unit for 4 inputs and 8 outputs or by a third unit to 4 inputs and 12 outputs and so on. A link is placed on the rear panel and an extension cable can be included.
A possibility for remote Volume Controls is given too by connection external wall panels to the system.
Each room needs a Cat5 or higher cable with RJ45 plugs at each end. Pin-out is 1:1.
Connecting Speakers to the unit, each amplifier output has a red and a black push in speaker connector. Make sure your loudspeaker + is connected to the red terminal and the loudspeaker - to the black terminal.

Smallest speaker-load is 4 Ohm, so check your speaker impedance to match this or get help.

Remote Controls

There are 2 types of remote controls so far. One is a simple "knob" Volume Control with a red LED for "Remote active" indication.
The other type will be a digital Volume Control with Volume "Up and Down" push-buttons
Currently these only fit in a certain PDL (Australia and New Zealand) product range. The standard wall panel colour is white.

How to match loudspeakers

All loudspeakers and speaker cabinets have a + and a - connection which is the polarity. Make sure you always have the right polarity when connecting a speaker to your amplifier. It defines the movement of the speaker cone which has to move forward, out of the frame. In series you connect plus of one speaker to minus of the next. In parallel you connect plus to plus and minus to minus, always!
The second important parameter is the speaker impedance, measured in OHM. Most speakers have 8 Ohm but some have 4 Ohm, older ones have even other measurements but let's concentrate on the modern ones.
That does not mean that you only can connect one speaker to your amplifier if you have a 8 Ohm speaker. You can match multiple speakers by wiring them in series or parallel to reach your main impedance. The following diagrams shall give you an idea how to do this. You also need to do the math as well.


Speakers in series are calculated as follows:
Z (stands for speaker impedance) Z1 + Z 2 + Z3 +....Zx = Z total
Example 8 + 8 = 16, so the total Z is 16 Ohm, or 8 + 8 + 8 = 24, so the total Z is 24 Ohm

Speakers in parallel : 1/Z1 + 1/Z2 + 1/Z3 + 1/ Zx = 1/Ztotal
Example: 8//8 = 4, so the total Z is 4 Ohm, or 8//8//8 = 2.7, so the total Z is 2.7 Ohm

So let's get practical, let's say you have 3 speakers in your room and want to connect them to one output of our MRA-4 multiroom  system.

Our system can handle 4 Ohm as the lowest output impedance, your speakers are 8 Ohm each. You connect 2 speakers in series and parallel to this 2 speakers you connect the third 8 Ohm speaker. That means you have 2 x 8 Ohm in series which brings you up to 16 Ohm and 8 Ohm parallel to the 16 Ohm brings it down to a total of 5.33 Ohm. That's well above the 4 Ohm minimum.  And don't forget the polarity.