Roon endpoint in old radio?


(Reader of the Internets) #1

I have an old Emerson AM radio disguised as a set of books labelled “History of Music”, similar to the one shown here:

https://radioattic.com/itemshow.htm?radio=1150595

I had thought to replace its guts with a Roon endpoint, probably a little class D amp and a Chromecast Audio. However, I’ll probably have to fit a single speaker which will have to have the same size as the existing speaker, and am not sure how to do that.

Any suggestions?


(simon arnold) #2

Raspberry pi 3 b+ and HifiBerry Amp2 fitted in the case connected to the speaker , use DietPi OS or Ropieee OS to install Roon Bridge and run the amp an use DSP in Roon to mono the output. I’ve used this combo in converting old speakers twice now and works flawlessly, sounds great and low cost.


(Reader of the Internets) #3

Thanks, Simon. Looks like good advice. I’ll go that way.

Any ideas about heat dissipation? This thing currently has one 4" hole in the back covered with silk scrim. I don’t want to add a fan unless I have to.

There are two knobs in front, one for tuning the AM dial, and one for volume. I thought I’d put in two high-precision potentiometers there, and run them into the RPi, which I think also has GPIO inputs? Or do I have to make them multi-position rotary switches?

The dial itself I thought could be replaced with a round LCD display, driven from the HDMI port of the RPi, running a Roon display, or perhaps a custom Roon extension letting me select from the most-played albums using one of the knobs. The volume knob would of course control the volume, though just how I don’t know yet.


(simon arnold) #4

No fans in any. Was a hot summer this year. They are still living. I guess the ports in my speakers help. A few holes will be fine, none evet got above normal operating temp. But it will depend on what’s around them. Too much wadding would effect them. But I would image you have plenty of room in thay box if you take all the main bits out.

If you want to use pots, then look at the IQaudio amp as it’s has the potential built in. Getting a volume pot on HifiBerry kit is a little trickier.


(Reader of the Internets) #5

I’ll post some pics in a couple of days. Ah, so no volume input on the HiFiBerry. I suppose the volume input could go back to the Roon Core via extension logic.


(simon arnold) #6

You can change the volume just not from a rotary controller easily. It’s doable but you need some extra bits. The IQAudio has a volume control that can be used in this way already I think.


#7

A few months ago, I ripped the guts out of my old Bush valve radio and installed a Pi with HifiBerry AMP+ , dietpi and Dynavox speakers.

I made a baffle to mount the speakers that was the same dimensions as the old speaker baffle but I had to build a frame around the edge so that the new (guitar amp) cloth would not touch the front-mounted speakers. (the original speaker was mounted behind the baffle).

I tried to get a rotary encoder to work to control the mixer volume but it didn’t seem to accurately sense the direction of rotation so I switched to plan b and installed an old USB IR sensor and blew the dust of an old remote control. Now buttons 1-9 play various internet radio stations and the volume up and down buttons control the volume. Sweet.(the knobs on the front current do nothing at all).

I have Spotyconnect installed so can plan to it from spotify from my phone and of course (when not doing either of the above) it works as a Roon endpoint just fine.

I plan to install some leds to back-light the tuner display (the leds I had had the wrong forward voltage so will need to buy some new ones).

I’m very happy with it and I like the sound very much (in the context of what it is and it’s intended purpose).

!


(Reader of the Internets) #8

The IQaudio also exposes the GPIO pins so I could add an A/D converter connected to the pots. Looks like a good solution.


(Reader of the Internets) #9

Very nice! So, what speakers are you using? I was thinking of a single 4" two-way car speaker.


#10

I went with 2 of these
https://uk.farnell.com/dynavox/55-5530/3-5-full-range-speaker-20-watt/dp/2827681

I had originally been hoping to install 4" drivers but they wouldn’t fit. In fact these only worked at all because they are square instead of round. I then found a site that bench tested 20 or so small full-range drivers and this one came or more or less at the top (and they’re pretty cheap). I can’t find the site at the moment.

I would personally recommend a hi-fi orientated driver rather than a car driver. You just need to figure out what size will work (which requires careful measurements and research).

This (US) site has some good info
https://www.parts-express.com/cat/woofers/15

For a 4",m something like this might work well. Again, you need to carefully measure if it will fit.


(Reader of the Internets) #11

Turns out there actually was a music historian named Ferguson.


(Reader of the Internets) #12

Yes, the IQaudio site has an encoder which it sells to use as volume control. Also explains how to hook it up in the technical documentation. Now I have to figure out how to replace the dial. And what to replace it with – the official Pi 7" display is probably too big to fit.


(Reader of the Internets) #13

This might work for the display:


(Reader of the Internets) #14

The unit, closed:

Open (only the right side opens, and the speaker is behind the left panel):

Control area is approximately 5" wide by 7.8" high by 1" deep:

So plenty of room for a flat-panel screen on this side, if necessary, though a Raspberry Pi 7" screen would be too wide. The diameter of that hole is 3.5", so a 3.4" round display would fit it nicely, I’d think, depending on the bezel.

Ventilation (and sound seems to be through the back:


(Reader of the Internets) #15

More pics…

Here it is with the back off, showing the antenna:

And with the antenna removed from its mounting bracket:

You can see that the chassis is attached to a board, which in turn is attached to the base of the cabinet with two screws, so easy to remove:

And from the front:

I’m wondering what the baffle over the speaker is:

And here’s the case without the old AM radio parts:


(Reader of the Internets) #16

Here are the mechanical specs on that 3.4" round display: