Log Vintage radio project needs a redesign

[Phuncz]

In the past I've made an internet radio out of the shell of an old radio:

Raspberry Pi 1st gen on the right, crappy power supply on the right.

It has been updated by then. The problem is, I have a amplifier that only plays one channel and a lot of issues I'd like to fix. But most of it can only be done by a full redesign. So I'm planning on changing almost everything except the case, speakers and RPi 3.

So let's start with the different issues. I need a new amplifier. Most likely a new power supply (currently 90W 19V laptop charger). A new solution for the audio source. I hope to get some advice about this.


Speakers:

High-end: 120-20.000Hz. Just the speakers, the PCB was broken.

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Unsure but I believe 9W RMS at 4 Ohms

Low-end: 20-120Hz

https://www.macrom.it/manuals/Speakers/Manual-i240-5410.pdf

About 50W RMS at 4 Ohms

I'd like a recommendation for an amplifier that will allow me to have low and high tones split. Something not too high-end in price as this is for streaming radio 50-70s music.


Audio Source:

I've used a Raspberry Pi 3 with the MusicBox distro. While it does everything, it doesn't do it without issues and isn't being updated. So I'm looking for a solution that can be controlled through web-interface and allows to play streams. Ideally it would also be an Airplay target. The older Raspberry Pi I had needed a seperate audio card to be remotely enjoyable but I found the 3rd generation Pi to be a lot better and I'll try and get good sound without it. Or use an USB DAC / Amp to keep the signal digital as long as possible.


Issues:

There are several things that need to be addressed but are not too huge:

• potentiometers working a correctly sized.
• easy to work with (connectors) but using quality wiring and layout. Recommendations to avoid electrical noise would be welcome.
• keep most of the wait at the middle, but I might make a box for the "subwoofers".
• figure out something for the old glass display so it is visible. I already have a warm LED strip in there but it's dispersing.

 

[Phuncz]

An update:

I'm looking at dealing with multiple problems by using a Sure Electronics / Wondom solution like these: http://store.sure-electronics.com/list/3/10
A lot of options with these kits.

 

[GuilleAcoustic]

Dr GuilleAcoustic has joined the conversation. I'll post a proper answer once I have access to a device with a keyboard .

There are a few great solution, OS wise and shieldwise (DAC + Amp Hats).

What's your budget ? I'll make a sélection with different budget range.

 

[GuilleAcoustic]

Here we go ....

Linux distribution of choice :

I'd suggest either Rune Audio or Volumio. Volumio has my preference as it also allows playing music from Spotify out of the box. It also has UPNP and Airplay playback. There's a version with annual fees if you want Tidal or Qobuz integration out of the box ......

Hardware wise :

It's a trickier question. For stereo, you can use something like this that will provide DAC and 2x 30W @ 8 ohms output.

If you want to add a subwoofer to the loop, the easy solution would be to use a crossover and run an amp per "channel" (one for high and one for low). I'll try to find something "off the shelves".

There are solution to make you own active sub too, like this one. It is a more ghetto solution as you'd have to route inputs and outputs in and out of the chassis (or play with the soldering iron), but it provides everything (2 speakers out, line in/out, crossover, etc.). It works as a 2.1 or 0.1 solution... just have Rpi line out --> sub module line in .... then ... sub module speaker outs --> "high freq" speakers.

Edit: For the "low" do you want to add a "sub" per channel or run a single mono "sub" à la 2.1 ?

 

[TinyAudio]

Beocreate | HiFiBerry

Can be used on any speakers not only B&O

 

[GuilleAcoustic]

Beocreate | HiFiBerry

Can be used on any speakers not only B&O

Ain't cheap but hifiberry works well with audio oriented Rpi distribution such as Rune or Volumio. I'm adding that to my bookmarks ...

 

[Phuncz]

Thanks for all the suggestions guys ! I've looked at the BeoCreate but it's just too expensive for the quality of the speakers. Volumio was also on my shortlist and RuneAudio I've also recently seen suggested, so I'll look into that.

I'm going to test the Macron speakers (spec sheet) with a decent amplifier first, as it might as well work good for full-range instead of using it just for the lows. It's designed for full-range, the yellow thingie on the back is the crossover. I was first contemplating using two amplifier boards from Sure Electronics, but I'm going to try just the Macron full-range speakers in a good enclosure first. This will also be the most cost-effective and will still allow me to expand to a second amplifier without sacrificing possibilities, as the Sure Electronics (Wondom) JAB2 and JAB3 amps can be intelligently connected to eachother (link).

They also have a PCB for using 18650 Li-ion batteries so it can become a battery powered solution with safe and smart charging built in. Making it an easy to use but more integrated product is a huge plus.

 

[GuilleAcoustic]

Those old radio were often rocking a single full range driver. Tang band has some nice and cheap full range speakers too.

