I have a pair of 737R's which I love, but recently one channel became fuzzy and muffled. I have carried out some basic inspection, but at this point not done any real testing so any advice would be great.
Attached are a couple of pics of the data plate and crossover on the speaker with the issue, nothing appears burnt out, or smelling such, although, I guess the shellac, has all dried and cracked off when I touched it, would I be better off to remove all components and remount on a board I then attach on the inside of the cabinet? I have taken a look at the coils on both woofer and tweeter, both of which visually appear fine from initial inspection. The only issue I found was that the studs for both +/- terminal were loose, which I have now tightened, electrolytic's appear visibly okay, but I understand these do not age well and perhaps should be replaced anyway.
In fact I am also looking on this as an opportunity to upgrade the units as the rubber surrounds and the poly cones on both speakers are clearly old and no longer flexible in the way they once were. So any advice or suggestions on any of this would be very much appreciated. Thanks, Stew
Attached are a couple of pics of the data plate and crossover on the speaker with the issue, nothing appears burnt out, or smelling such, although, I guess the shellac, has all dried and cracked off when I touched it, would I be better off to remove all components and remount on a board I then attach on the inside of the cabinet? I have taken a look at the coils on both woofer and tweeter, both of which visually appear fine from initial inspection. The only issue I found was that the studs for both +/- terminal were loose, which I have now tightened, electrolytic's appear visibly okay, but I understand these do not age well and perhaps should be replaced anyway.
In fact I am also looking on this as an opportunity to upgrade the units as the rubber surrounds and the poly cones on both speakers are clearly old and no longer flexible in the way they once were. So any advice or suggestions on any of this would be very much appreciated. Thanks, Stew
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Welcome to the forum, Stew!
A common cause of a 2-way speaker sounding "muffled" is that the tweeter is no longer working properly.
You could try swapping the tweeters over between the speakers to see if the problem switches speakers.
Upgrading the poly cone woofer would be problematical as any replacement would require to have the same characteristics as the Mission driver had from the factory. This is necessary in order for the replacement woofer to work hand in hand with the enclosure design.
P.S. I would not assume that there is anything wrong with the bipolar electrolytic capacitors.
A common cause of a 2-way speaker sounding "muffled" is that the tweeter is no longer working properly.
You could try swapping the tweeters over between the speakers to see if the problem switches speakers.
Upgrading the poly cone woofer would be problematical as any replacement would require to have the same characteristics as the Mission driver had from the factory. This is necessary in order for the replacement woofer to work hand in hand with the enclosure design.
P.S. I would not assume that there is anything wrong with the bipolar electrolytic capacitors.
Thanks Galu, I'll check this out over the weekend. Yes I did wonder if upgrading might be more problematic than I assumed, I guess my main concern is the black rubber surround appears dry, and in places is cracking. Not sure if I need to worry overly about it, I'll upload a pic tomorrow.....
Thanks Galu, I have had a bit of time this morning to have a good look at your suggestions, attached are pictures of the woofer and tweeter details, and you are indeed correct regarding woofer.... You can also see a clear picture of the deterioration to the rubber surround on the woofer, this is similar on both, I suspect from having been stored for some years in my attic, which although not damp is probably not the best place to have stored them. I have cleaned this one up gently with some warm soapy water and then rubbed in a little silicone, the rubber feels much more flexible now, but of course there are still the cracks.
I also swapped over the tweeter to the good speaker and on test it is now completely dead! I am concerned that this maybe following me taking out of the housing to visually inspect it, the ferrofluid looked okay, at least not all dried up or gungy, the coil looked good and I immediately reassembled it without touching anything. The whole subject pf ferrofluid seems to be enormous, with lots of different opinions. So there we are..... Have a good Sunday, and thanks again 🤠
I also swapped over the tweeter to the good speaker and on test it is now completely dead! I am concerned that this maybe following me taking out of the housing to visually inspect it, the ferrofluid looked okay, at least not all dried up or gungy, the coil looked good and I immediately reassembled it without touching anything. The whole subject pf ferrofluid seems to be enormous, with lots of different opinions. So there we are..... Have a good Sunday, and thanks again 🤠
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The cracks that are visible in the surround are not (yet) affecting the flexing, concave region, so pose no immediate problem.
For cosmetic purposes, you could simply disguise them with paint and hope they don't spread into the flexing region in the future.
A replacement Vifa Peerless D19TD-08 tweeter is available here: https://willys-hifi.com/products/peerless-d19td05-08-tweeter
While you are in there, it would be worth renewing those bipolar electrolytic capacitors with fresh ones like these from Wilmslow Audio:
https://wilmslowaudio.co.uk/mundorf-electrolytic-ecap-capacitors
Please return if you need further assistance.
EDIT: Willys Hifi also stock Mundorf bipolar electrolytic capacitors as well as other makes:
https://willys-hifi.com/collections/electrolytic-capacitors-non-polarised
For cosmetic purposes, you could simply disguise them with paint and hope they don't spread into the flexing region in the future.
A replacement Vifa Peerless D19TD-08 tweeter is available here: https://willys-hifi.com/products/peerless-d19td05-08-tweeter
While you are in there, it would be worth renewing those bipolar electrolytic capacitors with fresh ones like these from Wilmslow Audio:
https://wilmslowaudio.co.uk/mundorf-electrolytic-ecap-capacitors
Please return if you need further assistance.
EDIT: Willys Hifi also stock Mundorf bipolar electrolytic capacitors as well as other makes:
https://willys-hifi.com/collections/electrolytic-capacitors-non-polarised
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Here's a suggestion to fill those visible cracks in the rubber surround where it attaches to the poly cone - and, crucially, any cracks that may eventually extend into the concave section: https://www.halfords.com/motoring/p...nville-black-silicone-sealant-40g-173867.html
It's a sealant that remains permanently flexible - just the ticket if the worst should happen!
It's a sealant that remains permanently flexible - just the ticket if the worst should happen!
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@Stewgh
For future reference, the Monacor SPH-210 is said to be a "good replacement" for the Mission 737R 8" unit, a claim that is backed up by a customer review:
https://willys-hifi.com/products/monacor-sph-210-bass-mid-speaker
For future reference, the Monacor SPH-210 is said to be a "good replacement" for the Mission 737R 8" unit, a claim that is backed up by a customer review:
https://willys-hifi.com/products/monacor-sph-210-bass-mid-speaker
Okay, finally got time to fit my caps today, so stupid question time, my new Mundorf caps have no +- on them, and speakers being AC do I need to be worried about polarity, not something I have experience of so thought I should ask before potentially shorting anything out.
Success!!!! I am writing this sitting listening to my Missions back in action..... Thank you so much Galu for all your help , the sound better than ever. So pleased.
This tweeter looks surprisingly similar...
https://en.toutlehautparleur.com/br...voice-coil-front-plate-3-7-inch-diameter.html
EDIT: I am not the only one who has good eye, @Galu 🙂 Just now saw you in #7 post mentioned the same