Roberts RP28, Speakers Question - UK Vintage Radio Repair and Restoration Discussion Forum

Carlo · 13th Dec 2007, 11:04 am

Here I am again.
Yesterday I asked your precious help about repairing my Robert RP28 and you solved my problem.
Today I am listening to my radio, but I am not so happy.
In comparison with my other two radios it has a dull sound, weaker and less 'round'.
Through the cabinet I can see the speaker, and the speaker looks different from the two I already have. It has a different colour, its metal reflects light.
I think they changed it.
Do you know if it is possible to get original spare parts from Roberts somewhere? Or do you know what kind of speakers are the best for my RP28?
Thank you
Best regards,
Carlo

Nickthedentist · 13th Dec 2007, 11:21 am

Carlo,

Could you post a picture of your "bad" speaker, as well as one of your "good" ones as a comparison?

Nick.

Darren-UK · 13th Dec 2007, 11:22 am

Hi Carlo,

Before you go down the road to sourcing a replacement loudspeaker, you really should check to see if it actually is the speaker at fault.

I don't know, off the top of my head, what the 'speaker impedance of the RP28 is.......it might be 8ohms but that's just a guess. Another member will no doubt confirm, but the impedance is usually stamped on the 'speaker frame somewhere quite obvious.

Test the 'speaker first by substitution. Do you have another 'speaker laying around which you could temporarily connect to the RP28? Any old thing (in known good order) will do providing the impedance more or less matches. You can use one of slightly higher impedance but it'll give reduced volume. Transistor radio 'speakers are commonly of 8ohms so, if that's what that of the RP28 is, you shouldn't have much trouble.

If you can do this and you find the original 'speaker is ok, you will need to look elsewhere in the radio. Maybe dirty switch contacts, misalignment, a duff capacitor here and there......and so forth.

If you don't understand about alignment tell us this.....when you operate the radio, are stations on all bands coming in where they should do on the tuning scale?

That will do for now as we'll drift off-topic if we're not careful. Let us know if you can test the 'speaker by substitution and we'll progress from there.

Carlo · 13th Dec 2007, 11:30 am

Not really, as I have not digital cameras.
The more I look through the grids, the more I see that the original speaker is pretty 'invisible', maybe black, probably matt, and looks like a small woofer. The bad one is shining through the grid, has a brass color, look like a very cheap one and looks like a tweeter.
Something like this.

Dear Darren (thank you for your opening instructions,)
the bad speaker works the best it can. This is the problem. Probably this a very cheap loudspeaker. The previous owner changed it, now I am quite sure of it, they are different. The radio looks perfect, contacts and switches are fine, looks quite new inside.

The original Roberts RP28 is 8ohms and 100mm. Output Power 1watt into 8ohms.

Darren-UK · 13th Dec 2007, 12:06 pm

Ok. As you haven't confirmed you have a spare 'speaker laying around, try substituting it with a known good one from one of your other radios. You only need to do a temporary connection, not a complete transplant.

As Nick said, photos may be helpful but if you can't do that we'll have to progress without. From what you describe it does sound as if the radio has been given a replacement 'speaker though.

Paul_RK · 13th Dec 2007, 1:57 pm

Here's a quick photo of the speaker in my RP28: it's quite a substantial little 4" unit, and works well. Roberts have often changed the loudspeaker type fitted to particular radio models in the course of a production run. Having said that, the only black-framed speakers I'm aware of them having used this side of the mid-1970s are some rather nasty little plastic-framed ones. I think those had been given up on well before the RP28 came along.

Paul

Carlo · 13th Dec 2007, 2:16 pm

Thank you Paul,
this speaker is the one I have mounted on both my good working radios.
The bad one is different.
The main difference between the good and the bad, beside the colour, is the shape of front part (not pictured in your photo). The bad one is made like a small trumpet and this sort of trumpet is jutting out, protudes a lot from the very body of the speaker (sorry for my creative english...)

Darren-UK · 13th Dec 2007, 3:01 pm

I've been wondering if the radio has been damaged by attempts to run it with the loudspeaker disconnected. This is a more familiar risk with valve radios; anyone know how prone something like an RP28 is to such damage?

Whatever. Carlo, if you can't source another 'speaker locally and no forum members can help, you could try Pete Roberts. His site shows he has some 100mm 8ohm jobs available but I'm unsure how often he updates this info.

Roberts Radio themselves may also be able to help but, whether it's from RR or Pete Roberts, you'll need to take international postage into account.

Btw Carlo, do you not have a mobile 'phone with a camera? such should take a good enough picture of the bad 'speaker.

Nickthedentist · 13th Dec 2007, 3:45 pm

Quote:

Originally Posted by darren-uk

I've been wondering if the radio has been damaged by attempts to run it with the loudspeaker disconnected. This is a more familiar risk with valve radios; anyone know how prone something like an RP28 is to such damage?

It would be easy to connect the wires from this radio to the speaker in one of the good radios as a test.

CPC sell loads of generic speakers, several of which would no doubt do.

This type of speaker also crops up regularly in 1980s TVs

Nick.

