What's all this about...?

A nice young man called Adam, in an orange apron, cuts some MDF sheets...
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A day later, some embryonic cabinet work begins to appear in a make shift workshop...
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Meanwhile, a long suffering wife pretends not to notice an 18 inch Goodmans bass driver on a dining table...
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Comments

  • Love the perspective on that photo, it is a huge driver but it's dwarfing Mrs Df there. Don't blow the poor lady away on first test (Back To The Future styleee).
  • Tell her it a food mixer, my neighbour ask to borrow the lawn Hover , she wanted the lawn mower so I lent here a carpet sweeper. she was none the wiser.
  • cj66 said:

    Love the perspective on that photo, it is a huge driver but it's dwarfing Mrs Df there. Don't blow the poor lady away on first test (Back To The Future styleee).

    You're quite right. The perspective is doing a lot of the work there! And the fact that no one in the DF family is blessed with tallness :-D
    I actually managed to source a 2nd 18P driver last week, which is what has kick started things on this new speaker build (the first, the one in the photo was in an old bass cab I picked up for a tenner a couple of years ago).
  • AntiCrap said:

    Tell her it a food mixer.

    Possibly a post-modern salad bowl...?
  • Well with the right bass note it would mix it well and hands free!
  • AntiCrap said:

    Well with the right bass note it would mix it well and hands free!

    :-D
    I'm imagining a bass/salad bowl instruction manual with different recommended frequencies for mixing various salads depending on ingredients (rocket salad = 47Hz, tomato salad = 52Hz, avacado salad = 44Hz, etc.,....).
  • edited August 18
    That would certainly keep the salad dressing well mixed over the veggies, thrumming away in the middle of the dining table....

    Another shorty family too! I'm the, erm, tallest :D at a lofty 5'7" in my household!
  • Docfoster said:
    Well with the right bass note it would mix it well and hands free!
    :-D I'm imagining a bass/salad bowl instruction manual with different recommended frequencies for mixing various salads depending on ingredients (rocket salad = 47Hz, tomato salad = 52Hz, avacado salad = 44Hz, etc.,....).
    And the viscosity of the salad dressing, of course  :-B
  • Docfoster said:
    Well with the right bass note it would mix it well and hands free!
    :-D I'm imagining a bass/salad bowl instruction manual with different recommended frequencies for mixing various salads depending on ingredients (rocket salad = 47Hz, tomato salad = 52Hz, avacado salad = 44Hz, etc.,....).
    No 7Hz it will allow bowl movement also.
  • Doc, I wish you would stop messing about and do a proper job!
  • I've had fun this week. Will explain soon.
    (Spot the missing component...)
    image
  • Docfoster said:
    I've had fun this week. Will explain soon.
    (Spot the missing component...)
    image
    The veneer? Never mind, it's nothing to get cross over  X_X
  • edited August 25
    ;-)

    Veneer on the front is my patented felt-for-large-baffles. Used some high-gloss spray paint on the other panels.
    The felt went on fine with PVA. The spray paint is the sort of thing that I imagine one gets better at with practice. It looks OK. But "high gloss" finish is a bit patchy.  X_X

    image
    X_X
  • edited August 25
    A bit of background.
    The cabinets are just basic 18mm MDF with 20mm batons. I did think of using 25mm MDF, but was worried this would make the speakers just too heavy (the all-finished ones now weigh 30kg each).
    image

    I went for sealed back midrange speakers (Pyle PDMR5) to avoid the need to have a sub-enclosure. Woodwork is not my forte, and again wanted to limit the amount of MDF to keep weight down.
    The cabinet's proportions and volume were based on Goodmans own recommendations for the main 18P bass driver, as printed in their 1970s brochure). I made the cabinet slightly taller (and correspondingly narrower) to enable me to fit all 3 drivers in my project, vertically.
    I used a very simple strut / brace to reinforce the font baffle (an old floorboard offcut from some house repairs earlier this year).
    image

    I used a pre-built crossover from Monacor. It seemed the simplest / most time-efficient option. Also, the Monacor one had it's upper crossover point at 4500Hz. Most 3-ways appear to go for 5000Hz. To my ear during fiddlings on other projects, something important happens to sibilance around 4950Hz, so I wanted to try putting the crossover point as far away from that as possible. Also, I trusted the Monacor tweeters I had to hand more than the unknown Pyle midrange, so thought it made sense to give more responsibility to the tweeter.

    image

    Just waiting for the 2nd 18P driver to arrive and see what the results are.

    [-O<
  • uglymusic said:


    Docfoster said:

    I've had fun this week. Will explain soon.
    (Spot the missing component...)
    image

    The veneer? Never mind, it's nothing to get cross over  X_X

    You taking time out from your Edinburgh Fringe shows Dave ;)
  • Youve been super busy, Doc! Am liking the mix of research and give -it-a-go approach going on here.
  • edited August 26
    Suzy6toes said:
    Youve been super busy, Doc! Am liking the mix of research and give -it-a-go approach going on here.
    Ah yes! A "give-it-a-go-approach"...That IS my forte...
    :P
  • edited August 26
    Well, pretty much all done now. Just a few more upholstery pins to finish off the front edge trims...

    image

    ...They work! All drivers present and correct... :D

    And, I'm actually quietly pleased with how they're sounding. Genuinely surprised, in fact. :-)

    Straight "out of the box", they sounded a bit...sticky...? Possibly the new midrange drivers needed loosening up...? (Do crossover components and / or internal speaker cabling change after a few hours use...?) But after half a day's use yesterday the speakers have really opened out. Unexpectedly smooth and airy.

    Hard to know precisely what measures of luck and judgement have produced this. I'd like to think the 4500Hz upper crossover has helped...  :-B  ;-)  They're imaging well too.

