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Thread: A speaker project

  1. #1
    Join Date: Dec 2014

    Location: UK, East Midlands

    Posts: 972
    I'm Mike.

    Default A speaker project

    This will be a brief account of a mini project I embarked on in earnest last week but one that has had a gestation period spanning decades ...

    In the early 80s I bought a pair of B&W DM-10 brand spanking new from a dealer in Amsterdam after auditioning a bunch of stuff (most beyond my means) The very young chap who assisted me was very patient but really wanted to sell me a pair of JAMO speakers that were apparently 'what everyone was buying' - he thought they were brilliant - I thought they were bloated crap and went for the B&Ws partly to irritate him, but actually because they were the only pair I could actually afford that I liked the sound of.

    Fast forward to the early noughties and the DM-10 that had been my staunch sound buddies were relegated to the loft. Pressure of work and parenthood meant I had little time to listen to music and what listening I did do was computer based and through a pair of diddy bookshelf thingies or headphones. My Quad 33/303 were showing serious signs of age and also one tweeter in the DM-10s was playing up and I had no time or inclination to fix all the problems. Initially the speakers went to the loft but pressure on space a couple of years later meant they moved to garage storage where they pretty much stayed until I retired 5 years ago. One of the first things I resolved to do with my new found freedom was resuscitate my ailing HiFi set ... and this would include finally redeeming the DM-10 and fixing them up for service.

    Unfortunately time (and the weather) had not been kind on them .....

  2. #2
    Join Date: Dec 2014

    Location: UK, East Midlands

    Posts: 972
    I'm Mike.

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    To cut a long story short - one of the speaker cabinets had fallen victim of water ingress from a dodgy gutter connection (now fixed). Although not immediately apparent, when I took them out to have a better look the damage was obvious. The DM-10 were bottom of B&W's range when they came out and the cabinets were the typical cheap 'folded box' type made of laminated chip board which unfortunately does not take well to contact with water (basically the chip board swells up). At that point I pretty much gave up interest in them - obviously this would be a bit more than simply sourcing a replacement tweeter. They stayed in the garage and for a while I used them lashed up as they were with a Teac integrated. A year or so back, I removed the drivers, cut down both cabinets to remove the damaged section and put back the bass/mid drivers only; the working tweeter was passed on to an AoS member who needed one.

    For a while I did consider putting the remaining two drivers on ebay - they sell for surprising money (about 40 each) which is a bit daft considering a complete pair of DM-10s don't fetch that

    [IMG]B&W DM-10 by miktec101, on Flickr[/IMG]

    However - I started to get other ideas ...
    Last edited by mikmas; 27-06-2018 at 20:23.

  3. #3
    Join Date: Dec 2014

    Location: UK, East Midlands

    Posts: 972
    I'm Mike.

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    OK - I should stress at this point that this project was no more than simply having a bit of fun and maybe learning a little along the way (without getting a headache from thinking too much)
    My knowledge of all things speaker related is basic (to say the least) and my woodworking skills haven’t progressed much since failing to make a working mortice and tenon joint at school but as I said, if it looks like fun, I’ll give it a go. I also didn't want to spend any money .... at all.

    First thing I did was to remove the driver and terminal plate and strip out the remnants of the crossover. I then took a jigsaw to the cabinets and reduced them to baffle and bottom plate. I re-mounted the drivers and created a primitive ‘open-baffle’ set up. =



    Plugging into the garage system and playing a few tunes I have to say they actually sounded quite good - very bright, open and detailed with a great sound stage but (predictably?) totally devoid of bass.

    Back to the drawing board ....
    Last edited by mikmas; 27-06-2018 at 23:17.

  4. #4
    Join Date: Dec 2014

    Location: UK, East Midlands

    Posts: 972
    I'm Mike.

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    I spent a few happy hours looking into different types of speaker enclosures and their pros and cons and looked at a few project sites involving single 8 inch drivers (albeit full range rather than my limited example)

    For a while I toyed with the idea of building horn cabinets - as off of the frugal type or similar - but the sheer enormity of it and the expense of the wood required killed that idea stone dead - hardly worth it in this particular case (I also couldn’t be bothered…).

