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Multi-Way Conventional loudspeakers with crossovers

Open source Active Wifi speaker project
Open source Active Wifi speaker project
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Old 4th November 2017, 01:22 PM   #11
Neil Davis is offline Neil Davis  United States
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Originally Posted by CharlieLaub View Post
I was thinking more that one speaker is a Pi or similar SBC outfitted with two network adapters.
That should work if the latency through the entire protocol stack is low enough. The Sonos Linkplay Heos etal solution probably implements the AP function at a lower point in the TCP/IP protocol stack to ensure low latency and less variance. So that's why getting that code might be advantageous.

But I'm guessing how the AP function is implemented, because I haven't found any technical discussions on how they do their left/right synchronization. In the article that I referenced, TI suggests that some solutions use 802.11v, which appears to be a MAC/PHY-layer protocol. It might be worth looking at that standard for ideas (I haven't done that myself and don't intend to).

As a side note, I had some trouble returning to this thread because I couldn't easily find the original post. Is the Multi-Way forum really the right place to discuss active speakers with DSP and Wi-Fi? According to the sub-title, Multi-Way is about "Conventional loudspeakers with crossovers". I suggested over 2 years ago that we needed some new categories to cover active speakers with DSP and WiFi, but got a lot of push-back. That's one of the reasons I set up the Audiodevelopers.com web site--there isn't a logical place on diyAudio to discuss this modern approach to speaker building. Meanwhile, the WiFi based speaker market grew by 62% in 2016 to 14 million units according to a recent report from Strategy Analytics. I'd still like to see diyAudio address this issue...
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Old 4th November 2017, 03:28 PM   #12
CharlieLaub is offline CharlieLaub  United States
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Originally Posted by Neil Davis View Post
As a side note, I had some trouble returning to this thread because I couldn't easily find the original post. Is the Multi-Way forum really the right place to discuss active speakers with DSP and Wi-Fi? According to the sub-title, Multi-Way is about "Conventional loudspeakers with crossovers". I suggested over 2 years ago that we needed some new categories to cover active speakers with DSP and WiFi, but got a lot of push-back. That's one of the reasons I set up the Audiodevelopers.com web site--there isn't a logical place on diyAudio to discuss this modern approach to speaker building. Meanwhile, the WiFi based speaker market grew by 62% in 2016 to 14 million units according to a recent report from Strategy Analytics. I'd still like to see diyAudio address this issue...
According to what I have read, this forum will soon (but when?) be changing over to a TAG based system for identifying how the thread relates to DIY audio. Something similiar to what Stackexchage uses I am guessing. At Stackexchange you can create tags if they do not exist, and assign multiple tags to threads. Using this topic as an example, it could be tagged with:
loudspeaker
DSP
active
network audio
tcpip
etc.

I like that approach because it is more general and flexible and can accommodate things that this current system cannot. For example I do DSP but on a Linux box as a loudspeaker crossover. The speakers can use built in amps, and they could be class AB, D, or both. So, do I start the thread under under PC Based, Multiway-Loudspeakers, Solid State, Chip-Amp or Class-D?
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Old 11th November 2017, 01:12 PM   #13
Neil Davis is offline Neil Davis  United States
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Originally Posted by CharlieLaub View Post
According to what I have read, this forum will soon (but when?) be changing over to a TAG based system for identifying how the thread relates to DIY audio.
Yep, that's what was implied in that thread from June 2015. But I'm guessing that there will be massive push-back from a readership used to the existing organizational structure, so I'm doubtful that the Stackexchange approach will actually get implemented. Also, I think the existing forum structure works OK in many ways--it just needs to be updated. A lot has changed in audio in the past 10 years, and the diyAudio forum structure hasn't kept up.

Here's another example: I just added a page to my blog at Audiodevelopers about using the Analog Devices SuperBass algorithm. It's a psychoacoustic algorithm that is commonly used to extend the bass response of small WiFi and Bluetooth speakers. It's about audio, and it's now DIY, since anyone can download the Analog Devices tools, and the technologies to integrate these algorithms are readily available. But a discussion of a psychoacoustic algorithm like SuperBass doesn't fit into any of the categories here at diyAudio, even though it is a widely used technology in all of those millions of WiFi and Bluetooth speakers sold last year. You could try posting in the Subwoofers forum, but most people here refuse to accept anything less than 8" as a subwoofer. You could post it in Digital Line Level since it is code that runs in an ADAU1701 DSP, but I haven't had any luck getting anyone in that forum interested in DSP software. It definitely doesn't belong here in Multi-Way. It really belongs in an Active Speaker forum, along with the original post in this thread, where discussions about WiFi adapters and DSP algorithms would make sense. But since there isn't any Active Speaker forum at diyAudio, I was forced to start my own blog at Audiodevelopers.com. I would prefer to be a more active participant at diyAudio, but until there is an obvious place to contribute I don't feel welcome.
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Old 14th November 2017, 10:54 AM   #14
lowtherdream is offline lowtherdream  Canada
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Very interesting project

Here is a couple of ideas that can be explored:

PTP for Time synchronisation.
VBAN for the streaming protocol.
VBAN with multicast?
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Old 14th November 2017, 01:20 PM   #15
adason is offline adason  United States
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Originally Posted by MrVins59 View Post
Hello,

I'm glad to share with you my new wireless speaker project. It's still in progress but the first version runs and sounds well.