If you only need stereo, then the Hat I listed should be plenty enough and you'd even have hardware volume control through it.

The Hifiberry Amp2 is also a cheap DAC+ Amp solution: https://www.hifiberry.com/shop/boards/hifiberry-amp2/

Nice thing is that this board will also provide power to the Raspberry. All you'll need will be a 12-24V AC-DC.

Out of curiosity, do you know the brand and model of that chassis ?

 

[Phuncz]

The model is the Siera S243A: https://www.radiomuseum.org/r/siera_243a.html

 

[GuilleAcoustic]

The model is the Siera S243A: https://www.radiomuseum.org/r/siera_243a.html

Nice .... not thank you .... cause now I have one more project on my todo-list that I'll never manage to start/finish lol.

I had an old Philips 521A TSF that I wanted to restore, but I never found time for that and ended up throwing it away when I moved appartment.

Can't wait to see how everything will unfold.

 

[Phuncz]

Faster than expected the components from Sure Electronics (Wondom) have arrived:

Top middle: Wondom BCPB3 (battery charge/discharge unit)
Top right: Sanyo Panasonic NRC18650GA x5 (Li-Po 18650 size batteries)
Bottom far left: Wondom BCPB3/4 functional cable kit (cables and lights)
Bottom middle 1: Wondom L-bracket for JAB series (for easy mounting)
Bottom middle 2: Wondom JAB series functional cable kit (cables and lights)
Bottom far right: Wondom JAB250 (2x 50W amplifier with Bluetooth connectivity)

The battery system. It allows simultaneous charging and discharging, has plenty of protections and is designed to work with the amplifier in mind so no random pops when disconnecting or powering on/off. The batteries are a recommendation from a local battery shop who has all the good quality Li-Po cells on stock, it should suffice for this purpose but I have no idea how long it'll last.

The amplifier which will power the speakers but also allow Bluetooth 4.0 + APT-X and AD2P connectivity (works flawlessly) but also has a line-in. This will allow me to add the Raspberry Pi for independent playback. It's not much bigger than a pack of cards.

Connected and working !

Notice the RGB: Red = charging, Green = power on, Blue = Bluetooth connected. The four LEDs on the left are the charge indicator (25-50-75-100%).
It works flawlessly. The only thing I'm missing is the Interface Extension Board.

 

[Windfall]

I have nothing to contribute, but this is a super cool project!!
Honestly, audio stuff is just beyond me.

 

[Phuncz]

Thanks !

So after the first charge, I've have had it playing for about 12 hours, battery indicator still says it's above 75% on low volume (double pun) so it could fill a quiet room. No strange occurances of any kind, although I'm still trying to figure out the 10-pin connector.

The next step will be to mount the speakers on a piece of MDF and secure it to the case somehow.

 

[REVOCCASES]

although I'm still trying to figure out the 10-pin connector.

Great project. I also love combining something old with new technology.

The SURE products are nice. I also used them for many HiFi projects. Although their documentation is sometimes a bit vague.

The 10 pin connector is for some of their add-on boards but don't ask me which one. Maybe they even didn't design it yet.

For the retro factor maybe you could still add a tube pre amp between the line-in of the class-d ... there are some small boards which would even run on battery.

just an inspiration from one of my projects, although it's not a speaker:

 

[Phuncz]

Another weekend, another step for this project:

Using Pioneer mounting rings the speakers can be held down with 4 bolts each.

Everything for the audio is mounted here, except the Raspberry Pi, I'm waiting on a part to connect it. Everything is mounted using threaded inserts, making the install very solid and everything removable.

Side profile of the 18mm MDF construction. This going to be bolted in the case on the bottom where it has 4 holes.


Next up is figuring out lighting of the front glass panel, figuring out the knobs and switches, mount the LEDs on the rear and some other stuff.

It still sounds amazing and battery life is as well, I think it took 20 hours of low volume play to go from 100% to 75% battery.

 

[Phuncz]

It's been a while but the project version 2.0 is finished. Not much has happened, the front still looks the same:

A warm white LED strip has been integrated just above the glass, which has a velours black back to prevent seeing inside. The left knob controls mains AC on/off to enable/disable charging. The right knob is to control amplifier volume. The two center knobs are decorative

The rear has been severely modified:

The top row of LEDs are for the amplifier with a switch to power the amp. The LEDs indicate: Charging (battery bank), Mains connected, Bluetooth connection. The green button is for controlling Bluetooth pairing.

The bottom row is for the battery bank indicating charge (<25%, <50%, <75%, <100%). The green button shows the status:

On the previous image you can also see USB and audio along with a switch. These are for the Raspberry Pi running Volumio. The switch disconnects the audio but doesn't break the USB power connection to the Pi. This allows switching the Raspberry Pi as an audio source on/off without needing to boot the OS. I choose to have these connectors externally because of the button but also to make it possible to connect another device without having to open up the enclosure.