    Checking what bits and bobs and leftovers I had in the garage, I opted instead for a small enclosed cube. I had just about enough old shelving and crap for a roughly 30 x 30 x 30 cm effort entirely constructed from scrap 18mm ply. It would look something like this I hoped:



    According to B&W’s blurb about the Bass/Mid driver (officially a DW200/10) it was specifically designed to function in a ported enclosure - but what the hell, nothing ventured, etc, etc.

    I also figured that if it sounded utterly shit I could try it with a port ..... (although usually that's Xmas only)

  5. #5
    Join Date: Apr 2012

    Location: Southall, West London

    Posts: 35,725
    I'm Geoff.

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    Cubic enclosures tend to have resonance problems and can display unfortunate colourations. You might be able to pick up a pair of empty speaker cabinets from ebay for a modest outlay that could be more suitable for adaptation.

  6. #6
    Join Date: May 2016

    Location: Gloucestershire

    Posts: 338
    I'm Ian.

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    I've got a pair of KEF Q15.2 speakers - dual concentric so only one opening in the baffle + port. I bought them for a project but they didn't suit so they are lying around doing nothing. The rubbers on the main drivers are distorted so they were cheapish. For you they can be very cheap - the cost of picking them up! Probably a long way for you but you're welcome to them if they suit your needs.

  7. #7
    Join Date: Aug 2009

    Location: Staffordshire, England

    Posts: 21,112
    I'm Martin.

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    If a driver is specifically designed for a ported enclosure is there not a risk of damaging it in an infinite baffle? Or is it the other way around? I can never remember.

    What are you going to do for tweeters? I've some Audax metal domes and some Motorola piezo-electric horn tweeters lying about, you can have them for the postage if it helps. (The Motorolas are better than you'd think and they don't need a protective capacitor either. You can't blow them).
    Martin



    Current Lash Up:

    Technics SL1200P CD Player * NVA P90SA passive pre / Krell KSA50S Power amp * JM Lab Electra 926 loudspeakers *


    'This is the sort of music I'd be listening to if I was going shopping for a training bra.'

  8. #8
    Join Date: Dec 2014

    Location: UK, East Midlands

    Posts: 972
    I'm Mike.

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    Quote Originally Posted by walpurgis View Post
    Cubic enclosures tend to have resonance problems and can display unfortunate colourations.
    Not doubting that for a minute Geoff - but nothing like finding out first hand

    Quote Originally Posted by walpurgis View Post
    You might be able to pick up a pair of empty speaker cabinets from ebay for a modest outlay that could be more suitable for adaptation.
    That would defeat the 'no budget' clause ... and also rob me of a whole load of fun.
    My last fun project was building a small set of drawers from scratch to store hard drives and such - I already have loads of drawer space (including 8 sets of 'mini-drawers')

    Basically, I get bored just drinking coffee and picking my nose all day

  9. #9
    Join Date: Dec 2014

    Location: UK, East Midlands

    Posts: 972
    I'm Mike.

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    Quote Originally Posted by ianlenco View Post
    I've got a pair of KEF Q15.2 speakers - dual concentric so only one opening in the baffle + port. I bought them for a project but they didn't suit so they are lying around doing nothing. The rubbers on the main drivers are distorted so they were cheapish. For you they can be very cheap - the cost of picking them up! Probably a long way for you but you're welcome to them if they suit your needs.
    Thanks for the kind offer Ian - but this is just a fun project with what's at hand. If they work to my satisfaction they'll stay in the shed anyway

  10. #10
    Join Date: Dec 2014

    Location: UK, East Midlands

    Posts: 972
    I'm Mike.

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    Quote Originally Posted by Macca View Post
    If a driver is specifically designed for a ported enclosure is there not a risk of damaging it in an infinite baffle? Or is it the other way around? I can never remember.
    I thought an infinite baffle was basically an open baffle in a room rather than an enclosed one - now I'm confused

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