Vintage vs Modern Bells - UK Vintage Radio Repair and Restoration Discussion Forum

Sc00by121 · 15th Jan 2016, 7:58 pm

About a year ago I installed a new BT 50E bell and at the time I set it up I was disappointed by the ringing that I got from it. It was if the striker was hitting each bell so fast it wasn't giving it time to 'ring' it sounded like metal on metal.

I gave up in the end and left it at that.

Last week I was working on a building refurb and rescued a GPO bellset type 26 dated 1963. I found instructions on how to convert it to modern equipment and put in a resistor, hooked it upto an extension and heard the music of the 60's - Beautiful. What then crossed my mind is why the cheap plastic 50E unit i installed last year sounded rubbish.

I can't find any info on adjusting the 50E but have heard that they can be adjusted by rotating the bells? - Is this correct?

I also have since put up two external BT 80D. One sounds perfect out of the box but the other has the same issue as the 50E. Can these also be adjusted?

Cheers

TonyDuell · 15th Jan 2016, 9:49 pm

If the 50E and 80D are the bells I thnk they are, they actually use a traditional-ish bell mechanism. It's the single-coil one with the armature supported on a torsional leaf spring that turned up in very late 746s, etc. I've seen something similar (but with a 1K coil) in a Plessey Secretarial telephone.

Anyway, I seem to remember the 50E uses the traditional bell gongs, same as the ones in a 706, 746, etc. The mounting holes in the gongs are deliberately off-centre so you can adjust them by rotating. The hammer should not stay in contact with the gong, or it will sound very muffled. I am sure there are proper setting instructions but if you hold the armature one way and then the other you can turn the appropriate gong so the hammer is just clear of it. Then try it out.

The 80D has the concentric gongs, doesn't it? Again they have off-centre holes and can be set in much the same way, but it's a bit of a fiddle. Worth doing though!

AndiiT · 15th Jan 2016, 9:51 pm

Hi,
The volume of ringing on most dual gong bells can be adjusted by rotating the gongs as they are of eccentric design - generally the closer the gongs are to each other the lower the volume.

The only information that I can find on increasing the volume of Bell 80D is the last paragraph here

Regards

Andrew

Sc00by121 · 15th Jan 2016, 10:02 pm

Hi, thanks for the replies.
That actually sounds like that might get the 50E working properly, I never knew that with the rotation of the bells. Thinking back I remember the striker getting stuck on one bell when the ringing stopped, suggesting they are too close. I'll experiment next week and will report my findings.

With the 80D I'm not too sure about, I'll need to have another look at it. It's on the side of a building which is very exposed to the elements and even though it's been up only a few months an inspection at the end of last year has shown it to be very rusty and full of spiders and cobwebs. When ringing now all I get is a pathetic patter from the striker. I'll need to spend a bit of time on this one to see what's going on as the other 80D I have hidden under the eves of a shed is super loud. It could be a line issue as this particular line is fed via CAT-5 rather than traditional cable.

Sc00by121 · 16th Jan 2016, 12:26 pm

I'll check these out next week, but before I do, can I just clarify on how to know when the bells are adjusted correctly?

With the 50E, do I rotate one bell and keep ringing it until it sounds right or do I rotate both and measure the gap? - Is there an easy way to know how the adjustment is going by just looking at it?

With the 80D, I assume this will be roughly the same idea? - Slacken the main bolt and rotate then ring it to see if it's better or worse?

TonyDuell · 16th Jan 2016, 7:12 pm

What I do is to push the armature (not the hammer directly, as that is flexible) all the way one way with a screwdriver (you'll see what I mean). Then adjust that gong so that there is a small clearance (10's of thou) between the hammer and the gong. Repeat with the armature held the other way and adjust the other gong.

For the 80D, start by cleaning it, you may find evidence of insects/arachnids that is damping the gongs. Then bascally do the same thing, but of course the 2 gongs are on one bolt so you have to set one (inner one first I think), hold it in place and adjust the other.

OscarFoxtrot · 16th Jan 2016, 10:55 pm

Adjustment of Magneto Bells,

http://www.britishtelephones.com/belladj1.htm

Sc00by121 · 17th Jan 2016, 2:42 pm

Very interesting and detailed!

I'll have a go next week and will report back.

dagskarlsen · 20th Jan 2016, 8:22 am

Quote:

Originally Posted by Sc00by121

I'll check these out next week, but before I do, can I just clarify on how to know when the bells are adjusted correctly?

With the 50E, do I rotate one bell and keep ringing it until it sounds right or do I rotate both and measure the gap? - Is there an easy way to know how the adjustment is going by just looking at it?

