Jeb's Overnight Sensation Build/Impressions/Measurements thread

Discussion in 'Speakers' started by Jeb, Feb 1, 2017.

  1. Jeb

    Jeb Friend

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    I’ve wanted to build these for a while. To cut right to it – for the small outlay of cash - the OSMTS are legit & I cannot speak highly enough of them.

    The kits are expensive to ship so I built these myself, trying to source all the bits and pieces as inexpensively as possible. Here’s what I found worked best:
    • HiVi B4N drivers x 2 –there are a couple of European dealers, but strangely the cheapest was still with PE, but via ebay - £35 incl. delivery
    • Dayton Tweeters x 2 – Soundimports.nl via ebay again - £30
    • Crossover parts – HifiCollective, UK – substitute all the Dayton caps & resistors for Jantzen equivalents. The inductors are not kept in stock but can be ordered to the required spec. - £26
    • Adjustable 35mm ID Port-Tubes – falconacoustics - £7
    • Wool stuffing – 90p + delivery – Wingham Wool Work
    Total: ~£100
    (Not included: wood, wire, binding posts)

    I needed to account for metric plywood sizes. I created these quick sketchups to preserve the original baffle size, driver placement & internal volume of the imperial MDF plans but tweak the depth for 18mm ply.

    [​IMG]


    I’m using rabbet joints to make assembly easier, much like the PE kit cabinets. But you could just build one easily with butt joints though. Here’s a plan for that:

    [​IMG]


    BUILD:


    Plenty of info already out there so here's just a few pics of the build I took along the way. I decided to make the rear panel removable and add a couple of my own touches. If anybody would like further details about how to do anything I did, please feel free to ask.


    1) Frame pieces cut & routed. Allowing overlap of end-grain for final flush trim:

    [​IMG]

    2) Assembly:

    [​IMG]


    3) routing the woofer cut-out (for small baffles I always make a little jig to clamp it without obstructing the router. Screws in the middle prevent movement once final cut is made)

    [​IMG]


    4) cut tweeter hole with forstner bits - 45mm/33mm for exact press-fit.

    [​IMG]


    5) Chamfer rear of woofer hole. Also hit tweeter hole with one too to help clearance of wires/contacts

    [​IMG]


    6) secure baffle with Sapele through-dowels & trim with flush saw

    [​IMG]


    7) Create port hole with Sapele accent to opening and binding post plate

    [​IMG]

    8) Build my first ever crossover

    [​IMG]

    9) Fit crossover & apply gasket to seal rear panel

    [​IMG]


    10) Ready to enjoy. They still need some kind of clear finish or wax.

    [​IMG]

    [​IMG]

    [​IMG]


    DAMPING:

    These definitely need stuffing and I think it’s worth playing with the quantity a little bit. I can’t really improve on Paul Carmody’s advice which is to keep adding stuffing until the bass sounds “huge”. You’ll know it when you hear it. Without the stuffing there is a boxiness which diminishes the scale of the speaker and makes them sound a bit weedy & echoey.

    I started with too much, which made them better fleshed out but also kind of slow. I eventually halved the total amount and teased it out more. I weighed the final amount on some rudimentary kitchen scales and guesstimate it to be not more than around 10g per speaker.



    LISTENING & COMPARISONS:

    (OSMT, Rega RS1, Alpair 7.3 DIY - all similar size drivers)

    [​IMG]

    using Naim 50wpc integrated amp

    Vs Rega RS1

    Physically, in comparison, the Regas are very lightweight. Sonically they are drier, leaner and also a bit meaner than the OS, with noticeably less bass (especially mid-bass) presence. The OS seem slightly pronounced in this region. The Regas also have a more prominent boxy/resonant colouration which prevents them disappearing in the room as well. They sound a bit cleaner and I feel they resolve more fine detail in the midrange. Unfortunately, the treble has a roughness and grit, which has always bothered me. By contrast, the OS have a very balanced, natural, yet forgiving treble response. I would now place this as one of my top priorities for a speaker.

    One area I feel the OS fall slightly behind is dynamically. The OS sound just very slightly slow and one dimensional in comparison, while the Regas sound more snappy, lively and impactful - except for in the bass where they are lacking.


    Vs Alpair 7.3

    A single-driver cliché: by comparison, the 7.3s have some magic (realism, depth, nuance and micro-detail) in the midrange that the OS lack. If you listen to ‘Paris, Texas’ by Ry Cooder, the 7.3s resolve more of that fine shimmer of guitars, the decay of the notes, as well as conveying the strings being plucked with varying force & intensity. Just like the Regas, the 7.3s are less effective at disappearing than the OSMTs but that critical vocal area really does a decent job of just appearing centrally and holographically with nice depth.

