Copying content from the original thread main post verbatim. Design by CJD; Original build thread author —k—
The Sietecerocero Project! ND140/BC25SC06 MTM & TM
EDIT: 11/07/2011 – Winner at 2011 DIY Chicago.
http://www.htguide.com/forum/showpost.php4?p=540961&postcount=233
Original post from 2010:
Although I was waiting until Monday to announce this, I thought I would roll this bomb into the room and leave for the weekend…
Announcing the latest —K— & CJD collaborative project: ‘The Sietecerocero Project!’
This project is designed for my younger brother. My brother is big into music and movies with a collection of well over 2000 CDs. He loves all types of music from, first and foremost, classic rock to single female vocalists to world music. But unfortunately with having his first child arrived in November, he is low on budget. Up to now, he has used a HTIB. But, January brought him a lot of overtime hours, so he has challenged me to build him a complete 5.1 system for $700. Here we go…:
The project will be using the Dayton ND140 and Vifa BC25SC06. My intent is that there will be ‘The Ochocinco MTM’ and ‘The Seiscero TM’. Possibly, a thrid variety would be the MTM optimized to be placed beneath a large screen TV. With both a 8 ohm and 4 ohm version of the ND140 available, we intend to make these solid 8 ohm speakers so they work with low end receivers. My brother intends to power them with an Onkyo SR607.
ND140-4 http://www.parts-express.com/pe/show…number=290-216
ND140-8 http://www.parts-express.com/pe/show…number=290-218
BC25SC06 http://www.parts-express.com/pe/show…umber=264-1028
We’re looking to build a value leader that will be able to rock out but also sound great with whatever music is thrown at it. They will be placed in a larger basement family room. The center channel will go over/under a 46″ DLP.
If you haven’t picked up on the joke yet, the goal is to have each MTM cost $85 and the TM to cost $60 or $375 for the 5 speakers. I am also figuring on another $250 for a Dayton DVC and 240SA plate amp (TubaHT?). Then add in wood, terminal cups, poly fill, blah blah blah, and I’m slightly over the $700 limit – and I haven’t paid CJD yet! 😮
For the MTM drivers will cost $62/ea, while the TM will cost $37/ea. That doesn’t leave much room for complex or fancy crossovers. CJD has pointed out that the drivers are quite wideband and shouldn’t need a sledge hammer to bring into submission, so hopefully the part count will be kept down.
Box size and everything else is still to be designed. I’ll be building the boxes from scratch, but had thoughts about making them standard PE box size to make it easier for others. But, a 5-1/4 driver on a 10″ wide baffle??? I’ll leave it up to CJD. As soon as CJD says the word, I’ll begin cutting wood and order the drivers.
And with that, I think I will leave for the weekend and let you all discuss it amongst yourselves. I’m driving home home tomorow morning to see my father for his birthday and collect the $$ for this project from my brother. I’ll be back Sunday night.
(PS, I’m not a Cincinati Bengals or Chad ‘Ochocinco’ Johnson fan at all, but I do enjoy his sense of humor. And, when I saw in my budget estimate that the MTM was $85/ea, it just made me chuckle and continue to chuckle for a couple of weeks)
EDIT: 06/06/2010 – PROJECT DONE!!!
The project is done and delivered to my brother. I think they turned out fantastic, and when considering the price they are excellent. I found 3 MTM’s up front delivered plenty of dynamics for HT use. They sound plenty detailed and articulate for music. The sound is clean, crisp and clear with a big room filling soundstage. The speakers look good upfront too: Not too big, not to small, and are designed to be close to the back wall so they’ll fit in with most decors.
Please note that my boxes and crossovers are constructed to hit specific price points and level of effort. I’ve tried to note areas where I recommend upgrades / optimizations to increase performance.
PE 0.75cuft box: 20″h x 8″w x 13″d, 3/4″ roundover along the vertical edges.
Cut sheet for the front 3 – 0.75cuft MTM from a 48″x96″ sheet (Save the big scrap, we’ll use that later for the rear TMs):
Crossover:
(Speaker wire is the input. The white disconnects along the bottom are the driver negative terminals, top-left disconnect is the tweeter positive terminal, top-right disconnect is the midwoofer positive terminal)
Light fiberglass stuffing inside – about 1.5″ to 2″ thick. I also put a fistfull behind each driver.
BOM for As-Built – REV0. -NEED TO UPDATE FOR REV1!-
An all PE BOM. With free shipping, the cost difference is minor. This has the upgraded poly cap on the tweeter. You’ll also need to parallel two – 8uf caps to make the 16uf cap.
TM
PE 0.25cuft box: 12″h x 7.5″w x 10″d
Cut sheet for 2x 0.25cuft TM from a 34″x48″ sheet left over from 3-MTM.
(Note, these aren’t all to the same scale.)
Crossover:
BOM for Rev0.-NEED TO UPDATE FOR REV1!-
Sietecerocero / Ochocinco TM – Take 2
http://www.htguide.com/forum/showthread.php4?t=39902
These are my personal speakers I built for our small second living room. These speakers came out way better than I expected them to and really make me happy. I’m typically feeding them mp3’s through an Denon ipod dock. They might not be as resolving as my Khanspires, but they have a great sound. While they appear to be a tower, they really are a small sealed bookshelf made to look like a tower – the beauty of DIY.
One small note, these speakers are NOT efficient. Anticipate having to turn up the channel levels in your receiver and using a little more of those 120W than you normally do. Some on the internet would decry this, but in my opinion there is a reason we have big amps. I have these in my small living room and they can fill it and sound good using a low end Denon. I’m very happy. I just wouldn’t recommend them for a big room.
