PROPOSAL: wireless digital loudspeaker with remote volume and on/off control - Page 2 - diyAudio
Go Back   Home > Forums > Commercial Sector > Manufacturers > miniDSP

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

Reply
 
Thread Tools Search this Thread
Old 7th June 2013, 08:14 PM   #11
diyAudio Member
 
Join Date: Mar 2007
Location: California
PROGRESS UPDATE:

Ah, the sweet taste of success - the redesigned circuit works great!

Using a 1kHz square wave as the input, and varying the amplitude from 0 to 1V pk-pk I get a DC output from 0 to 4.6V. With no input signal there is only a couple of millivolts of offset. This is great dynamic range for controlling the volume.


MOVING FORWARD:

The next circuit to work up is the relay driver with delay on/off. This is used to remotely toggle system components on and off (e.g. the line level circuitry and the power amps), each with their own delay. The independent delays are needed because the line level circuits are usually first on and last off while the amps are usually last on first off. I could also toggle a relay on and off in the same way. This would be needed for instance if the amp start up or shut down produced thumps, pops, or other undesirable signal. Since Multiple delay circuits can be connected to the control circuit I can implement additional channels as needed.

-Charlie
  Reply With Quote
Old 10th June 2013, 09:05 PM   #12
diyAudio Member
 
Join Date: Nov 2011
Quote:
Originally Posted by CharlieLaub View Post
I'm not following you here - how is there a time/phase problem related to the clocks of each MiniDSP??? If there is, what is the magnitude of the "error"? Your assertion would be much more convincing if you could provide some numbers or calculations.

Also, your "solution" seems to forget that an AC EM field travels quite rapidly in a wire, so that the delay the signal experiences when traveling from one speaker to the other through the wire is so short as to be insignificant. (See: Speed of electricity - Wikipedia, the free encyclopedia) It's also defeating the whole purpose of my wireless system: no additional wires.

-Charlie
I am not an technical expert on this topic, but referring to this thread:

Hypex UcD AS2.100

and particularly this quote by Achim:

"Just to let you know:

After using the AS2.100d in my Manger project my impression is that, indeed, not implementing a masterclocking mechanism that two modules can use for syncing degrades stereo imaging considerably.

This is a real pity, as the DSP chip used offers a means for implementation:
http://www.analog.com/static/importe...s/ADAU1701.pdf (cf. p. 18).

My listening experience is that one module on its own delivers amazing quality which far exceeds the price tag of the AS2.100. But add a second module for stereo and use the digital in, the soundfield is everywhere and nowhere. Resolution and drive is still there, but the left and the right channel just don't come together.

The situation is improved by not using the digital ins, but the analogue ones instead. Imaging becomes better, resolution is reduced though. Still, analogue in is the only way, for me, of sensibly using two modules.

A pity, really. So, on to the DLCP. I assume that all DAC stages in the DLCP are masterclocked? Could you please confirm this?"

Hypex indeed confirms that the 6 channels are masterclocked. Also, if my memory keeps me well, when you chain two MiniDSP 2x4 units for a 3 or 4-way cross-over, the "slave" unit will be clocked by the "master" unit.

Are you familiar with the WIFA association with Summit Semiconductor presumably as the driving force, and with some rather impressive industry backing already now. Your concept has a similar objective. Summit comments the clock sync issue in the transmitter specs:

Speaker-to-Speaker Clock Error: < 200 ns

http://summitwireless.com/Summit__TX_Mod_PB_v2_1.pdf

I don't know if you can calculate, simulate or measure what the clock error might be in your solution, but obviously 200 ms is some kind of benchmark. The fact that they present a value for the clock error indicates that there indeed may be quality issues if the clocks of left and right DSP:s and DAC:s are out of sync.
  Reply With Quote
Old 11th June 2013, 02:11 AM   #13
diyAudio Member
 
Join Date: Mar 2007
Location: California
I've gotten the rest of the circuitry working now. I need to run everything through the wireless system as well, to check for any problems, check the volume control with the 2x4, etc. After that I will design some PCBs for the project and start to integrate this into an active speaker project.

-Charlie
  Reply With Quote
Old 24th June 2013, 04:43 PM   #14
diyAudio Member
 
Join Date: Mar 2007
Location: California
PROJECT UPDATE:

I'm currently experiencing a small setback - It seems that I have managed to kill the wireless transmitter video channel while I was testing it (oops) so I am waiting for a replacement to arrive.

In the meantime, I've designed a SPDIF digital switch using TTL logic circuits, loosely based other similar projects I found on the web. After doing some SPICE modeling, it looks like this will work great.

The switch can accept up to 8 inputs. Inputs are selected using momentary pushbuttons on the front panel. Unfortunately I don't currently have any experience doing PIC programming so I can't implement an LCD readout or remote control of volume and switching. If someone wants to join in on the project and help me with that side of things, I would be open to that.

