Question about speakers - UK Vintage Radio Repair and Restoration Discussion Forum

Strongbowpeter · 1st Apr 2015, 9:19 pm

Why do some speakers have a coil fitted to them? And can you replace them with normal speakers

Wellington · 1st Apr 2015, 9:50 pm

Hi SBP

I'm not sure what you mean, here. When you say 'coil fitted to them', do you mean like in the middle picture in this post?

That thing hanging below the speaker is the output transformer - is that what you mean? (Apologies if this is a patronising question - just want to clarify

).

Dickie · 1st Apr 2015, 9:59 pm

The OP could also be referring to "energised loudspeakers" where the main magnetic field is provided by a large coil driven by the main HT current, or possibly even small coils attached to the frame of the loudspeaker for convenience that are part of a crossover network.

AC/HL · 2nd Apr 2015, 2:37 am

The link in post 2 illustrates both of the above answers. More information, or a photo are needed to answer your question, which is not Manufacturer specific.

Strongbowpeter · 2nd Apr 2015, 5:14 am

Quote:

Originally Posted by Wellington

That thing hanging below the speaker is the output transformer - is that what you mean?

Yes that's it, can a normal speaker be used

Diabolical Artificer · 2nd Apr 2015, 7:24 am

Yes as long as you make sure that the "coil" on the speaker you are replacing is replaced itself by either a choke or other inductor. That is if the speaker in question is part of a radio or valve tape deck.

Andy.

Radio Wrangler · 2nd Apr 2015, 9:27 am

The coil like item mounted below the magnet on the speaker in that middle photo is the radio's output transformer, and is more a part of the radio than the speaker. The manufacturer put it there to save space on the main radio chassis.

If you buy a 'normal' speaker, it will come without one and you will need to re-use the one from the existing speaker.

The speaker in that middle photo is unusual by todays standards because it doesn't use a permanent magnet, it has a coil for an electromagnet hidden from sight inside that brown dome shape, you can see two wires sneaking in from the bottom side. These coils run at high voltage and the way they were wired makes it more work to keep the set funttional after a speaker is changed.

There are two terminals on that speaker shown over at the right hand side, and these are the connections to the 'voice coil' the connections that the sound signal fro the radio chassis is fed to (via that output transformer.

Then there are some radios with added coils to split high and low sounds between different speakers.

Without photos or a model number, the only advice you can be given will be so general that it won't help you.

David

1st Apr 2015, 9:19 pm	#1
Strongbowpeter Retired Dormant Member Join Date: Nov 2013 Location: Leighton Buzzard, Bedfordshire, UK. Posts: 20	Question about speakers Why do some speakers have a coil fitted to them? And can you replace them with normal speakers

1st Apr 2015, 9:50 pm	#2
Wellington Hexode Join Date: Jun 2009 Location: Cheshire, UK. Posts: 363	Re: Elac speaker Hi SBP I'm not sure what you mean, here. When you say 'coil fitted to them', do you mean like in the middle picture in this post? That thing hanging below the speaker is the output transformer - is that what you mean? (Apologies if this is a patronising question - just want to clarify ).

1st Apr 2015, 9:59 pm	#3
Dickie Octode Join Date: Sep 2004 Location: St. Albans, Hertfordshire, UK. Posts: 1,478	Re: Elac speaker The OP could also be referring to "energised loudspeakers" where the main magnetic field is provided by a large coil driven by the main HT current, or possibly even small coils attached to the frame of the loudspeaker for convenience that are part of a crossover network. __________________ Regards, Richard, BVWS member

2nd Apr 2015, 2:37 am	#4
AC/HL Dekatron Join Date: Nov 2003 Location: Heckmondwike, West Yorkshire, UK. Posts: 9,643	Re: Question about speakers The link in post 2 illustrates both of the above answers. More information, or a photo are needed to answer your question, which is not Manufacturer specific.

2nd Apr 2015, 7:24 am	#6
Diabolical Artificer Dekatron Join Date: Jul 2009 Location: Sleaford, Lincs. UK. Posts: 7,670	Re: Question about speakers Yes as long as you make sure that the "coil" on the speaker you are replacing is replaced itself by either a choke or other inductor. That is if the speaker in question is part of a radio or valve tape deck. Andy. __________________ Curiosity hasn't killed this cat...so far.

2nd Apr 2015, 9:27 am	#7
Radio Wrangler Moderator Join Date: Mar 2012 Location: Fife, Scotland, UK. Posts: 22,905	Re: Question about speakers The coil like item mounted below the magnet on the speaker in that middle photo is the radio's output transformer, and is more a part of the radio than the speaker. The manufacturer put it there to save space on the main radio chassis. If you buy a 'normal' speaker, it will come without one and you will need to re-use the one from the existing speaker. The speaker in that middle photo is unusual by todays standards because it doesn't use a permanent magnet, it has a coil for an electromagnet hidden from sight inside that brown dome shape, you can see two wires sneaking in from the bottom side. These coils run at high voltage and the way they were wired makes it more work to keep the set funttional after a speaker is changed. There are two terminals on that speaker shown over at the right hand side, and these are the connections to the 'voice coil' the connections that the sound signal fro the radio chassis is fed to (via that output transformer. Then there are some radios with added coils to split high and low sounds between different speakers. Without photos or a model number, the only advice you can be given will be so general that it won't help you. David __________________ Can't afford the volcanic island yet, but the plans for my monorail and the goons' uniforms are done