Speaker crossover capacitor - UK Vintage Radio Repair and Restoration Discussion Forum

egerton · 26th Jul 2018, 3:04 pm

Ferranti A1016 - tweeter not outputting much at all. I found the crossover 'filter' cap. between main unit and tweeter is cracked and measures very high. It's a large Hunts black tar type marked A103 'Metallised' 2.0 uF 150V. It measures as nearer 7uF ! Tweeter tested in isolation it seems ok, so want to replace this cap. but can't find any non electrolytics suitable online. As it's mounted in a clamp I might have to make up a container if a modern one is smaller - but first need to find any suitable one.
Thanks - Paul

Nuvistor · 26th Jul 2018, 3:13 pm

Use a couple of 4.7uf electrolytics back to back, no point spending lots on a non electrolytic for the A1016.

jonnybear · 26th Jul 2018, 3:18 pm

Motor run capacitor?https://www.ebay.co.uk/itm/CBB61-mot...bxnftOkISe9VDA.https://www.ebay.co.uk/itm/Metalised...21KOHlIBvWaT7w
John

crackle · 26th Jul 2018, 3:41 pm

2.2uF 630v polyester cap on ebay is £3.35 for 2.
These tweeters were never designed to give out much sound.

Mike

egerton · 26th Jul 2018, 6:13 pm

Quote:

Originally Posted by Nuvistor

Use a couple of 4.7uf electrolytics back to back, no point spending lots on a non electrolytic for the A1016.

You mean in series to give around 2.3 uf? Won't they be reverse polarised by some of the signal voltage? Not sure if it matters....

ajgriff · 26th Jul 2018, 7:48 pm

Back to back electrolytics should behave much like a single non-polarised capacitor. Sonic artefacts are likely to be minimal as far as human hearing is concerned. Also, it doesn't matter which 'poles' are connected together.

Alan

Nuvistor · 26th Jul 2018, 8:01 pm

The polyester caps from posts 3 and 4 are a decent price, I didn’t want you spending lots of money on “special Audio” capacitors. If you have the electrolytic ones I would use them, if you have to order them you may as well order the ones in either post 3or 4.

julie_m · 26th Jul 2018, 11:01 pm

When electrolytic capacitors are wired back-to-back, if the dielectric layer begins to break down in the capacitor which is "in reverse", then the capacitor which is "the right way round" limits the fault current. The dielectric layer will begin to re-form after the next reversal of polarity.

It sounds crude, but it works!

Refugee · 27th Jul 2018, 12:49 am

You can get ordinary yellow ones at 2.2uf for a couple of quid.
http://uk.farnell.com/vishay/mkt1813...ial/dp/1166846

boxdoctor · 27th Jul 2018, 8:44 am

Cricklewood do these at £1-50 plus postage.
https://www.cricklewoodelectronics.c...vers-etc..html 3rd item down.
Purpose made part. Tony

Nuvistor · 27th Jul 2018, 9:13 am

Hi Paul,
Lots of choices, use which ever is the easiest for you, they will all work.

26th Jul 2018, 3:04 pm	#1
egerton Pentode Join Date: May 2018 Location: Beverley, East Riding Posts: 110	Speaker crossover capacitor Ferranti A1016 - tweeter not outputting much at all. I found the crossover 'filter' cap. between main unit and tweeter is cracked and measures very high. It's a large Hunts black tar type marked A103 'Metallised' 2.0 uF 150V. It measures as nearer 7uF ! Tweeter tested in isolation it seems ok, so want to replace this cap. but can't find any non electrolytics suitable online. As it's mounted in a clamp I might have to make up a container if a modern one is smaller - but first need to find any suitable one. Thanks - Paul

26th Jul 2018, 3:13 pm	#2
Nuvistor Dekatron Join Date: Aug 2013 Location: Wigan, Greater Manchester, UK. Posts: 9,433	Re: Speaker crossover capacitor Use a couple of 4.7uf electrolytics back to back, no point spending lots on a non electrolytic for the A1016. __________________ Frank

26th Jul 2018, 3:18 pm	#3
jonnybear Octode Join Date: Nov 2010 Location: Cullompton, Devon, UK. Posts: 1,435	Re: Speaker crossover capacitor Motor run capacitor?https://www.ebay.co.uk/itm/CBB61-mot...bxnftOkISe9VDA.https://www.ebay.co.uk/itm/Metalised...21KOHlIBvWaT7w John Last edited by jonnybear; 26th Jul 2018 at 3:24 pm.

26th Jul 2018, 3:41 pm	#4
crackle Rest in Peace Join Date: Mar 2011 Location: Basildon, Essex, UK. Posts: 4,100	Re: Speaker crossover capacitor 2.2uF 630v polyester cap on ebay is £3.35 for 2. These tweeters were never designed to give out much sound. Mike

26th Jul 2018, 7:48 pm	#6
ajgriff Nonode Join Date: May 2004 Location: Halifax, West Yorkshire, UK. Posts: 2,587	Re: Speaker crossover capacitor Back to back electrolytics should behave much like a single non-polarised capacitor. Sonic artefacts are likely to be minimal as far as human hearing is concerned. Also, it doesn't matter which 'poles' are connected together. Alan

26th Jul 2018, 8:01 pm	#7
Nuvistor Dekatron Join Date: Aug 2013 Location: Wigan, Greater Manchester, UK. Posts: 9,433	Re: Speaker crossover capacitor The polyester caps from posts 3 and 4 are a decent price, I didn’t want you spending lots of money on “special Audio” capacitors. If you have the electrolytic ones I would use them, if you have to order them you may as well order the ones in either post 3or 4. __________________ Frank

26th Jul 2018, 11:01 pm	#8
julie_m Dekatron Join Date: May 2008 Location: Derby, UK. Posts: 7,735	Re: Speaker crossover capacitor When electrolytic capacitors are wired back-to-back, if the dielectric layer begins to break down in the capacitor which is "in reverse", then the capacitor which is "the right way round" limits the fault current. The dielectric layer will begin to re-form after the next reversal of polarity. It sounds crude, but it works! __________________ If I have seen further than others, it is because I was standing on a pile of failed experiments.

27th Jul 2018, 12:49 am	#9
Refugee Dekatron Join Date: Apr 2012 Location: Worksop, Nottinghamshire, UK. Posts: 5,554	Re: Speaker crossover capacitor You can get ordinary yellow ones at 2.2uf for a couple of quid. http://uk.farnell.com/vishay/mkt1813...ial/dp/1166846

27th Jul 2018, 8:44 am	#10
boxdoctor Rest in Peace Join Date: Sep 2010 Location: Ripley, Derbyshire, UK. Posts: 785	Re: Speaker crossover capacitor Cricklewood do these at £1-50 plus postage. https://www.cricklewoodelectronics.c...vers-etc..html 3rd item down. Purpose made part. Tony

27th Jul 2018, 9:13 am	#11
Nuvistor Dekatron Join Date: Aug 2013 Location: Wigan, Greater Manchester, UK. Posts: 9,433	Re: Speaker crossover capacitor Hi Paul, Lots of choices, use which ever is the easiest for you, they will all work. __________________ Frank