First time DIY - Overnight Sensations MT

I think Fusion-8 and rest are better if you are farther away.

Since then I have built Speedster and it sounds bigger than OSMT and I like em more.

 

I am definitely interested in the speedsters, but I assumed those were destined for the desktop as well.

I see there's an MTM version so I might just go with that.

https://sites.google.com/site/undefinition/overnightsensationmtm

 

I received my OS MTM kit from DIYSG and holy crap can that guy pack a kit! I tried to buy peg board to be like Dr. Hooncake, but no love at Micro Center. So some googling around I found the ultimate lazy man’s solution here. On the Hifi Circuit forum they sell PCBs that make this whole thing a piece of cake, for $18/pair shipped, it was a no-brainer.
I will post my MTM build pics and experiences here. On @thegunner100 advice I also purchased the ISO Acoustics L8R155 stands to get my setup correct.

 

OSMTM

Building experience

I recently purchased the OSMTM kit from DIY Soundgroup and the crossover PCBs from Matt Grant (see post above for link). This was my first DIY project, other than attempting to modify the TC-750 and re-terminating a headphone cable. For instructions, I mainly watched YT videos and consulted @Hooncake excellent thread here. I also found a good resource was Paul Carmody's website.

I found this a challenging but ultimately straightforward project, it just took longer than I thought, but it took about a weekend to complete. It was my first time since junior high woodshop class that I was glueing, sanding and staining wood.

I finally got the hang of soldering and found that it was the least challenging part of the build. The hardest was decently finishing the cabinet and getting the amount of polyfil stuffing right. I had to do my staining and polyurethane applications mostly in the garage while freezing my ass off. I think I will do another coat of staining and poly once it warms up in the spring.

I put together the speaker and purposely left off the front baffle and installed the ports, crossover and wiring. I then experimented with the polyfil as Paul Carmody recommended by overfilling and then listening. Over three sessions with subsequent removal of stuffing, I listened until the bass really opened up and didn't have a muffled aspect. I also knew I had the right balance when the front baffle started resonating since it wasn't glued on yet and only secured with painter's tape.

Initial Listening impressions:

I installed the OSMTM in my 2 channel system which is a single Vidar and Freya and source either WAV/FLAC Gungnir Multibit gen 5 USB or coax CDP. I haven't listened to vinyl yet. The Freya used either a quad of EH 6SN7s or mainly Sylvania 6SN7GT as the driver tubes.

The OSMTM replaced ELAC B6's on ISO Acoustics L8R155 stands. It was very apparent on initial listening that these speakers are just as awesome as I remember the OSMT sounding when I heard them at the NYC meet a little over a year ago. They easily outclass the ELAC B6 through the entire frequency spectrum and threw a larger (both width and depth) soundstage. The detail retrieval is on another level which is what I'm most thrilled about. For the first time I can really hear the effects different tubes have in tube buffer stage of Freya. The Sylvania 6SN7GTs throw a larger soundstage than the JFET buffer, however the image is artificially stretched and blurred a bit. I never heard this via the ELACs but only heard the blurriness and loss of details via HD800 and T3. I think it says a great deal that these speakers are resolving enough that I can evaluate differences in tubes in the Freya. I actually prefer the JFET buffer currently with these speakers because I like the transparency and fuller bass. With the OSMTM, I now appreciate the interest in Saga or preamps with less errors of omission.

I am very impressed with the bass response of the speakers, it extends low enough for 4 x 4 inch drivers. The bass quality is detailed enough but the bass guitar on Khruangbin or Greyboy Allstars is missing most of the snapping of strings and percussive aspects that I hear via HP that I would ultimately like via speakers. However, I need to be realistic these are small drivers and I am very happy with quality of what bass is there. I never once thought that there is a subwoofer hidden somewhere, I think that is wishful thinking. In comparison, through the ELACs, bass is even less detailed and way more loose and flabby.

Overall in my short time so far with the OSMTM, I can easily see there is a huge amount of value in this DIY project. Both in the satisfaction that I was able to put together this kit, and in the quality of speaker for the money spent and sweat equity.

I think for my medium-sized room, and a under $2000 outlay, this is a great budget system with Vidar and Freya or Saga. In fact, depending on results of more listening with EH 6SN7s, I may be looking to change at some point to Saga. Although, I love the JFET buffer with headphones and RSA Nighthawk. I will add more impressions with vinyl and listening with different tubes.
I am excited to show these speakers off to others in town and if I can get my butt up to NYC.

Thanks again to @thegunner100 for the recommendations!

 

Thanks for the feedback on the MTM in a room setting as opposed to desktop. Seems like this is what I'm doing next along with speaker stands.

 

Great comparison with the ELACs!

Considering how the ELACs are so highly regarded for an affordable speaker, I'm really tempted to build a pair of these now.

 

Great read. I think you're right about the 4" woofers, even in the TMM tower configuration. I saw he had a 5" design but it doesn't seem like that's currently offered as a kit. What works for a room isn't always what works well near field though.

I saw this HiVi kit on Amazon looking up someone else's non-kit speaker link, I remember the assembled version of this being FOTM when I first started getting into audio and it was known for surprising bass but it wasn't efficient and I'm not sure how it'd really work in near-field:

https://www.amazon.com/HiVi-Bookshelf-Speakers-Near-Field-Compact/dp/B072KTZ2VC/

Edit: nvm, seems like they're using cut rate drivers in the kits: http://techtalk.parts-express.com/f...1345005-big-forest-cut-down-swans-disappeared

 

I've just finished a very leisurely OSMT build, using this thread as a source of information. These are going to be a gift for my niece, so I went out and found an SMSL Bluetooth-capable amp to match with it.

Several more points for future reference:

• I had no chipping problem with the birch plywood, I used calipers to measure the solid core of the screws, and matched the drill bit to fit.
• Like @Hooncake, I also used a perforated board to mount components, to get a hands-on idea of how a crossover circuit gets wired up. Otherwise, using a pre-made PCB such as the one @Gaspasser located would have made things much faster.
• Lego bricks make for ideal crossover board 'feet', and angled Lego bricks can be used to angle the terminal blocks at a 45 degree angle for slightly easier wire insertion.
• Slathering hot glue over the bottom of the crossover board, then flipping it over to place into the cabinet, results in a hand covered in hot glue and much swearing. Don't do this.

Overall, they sound great nearfield. I'm not a discerning listener though and have little to add to what others have already written. They don't go as low as the Vanatoo Transparent One Encores which recently arrived, and have noticeably less bass impact than using the HD800S.

They don't look as visually flat in real life- they were quite hard to photograph with interior lighting.

 

You might try teasing out the stuffing a bit more or playing around with the amount if you aren't happy with the bass. I wasn't impressed with any of the sound until I put more stuffing than I was expecting in.

 

+1 that seems light. Nice use of legos on the xo board too.

 

Way more stuffing will bring up the bass. I added probably 2x more than what I show in the pics.

 

Due to this thread popping back up, I revisited my build and put both a little bit of recycled blue jean material on the back wall and replaced the possibly cancerous ancient pillow stuffing with properly weighed Acousta-stuf. Not a huge difference, but I think I originally had too much stuffing as, they sound a touch more open, and with a stronger center image (positioning did not change). I didn't realize I didn't have a good center image until I got one The blue jean material on the back wall also helped alleviate the last of the metallic twang that I could hear every once in a while. I like these speakers even more now and have decided not to build a different, larger set for my office.