Do you have a Roberts analogue radio with muffled or distorted sound?
The loudspeaker fitted to the R250 and larger R550 is a small lightweight 3 inch / 75mm driver which usually produces poor sound quality – see the “Dynamic” speaker on the right hand side below. It’s not that difficult to find and fit a better quality driver that improves the sound.
R250 Loudspeakers
R250 Loudspeakers
For example, the speaker with the much larger magnet on the left adds clarity and a little more depth to the bass response. Look for the “Eagle” L018A which are inexpensive and well made. Best keep to 8Ω types rather than 4 ohms which can require more power than the tiny 1 watt audio amplifier can provide. The larger magnet does make the radio heavier to carry about so there’s no gain without pain.
With the replacement speaker the detail in higher frequencies is impressive and sounds almost hifi on decent FM programmes – sound quality on par with the solid wooden case. Improving the bass response further is not so easy and requires fitting a larger elliptical driver echoing the original R200 design. There’s not much space inside due to the large 9v battery taking up nearly a third of the width – even though from outside the grille suggests otherwise.
Avoid the transparent Mylar coned drivers that sound awful and are meant for siren alarms rather than good quality audio.
Added picture of replacement speaker mounted inside a R250. It just clears the circuit board by about 5mm.
Replacement speaker fitted inside R250.
25/05/2018 at 6:12 pm
Tried this to improve sound as you say, however the strong magnet being so close to the tuning components appear to affect the tuning performance. Put back the original speaker and now things are back to normal.
Not a good idea
25/05/2018 at 8:29 pm
That’s strange, I’ve modified five R250s with no such problem. Which wavebands were affected?
25/05/2018 at 8:57 pm
It affected all three bands but especially FM.
Really bad.
Sorry but when old speaker was put back in all was well.
The magnet is really powerful.
It really affected tuning and reception like a low signal area which this is not.
25/05/2018 at 10:12 pm
I’m intrigued – was your Roberts R250 the same model with the FM aerial on the right hand side? Or the R250 mark 2 with the aerial on the left?
Did you use a 9v power adapter or battery?
The only components I can think of that could be affected by the magnet are the ferrite coils which have a shield. The AM ferrite aerial would not affect FM and the FM IF uses a ceramic filter.
26/05/2018 at 3:35 pm
Aerial right hand side using full battery.
It was affecting the tuning in this case because when the original speaker was refitted it is normal.
Money wasted.
26/05/2018 at 5:11 pm
Have added picture of the upgraded speaker I’ve fitted to several R250s. It works perfectly with only 5mm clearance between tallest PCB components.
I can only assume the speaker you bought is faulty. I’ve tried a very strong magnet close to the tuning capacitor on one R250 I have and it’s unaffected.
You could try a magnet near your tuning capacitor and see if it changes the signal or test your speaker on another radio to check it’s not faulty / low sensitivity. Sorry it did not work for you.
05/08/2020 at 10:54 pm
Just to let you know I did this on three R250s using the 8ohm 1watt eagle speaker and they all sound fab! Thanks for the tip.
06/08/2020 at 6:47 am
Thanks, surprising that a simple upgrade can make such an improvement. Glad it helped.
08/01/2023 at 8:22 pm
Hi, I have a Roberts R250 revival radio.
I have been reading the comments regarding the poor quality speaker fitted to this model.
I am interested in upgrading the speaker, we’re do obtain the upgraded speaker mentioned in this forum?
08/01/2023 at 9:25 pm
Hello Paul, eBay usually have several new drivers listed. Try searching for 3 inch or 75mm 8 ohm speaker. Check the depth of the driver will fit as mentioned in the post. For best bass results you may find an oval / elliptical speaker that will fit. Let us know how you get on.
08/01/2023 at 10:43 pm
Found the box from one replacement speaker I used, a Visaton FR8JS – it’s ~ 37mm deep if the cardboard ring is removed so just clears the PCB. This was little more expensive but is full range down to 100Hz.
25/01/2023 at 5:25 pm
Hello Rick, Thank you for your reply and sorry for the late response.
Information gladly appreciated.
I will try and track down the FR8JS.
I will let you know how I get on.
30/08/2023 at 9:58 am
Hello Rick, can the sound on the original speakers sometimes begin to sound ‘robotic’. This happened to mine, and I re-centred the coil, covered a small perforation with tissue paper and p.v.a. All sounds good now, just hoping it stays that way, thanks Amanda
30/08/2023 at 6:56 pm
Yes the small speaker Roberts fitted to the Revival series of that era are prone to ‘raspy’ distortion – like a sci-fi robot! You did well to recenter the voice coil – they can distort and catch between the magnet centre. Sounds like it was caused by physical damage to the paper cone. Similar distortion can also occur if there’s a DC voltage across the speaker when there’s a leaky 470uF electrolytic capacitor from the audio chip. Hope your fix continues to sound good. If not, in this post I show some speaker upgrade options that can improve sound quality although it does depend on finding a good quality driver that fits inside.