    I am perceiving a very slight lift in the mids, perhaps a result of the midrange speaker being 1dB more sensitive than the tweeter. Compressed snare drums sound a bit un-crisp, with a bit more bloat than I'm used to. But vocals seem to love these DIY speakers.

    I really am a sucker for large bass drivers these days. They present so much body and substance to all sounds. These old Goodmans 18P ones are great. In these speakers, they are I think cleaner sounding than the 15 inch woofer in the Magisters. Although, my subjective impression is that I'm getting a wee bit less deep bass with the DIY speakers (if so, evident only on certain dub tracks). Whether that's the driver or my dicking about with Goodmans cabinet dimensions, or something else, I don't know. I'm tempted to wire the 18Ps directly from the binding posts (the woofers in the Magisters are connected this way, bi-passing the crossover), but there is such a smoothness to the upper bass > mid in the DIY speakers, I'm reluctant to take the crossover out of the equation (and, the 18P's response curve is a bit eratic after 1kHz).  

    So, my first impressions were "OK, not bad...but I'll probably return to the Magisters". Now, I'm not so sure. The DIY ones are certainly doing some things better, and without any help from DSP curves / shelves. I'll probably switch back and forth between these DIY jobbies and the revamped Magisters over the next week. Or at least, as often as my back and arms will allow.
  • Nice! You're going to have so much fun...

    Great project Ben, well done!
  • I've not done any serious work on speakers thus far. A tweak here and there but certainly nothing as ambitious as this. The feeling of creating something you really enjoy is fab. The most I've done is convert a single wired speaker to biwire and bi-amp and some upgraded x-overs.

    Nice one Ben.
  • Thanks guys.
    Yes, I do enjoy creative projects like this. Especially when they're successful!
    Making speakers from scratch(ish) seem "doable" to me, in a way that other hifi components don't (yet). Especially since I worked on the Magisters, and realised how simple a design they are.
    I find myself drawn to extremes so the idea of creating something on the Magister model, but turned up to 11, is inevitably where I found myself!
    And of course, Google is one's friend when researching / checking details and points of uncertainty.
    Also I want to say that I draw significant confidence and enthusiasm from being part of a community like chews, where DIY and tinkering is seen as very possible and desireable.
  • Beatifully project Ben, love them in white too.

    Quick question, why two washing machines in the listening room?
  • Silly! The right one is a tumble dryer... :O)
  • cj66 said:

    Silly! The right one is a tumble dryer... :O)

    =))
  • cj66 said:
    Silly! The right one is a tumble dryer... :O)
    No, he's bootstrapping a retro laundrette startup. 
  • I have worked out how to get them on to the spin cycle, but unfortunately Colin's UB speaker cables are too narrow to allow drain-away of the water. :-(
  • edited September 3
    The mid and bass anomolies that I was experiencing disappeared when I moved the speakers forward a bit. I'm really genuinely chuffed with them now.
    Haven't switched the Maggies back in to get a comparison yet, but I will.
  • edited September 4
    Well done Ben, needs re-wiring with Woolworth Bell Wire it might help.

    What amp did you test them with ?

    Also try hot melt glue to fix the wire down, then no flapping noises .
  • Chewing gum did the anti-flapping trick.

    I tested them with your lovely beastie Col. Maybe I should have used something less precious... :-/
    Anyway, all good and the amp and speakers are getting on splendidly. Daren't leave them alone actually. :x
  • Latest tweaks are to put one of these on the mid-range and tweeters...image
    After moving the speakers forward and fiddling with their positioning for a good while, I found that the position that gave the best imaging also gave a little too much to the mid and top frequencies. Nothing extreme, but enough for me to look in to.

    Using the faithful old EQ facility in JRiver DSP studio, I found that knocking around just 0.5dB off the signal above the 800Hz crossover point from the 18P woofer brought the drivers into balance.
    I had expected that only the midrange would require attenuating as it is rated as 92dB whereas the tweeter is 91dB, but after a lot of listening the overall sound was too bright with the tweeters left alone. Maybe the specs are unreliable, or there's something about the acoustics of my room, or its a personal preference thing.

    I was told by the internet that a basic rule of thumb is that 1dB = 1ohm, so went for 0.5ohm resistors to meet my need for a 0.5ohm reduction. (I thought about an L-pad, but wasn't sure how necessary that would be given that the attenuation I was after was so slight. I'll leave my first L-pad experiment for the Magisters, where I require -12dB.)

    Having fitted the resistors to the squawkers and tweeters, I'm happy with the results. I watched a couple of bluray movies last night and speech on both soundtracks was both crisp in the mouth and warm in the chest. Just as I like. Neither bright nor bloated.

    I'm hoping that's it for the DIY speakers.
    But who knows. I might possibly fit ribbon tweeters at some point.
    These meet the requirements (but aren't cheap)...

    image
  • No good Ben not pink ribbon he he
  • edited September 16
    image

    Pink ribbon tweeter.
    Happy now?
  • Decided to try dropping the speakers off the 10 inch stands, to the floor a couple of weeks ago.
    Spikes fitted. A few internal tweaks...

    ...Utterly awesome bass in combo with the One4 SECA. :-D

  • edited October 23
    uglymusic said:
    Sorry, you cannot see that song in your region....
    :-\"

    How about;



    Sorry Harry, prefer this version!
  • Docfoster said:
    Decided to try dropping the speakers off the 10 inch stands, to the floor a couple of weeks ago. Spikes fitted. A few internal tweaks... ...Utterly awesome bass in combo with the One4 SECA. :-D
    Put cushions on top and you have massage seats!
  • cj66 said:
    uglymusic said:
    Sorry, you cannot see that song in your region....
    :-\"

    You have a reprieve!
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