Recapping EMI elliptical speakers - UK Vintage Radio Repair and Restoration Discussion Forum

Goodizzy · 10th Dec 2019, 2:53 pm

I have been going thru my EMI "dangerous loudspeaker" collection and documenting the crossover parts in order to upgrade the crossovers. I have a pair of DLS-529 which use (2) 1.0uf Hunts black caps as well as a single 6.0uf electrolytic. I also have a pair of DLS-1 studio monitors which have the same 6.0uf electrolytic cap.

I know the electrolytic caps will need to be replaced due to their age and drift. I was also going to replace the Hunts caps while in there just to be safe. I'd love to keep these speakers going another 40 years if that's possible. The DLS-1 studio monitors are rare as hen's teeth, so I'd really like to get the best cap I can afford in the crossover.

Is there any advice on the type of cap to replace these with? It's my understanding that polypropylene film caps are the standard here, but I had also been reading about using PIO for the smaller value caps. Would elliptical speakers benefit from a certain type of cap?

I'll be checking the resistors as well and replacing any that are out of tolerance. They are those 5% green ******* and appear to be 3-5W. Should these be non-inductive?

I really appreciate any help you guys can lend. It's pretty hard to glean info from American forums regarding these speakers as no one seems to own them! I have found them to be very musical and pleasing to the ear when paired with similar period amps and receivers. Plus the metal grilles are too cool!

Silicon · 10th Dec 2019, 10:21 pm

From a technical perspective, the polypropylene capacitors would be the closest to 'the perfect capacitor'.

They would be my choice.

I cannot comment on the audiophile qualities of any capacitors.

Herald1360 · 11th Dec 2019, 11:34 am

Polypropylene yes, unless a clever clogs designer has used the ESR of the electrolytic to get a particular degree of frequency response or damping in the crossover network, in which case a suitable value resistor may be needed as well.

Goodizzy · 11th Dec 2019, 4:19 pm

I appreciate the replies.

I understand not wishing to comment on the pandora's box that is film caps in speaker crossovers. My concern is solely in not damaging the drivers by changing the crossover frequency or somehow passing unwanted frequencies to the tweeters.

The EMI DLS-1 uses a single 92390G mid/woofer and two GEC BCS1853 tweeters. These are the predecessor of the famed Celestion HF1300 tweeters. Each crossover consists of (2) inductors, (1) 6uf electrolytic, (2) 10R resistors and (1) 47R resistor. Fairly simple as far as crossovers go, I believe. They look similar to the DLS-529, which was also designed by Dr. Dutton and based off the DLS-1.

If you couldn't already tell, I am fairly ignorant when it comes to doing anything with speaker crossovers besides replacing components.

How would I be able to tell if the ESR was used in the crossover for freq. response or damping? And to calculate the resistance needed? I will post a picture later today and perhaps that will help! This is all a bit above my element, haha.

dave cox · 11th Dec 2019, 5:53 pm

Do you have a circuit diagram of the crossovers ?
Or can you reverse engineer it

?
An opinion as to the significance of ESR could then be offered ...

A typical 6uF 'reverse-o-lytic' will have an ESR of some fraction of an ohm, when it was new. Probably, it was not very close to 6uF anyway, as its just too expensive to do the selection for close tolerance and nobody will ever know that they didn't bother

It will drift like hell in any case!

Just replace it with some poly caps in parellel to make 6uF.
If you're very fussy, measure it and trim to close tolerance, matching L&R.

dc

Goodizzy · 11th Dec 2019, 6:11 pm

Thanks! I do have a diagram for the crossover. I will post the diagram and a few pictures later this afternoon, as I'm not at home right now.