With the 80D, I assume this will be roughly the same idea? - Slacken the main bolt and rotate then ring it to see if it's better or worse?

Yes you may adjust by visual observation. In rest position the clapper should almost hit the closest bell, and similar in the oposit position. The small gap will be eliminated during ringing by the spring action in the clapper armature. By fine tuning during ringing, you may even get a more comfortable sound. Of-course this will vary by the mass and resonant frequency of the gong and the base it is mounted in. The older heavier phones has another sound than light plastic bases with small lightweight gongs. On pictures I have seen gongs made of hardwood, glass etc, and may just imagine the sounds.

The modification with the resistor is just to make the older ringers not draw that heavy load, and may weaken the volume. With resistor the exchange may not "see" the difference of an old or a new ringer.

dsk

Sc00by121 · 20th Jan 2016, 8:09 pm

hi all

just to keep you all updated, I had a look at the outdoor 80D today and found it to have a faulty armature and lots of spiders muffling any sound that was generated. I put in a new armature from another scrap bell and rotated each gong until it was at its max distance from the striker but still allowing the striker to hit. I think i have adjusted the inner gong a bit too much as I think it's missing on every odd ring but its nice and loud for the yard it's covering. Being high up its a bit of a faff getting to it to work on.

I also looked at one of our indoor 50E and found it not working at all. Turns out it had magnitised itself on one side so kept getting stuck. I got that going again with a clean and adjusted the gongs. It still doesnt sound as good as the old type 26 but i suppose you get what you pay for.

Thanks for everyones help and advice

Nickthedentist · 21st Jan 2016, 12:01 pm

The actual gongs on 50E bells don't have the same, rich in harmonics, ring as those found on earlier incarnations. Maybe you could nab a couple from a scrap 746 phone and swap them?

Sc00by121 · 21st Jan 2016, 5:50 pm

I'll have a rummage and will see if I can find anything.

I have just had a look at our other 80d and found there to be little clearance on one side or the armature. I can't see how to tweak that bit but have rotated the bells as best as I can

Build quality seems to vary greatly across these items with most of the issues I've came across would have been present out of the box.

15th Jan 2016, 7:58 pm	#1
Sc00by121 Retired Dormant Member Join Date: Dec 2013 Location: Aberdeen, UK. Posts: 9	Vintage vs Modern Bells About a year ago I installed a new BT 50E bell and at the time I set it up I was disappointed by the ringing that I got from it. It was if the striker was hitting each bell so fast it wasn't giving it time to 'ring' it sounded like metal on metal. I gave up in the end and left it at that. Last week I was working on a building refurb and rescued a GPO bellset type 26 dated 1963. I found instructions on how to convert it to modern equipment and put in a resistor, hooked it upto an extension and heard the music of the 60's - Beautiful. What then crossed my mind is why the cheap plastic 50E unit i installed last year sounded rubbish. I can't find any info on adjusting the 50E but have heard that they can be adjusted by rotating the bells? - Is this correct? I also have since put up two external BT 80D. One sounds perfect out of the box but the other has the same issue as the 50E. Can these also be adjusted? Cheers

15th Jan 2016, 9:49 pm	#2
TonyDuell Dekatron Join Date: Jun 2015 Location: Biggin Hill, London, UK. Posts: 5,213	Re: Vintage vs Modern Bells If the 50E and 80D are the bells I thnk they are, they actually use a traditional-ish bell mechanism. It's the single-coil one with the armature supported on a torsional leaf spring that turned up in very late 746s, etc. I've seen something similar (but with a 1K coil) in a Plessey Secretarial telephone. Anyway, I seem to remember the 50E uses the traditional bell gongs, same as the ones in a 706, 746, etc. The mounting holes in the gongs are deliberately off-centre so you can adjust them by rotating. The hammer should not stay in contact with the gong, or it will sound very muffled. I am sure there are proper setting instructions but if you hold the armature one way and then the other you can turn the appropriate gong so the hammer is just clear of it. Then try it out. The 80D has the concentric gongs, doesn't it? Again they have off-centre holes and can be set in much the same way, but it's a bit of a fiddle. Worth doing though!

