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Old 16th July 2013, 11:07 PM   #11
gpapag is online now gpapag  Greece
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Using the data provided in the 2.1 Plug-in (1st attachment), I drew the “I2S-Data_In” and “I2S_Data_Out” routing channels between the boards(2nd attachment) of my stack.

There are the timing channels as well but writing details over it, is another difficult exercise for me (I don’t know how many drummers are giving the pace, who is playing when and if they are synchronized)

http://www.youtube.com/watch?feature...wC5mwlg94&NR=1

George
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File Type: jpg Plug-In designation.JPG (32.6 KB, 277 views)
File Type: jpg Data lines.JPG (97.4 KB, 277 views)
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Last edited by gpapag; 16th July 2013 at 11:16 PM.
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Old 19th July 2013, 07:31 AM   #12
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Hi, good job how about the sound? I want to make the same system... is there any problems to stack two amps? Why did you use the usbstreamer of miniDsp? Your comment of the stack is the useful information to me. Thsnks
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Old 19th July 2013, 08:04 AM   #13
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Smile how about sound quality?

Quote:
Originally Posted by gpapag View Post
As you can see, this is a “cost no-object” stack implementation

George
Hi you made a good job for us who have a interesting about minidsps. How about the sound quality ? Is there any noise? Do you have any problems to make stacks of the miniAmps? How to make the connection among the amps and miniDsp?
Is there any merit to use the ministreamer instead of usbstreamer?
your detail work diary is very useful information for us
thanks
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Old 22nd July 2013, 08:35 PM   #14
gpapag is online now gpapag  Greece
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Quote:
Originally Posted by lube2946 View Post
Quote:
Originally Posted by lube2946 View Post
Sorry for the delayed response

Hi lube2946
Thank you for your kind words about my work diary (my posts are exactly this).

Quote:
Is there any merit to use the ministreamer instead of usbstreamer?
I haven't tried USBStreamer
For me, MiniStreamer:
- Is cheaper (I am on a tight budget)
- It works without dedicated drivers. Apart from the ease of installation, this makes it certain that it will work on any operating system ( I had a few problems with other drivers when I changed OS).
- In single operation (playback or recording but not both simultaneously) it supports up to 24bit/96KHz. In dual mode (playback and recording simultaneously) it supports up to16-bit/96KHz. My needs are covered as I go for even lower resolution/sampling rates.


Quote:
I want to make the same system... is there any problems to stack two amps?
If you use the 2way Crossover ADV 2.1 plug-in, the two MiniAMPS will work fine if you place the jumpers as I have shown in post #3. (The 2way plug-in will not work!)

Quote:
How to make the connection among the amps and miniDSP?
Through the ribbon cables.
I made my own (it takes ribbon, connectors and a vice) but you can ask from MiniDSP devteam to send you two.

Quote:
How about the sound quality ?
For my ears, the only issue was caused by overloading the MiniDSP.
After I paid attention not to overload the MiniDSP and the MiniAMPS (see these two posts: )
Quote:
Originally Posted by gpapag View Post
Quote:
Originally Posted by gpapag View Post
the sound is very good for me.
I was really surprised with the -power/sound fidelity- capabilities of the MiniAMPS.
Try them and report back

Quote:
Is there any noise?
The speakers are dead quiet.
With my ear over them and even at the highest volume setting, I can’t detect any noise.
What I can say from my working with the MiniDSP and other dedicated power amplifiers (class A, AB, D) I have connected them to it, is that in terms of noise, the MiniAMPs win hands down due to their I2S connectivity with the MiniDSP board.
The SPDIF isolation transformers of MiniSTREAMER and MiniDIGI greatly add to the “silence” of the stack.

Tomorrow I hope to be able to show some measurements regarding noise levels.

George
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Last edited by gpapag; 22nd July 2013 at 08:46 PM.
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Old 22nd July 2013, 11:26 PM   #15
gpapag is online now gpapag  Greece
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During the course of doing noise level measurement recordings of the MiniSTREAMER-MiniDIGI-MiniDSP part of the stack, I noticed that these recordings showed a peculiarity.

The recorded files are a bit longer in duration and shifted lower in frequency compared to the test signal files fed into the stack.

The test signal files were silent signal and sinusoidal 997Hz tone of various amplitudes made through Audacity sw, at 16/44.1kHz and 16/48kHz.
I burned the16/44.1kHz files into a CD and I used my CD player to feed the stack as an analog signal and as an SPDIF signal.
I fed the 16/48kHz files from my pc through the USB port to the MiniSTREAMER

The playback is true to the fed-in signal. No frequency shift. (I tested it with a frequency meter at the speakers posts)

The problem is on the recording-out side.
The recordings were done by a pc fed from the USB port of the MiniSTREAMER.
Regardless of the input (analog, SPDIF, USB) and regardless of whether the test file is 44.1kHz or 48kHz sampling rate, the recorded file is 1.08846 times longer than the original and the 997Hz test tone is shifted down to 916Hz, that is 0.91873 times (the reciprocal of 1.08846).