Goodizzy · 12th Dec 2019, 6:39 pm

I apologize, I got caught up with house stuff last night and didn't have a chance to snap the pictures. Here they are along with the crossover diagram from the schematic-

Luxman1050 · 12th Dec 2019, 8:48 pm

Just suggestion I used these components to update a pair of B&W DM2 speakers and the highs and lows are well balanced worth a try.
Claritycap SA capacitors and Amtrans AMRG resistors.

crackle · 12th Dec 2019, 10:56 pm

Looking at the size of that capacitor I would guess it is not an electrolytic but some type of foil capacitor.
I would check the DC leakage and if it proves to be negligible leave them alone.
I would use a DC supply the same voltage as the caps are rated for, and measure the volt drop across a 5k resistor. It will be high to start with but should drop down to near zero as the capacitor charges up.
Mike

Goodizzy · 14th Dec 2019, 3:53 pm

Thank you Mike. I don't have a proper DC supply and have been meaning to purchase one for quite some time now. I will be purchasing one, hopefully, this weekend if al works out. I will post back after as I may need a bit more guidance.
chris

Luxman1050 · 14th Dec 2019, 5:46 pm

Pretty basic crossover and as Mike said it's not going to be an electrolytic it's just a non polarized cap. The crossover not much different to a Celestion XR15 crossover with a single cap. I changed out the caps left resistors in and they sounded pretty good spent about £1.50 on each cap can't remember what I bought. The caps had dried out.
So in essence all you need to do is change the cap and resistors pretty simple. If you don't like the sound try something different or just put the originals back. Personally I don't think it's worth going to the extreme of buying test gear just to measure ripple, voltage loss etc. Unless your going to be doing lots of refurb work.

That's just my personal opinion.

Good luck with your project.

Goodizzy · 14th Dec 2019, 6:24 pm

I agree with you, and may end up doing just that. I still am working on both amps for these monitors as I have to sand and repaint the chassis and transformer end bells due to rust. I have completed one already but ran out of time before winter set in here for the other.

I actually have been looking to buy a regulated, variable HV DC supply for awhile now, as I have quite a few other valve projects in the pipeline. So it wouldn't really be an off-the-cuff purchase.

I will measure the resistors to determine if they are out of tolerance, but replacements should be non-inductive? I think I should be able to find all of these parts at parts connexion or the like.

14th Dec 2019, 9:15 pm

Quote:

but replacements should be non-inductive?

An inductive resistor won't have an inductance to make any difference at audio, even a wire-wound one. Stick with a good metal oxide or film type. All modern components are so much better than the old ones.

Luxman1050 · 15th Dec 2019, 12:38 pm

Chris
I forgot I've attached a pic of a little unit I use for testing caps, resistors, diodes etc. This will even tell you voltage loss on caps as well think it cost me 10 quid and I would say it,s accuracy is around 99%. Much better than meters I have.
Don't know make.

Chris

Goodizzy · 15th Dec 2019, 3:37 pm

Thank you for those replies. This is most helpful.

After searching for caps, it seems the most difficult part is going to be finding correct values. Not nearly as many options for 3uf and 6uf, as there is for 3.3uf and 5.6uf. But I certainly don't wish to change the value...

The search continues!

Luxman1050 · 15th Dec 2019, 3:47 pm

Just add two 3.3uf caps in parallel it will give you 6.6uf which is in the 10% range and will not cause any problems. 6uf or 3uf not made anymore you would have to look at NOS capacitors.

It's really not that difficult.

I'll have a dig around later and see if I have any 6uf or 3uf caps if I have you can have them. Forgot is it a 350v?

Chris

Goodizzy · 15th Dec 2019, 4:47 pm

I will have to check again but I think I remember seeing 150/200V. I haven't pulled the bracket off holding the caps for either set of speakers yet.

There are still new caps made in 3uf and 6uf values, just not as many options. Additionally, if the new 3.3uf or 6.6uf caps are 10% tolerance caps and are off by that much, (or more from what I've read in other forums where people have tested), that could put them out of tolerance for the crossover specs. I would need to get tighter tolerance caps for my own peace of mind. I am not as concerned in doing this with the DLS-529, but the DLS-1s I want to baby a bit just because the drivers are unobtanium now.

stevehertz · 15th Dec 2019, 7:04 pm

The tolerances that are being referring to (10%), even if at their extremes will not cause damage to your speakers. With the greatest respect these are old speakers and the crossovers are hardly sophisticated. 6 or 6.6, it's extremely unlikely that you'll be able to hear the difference, and secondly, no damage will be done. If you're insistent on being purist, then 6uF it is. Either find a bespoke 6uF cap manufacturer (expensive) or make that value up using separate caps. And of course, you will need to measure the resultant capacitance otherwise there's no point to the exercise. I would avoid NOS caps if, as you allude to, you're looking for a long term, 'quality' fix.