This design is free for non-commercial use. We only request that you post a picture of your completed project and tell us what you think. Also, we request that you do not repost or reproduce the design information. Please point everyone to this site for information about this design.
FAQ:
1. Can I build the MTM ported to get full range bass? / Can I build the MTM floor standing?
Yes. I recommend using the box that Curt Campbell designed for his AviaTrix. They use the same midwoofers, so the box tunning is the same.
2. What crossover upgrades do you recommend?
Definitely a high-quality 4.7uF cap Metallized Polypropylene Capacitors, such as the Erse Pulse-X or the Dayton, on the tweeter. That will only add like $2/ea. Almost nothing. Also consider metallized Poly caps for the midwoofer, but you’ll have to parallel caps to build your own 8.0uF and 16uF values. I do believe that more expensive caps can sound better. But, you have to weigh using a $12 tweeter with a $25 cap. The most I would spring for would probably be regular Dayton polys on the mids and a $4 4.7uF Jantzen Z-Standard.
Also consider a thicker gauge on 1.2 mH inductor for the midwoofers. This will increase the bass response slightly – though Don’t do this if you’re pushing them up against the wall though. Erse has 14, 16, 18 gauge available. You’re on you’re own selecting which one you want. If I were building these again, I probably would select the 16 gauge and keep them placed with about 6″ – 10″ (19″ – 24″ to the baffle) between the back of the speaker and the wall. This adds about $5 per speaker.
3. What is the Baffle Thickness?
Boxes are constructed w/ 3/4″ front face. Doubling up the front baffle is a recommend optimization – increase the depth to account for the extra baffle thickness. I recommend adding bracing to the MTM box.
4. Is the Roundover Required?
It is recommended that you have a 3/4″ roundover along the vertical edges. This will provide a smoother response. But, it is a small optimization and can be eliminated if you’re able to sleep at night knowing that your speakers aren’t perfect.
5. How close can I place them to the wall?
They are intended for nearer to the wall placement. I had them in my room with only about 4″ behind the speaker. So, the front of the speaker was about 20″ from the wall. This made the speaker about flush with my DLP TV.
6. Do I have to recess the tweeter?
I did. This is how they were measured and designed. However, like the roundover, it is an optimization to smooth out the tweeter response. The small horn loading on the tweeter and high crossover probably doesn’t make this as big of an optimization as on other designs.
Because the midwoofers are surface mounted, eliminating the tweeter recess would mean that you could then build these using the PE boxes without a router. Use a hole saw for the tweeter and a jig saw for the midwoofers. This is something really to consider for those who are tool and/or woodworking challenged.
7. Is there a different design for the center channel?
No. Upon completing the initial design, CJD didn’t feel it is necessitate. Usually the two problems are the 1) horizontal off-axis response and 2) the BCS.
For the off-axis response, we tried to keep the drivers as close together as possible. Walking around the room, I can hear a difference in the sound when I get some where around 35 – 40 degrees off-axis. But, it is just a little duller, not horrible. Everyone on the sofa directly in front hears great sound.
For the BSC. I built the exact same speaker for the mains for the center, and they are already designed for for near wall placement. The center sounds ever so slightly warmer with a hint more bass when placed directly under the TV inside my entertainment center. But it still matches very well. Not enough for me to worry about. Switching between Stereo and Dolby Pro Logic while listening to music really reveals that they match well. Just don’t bump the inductor size up on the center if you’re going to place in close to a big screen.
8. What should I set the crossover to my subwoofer at?
Audyssey recommended 60hz in my brother’s room. This was with the front baffles about 20″ from the back wall (about 8″ behind them). So, the room gain was extending the bass nicely. I think Audyssey sets the crossover at the measured f3 point. You could definitely hear good strong bass down that low. In listening to them, I preferred 100hz because I was running the sub slightly hot and this gave the bass a little extra oomph. I set his to 80hz and called it good. 80hz is probably what I would recommend, but always season to taste.
9. Can I use PE Sonic Barrier, Whisper Mat, Acoustic Stuff or something like that instead of the fiberglass insulation?
Sure. I like the PE Sonic Barrier and use it in projects with greater budget. I also have a bag of Acoustic Stuff. This project was about cost. I bought a roll of R13 a while ago that I’ve been using slowly for lots of projects – much more cost effective. Used properly, fiberglass is excellent. Using different lining and fill can and will affect the sound. You may have to experiment a little. Even with using the same exact fiberglass, you may want to experiment to season the sound to your own taste. Not necessarily required. But, this is the fun in DIY.
10. What is the deal with the Rev0 and Rev1 tweeter?
When building a second pair of TM for myself (parts ordered in November 2011), we discovered that Vifa had changed the tweeter. CJD did measure the new tweeter in the TM box and listened to the revised design. The MTM wasn’t listened to, but hopefully is good. One is in construction, and we hope to get feedback in July 2012.
Original data sheet from Parts Express:
Data Sheet for “Rev 1” from Vifa / Tymphany’s website.
The original tweeters used for the design measured flat and similar to the first response above. The tweeters purchased from PE around November 2011 measured very similar to the response posted on Typhany’s website labeled as Rev 1.
11. Room placement?
These were designed to have about 2″ – 6″ between the wall and the back. If you would like to place them further into the room, increase the 1.2mH inductor up to 1.5mH, or anywhere in between to fit your placement. See CJD 2012 posts.