I wouldn’t have noticed the time shift but the pitch change is noticeable (In musical terms, it is 1 semitone + 46 cents, almost a tone lower).

I checked the sampling rate of the recordings.
It is the same as the sampling rate of the original test signal files.

And yet these numbers match the 44.1kHz/48 kHz ratio (0.91875).
It seems that a sampling rate conversion takes place somewhere but where?

I tested the two functional combinations of the Master/Slave jumpers of the stack (see post #8):
MiniSTREAMER Master/MiniDIGI Slave/MiniDSP2x4 Master
MiniSTREAMER Master/MiniDIGI Slave/MiniDSP 2x4Slave

Recordings with both combinations have the same problem.

I checked the SPDIF settings on my pc. Nothing there.
I checked the settings of the recording sw. No success.
I did again the recordings with different sw packages (Steinberg Wavelab, Audacity, Wavepad Editor). No luck.

As I am newbie to the digital world, I can’t figure out what else I can do to find the location of the problem and fix it.

I would appreciate a response from any of you who has implemented a MiniSTREAMER/MiniDIGI/MiniDSP2x4 combination and could test the USB rec-out

George
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Last edited by gpapag; 22nd July 2013 at 11:42 PM.
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Old 25th July 2013, 05:02 AM   #16
minidsp is offline minidsp  Hong Kong
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@ George,

I wonder if the issue is simply because you're recording @ 16bit while all our DSP/I2S run @ 24bit. Also note that you should record at the rate of the DSP (48k). A 44.1kHz recording will be an issue.

Also pay attention when you go to 44.1kHz in recording. Sometimes, you may need a reset to actually "reset" to 48kHz the miniStreamer.

Using Audacity you can control all these settings correctly, then make sure that you're playing a 48kH AND recording 48k. (must be in the same clock domain for loopback) You can easily get into a state where you'd believe that you're running @ 48k but indeed Windows didn't reset the USB from an earlier 44.1 test. Just use a scope to double confirm the LRCLK.

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Old 26th July 2013, 06:30 PM   #17
gpapag is online now gpapag  Greece
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Thank you DevTeam for responding.

I am away from home now.
In two weeks I will put my hands over my stack again, so i will try then all what you suggest.

Stupidly enough I haven't tried 24bits, although I still don't think that this is what it causes the issue I have. The rest of your suggestions seem to be closer to it.

George
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Old 9th August 2013, 09:05 PM   #18
gpapag is online now gpapag  Greece
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As soon as I returned back home I checked again what is with the recording side of my stack.
I located the problem on the PC side (Win 7 Home, SP1), at the settings of the SPDIF device.
I attach a pic with the steps I took for proper set-up.
After setting the SPDIF device to 24bits/48kHz, I performed some test recordings which were OK in terms of pitch/duration even when I changed the bit depth/sampling rate (16/44.1k, 24/44.1k, 16/48k, 24/48k) of the recording within the recording software.

So all is well with the stack when recording. Thank you DevTeam

George
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Last edited by gpapag; 9th August 2013 at 09:12 PM.
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Old 14th August 2013, 11:59 PM   #19
gpapag is online now gpapag  Greece
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Here are some FFT screenshots from the MiniAmp output of my stack .
Analog input was connected to the analog preamplifier, SPDIF input was connected to the CD player but no signal was applied.

The MiniAmp output signal was picked up from one of the FR speakers terminals through 1.5m twisted wire feeding the primary of a signal transformer (turn ratio1:3.1).
The secondary of the transformer was connected to the input of an Maudio USB Audiophile card.
I used RMAA to do an FFT (size 131072 samples) on the 16/44.1k wav. recordings.
The signal amplitude (mVrms) which I have marked at the right side of the screenshots corresponds to the actual signal at the speaker terminals (and not to the +9.8dB signal at the secondary side of the transformer)
0dB of the soundcard is 1.286Vrms

George
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Last edited by gpapag; 15th August 2013 at 12:04 AM.
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Old 28th September 2013, 12:27 AM   #20
Pacogun is offline Pacogun  Australia
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Firstly, big thumps up for you! Inspirational!
You said on post #14 "For my ears, the only issue was caused by overloading the MiniDSP.
After I paid attention not to overload the MiniDSP and the MiniAMPS (see these two posts: )", Was it possibly caused by PSU 24v only 3.5 A? miniAmp's manual is suggest 2.5 A for ONE miniAmp. Have ever try to use i.e 24v 5A psu?
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