    However, the OS are much better in other areas. Firstly, they give me maximum bandwith for my music collection. If you listen to simple acoustic music the Alpairs offer a more interesting experience, but throw something like Radiohead’s ‘Idioteque’ at them and while not being a disaster, they sound a bit of a mess. They really can struggle a bit with complex, multi-layered music. The treble is not as well resolved as the OS and there’s also a bit of roughness and peakiness that I think bears out in the measurements of the Alpair 7s I took before. With the single driver speakers I own, there is the sense of them notably excelling in some areas (which I love) but missing in others, whereas the OS are perhaps a more complete package and a safer choice.


    OSMTS Final thoughts.

    The Overnight Sensations are fantastic. I’ve explained some of their weaknesses but where they really succeed is in the way they tie it all together. I found that some of the comparisons with the HD-650 are apt. They have an overall tonal ‘correctness’, decent resolution and a pleasing warmth that makes them an excellent, all purpose budget speaker. Just as with the HD-650, some may find them slightly too warm or a bit ponderous - but for my tastes they are not too far off being just-right.



    MEASUREMENTS (unsanctioned by SBAF)

    all ungated, 1/12 octave smoothing.


    NOTE: conditions were tough. I've been battling with the weather and it was quite windy. It always seems to be noisy.. church bells, birds, pneumatic drills etc. The ground is concrete. I got some quite strange readings but think I have ended up with something usable:


    1) Outside - 0 degrees, 1m from mic & floor

    [​IMG]


    2) L+R Comparison

    [​IMG]


    3) Outside - 45 degrees, 1m from mic & floor

    [​IMG]



    In room listening position in my test set-up (2m from speakers)

    [​IMG]


    THOUGHTS:

    • somewhat better off-axis performance than I saw with the single-driver speakers I built. Some loss of top end but nothing to cry about in my listening while moving around the room
    • I have found these to be very room friendly - again, more forgiving than the fullrangers. In the graph you can see the room causing some boost to the low end which probably contributed to my impression of their extra bass. All in all it looks quite respectable to my untrained eye for ungated measurements in an untreated room. The stands are also a bit low.
     
    Last edited: Aug 12, 2017
  2. kiss m

    kiss m Dill weed - acquaintance

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    the sub bass performance here surprised me, are the graphs exaggerating or do you hear it like that?
     
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  3. purr1n

    purr1n Finding his inner redneck

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    Your woodworking skills are fantastic!
     
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  4. thegunner100

    thegunner100 Hentai Master Chief

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    @Jeb Nice build! I agree with you that the OSMTs are great all-rounders, especially for its price. They also play well with small-medium sized rooms.

    For me, I do hear them that way because I have the min my bedroom in a corner. The further back that I sit, the more subbass that I get.
     
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  5. Serious

    Serious Inquisitive Frequency Response Plot

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    Those must be the best looking OSMTs I've seen. Great work!

    From what I heard (in other rooms) the graphs seem accurate to me. Keep in mind they're on a 10db scale and with the lowest frequency at 30Hz, instead of 20Hz. Looks like in the room they extend flat to 60Hz (this obviously depends on the room modes, some rooms probably give better extension) and are down -10db in the upper 40s. You do trade efficiency and bass distortion for better extension from a small speaker here.


    I think for many people the OSMTs are an excellent choice for a first speaker: Inexpensive, small and they don't do much wrong. Needs a more powerful amp than ideal, but that's what you get for expecting bass from a small speaker. Ultimately I felt they were too limited technically for critical listening, but that's also something that I'd say about my cheap OBs and probably 90% of commercial multi-way speakers.
     
    Last edited: Feb 1, 2017
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  6. Armaegis

    Armaegis Friend

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    Wow, so that's what having proper tools and woodworking skill looks like. :eek:


    Meanwhile I've got a hacksaw and a power drill... just barely enough to build a shoddy picnic bench.
     
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  7. TheIceman93

    TheIceman93 El pato-zorro

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    I miss my overnight sensations. I gave them to my brother when I had roommates who asked for quiet after 10pm. Maybe I should get them back. :headbang:

    Your woodworking skills are first rate. Mine didn't look nearly that nice.
     
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  8. Jeb

    Jeb Friend

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    Thanks guys, I appreciate it.

    The bass surprised me. For a little driver/box, there's an element of being able to almost feel it in the chest that was absent in the other 2 speakers. Obviously this is relative - it's not going to rattle your teeth, but in a small room (or near-field) it does give you something just a little bit tactile - as @thegunner100 says. Just a nice inexpensive speaker to enjoy and not have to worry too much about.

    @Serious - thanks for your thoughts on that and for pointing out the graph scale! - still getting to grips with the software.
     
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  9. Armaegis

    Armaegis Friend

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    Perhaps a relevant question here though... how much do you have invested into your woodshop?
     
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  10. Cspirou

    Cspirou They call me Sparky

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    I really like how the back panel is screwed instead of glued for accessibility. I'm a big fan of using the small pull saw as well to cut off bits that are sticking out.

    What software did you use to draw the speaker mockup? SketchUp?
     
