There’s an uneasy meeting in the world of audio between digital and analogue. Traditional analogue audio reached a level of very high quality, but as old-style media-based audio sources have fallen out of favor there’s a need to replace them with ones that reflect a new digital audio world. To do this there are several options involving all-in-one Hi-Fi separates at a hefty price, a cheaper range of dongles and boxes for each digital input, or to do what [Keri Szafir] has done and build that all-in-one box for yourself.
The result is a 1U 19″ rack unit that contains an Orange Pi for connectivity and streaming, a hard drive to give it audio NAS capability, plus power switching circuitry to bring all the older equipment under automation. Good quality audio is dealt with by using a Behringer USB audio card, on which in a demonstration of how even some digital audio is now becoming outdated, she ignores the TOSlink connector.
The rear panel has all the connectors for power, USB, network, and audio laid out, while the front has an array of status lights and switches. We particularly like the hand-written lettering, which complements this as a homebrew unit. It certainly makes the Bluetooth dongle dangling at the back of our amplifier seem strangely inadequate.
If audio is your thing, we had a look at some fundamentals of digital audio as part of our Know Audio series.
I have done similar but simpler: A wooden box the width of my amplifier, which sits under it, with a Raspberri Pi (1), a USB power adapter, a mains relay (for detecting the amp is on) and IR inputs, and also IR output that I didn’t implement yet. The Pi has Audio out only, and happily plays audio out and MPD.
To listen to the sound of the RPi 4 with kodi on beamer, I have to manually switch the amp to another input, so [keri]’s solution is way better in that respect.
I think I did a better job at the “homemade lettering though”, using embossed tape!
*Happily plays web radio streams. The box is painted black and has two LED’s (power and status) and a shutdown button at front, nothing more.
I wish HaD comments had an edit function.
Yeah, I could do better on that lettering… probably with laser-printed foil.
I was entirely joking. With hacks like these I don’t care what (the backside of) a project looks, functionality first!
No! You can’t !! :-)
It looks *great* the way it is. Seriously – things made by my own hands deserve to be labelled by them too. Fills up the ol’ satisfaction tank to the top….and screams “one-of-a-kind” to those who know what they’re looking at (and IIVQ said: function first). Anyone who scoffs b/c it doesn’t look OEM/Factory fresh is a dolt and deserves to be taped to a chair with heeh@w reruns playing in an infinite loop. On a CRT. With static….. :-)
Anyone who has made anything for themselves gets this.
I find it strange that people are holding on to analog audio. The holdouts seem to be dying off though as more people grow up in age of digital audio.
The human ear is analogue (though the hearing itself may not). There’s always a need for high quality D/A converters and analogue amplifiers.
The other way round, too. The world is analogue, there’s a need for A/D converters, do digitize information.
Do they have speakers yet that are 100% digital?
Not really, if anything we’re gaining more converts.
Find an old 400 Watt Marantz amp and listen to the difference in sound between it and any modern amp of up to 1500 Watts in the same setup. Your choice of music genre it won’t matter, I can guarantee you’ll be blown away and odds are you’ll become a convert.
what I like about the building style is that it reminds me of old guitar amplifiers or scientific equipment, which cable bundles snaking around.
Waxed cord vs. dozens of plastic tails clipped off as waste and plastic barbs ready to cut skin.
The lack of TOSlink isn’t exactly brilliant, I think. As a CB radio fan, I know how important galvanic insulation is. RF noise is everywhere. Long, unshielded wires make it even worse. As if switching-PSUs aren’t worse enough these days.
Ethernet via 10BaseT isn’t great. Seriously.
Those cables are aqueducts for all sorts of RF noise.
The ethernet cards in a PC also can accidentally connect a “hot” PC chassis with other devices, such as routers and/or game consoles (all plugged in same router).
If it only consumer’s tech like this had an optical network jack.
It depresses me how less people of today know about how useful optical connections are.
Back in the 70s/80s/90s, fibre was held in high regards – for a good reason. Not just speed.
It has no cross-talk, either. It’s not sensitive to electro magnetic fields if any kinds.
It does not have potential or voltage level issues.
It does not cause ground loops etc.
But all that people do is complaining how fragile optical cables are and that they can’t be bent. *sigh* 😞
Ethernet is magnetically coupled. It’s galvanically isolated by design. You’re not connecting hot chassis to anything with modern Ethernet. 10baseT hasn’t been used commonly for decades. Please be more clear when you’re off-topic. Someone might make the mistake that your complaints about it are relevant to the article in some way.
Is it true if you use shielded cables (STP) instead of unshielded ones (UTP)? Shielded cables connect ground between different devices so ground loops are possible.
Also this articles says that noise isolation is not perfect and that some 60 Hz hum stills slip through: https://www.thewelltemperedcomputer.com/Intro/SQ/GalvanicIsolationEthernet.htm
Probably has little to no effect on digital data transmission, but at the DAC level, this can lead to noise transmission in the analog lines.
This /\. To add.. there’s “coupling” all over the place including effective “diodes” that demodulate the high freq noise into the audio spectrum. Not to mention ground loops galore.
There’s ground loops all over that kiddy design, optical solves that , simple as that. Guessing ur not a pro working at say TI analog.. funny how the most clueless r always the most douchey.
I guess we are far enough removed from the peak of analog audio that this kind of advice regarding cross-talk is forgotten.
Use “fewer” in regard to things countable and “less” in regard to things uncountable.
All my homebrew radio equipment has hand lettered sharpie markings and all my volume knobs go to 11.
Mad respect for everything about this project. Also acceptable is plastic label maker tapes, the old kind not the new thermal variety.
I have always loved the simplicity of old school amplifier so I set out to make the most simple one it was my first circuit board that I orderd
I started whit 2 huge transformers 10 volts and probably 20A each. Bigger then a microwave oven transformer
But don’t get as hot or noisy
Recifyed those whit some rectifiers I got from broken pc power supplies
I hooked toss up to extremely overkill capasitars 20v 0.5 Farad trust me ter is no noise anymore
Those make up the +10 -10 volts that the 2 amplifier boards
Each contains 2 opamps and 4 power transistors one opamp aplyfies the signal enoug for the transistors to function
The second opamp compares the output signal to the input signal and makes it super low distortion
Tere is no volume bass ar treble at all you don’t need it. We got modern pc soundcards for that.
Been listening to it on some big DIY speaker for 4 years now and I love it never gets hot
Could really use some more volts but full volume is enough so it’s no problem
Or 4 ohm speakers
I never really turn it of it makes no his in the speaker what so ever