15th Jan 2016, 9:51 pm	#3
AndiiT Octode Join Date: Aug 2005 Location: Saltburn-East, Cleveland, UK. Posts: 1,786	Re: Vintage vs Modern Bells Hi, The volume of ringing on most dual gong bells can be adjusted by rotating the gongs as they are of eccentric design - generally the closer the gongs are to each other the lower the volume. The only information that I can find on increasing the volume of Bell 80D is the last paragraph here Regards Andrew

15th Jan 2016, 10:02 pm	#4
Sc00by121 Retired Dormant Member Join Date: Dec 2013 Location: Aberdeen, UK. Posts: 9	Re: Vintage vs Modern Bells Hi, thanks for the replies. That actually sounds like that might get the 50E working properly, I never knew that with the rotation of the bells. Thinking back I remember the striker getting stuck on one bell when the ringing stopped, suggesting they are too close. I'll experiment next week and will report my findings. With the 80D I'm not too sure about, I'll need to have another look at it. It's on the side of a building which is very exposed to the elements and even though it's been up only a few months an inspection at the end of last year has shown it to be very rusty and full of spiders and cobwebs. When ringing now all I get is a pathetic patter from the striker. I'll need to spend a bit of time on this one to see what's going on as the other 80D I have hidden under the eves of a shed is super loud. It could be a line issue as this particular line is fed via CAT-5 rather than traditional cable.

16th Jan 2016, 12:26 pm	#5
Sc00by121 Retired Dormant Member Join Date: Dec 2013 Location: Aberdeen, UK. Posts: 9	Re: Vintage vs Modern Bells I'll check these out next week, but before I do, can I just clarify on how to know when the bells are adjusted correctly? With the 50E, do I rotate one bell and keep ringing it until it sounds right or do I rotate both and measure the gap? - Is there an easy way to know how the adjustment is going by just looking at it? With the 80D, I assume this will be roughly the same idea? - Slacken the main bolt and rotate then ring it to see if it's better or worse?

16th Jan 2016, 7:12 pm	#6
TonyDuell Dekatron Join Date: Jun 2015 Location: Biggin Hill, London, UK. Posts: 5,213	Re: Vintage vs Modern Bells What I do is to push the armature (not the hammer directly, as that is flexible) all the way one way with a screwdriver (you'll see what I mean). Then adjust that gong so that there is a small clearance (10's of thou) between the hammer and the gong. Repeat with the armature held the other way and adjust the other gong. For the 80D, start by cleaning it, you may find evidence of insects/arachnids that is damping the gongs. Then bascally do the same thing, but of course the 2 gongs are on one bolt so you have to set one (inner one first I think), hold it in place and adjust the other.

16th Jan 2016, 10:55 pm	#7
OscarFoxtrot Heptode Join Date: Apr 2011 Location: Edinburgh, UK. Posts: 805	Re: Vintage vs Modern Bells Adjustment of Magneto Bells, http://www.britishtelephones.com/belladj1.htm

17th Jan 2016, 2:42 pm	#8
Sc00by121 Retired Dormant Member Join Date: Dec 2013 Location: Aberdeen, UK. Posts: 9	Re: Vintage vs Modern Bells Very interesting and detailed! I'll have a go next week and will report back.

20th Jan 2016, 8:09 pm	#10
Sc00by121 Retired Dormant Member Join Date: Dec 2013 Location: Aberdeen, UK. Posts: 9	Re: Vintage vs Modern Bells hi all just to keep you all updated, I had a look at the outdoor 80D today and found it to have a faulty armature and lots of spiders muffling any sound that was generated. I put in a new armature from another scrap bell and rotated each gong until it was at its max distance from the striker but still allowing the striker to hit. I think i have adjusted the inner gong a bit too much as I think it's missing on every odd ring but its nice and loud for the yard it's covering. Being high up its a bit of a faff getting to it to work on. I also looked at one of our indoor 50E and found it not working at all. Turns out it had magnitised itself on one side so kept getting stuck. I got that going again with a clean and adjusted the gongs. It still doesnt sound as good as the old type 26 but i suppose you get what you pay for. Thanks for everyones help and advice

21st Jan 2016, 12:01 pm	#11
Nickthedentist Dekatron Join Date: Jan 2005 Location: Oxford, UK. Posts: 17,858	Re: Vintage vs Modern Bells The actual gongs on 50E bells don't have the same, rich in harmonics, ring as those found on earlier incarnations. Maybe you could nab a couple from a scrap 746 phone and swap them?

21st Jan 2016, 5:50 pm	#12
Sc00by121 Retired Dormant Member Join Date: Dec 2013 Location: Aberdeen, UK. Posts: 9	Re: Vintage vs Modern Bells I'll have a rummage and will see if I can find anything. I have just had a look at our other 80d and found there to be little clearance on one side or the armature. I can't see how to tweak that bit but have rotated the bells as best as I can Build quality seems to vary greatly across these items with most of the issues I've came across would have been present out of the box.