I'd like to have more than just digital inputs. For instance a USB input, and one or two analog inputs would be nice. I can implement these in various ways, but it looks like the most straightforward one for me (since I am not confident in my ability to design this stuff) would be to purchase one of these:
USB & Analog to SPDIF Digital Audio Converter
Before seriously considering this I did some research on the web. There are some nice commercial USB to SPDIF converters but they tend to start around $200 and go up from there if they can reliably run at 192kHz under Win and Mac OSes. The QA01 is limited to 96kHz but seems to be natively supported in both platforms. It also has an ADC, so I can have my analog input channels, too. The price is very affordable, too.

So the project looks like it will consist of:
  • input switching between digital (SPDIF), USB (24/96kHz max), and analog inputs
  • remote volume control of loudspeakers
  • remote power on/off for loudspeaker amplifiers
The remote control of power and volume is rather specific to the MiniDSP products at this point and there seems to be many options for wireless transmission, so I will probably just provide for external connections to a commercial wireless unit and let the end user choose whatever works for them. In this way, the unit could also be built up as a digital switch only if that was of interest to someone.

-Charlie
  Reply With Quote
Old 18th July 2013, 07:34 AM   #15
tigro is offline tigro  Romania
diyAudio Member
 
Join Date: May 2006
Hi Charlie

I read about your use of an Adio/Video sender for transmitting a SPDIF audio signal. This is precisely what I need. I have a DAC with SPDIF coaxial input and I want to transfer the SPDIF signal from my computer which is in an another room. I thought about using the NY-GS3200 5.8GHz 6 Channel Wireless Audio/Video Sender for this task. I would like to know what do you think, as somene who has experience in this domain.

Regards

Tigro
  Reply With Quote
Old 22nd July 2013, 05:53 PM   #16
diyAudio Member
 
Join Date: Mar 2007
Location: California
Quote:
Originally Posted by tigro View Post
Hi Charlie

I read about your use of an Adio/Video sender for transmitting a SPDIF audio signal. This is precisely what I need. I have a DAC with SPDIF coaxial input and I want to transfer the SPDIF signal from my computer which is in an another room. I thought about using the NY-GS3200 5.8GHz 6 Channel Wireless Audio/Video Sender for this task. I would like to know what do you think, as somene who has experience in this domain.

Regards

Tigro
It should work. You will likely only be able to send at up to 48kHz.
  Reply With Quote
Old 22nd July 2013, 05:58 PM   #17
diyAudio Member
 
Join Date: Mar 2007
Location: California
Quick update:

I'm still working on this project, but I've decided to use an Arduino for the user interface in the preamp. This will let me have an LCD display, some buttons for changing inputs and volume, and an IR remote control.
  Reply With Quote
Old 23rd July 2013, 06:53 AM   #18
tigro is offline tigro  Romania
diyAudio Member
 
Join Date: May 2006
Dear Charlie

Thank you very much for your answer

Best regards

Tigro
  Reply With Quote
Old 24th July 2013, 04:31 AM   #19
diyAudio Member
 
Join Date: Mar 2007
Location: California
I finally got the Arduino up and running and have implemented some code that will read user button input and increment volume up/down and/or change inputs. See pics, attached below. Fun stuff!
Attached Images
File Type: jpg IMG_2497.JPG (76.3 KB, 151 views)
File Type: jpg IMG_2501.JPG (55.0 KB, 150 views)
File Type: jpg IMG_2502.JPG (52.5 KB, 150 views)
  Reply With Quote
Old 24th July 2013, 08:55 PM   #20
diyAudio Member
 
Join Date: Mar 2007
Location: California
I did some more coding and have added the feature that the user can rename the inputs.

Instead of having to choose from INPUT 1, INPUT 2, INPUT 3, INPUT 4, etc. the user can enter up to 16 characters that describe the source equipment connected to the input, like "USB INPUT", "TUNER", "Berkeley Alpha", or whatever 16 characters the user chooses from the set of printable ASCII characters (ASCII 32-127).

The input names are saved to the EEPROM and loaded into memory each time the board starts up.

-Charlie
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Looking for: wireless remote control of volume/balanceH ronanski Analog Line Level 3 10th February 2011 12:44 AM
Multiway volume control proposal davelowe Solid State 2 22nd November 2010 07:49 AM
Digital volume control with remote and optical S/PDIF DEQ+TheEnd Digital Source 0 21st November 2005 03:58 PM
Creating a remote volume control for Creative 4.1 Digital Surround Sound Speakers mrcheese321 Parts 3 13th August 2004 07:40 AM
remote volume control digital? analog? happyben3 Solid State 8 5th August 2002 01:49 PM


New To Site? Need Help?

All times are GMT. The time now is 09:30 PM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright 1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2