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miniDSP Low cost, modular Digital Signal Processor (DSP) kits for the DIYer from miniDSP.

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Old 8th July 2013, 06:40 PM   #1
gpapag is offline gpapag  Greece
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Default My stack

As you can see, this is a “cost no-object” stack implementation

George
Attached Images
File Type: jpg 1 Assy front.JPG (410.7 KB, 629 views)
File Type: jpg 2 Assy rear.JPG (405.8 KB, 598 views)
File Type: jpg 3 Assy in situ front.JPG (343.7 KB, 565 views)
File Type: jpg 4 Assy in situ far.JPG (366.0 KB, 525 views)
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Old 8th July 2013, 06:53 PM   #2
gpapag is offline gpapag  Greece
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My stack consists of the following boards:
One MiniSTREAMER
One MiniDIGI
One MiniDSP
Two MiniAMP

The miniSTREAMER is connected to the MiniDIGI through it’s SPDIF in/out. It is connected to a PC through the USB port for to receive from (playback) and send to (record) digital music files.

The MiniDIGI has a switch for Analog/Digital Input selection and a four position selector for the digital inputs.
The SPDIF#1in is allocated to the PC, the SPDIF#2 in to the CD transport digital out.
The optical inputs are still free.

The MiniDSP receives digital signals from the MiniDIGI through the I2S lines (ribbon cable) and left/right channel analog through it’s analog RCA inputs.
In these analog inputs I have connected the output of my preamplifier, where the selection of the various analog sources is accomplished.
The MiniDSP has a a single potentiometer volume control, digitally adjusting the four output channels of the MiniDSP.
The controlling software is the 2.1 audio plug-in (stereo mode).
The four I2S outputs feed the two MiniAMP boards through the ribbon cable.

Each MiniAMP board is configured as 2x20W amplifier, -3db input gain.
One board is outputting ch1&2 for feeding two JX92S Jordans omnis.
The other board is outputting ch3&4 for feeding two 12inch KODA woofers in a W frame enclosure.

For now, MiniSTREAMER is powered through the USB port and all the other boards share power via the ribbon interconnect. The PSU is analog 24V/3.5A stabilized and is connected to one of the MiniAMP boards only.

Setting the various jumpers was the hardest part to arrange but it’s all over now. Everything functions properly.
I will provide details for the jumpers and the selectors wiring.

There is no turn-on/turn-off thumb, no input selectors electrical clicks and speakers are dead quiet in idle with any volume setting.

George
Attached Images
File Type: jpg 1 miniStreamer.JPG (401.7 KB, 491 views)
File Type: jpg 2 MiniDigi top.JPG (388.8 KB, 128 views)
File Type: jpg 3 MiniDigi bottom-Switches.JPG (382.1 KB, 127 views)
File Type: jpg 4 MiniDigi-ministreamer.JPG (402.3 KB, 111 views)
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Old 8th July 2013, 07:26 PM   #3
gpapag is offline gpapag  Greece
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MiniAMP board jumper setting

George
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File Type: jpg miniamp for xo1-2 ch.JPG (87.8 KB, 129 views)
File Type: jpg miniamp for xo3-4ch.JPG (89.5 KB, 69 views)
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Old 8th July 2013, 08:06 PM   #4
gpapag is offline gpapag  Greece
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MiniDSP jumper settings and Volume potentiometer connection

George
Attached Images
File Type: jpg jumpers.JPG (108.6 KB, 81 views)
File Type: jpg MiniDSP.JPG (266.6 KB, 95 views)
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Old 8th July 2013, 08:53 PM   #5
gpapag is offline gpapag  Greece
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MiniDIGI jumper settings and Input selectors connection

George
Attached Images
File Type: jpg jumpers-wires.JPG (103.6 KB, 86 views)
File Type: jpg 2 MiniDigi top.JPG (388.8 KB, 65 views)
File Type: jpg 3 MiniDigi bottom-Switches.JPG (382.1 KB, 55 views)
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Old 8th July 2013, 09:35 PM   #6
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MiniStreamer SPDIG connection to MiniDIGI.

With such a connection, the Master /Slave jumper is non-functional.
I keep the DC jumper closed (in place) because I power the board from the USB connection.