Carlo · 13th Dec 2007, 4:54 pm

I just connected the 'bad' radio to the speaker of the good one and it sounded perfectly.
So it means I need to find a new speaker to install. Not a big deal. But I thought that Roberts radio mounted special speakers, am I wrong? Yes I guess...
(Thank you)

Darren-UK · 13th Dec 2007, 4:57 pm

Yes, you're wrong. They're standard mass-produced items.

Carlo · 13th Dec 2007, 5:03 pm

Oh.
But they sound so good in comparison to the other radios I have.

Darren-UK · 13th Dec 2007, 5:09 pm

It's the wooden cabinets which make the difference. If you listen to, say, an R707 you'll think twice about the audio quality of the RP28. It's all relative really.

Carlo · 13th Dec 2007, 5:15 pm

I will.
Here in Italy it is impossible to find a Roberts radio.
So I need to buy them in UK, so next purchase will be a R707 in good conditions (hopefully)...

Nickthedentist · 13th Dec 2007, 5:17 pm

Almost completely off-topic, but do try a HACKER if you want a really nice sounding portable radio. These usually have big Goodmans or Celestion speakers.

Carlo · 13th Dec 2007, 5:21 pm

Thank you Nick,
I will search for infos about HACKER, I am sure they are great but I don't know how do the look.
But I must say I like the old style look of the Roberts.

I just at Hacker radios and they have a very similar look.
So I will search for a good Hacker.
There is a specific model that is more valuable?
Too much Off Topic?

Nickthedentist · 13th Dec 2007, 8:29 pm

Quote:

Originally Posted by Carlo

Too much Off Topic?

Definitely

See this thread: https://www.vintage-radio.net/forum/...ghlight=hacker and also search for "Hacker" in this forum.

Now back to RP28 speakers....

Nick

13th Dec 2007, 11:04 am	#1
Carlo Retired Dormant Member Join Date: Dec 2007 Location: Milan, Italy Posts: 31	Roberts RP28, Speakers Question Here I am again. Yesterday I asked your precious help about repairing my Robert RP28 and you solved my problem. Today I am listening to my radio, but I am not so happy. In comparison with my other two radios it has a dull sound, weaker and less 'round'. Through the cabinet I can see the speaker, and the speaker looks different from the two I already have. It has a different colour, its metal reflects light. I think they changed it. Do you know if it is possible to get original spare parts from Roberts somewhere? Or do you know what kind of speakers are the best for my RP28? Thank you Best regards, Carlo

13th Dec 2007, 11:21 am	#2
Nickthedentist Dekatron Join Date: Jan 2005 Location: Oxford, UK. Posts: 17,844	Re: Roberts RP28, Speaker's Question Carlo, Could you post a picture of your "bad" speaker, as well as one of your "good" ones as a comparison? Nick.

13th Dec 2007, 11:22 am	#3
Darren-UK Retired Dormant Member Join Date: Apr 2003 Location: Blackpool, Lancashire, UK. Posts: 4,061	Re: Roberts RP28, Speaker's Question Hi Carlo, Before you go down the road to sourcing a replacement loudspeaker, you really should check to see if it actually is the speaker at fault. I don't know, off the top of my head, what the 'speaker impedance of the RP28 is.......it might be 8ohms but that's just a guess. Another member will no doubt confirm, but the impedance is usually stamped on the 'speaker frame somewhere quite obvious. Test the 'speaker first by substitution. Do you have another 'speaker laying around which you could temporarily connect to the RP28? Any old thing (in known good order) will do providing the impedance more or less matches. You can use one of slightly higher impedance but it'll give reduced volume. Transistor radio 'speakers are commonly of 8ohms so, if that's what that of the RP28 is, you shouldn't have much trouble. If you can do this and you find the original 'speaker is ok, you will need to look elsewhere in the radio. Maybe dirty switch contacts, misalignment, a duff capacitor here and there......and so forth. If you don't understand about alignment tell us this.....when you operate the radio, are stations on all bands coming in where they should do on the tuning scale? That will do for now as we'll drift off-topic if we're not careful. Let us know if you can test the 'speaker by substitution and we'll progress from there.

13th Dec 2007, 11:30 am	#4
Carlo Retired Dormant Member Join Date: Dec 2007 Location: Milan, Italy Posts: 31	Re: Roberts RP28, Speaker's Question Not really, as I have not digital cameras. The more I look through the grids, the more I see that the original speaker is pretty 'invisible', maybe black, probably matt, and looks like a small woofer. The bad one is shining through the grid, has a brass color, look like a very cheap one and looks like a tweeter. Something like this. Dear Darren (thank you for your opening instructions,) the bad speaker works the best it can. This is the problem. Probably this a very cheap loudspeaker. The previous owner changed it, now I am quite sure of it, they are different. The radio looks perfect, contacts and switches are fine, looks quite new inside. The original Roberts RP28 is 8ohms and 100mm. Output Power 1watt into 8ohms. Last edited by Carlo; 13th Dec 2007 at 11:41 am. Reason: To Darren

13th Dec 2007, 12:06 pm	#5
Darren-UK Retired Dormant Member Join Date: Apr 2003 Location: Blackpool, Lancashire, UK. Posts: 4,061	Re: Roberts RP28, Speakers Question Ok. As you haven't confirmed you have a spare 'speaker laying around, try substituting it with a known good one from one of your other radios. You only need to do a temporary connection, not a complete transplant. As Nick said, photos may be helpful but if you can't do that we'll have to progress without. From what you describe it does sound as if the radio has been given a replacement 'speaker though.

