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Post by gruntfuttock on Oct 2, 2018 9:31:01 GMT
Not sure if I'm allowed to post this here! I have a pair of B&W DM2 Series 2 Speakers circa 1978. I've had them from new, and they are great. As the crossovers are 40 yeaers old, I'd like to have them upgraded. Does anyone know an expert or company that can provide this service? All help advice gratefully received. Many thanks. Dave
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Post by gruntfuttock on Oct 2, 2018 14:37:49 GMT
I have found an experienced person in the UK who can refurbish my crossovers Many thanks Dave
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Post by twang46 on Oct 3, 2018 18:11:06 GMT
Bit of an interesting one this Dave If you are wanting to setup the Xovers to a different frequency/slope I can understand that, or do you think they are faulty? Capacitors can (& do) drift over time & resistors also so after 40 odd years it wouldn't hurt to check things over Some "housekeeping" inside the cabinets will be worthwhile while you have the Xovers out, tightening chassis bolts & checking the bracing, cleaning out the damping etc.... Be interesting to hear what you think of them when you get them put back together Dick.
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Post by gruntfuttock on Oct 3, 2018 22:15:57 GMT
Thanks for your reply Dick. I don’t have any technical knowledge about capacitors etc. From what I’ve read changing some XO components or upgrading to later designs, Re-aligning some components can greatly improve the sound. My speakers have travelled to several counties during their 40 years. They were also stored in a garage in South Africa for five years where it can get very hot. So I feel a XO overhaul would be a good idea. I approached B&W in the UK and North America but they were not able to assist. It has been a struggle to find anyone who will take on the task of an overhaul. Re feedback. I think it will be a long process. Sending from Japan to the UK is a 7-10 day process. Then join the queue waiting for the actual overhaul / refurbishment. So I imagine a month long process - all being well. Dave
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Post by gruntfuttock on Oct 20, 2018 7:05:07 GMT
Bit of an interesting one this Dave If you are wanting to setup the Xovers to a different frequency/slope I can understand that, or do you think they are faulty? Capacitors can (& do) drift over time & resistors also so after 40 odd years it wouldn't hurt to check things over Some "housekeeping" inside the cabinets will be worthwhile while you have the Xovers out, tightening chassis bolts & checking the bracing, cleaning out the damping etc.... Be interesting to hear what you think of them when you get them put back together Dick. Hi Dick. Feedback to date. I attempted to post my crossovers at my local post office. A “Jobsworth” said they can’t send speaker parts by air because of the magnets. Although I could show a photo of the units! Contacted the main PO and they said no problem. The package arrived in the UK within 3-4 days which was amazing - especially as our main air was closed due to the recent typhoon. UK Customs then held on to my package for some 8 or 9 days. Then they wanted to charge me £25 customs import duty, then the PO wanted a further £11 collection fee. This is in addition to the £70 it cost to send the XO’s. Any how, the person who will refurbish the said units has received them - after two weeks! While I’ve been waiting I have cleaned the damping material. Some is actually lambs wool! The other are loose sheets of a damping material. Some years ago the moulded foam damping had crumbled. I’ve now replaced it with sheets of acoustic felt and sheets of pyramid acoustic tiles. (After cleaning out the cabinet interiors) They are critically damped cabinets so a bit of guess work on my part. I changed the binding posts as the originals had become slightly corroded. I hope all of the above will improve the sound!! Dave
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Post by twang46 on Oct 20, 2018 10:18:19 GMT
Thanks for the update Dave As long as you followed the sizes & shapes of the original damping & didn't vary too far from the original spec with the replacement materials you should be fine The "housekeeping" you have done so far is worthwhile & will help with the performance, don't forget to check the bolts holding the drive units & also look to see if any of the gaskets have perished/distorted Be interesting to hear what the XO's needed doing as well Next job is to set about the exterior of the cabinets & make them look pretty again Cheers Dick.
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Post by gruntfuttock on Nov 26, 2018 2:37:35 GMT
Bit of an interesting one this Dave If you are wanting to setup the Xovers to a different frequency/slope I can understand that, or do you think they are faulty? Capacitors can (& do) drift over time & resistors also so after 40 odd years it wouldn't hurt to check things over Some "housekeeping" inside the cabinets will be worthwhile while you have the Xovers out, tightening chassis bolts & checking the bracing, cleaning out the damping etc.... Be interesting to hear what you think of them when you get them put back together Dick. Hi Dick. Feedback to date. I attempted to post my crossovers at my local post office. A “Jobsworth” said they can’t send speaker parts by air because of the magnets. Although I could show a photo of the units! Contacted the main PO and they said no problem. The package arrived in the UK within 3-4 days which was amazing - especially as our main air was closed due to the recent typhoon. UK Customs then held on to my package for some 8 or 9 days. Then they wanted to charge me £25 customs import duty, then the PO wanted a further £11 collection fee. This is in addition to the £70 it cost to send the XO’s. Any how, the person who will refurbish the said units has received them - after two weeks! While I’ve been waiting I have cleaned the damping material. Some is actually lambs wool! The other are loose sheets of a damping material. Some years ago the moulded foam damping had crumbled. I’ve now replaced it with sheets of acoustic felt and sheets of pyramid acoustic tiles. (After cleaning out the cabinet interiors) They are critically damped cabinets so a bit of guess work on my part. I changed the binding posts as the originals had become slightly corroded. I hope all of the above will improve the sound!! Dave
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Post by gruntfuttock on Nov 26, 2018 3:09:16 GMT
Hi Dick.
A further update. I received my upgraded crossovers a couple of weeks ago, and the speakers sound so much better now. The mids and highs are there now where-as they weren't too evident before. The bass is tighter and overall the three drive units sound more balanced. I made new gaskets for all drive units, and bought new bolts for the mid drive units and tweeeters. I cleaned the long haired sheeps wool (I kid you not!!) I added stiff felt panels to internal surfaces, and then added pyamid acousic foam.
Here's a quote from the guy who did the upgrade.
"I've matched and ordered all replacement capacitors, some of which will use bridged values to achieve tolerance. Where appropriate, I have used up-graded electrolytics (which exhibit lower equivalent series resistance and smoother signal transfer) in place of RAW standard caps. All are Mundorf axial series.
I have also upgraded the polys considerably using a mix of Claritycap ESA and Jentzen standard caps.
There were a total of 26 capacitors (from memory!) required"
I am very pleased with the result, but it was quite a frustrating experience as customs both in Japan and England held on to the package, and of course I didn't know if the excercise would be successful until I fitted the upgraded crossovers!!
I attempted to attach a photo of the original crossovers, but gave up!!
Dave
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Post by twang46 on Nov 29, 2018 10:14:12 GMT
Hi Dave
Pleased to hear it's gone well
It's always pleasing when you have input yourself as well, sorting out the acoustic stuff in the cab is very often overlooked by people
Now you need a good (vinyl) copy of Zeppelin I to give them a good blast as there's some serious swings in frequency response down to around 25hz in places
Whats next then ?
Dick.
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Post by gruntfuttock on Nov 29, 2018 14:35:08 GMT
Hi Dick. I had the bass drivers re-coned by Bowers & Wilkins when I still lived in England. I would really like to get the mid range units re-coned but so far haven’t found anyone who can/will do that in Japan. The local Post Office told me that I can’t send speakers by Air because of their magnets so a degree of frustration! Dave
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