George
Attached Images
File Type: jpg wires.JPG (56.8 KB, 64 views)
File Type: jpg 4 MiniDigi-ministreamer.JPG (402.3 KB, 63 views)
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Old 8th July 2013, 09:55 PM   #7
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With the software (2.1 way advanced plug-in)
I selected “Digital input (I2S)”
I enabled the “External Volume Control”
I selected “Stereo Mode” for the Sub Output

George
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File Type: jpg plug-in.JPG (86.5 KB, 80 views)
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Old 9th July 2013, 08:01 PM   #8
gpapag is offline gpapag  Greece
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The first objective I had in my mind for my new diy sound system was the requirement for routing to the speakers the signal from any of the sources I have, with a minimum number of signal conversion steps between source and speakers.
The second objective was the minimum disturbance (noise, buzz, ground loops ect ) from the interface of the system components and their interconnects.
These two objectives were achieved by selecting the boards that made this stack.

The third objective was to be able to route any selected signal source to a USB port for the purpose of doing digital recordings with my PC easily and without using an additional signal conversion (soundcard).
This is achieved by routing to the MiniDIGI SPDIF Out the I2S DATA_OUT 7&8.
The MiniDIGI SPDIF Out is rooted to the USB port of the MiniSTREAMER.

I had a problem with this last step , and I had to look at the issue of the three Master/Slave jumpers present in the boards, in a systematic way.

I made a Truth Table with all the possible M/S jumpers combinations (2^3 =8) and I tested the stack how it behaves in each combination. That is, if every kind of signal source is routed to the speakers and to the recording program in the PC.
You can see the results in the attachment.

There are two jumper combinations (A/A 5 and 6) that work in all cases, noise and distortion free.
There are two jumper combinations (A/A 1 and 2) that work partially.
There are three jumper combinations (A/A 3, 4 and 8) that produce silence or noise.
The jumper combinations A/A 7 produces a mixture of interrupted signal, distortion and noise that is dangerous to the system.

After you will read the table results, you will notice that what I wrote in post #6
Quote:
Originally Posted by gpapag View Post
With such a connection, the (MiniSTREAMER) Master /Slave jumper is non-functional.
was only partially correct. Sorry for that. I was misleaded too.

George

>Edit: The results of the table hold true for the SPDIF connection between MiniSTREAMER and MiniDIGI.
I don’t know what happens with a I2S connection between these two boards
Attached Images
File Type: jpg Master-Slave Jumpers truth table.JPG (91.2 KB, 78 views)
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Last edited by gpapag; 9th July 2013 at 08:26 PM.
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Old 11th July 2013, 09:40 PM   #9
gpapag is offline gpapag  Greece
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This is a drawing showing the signals routing between the five Mini boards on my stack and the outside world.

George
Attached Images
File Type: jpg Signal distribution.JPG (74.3 KB, 123 views)
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Old 15th July 2013, 04:23 PM   #10
gpapag is offline gpapag  Greece
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While reading all the boards manuals, I was puzzled as to what the “Data_In” and “Data _Out” mean.
The “In”/”Out” designation is referring to which board exactly ?

I started looking into this by comparing the pin assignment at the boards expansion slots, through which, the ribbon cable carries the I2S channels along the four boards.

The comparison (see first attachment) brings out some differences among the boards but focusing only on the I2S pins, all expansion slots have the same pin assignment, except for one pin (Pin #12).
Then I started testing the electrical routing between the expansion slot of the Mini DSP board and the pins of the ADAU1701 chip, the heart of the Mini DSP board (see second attachment and http://www.analog.com/static/importe...s/ADAU1701.pdf )

After this test, I was certain that in all the technical manuals of the boards, “I2S_Data_In x&x” means “ADAU1701 SDATA-In x” and “I2S_Data_Out x&x” means “ADAU1701 SDATA-Out x” . Ditto for the BCLK and LRCLK lines.

George
Attached Images
File Type: jpg Expansion Connector.JPG (118.9 KB, 104 views)
File Type: jpg ADAU-Board Connectivity.JPG (94.5 KB, 48 views)
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