Basically, it is :
- Raspberry Pi based audio player stacked with DSP and amplifier boards
- active filtering based on ADAU1701 DSP
- PCM5102 I2S digital to analog converters
- Class-D amplification based on TPA3118
- Low latency (<1ms) WIFI connected speakers that share audio (no cable between Left and Right speakers)
- Scalable speaker system (you can use 2 for wideband stereo, 3 for 2.1 system...)
- Easy DSP configurator software based on text file. You don't need to have SigmaDSP connected to your board to change the DSP settings, all you need is to edit a file with your settings (see here for more info)
- Free and open source

Right now, it's limited to stereo configuration but soon I'll extend the speaker configuration to 4.0, 5.1 and even 7.1 for anyone desiring to build a wireless multichannel speaker setup.

I have done a prototype based on this electronic & software architecture that is described in more details on the website, and look like this.

Click the image to open in full size.

By the way, if anybody wants to join the project to give a hand for hardware, software or website developpement, feel free to contact me.

Website link (for speaker details) : mydspi
GitHub link (to share the hardware and software design) : GitHub - V2Ale/MyDSPi: MyDSPi is an electronic and software solution that works with Raspberry Pi boards to make active speakers
Thanks,
What is the art object at bottom right? Just curious. Thanks.
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Old 21st November 2017, 09:37 PM   #16
MrVins59 is offline MrVins59  France
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Ooops I did not get notified of new messages and just discovered that. I'm glad to see that some people are also interested in similar topics.

Regarding synchronicity between speakers, the exchanges are very interesting. Thanks for sharing your experience and knowledge.
In my point of view, the value in itself is not that much important. What count is how stable is the value in time. From memory, the measurements I did with an oscilloscope was all around maximum 1ms.. but I do not remember the typical difference and that would be interesting to measure. For this project, I do not aim to get a so good time difference of around hundreds of microseconds because anyway my speakers are not placed perfectly.. it just have to find a good enough position for stereo that match the WAF factor . In my case, since the delay seems pretty constant, I make up the left/right balance (due to delay, listening position..) with a simple gain that Snapcast allows you to set easily, and it works fine.

Last, the to answer about the art object at the bottom right of the picture, it's Tom Dixon's etch tea light holder copper.
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Old 17th March 2018, 04:40 PM   #17
GDO is offline GDO
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Quote:
Originally Posted by MrVins59 View Post
In my case, since the delay seems pretty constant, I make up the left/right balance (due to delay, listening position..) with a simple gain that Snapcast allows you to set easily, and it works fine.
+1 It does work fine for me too!

I must say that i was terribly biased against the idea of using a pair of L/R snapclients because i also found that 1ms delay variance or whatever ( 30cms ) unacceptable...

But after giving it a try i shamefully have to admit that it sounds good enough for me...

Btw, i am now on a project of a wifi subwoofer based on this idea.
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Last edited by GDO; 17th March 2018 at 04:43 PM.
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Old 17th March 2018, 10:58 PM   #18
GDO is offline GDO
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After a few hours of more careful listening I have to admit I am not so satisfied...

The problem is with the soundstage which constantly changes. This is especially obvious with very simple musical programs, for instance one classic guitar performance, the phantom image constantly changing in size and position.

It does not sound too disturbing at the beginning, and i don't find it sounds an unnatural artifact, because atmospheric changes at a live event outdoors or in a large hall produce similar changes to the soundstage and in a manner of speaking a rock solid studio one is indeed artificial (too good to be realistic...) , but i have to admit that it's an artifact resulting from the wandering sync between L and R channels allowed by Snapcast, not present in the recordings.
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Old 23rd March 2018, 01:50 PM   #19
adason is offline adason  United States
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Quote:
Originally Posted by MrVins59 View Post
Last, the to answer about the art object at the bottom right of the picture, it's Tom Dixon's etch tea light holder copper.
Thanks!
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Old 23rd March 2018, 03:25 PM   #20
CharlieLaub is offline CharlieLaub  United States
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Originally Posted by GDO View Post
After a few hours of more careful listening I have to admit I am not so satisfied...

The problem is with the soundstage which constantly changes. This is especially obvious with very simple musical programs, for instance one classic guitar performance, the phantom image constantly changing in size and position.

It does not sound too disturbing at the beginning, and i don't find it sounds an unnatural artifact, because atmospheric changes at a live event outdoors or in a large hall produce similar changes to the soundstage and in a manner of speaking a rock solid studio one is indeed artificial (too good to be realistic...) , but i have to admit that it's an artifact resulting from the wandering sync between L and R channels allowed by Snapcast, not present in the recordings.
This is exactly the problem that you cannot overcome with e.g. SnapCast, Airplay, DNLA, etc. They just can't get the synchronicity low enough.

The new version of my streaming audio controller (actually even the old version) can do this much better, at least 10x better. The new version allows for the user to do LADSPA (IIR) filtering in the playback chain on the clients, so you can implement a DSP crossover as well. No need to pass off the audio to another program.

Send me a PM if you want to give it a try. You 2-speaker system might be a good test bed.
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