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  11. johnjen

    johnjen Doesn’t want to be here but keeps posting anyways

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    NICE!

    I like your use of dowels, it makes your build unique and adds a touch of distinction.
    And with your woodworking capabilities you should be able to easily take the next step up when so motivated.

    JJ
     
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  12. Jeb

    Jeb Friend

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    Are you thinking about getting set-up with one? If so, awesome - I doubt you'll regret it if you feel the pull!

    My set-up is nothing crazy at all. It's just a small space with a solid workbench I built to fit and some storage space for all the tools. I do most of the work outside on a portable bench made of 2 trestles and a piece of IKEA worktop. I have 2 routers (a 1/2" and a smaller 1/4" trimmer), a small drill press, a hand drill, mitre-saw, circular saw, jigsaw & orbital sander. That's about it. Probably not much more than £1200, accumulated over the years. In the past I have usually bought 'good' (Dewalt, Makita, Bosch-pro) rather than 'excellent' stuff (Festool, Mafell). They're fine for most things I do.

    All the hand-tools, clamps, accessories, jigs, and stuff do add up. I tend to not skimp on hand-tools, because I feel like those are a life-long investment and i've inherited some lovely tools from other people. This year I upgraded my measuring/marking equipment. I never thought I would spend £30 on a 12" ruler or £60 on a small carpenters square - but they're fantastic, and have taken my accuracy to a much better level. Likewise, for bits & cutters. That forstner bit in the picture is made by FAMAG and it costs as much as a set of 10 cheap bits but it's magnificent - so clean and accurate. The Germans really know how to engineer a drill bit. I'm accumulating nice stuff gradually as I need and can afford it.

    It's tricky when starting out because there's a tendency to want to do things cheaply, which isn't wrong because it's ultimately just about getting started and enjoying it. Money may be tight and you need to find out if the hobby is for you. On the other hand, the frustrations and inaccuracies of some cheaper power tools can quickly kill your enthusiasm. I would get the very best you can afford and not be too proud to have great stuff even when you're learning. If you value quality and accuracy, you will appreciate it.

    Anyway, none of this should discourage anyone who can't get hold of the kit from having a go at the Overnight Sensations. A 4' x 3' piece of ply or MDF would only be about £20. You could even get the store to cut it to size and just glue/screw it together. There's no need to recess the drivers. You could cut the woofer hole with a jigsaw (even a coping-saw) and the tweeter hole with a hole-saw/spade bit in a hand-drill (be careful). If the holes are a bit rough, no one will see them. They'll sound exactly the same as mine.

    One final word on tools - the Jasper circle jig is brilliant. I wish I'd just sucked up the shipping/VAT and got one sooner.


    Thanks - I borrowed the removable panel idea from other builders' pictures on Paul Carmody's website. Yep SketchUp. It's new to me, but I found it very intuitive. I just can't get my head around adjusting plans for different wood sizes or rabbet joints unless I see it in a plan like that. I'm with you on the Japanese saws - they're a pleasure to use.
     
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  13. Cspirou

    Cspirou They call me Sparky

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    I'm with you on investing in good measuring equipment. I bought a crappy plastic ruler once thinking it was accurate enough. After cutting though I saw that the ruler wasn't straight at all and had an inherent curvature. Not only that but the lengths weren't that accurate either. Drawing a line from 0-4cm twice was not the same length as 8cm. Since then I got a nice metal ruler. Unlike tools, measurement equipment will not wear down. I would rather start off with really good measurement and crappy tools then the other way around.
     
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  14. Poleepkwa

    Poleepkwa Friend

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    Damn, thats a nice looking build! Really like what you have done there with the "back" plate! Makes playing around with the damping so much easier. Why did I not think of that, when I was building... Do you have a picture of the bottom of your crossover?
     
    Last edited: Feb 2, 2017
  15. Jeb

    Jeb Friend

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    [​IMG]

    I pretty much just copied the picture from the Parts Express manual (available on their website) as best I could, but instead routed the wires to the screw-down terminal blocks. I think I could have laid it out better because I seemed to need to do more extending of the leads than some others i've seen.

    There's some nice info on a neater layout here: http://techtalk.parts-express.com/f...night-sensation-build-two-sets/page4?t=223751

    Some good info in that whole thread actually.

    I needed to move things around a bit to ensure the terminal blocks for the inputs were located centrally.
     
    Last edited: Aug 12, 2017
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  16. Armaegis

    Armaegis Friend

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    Thanks for all the wonderful info! It's not something in the immediate plans, but certainly an interest... although my little lab for soldering and fixing electronics already takes up enough room! Sure, I could set up woodworking equipment in the garage, but as a small single-car garage I actually prefer to pack my car in there :p
     
  17. Cspirou

    Cspirou They call me Sparky

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    I think a table saw is a lot more universal than people think. Along with a drill you can do build a lot of speakers. I do chamfering by hand with a rasp. It looks ugly, but it's inside the speaker and no one see's it.
     

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