13th Dec 2007, 1:57 pm	#6
Paul_RK Dekatron Join Date: Nov 2003 Location: Fakenham, Norfolk, UK. Posts: 4,255	Re: Roberts RP28, Speakers Question Here's a quick photo of the speaker in my RP28: it's quite a substantial little 4" unit, and works well. Roberts have often changed the loudspeaker type fitted to particular radio models in the course of a production run. Having said that, the only black-framed speakers I'm aware of them having used this side of the mid-1970s are some rather nasty little plastic-framed ones. I think those had been given up on well before the RP28 came along. Paul Attached Thumbnails

13th Dec 2007, 2:16 pm	#7
Carlo Retired Dormant Member Join Date: Dec 2007 Location: Milan, Italy Posts: 31	Re: Roberts RP28, Speakers Question Thank you Paul, this speaker is the one I have mounted on both my good working radios. The bad one is different. The main difference between the good and the bad, beside the colour, is the shape of front part (not pictured in your photo). The bad one is made like a small trumpet and this sort of trumpet is jutting out, protudes a lot from the very body of the speaker (sorry for my creative english...)

13th Dec 2007, 3:01 pm	#8
Darren-UK Retired Dormant Member Join Date: Apr 2003 Location: Blackpool, Lancashire, UK. Posts: 4,061	Re: Roberts RP28, Speakers Question I've been wondering if the radio has been damaged by attempts to run it with the loudspeaker disconnected. This is a more familiar risk with valve radios; anyone know how prone something like an RP28 is to such damage? Whatever. Carlo, if you can't source another 'speaker locally and no forum members can help, you could try Pete Roberts. His site shows he has some 100mm 8ohm jobs available but I'm unsure how often he updates this info. Roberts Radio themselves may also be able to help but, whether it's from RR or Pete Roberts, you'll need to take international postage into account. Btw Carlo, do you not have a mobile 'phone with a camera? such should take a good enough picture of the bad 'speaker.

13th Dec 2007, 4:54 pm	#10
Carlo Retired Dormant Member Join Date: Dec 2007 Location: Milan, Italy Posts: 31	Re: Roberts RP28, Speakers Question I just connected the 'bad' radio to the speaker of the good one and it sounded perfectly. So it means I need to find a new speaker to install. Not a big deal. But I thought that Roberts radio mounted special speakers, am I wrong? Yes I guess... (Thank you)

13th Dec 2007, 4:57 pm	#11
Darren-UK Retired Dormant Member Join Date: Apr 2003 Location: Blackpool, Lancashire, UK. Posts: 4,061	Re: Roberts RP28, Speakers Question Yes, you're wrong. They're standard mass-produced items.

13th Dec 2007, 5:03 pm	#12
Carlo Retired Dormant Member Join Date: Dec 2007 Location: Milan, Italy Posts: 31	Re: Roberts RP28, Speakers Question Oh. But they sound so good in comparison to the other radios I have.

13th Dec 2007, 5:09 pm	#13
Darren-UK Retired Dormant Member Join Date: Apr 2003 Location: Blackpool, Lancashire, UK. Posts: 4,061	Re: Roberts RP28, Speakers Question It's the wooden cabinets which make the difference. If you listen to, say, an R707 you'll think twice about the audio quality of the RP28. It's all relative really.

13th Dec 2007, 5:15 pm	#14
Carlo Retired Dormant Member Join Date: Dec 2007 Location: Milan, Italy Posts: 31	Re: Roberts RP28, Speakers Question I will. Here in Italy it is impossible to find a Roberts radio. So I need to buy them in UK, so next purchase will be a R707 in good conditions (hopefully)...

13th Dec 2007, 5:17 pm	#15
Nickthedentist Dekatron Join Date: Jan 2005 Location: Oxford, UK. Posts: 17,844	Re: Roberts RP28, Speakers Question Almost completely off-topic, but do try a HACKER if you want a really nice sounding portable radio. These usually have big Goodmans or Celestion speakers.

13th Dec 2007, 5:21 pm	#16
Carlo Retired Dormant Member Join Date: Dec 2007 Location: Milan, Italy Posts: 31	Re: Roberts RP28, Speakers Question Thank you Nick, I will search for infos about HACKER, I am sure they are great but I don't know how do the look. But I must say I like the old style look of the Roberts. I just at Hacker radios and they have a very similar look. So I will search for a good Hacker. There is a specific model that is more valuable? Too much Off Topic? Last edited by Carlo; 13th Dec 2007 at 5:39 pm. Reason: Update