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My first “DIY” speakers

Discussion in 'd.i.y.' started by flashgo, Mar 18, 2010.

  1. flashgo

    flashgo DIY Practitioner

    It’s been over a year, but I’ve finally finished my first “DIY” mini-monitors:

    [​IMG] [​IMG]

    (Click to view larger pix.)

    A long time ago, I thought that I had fried 2 tweeters on my ‘briks, so I ordered some replacements. Of course, when I swapped in the replacements, I discovered that the original Hiquphons were fine. So they sat in a cabinet for over a decade. Then, more than a year ago, my wife needed some small speakers to go on the wall in her studio, and I figured that I could finally put the Hiquphons to use. Paul (a.k.a. Pulse Studio) recommended that I build up some clones of a long defunct Falcon mini-monitor in the BBC tradition. Because they’ll be in a large room, the cabs would be 2 inches deeper than the base build. They would use the same KEF B110s found in the ‘briks. And they would work well on the wall.

    So….
    1. I found some nearly unused B110s of the appropriate series on eBay (thankfully, just before these things turned into gold in the current market).
    2. Jim, a carpenter buddy, built up the cabs out of Baltic birch ply. (But I paid him, so I don’t know if this is pukka DIY.) Note the cool rabbeting at the corners. There is no internal bracing, as Paul says the sealed cabs are supposed to behave like wooden balloons. The cut-outs for the B110s were a pain, and I certainly couldn’t have done them myself.
    3. I bought the bits for the passive X-overs but then couldn’t figure out how to mount and align them. I sent them to the Skiing Ninja who built up some really ace X-overs and mounted them on the cabinet backs. (I paid the Ninja, so this is really not sounding like DIY….) It’s all point-to-point wired and mounted on painted MDF, then screwed to the backs with some rubbery spacers in between. One resistor can be easily swapped out in order to adjust the balance between the drivers. The speaker jacks provide simultaneous connections via bananas to the speaker cables and via spades to the X-overs and bi-wire couplers. A sealed port sends the X-over outputs through the back panel.
    4. The cabs are lined with NoRez, and I siliconed some Spectra Dynamics Deflex circles to the backs of the B110s. I forgot to add polyfill, but I really like the way they sound as is, so I think I’m leaving the polyfill out.
    5. I assembled all the bits and plugged the speakers into a StarFish/NAP250.
    :D Boy these speakers are sweet! They’re some of the best I’ve ever heard. They’ve got great throttle. When the sound comes, it just flows without inhibition. It is amazing how loud and clean they are. It’s also amazing how much bass there is for such small boxes. Since the drivers are the same as those in my ‘briks, I’m pretty copacetic with the sound. In comparison to the ‘briks, the minis are leaner and have more spatial definition, especially in depth. They’re different presentations, and I’m not sure that one is necessarily better than the other. In the long run, I may want these mini-monitors to use as surround speakers with my ‘briks. The matching drivers should sound pretty ultimate.

    After a few days with the minis, the ‘briks are back in. The soundstage is bigger and fuller with the ‘briks. It fills the room and is very relaxed and natural. In contrast, the minis invite you into their intimate sweet spot. The minis are very, very tempting (and cheaper and easier to drive). My daughter prefers the ‘briks, but my wife and I like them both. I can’t remember the last time in hi-fi that I liked 2 options equally!

    So now my wife whisks the minis away, and I’m wanting to build James’ PFM-SIIs. Jim, my carpenter buddy, says I can use his shop, and with this model X-over, I think I can layout and construct the next passive X-over. The next build will be real DIY. (Well, at least I know where to go for help.)

    A big thanks to Pulse Studio and the Skiing Ninja for all their advice! Paul really knows his mini-monitors and is just an all around great guy. And the Ninja defined what “personal attention to detail” means.
     
    Last edited: Apr 13, 2018
  2. Uzinusa

    Uzinusa Happy Chappy

    Utterly fabulous, i am again humbled and ground in the earth by the heels of those PinkFIshers who really "can"! Well done.
     
  3. CJ1045

    CJ1045 You want Briks with that?

  4. Yank

    Yank Bulbous Also Tapered

    What crossover design did you use? Is there a published schematic?
     
  5. James

    James Lord of the Erg\o/s

    We need more loudspeaker DIYers here, so I congratulate your first effort. DIY brings an unmistakable sense of achievement and satisfaction that money simply can't buy. You will learn and get even better with the next ones.

    Just to satisfy my curiousity, are the XOs permanently mounted on the exterior of the cabinets, or will they be reversed and installed inside once you have finished tuning them? If not, then you might like to consider the effect of the hole through which the wires egress the cabinet.

    James
     
  6. chiily

    chiily PFM Special Builder

    Yep, they look damn fine. I just love Birch play end on.

    Good work.
     
  7. flashgo

    flashgo DIY Practitioner

    Thanks, all.

    CJ, yes these are closely related to the Kans. I looked for an appropriate pair but could never find them at a “reasonable” price. Great that you’re bringing your daughter up with quality sound! ;)

    Yank, Paul swore me to secrecy on the X-over, but I’m sure we could get you a copy. None of this stuff was on the internet. Paul had it all in hardcopy. Send me a PM.

    James, now that I’ve found my way to speaker DIY, I’ll be coming back. This was so satisfying that I’m ready for the next speaker project – yours! :)

    The X-overs were a big debate. I wanted access to the resistor for tweaking the driver balance and was afraid that I’d never get the back off after sealing it in. The original plan was to have the X-over inside and run the wires to the resistor through the back to the outside world. The Skiing Ninja was uncomfortable about fitting the whole X-over into what was a small cavity once the NoRez was applied to the walls. Once it was clear that the X-over was a thing of beauty, it became part of the look on the outside. In the end, I used gasket foam tape on the back, so it is possible to pull the backs and flip them around. The hole in the back through which the wires pass has some expanding, air-tight foam in it. Looks like it disappeared in the picture. When the speakers find their way back to a surround system, I can settle the balance resistor and fit new backs with the X-overs inside. I also need to experiment with bi-amping, but that’s another day….

    Garf, I downloaded your PFM-SI doc from your signature. Wow! I really appreciate your diary of the build and your level of organization! I’ve now got a much better sense of what I’m in for and what to think about in the PFM-SII effort. And what a relief to read “I had all the MDF panels cut by a local wood merchant”.
     
  8. chiily

    chiily PFM Special Builder

    I'd go for methodical rather than organised :)

    What paid dividends for me was spending time thinking through the construction of the speaker; imagining piecing the panels together and figuring out in what order to do jobs in. I enjoyed the thinking as much as the building.

    Good luck with the PFM Special IIs.
     

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