Goodizzy · 15th Dec 2019, 8:20 pm

Thank you steve. I certainly was not planning on putting NOS caps back in the speakers. I will do as you and others suggested and purchase caps with newer values. I can always replace them if need be as the crossovers are very easy to get to in the DLS-1.

A final question- Is there any advantage to using parallel 3.3uf caps over a single 6.6uf? The crossovers are quite spacious so room is not a consideration.

10th Dec 2019, 2:53 pm	#1
Goodizzy Pentode Join Date: Jan 2016 Location: Lynchburg, Central Virginia, USA. Posts: 137	Recapping EMI elliptical speakers I have been going thru my EMI "dangerous loudspeaker" collection and documenting the crossover parts in order to upgrade the crossovers. I have a pair of DLS-529 which use (2) 1.0uf Hunts black caps as well as a single 6.0uf electrolytic. I also have a pair of DLS-1 studio monitors which have the same 6.0uf electrolytic cap. I know the electrolytic caps will need to be replaced due to their age and drift. I was also going to replace the Hunts caps while in there just to be safe. I'd love to keep these speakers going another 40 years if that's possible. The DLS-1 studio monitors are rare as hen's teeth, so I'd really like to get the best cap I can afford in the crossover. Is there any advice on the type of cap to replace these with? It's my understanding that polypropylene film caps are the standard here, but I had also been reading about using PIO for the smaller value caps. Would elliptical speakers benefit from a certain type of cap? I'll be checking the resistors as well and replacing any that are out of tolerance. They are those 5% green ******* and appear to be 3-5W. Should these be non-inductive? I really appreciate any help you guys can lend. It's pretty hard to glean info from American forums regarding these speakers as no one seems to own them! I have found them to be very musical and pleasing to the ear when paired with similar period amps and receivers. Plus the metal grilles are too cool!

10th Dec 2019, 10:21 pm	#2
Silicon Nonode Join Date: Jun 2007 Location: Coulsdon, London, UK. Posts: 2,162	Re: Recapping EMI elliptical speakers From a technical perspective, the polypropylene capacitors would be the closest to 'the perfect capacitor'. They would be my choice. I cannot comment on the audiophile qualities of any capacitors.

11th Dec 2019, 11:34 am	#3
Herald1360 Dekatron Join Date: Feb 2007 Location: Leominster, Herefordshire, UK. Posts: 16,535	Re: Recapping EMI elliptical speakers Polypropylene yes, unless a clever clogs designer has used the ESR of the electrolytic to get a particular degree of frequency response or damping in the crossover network, in which case a suitable value resistor may be needed as well. __________________ ....__________ ....\|____\|\|__\|__\_____ .=.\| _---\__\|__\|_---_\|. .........O..Chris....O

11th Dec 2019, 4:19 pm	#4
Goodizzy Pentode Join Date: Jan 2016 Location: Lynchburg, Central Virginia, USA. Posts: 137	Re: Recapping EMI elliptical speakers I appreciate the replies. I understand not wishing to comment on the pandora's box that is film caps in speaker crossovers. My concern is solely in not damaging the drivers by changing the crossover frequency or somehow passing unwanted frequencies to the tweeters. The EMI DLS-1 uses a single 92390G mid/woofer and two GEC BCS1853 tweeters. These are the predecessor of the famed Celestion HF1300 tweeters. Each crossover consists of (2) inductors, (1) 6uf electrolytic, (2) 10R resistors and (1) 47R resistor. Fairly simple as far as crossovers go, I believe. They look similar to the DLS-529, which was also designed by Dr. Dutton and based off the DLS-1. If you couldn't already tell, I am fairly ignorant when it comes to doing anything with speaker crossovers besides replacing components. How would I be able to tell if the ESR was used in the crossover for freq. response or damping? And to calculate the resistance needed? I will post a picture later today and perhaps that will help! This is all a bit above my element, haha.

