Hello, new here.
I'm looking to build the two front stereo speakers from the wireless surround project but to make a "wireless" turntable for my daughter (21 in July). I'm gathering all the parts and have the 3D printer but am a bit unsure about some aspects. With the surround system I am sussing the volume comes from the original HDMI (ARC?) into the surround processor that splits it into the channels for full surround so that will work off the TV remote. If I was going to take two channels from a pre-amp (80s Sansui vintage), would I need to control the volume via the pre-amp before it goes into the two D/A convertors for the lasers? I will ask more as I start building I guess but for now It's all about what I need to buy.
Thanks for any suggestions.
I know my original post hasn't been moderated yet but I'm going to add further questions here on the hope I get in soon.
1. Is there a wiring diagram for the power and signals for the DSP and 4 channel amp to speakers published anywhere, I've spent a lot of time trying to get data sheets or any instructions for either the DSP or the amp that would make it clear how to wire them together. There's no end to end connections shown in the videos. I can't see what needs to be wired to where, I can work out power I'm sure but the video says the DSP splits it into 3 channels (four if you include the dedicated sub) but then shows some soldering on the DSP and says connect it to the amp. There are two inputs on the amp that both have INL GND and INR (left, ground, right?). When Matt wires the DSP to the amp he appears to use the lead supplied with the amp to connect outputs one two and three to red white and black and two more connections to clock 0 and clock 1 but I've no idea how they connect at the DSP, they plugs can only go into inputs 1 and 2? If anyone has done the old speakers and can send me some pictures of what connects where I will be very grateful thanks?
I'm days into printing off the enclosures for the surround speakers so am hoping for some guidance somewhere (I can't believe Matt hasn't got some circuit diagrams somehwere and I am just missing where they are??)
Thanks in advance for any help.
Welcome. I'll ask Matt next time we get time to chat. I'm leery of weighing in on this because it's not my design - but ARC (over HDMI) is a pure bitstream, so zero analogue components. Analogue signals have limits, digital ones not so much (the limitation there is the quantization error). If I get chance I'll take a look at the videos and see what I can figure out. Sounds like a wonderful surprise - my girl's about the same age as yours - 21 in a couple of months. How time flies!
Take everything I say with a pinch of salt, I might be wrong and it's a very *expensive* way to learn!
Thanks for the reply. I am printing all the parts for one speaker first. I aim to build one and get it working then do the second I have until July so lots of time (just lacking in the understanding).
I look forward to your reply. If Matt has any circuit diagrams for the final design that would be of immense help.
Stuart.
Happy to help.
Here's a discussion of where I goofed with the V2 Ultimate USB 3 and how I learned from it.
The thing with ADCs is you need to know the ADC reference voltage. I'll explain the thing that's been bugging me for what seems like two years now - all because I ASSUMED (and you know what assume does - makes an ass out of ... me) that the device was set for "normal" voltages for Line In - which is about 600mV to 1V.
After repeated failures and a couple of blown Audiograbbers I started to question my own knowledge and persisted, eventually bought a cheap piece of test gear to find out what the *** was going on.
A signal generator - which (handily) uses a DDS to generate a waveform of up to 5V.
And (shock, horror, face-plant the desk) the Audiograbber is biased for 5V and it's not clamped. Which makes perfect sense for the designer using a 5V powered but not - and this is key - a standard swing for which is about 20% of that. On the Arduinos the ADC reference is IIRC 3.3V but you can amplify the signal using either analogue components (usually an op-amp) or digitally.
The Audiograbber does not do this, despite coming with RCA sockets which is a bit naughty. The issue here is resolution - that's the quantisation resolution. Tiny signals really struggle here because when we digitally amplify the signal those errors get amplified too.
The other problem is that exceeding the max voltage, by a few tenths of a volt, can be sufficient to blow the input stage.
Such issues have plagued the development of the microphone which I've been working on in my spare time. The irony of these multiple failures, apart from being an excellent learning experience, have been the mother of invention.
The main development is a tiny board, that wires directly to the JLI2555 capsule and produces professional level signals for a P48 (a traditional phantom power used on professional stage mixers) & the 15V supply available from Matt's original Vero design.
Over the holiday period I've had time to work on a whole new design that works from just 5V - the USB supply so it's lower cost and simpler to make. Assuming I didn't nix it by mentioning it here (!) this new board (there it's in two parts, though one is optional) does everything, even to the point of what's called "soft" clipping known as the "valve sound" - rich in even harmonics - the warm sound eventually moving into clipping when the mic is pushed to it's limits. This is all in simulation so it's going to be a few weeks before i get physical boards.
Another issue we've all faced with USB supplies is noise - and a lot of it. Every PC is different so that resulted in a active smoothing circuit. Laptops, for example, have boatloads of noise and they're not earthed (a typical desktop is). Digital components, while sensitive to supply variations are nowhere near as affected as discrete amplifiers which will pass any noise to the output. Operational amplifiers are much more predictable here but the space on the board is very limited.
I'm still tinkering across several SPICE simulators (Tina TI and LT Spice) because the tolerances are tighter that my underpants. The actual circuit runs from just 3.6V which makes biasing a little tricky (a supply variation of a few tenths of a volt can throw everything off. And just to add insult to injury the main amplification stage (a JFET) has ridiculously wide tolerances in gain (even the best JFETs are feeble in this regard, with gains, at high current still just a tenth of a typical bipolar transistor). The JFETS I can source (2SK208, J201, etc.) have best case gains of just 1.2!
A higher supply voltage (20+) makes the situation much more predictable - but I don't have that. I knew this walking into the problem and I knew it was going to be a challenge, especially keeping the noise as low as possible - but the challenge was to meet or improve on Matt's original with a simpler design. On paper at least, I've met these requirements... the proof is coming, fingers crossed. The old 48V adaptor works a treat so I've added a simple option to run it from 15V too.
I've made everything Open Source Hardware so people smarter than me can improve upon it. One option would be to go double-sided giving space for more components... but there comes a time when it's "good enough". The 48V versions are designed for my video camera and work beautifully with the (albeit expensive, but quite superlative) Focusrite Solo. I've made a special board based on Matt's original for this purpose.
However - this design is almost certainly deprecated as the new ones are cheaper and simpler to make.
If you're curious you can see the experimental designs on my GitHub page (github.com/marcdraco). I haven't done a write up of how they work but I probably will just for the sake of it (and for others to improve upon).
Take everything I say with a pinch of salt, I might be wrong and it's a very *expensive* way to learn!
That's a lot to take in. I will be reading all this tomorrow, just set off another print as the 3D printing is taking days (mostly done now). Early start tomorrow and meetings for most of the day. Thanks for taking the time to help.
We help each other Stuart, if people spend the time to ask the questions, finding the answers helps everyone. That in essence is how Open Source hardware and especially software works. My Halo board (an LED Vu meter) ONLY works at all because of Open Source software for the Arduino.
Take everything I say with a pinch of salt, I might be wrong and it's a very *expensive* way to learn!