11th Dec 2019, 5:53 pm	#5
dave cox Nonode Join Date: Jan 2009 Location: Bristol, UK. Posts: 2,061	Re: Recapping EMI elliptical speakers Do you have a circuit diagram of the crossovers ? Or can you reverse engineer it ? An opinion as to the significance of ESR could then be offered ... A typical 6uF 'reverse-o-lytic' will have an ESR of some fraction of an ohm, when it was new. Probably, it was not very close to 6uF anyway, as its just too expensive to do the selection for close tolerance and nobody will ever know that they didn't bother It will drift like hell in any case! Just replace it with some poly caps in parellel to make 6uF. If you're very fussy, measure it and trim to close tolerance, matching L&R. dc

11th Dec 2019, 6:11 pm	#6
Goodizzy Pentode Join Date: Jan 2016 Location: Lynchburg, Central Virginia, USA. Posts: 137	Re: Recapping EMI elliptical speakers Thanks! I do have a diagram for the crossover. I will post the diagram and a few pictures later this afternoon, as I'm not at home right now.

12th Dec 2019, 6:39 pm	#7
Goodizzy Pentode Join Date: Jan 2016 Location: Lynchburg, Central Virginia, USA. Posts: 137	Re: Recapping EMI elliptical speakers I apologize, I got caught up with house stuff last night and didn't have a chance to snap the pictures. Here they are along with the crossover diagram from the schematic- Attached Thumbnails

12th Dec 2019, 8:48 pm	#8
Luxman1050 Octode Join Date: Apr 2019 Location: Margate, Kent, UK. Posts: 1,728	Re: Recapping EMI elliptical speakers Just suggestion I used these components to update a pair of B&W DM2 speakers and the highs and lows are well balanced worth a try. Claritycap SA capacitors and Amtrans AMRG resistors.

12th Dec 2019, 10:56 pm	#9
crackle Rest in Peace Join Date: Mar 2011 Location: Basildon, Essex, UK. Posts: 4,100	Re: Recapping EMI elliptical speakers Looking at the size of that capacitor I would guess it is not an electrolytic but some type of foil capacitor. I would check the DC leakage and if it proves to be negligible leave them alone. I would use a DC supply the same voltage as the caps are rated for, and measure the volt drop across a 5k resistor. It will be high to start with but should drop down to near zero as the capacitor charges up. Mike

14th Dec 2019, 3:53 pm	#10
Goodizzy Pentode Join Date: Jan 2016 Location: Lynchburg, Central Virginia, USA. Posts: 137	Re: Recapping EMI elliptical speakers Thank you Mike. I don't have a proper DC supply and have been meaning to purchase one for quite some time now. I will be purchasing one, hopefully, this weekend if al works out. I will post back after as I may need a bit more guidance. chris

14th Dec 2019, 5:46 pm	#11
Luxman1050 Octode Join Date: Apr 2019 Location: Margate, Kent, UK. Posts: 1,728	Re: Recapping EMI elliptical speakers Pretty basic crossover and as Mike said it's not going to be an electrolytic it's just a non polarized cap. The crossover not much different to a Celestion XR15 crossover with a single cap. I changed out the caps left resistors in and they sounded pretty good spent about £1.50 on each cap can't remember what I bought. The caps had dried out. So in essence all you need to do is change the cap and resistors pretty simple. If you don't like the sound try something different or just put the originals back. Personally I don't think it's worth going to the extreme of buying test gear just to measure ripple, voltage loss etc. Unless your going to be doing lots of refurb work. That's just my personal opinion. Good luck with your project.

14th Dec 2019, 6:24 pm	#12
Goodizzy Pentode Join Date: Jan 2016 Location: Lynchburg, Central Virginia, USA. Posts: 137	Re: Recapping EMI elliptical speakers I agree with you, and may end up doing just that. I still am working on both amps for these monitors as I have to sand and repaint the chassis and transformer end bells due to rust. I have completed one already but ran out of time before winter set in here for the other. I actually have been looking to buy a regulated, variable HV DC supply for awhile now, as I have quite a few other valve projects in the pipeline. So it wouldn't really be an off-the-cuff purchase. I will measure the resistors to determine if they are out of tolerance, but replacements should be non-inductive? I think I should be able to find all of these parts at parts connexion or the like.

15th Dec 2019, 12:38 pm	#14
Luxman1050 Octode Join Date: Apr 2019 Location: Margate, Kent, UK. Posts: 1,728	Re: Recapping EMI elliptical speakers Chris I forgot I've attached a pic of a little unit I use for testing caps, resistors, diodes etc. This will even tell you voltage loss on caps as well think it cost me 10 quid and I would say it,s accuracy is around 99%. Much better than meters I have. Don't know make. Chris Attached Thumbnails

15th Dec 2019, 3:37 pm	#15
Goodizzy Pentode Join Date: Jan 2016 Location: Lynchburg, Central Virginia, USA. Posts: 137	Re: Recapping EMI elliptical speakers Thank you for those replies. This is most helpful. After searching for caps, it seems the most difficult part is going to be finding correct values. Not nearly as many options for 3uf and 6uf, as there is for 3.3uf and 5.6uf. But I certainly don't wish to change the value... The search continues!

15th Dec 2019, 3:47 pm	#16
Luxman1050 Octode Join Date: Apr 2019 Location: Margate, Kent, UK. Posts: 1,728	Re: Recapping EMI elliptical speakers Just add two 3.3uf caps in parallel it will give you 6.6uf which is in the 10% range and will not cause any problems. 6uf or 3uf not made anymore you would have to look at NOS capacitors. It's really not that difficult. I'll have a dig around later and see if I have any 6uf or 3uf caps if I have you can have them. Forgot is it a 350v? Chris

15th Dec 2019, 4:47 pm	#17
Goodizzy Pentode Join Date: Jan 2016 Location: Lynchburg, Central Virginia, USA. Posts: 137	Re: Recapping EMI elliptical speakers I will have to check again but I think I remember seeing 150/200V. I haven't pulled the bracket off holding the caps for either set of speakers yet. There are still new caps made in 3uf and 6uf values, just not as many options. Additionally, if the new 3.3uf or 6.6uf caps are 10% tolerance caps and are off by that much, (or more from what I've read in other forums where people have tested), that could put them out of tolerance for the crossover specs. I would need to get tighter tolerance caps for my own peace of mind. I am not as concerned in doing this with the DLS-529, but the DLS-1s I want to baby a bit just because the drivers are unobtanium now.

15th Dec 2019, 7:04 pm	#18
stevehertz Dekatron Join Date: Sep 2011 Location: Rugeley, Staffordshire, UK. Posts: 8,830	Re: Recapping EMI elliptical speakers The tolerances that are being referring to (10%), even if at their extremes will not cause damage to your speakers. With the greatest respect these are old speakers and the crossovers are hardly sophisticated. 6 or 6.6, it's extremely unlikely that you'll be able to hear the difference, and secondly, no damage will be done. If you're insistent on being purist, then 6uF it is. Either find a bespoke 6uF cap manufacturer (expensive) or make that value up using separate caps. And of course, you will need to measure the resultant capacitance otherwise there's no point to the exercise. I would avoid NOS caps if, as you allude to, you're looking for a long term, 'quality' fix. __________________ A digital radio is the latest thing, but a vintage wireless is forever..

15th Dec 2019, 8:20 pm	#19
Goodizzy Pentode Join Date: Jan 2016 Location: Lynchburg, Central Virginia, USA. Posts: 137	Re: Recapping EMI elliptical speakers Thank you steve. I certainly was not planning on putting NOS caps back in the speakers. I will do as you and others suggested and purchase caps with newer values. I can always replace them if need be as the crossovers are very easy to get to in the DLS-1. A final question- Is there any advantage to using parallel 3.3uf caps over a single 6.6uf? The crossovers are quite spacious so room is not a consideration.