Project NEXUS... A timbre matched family of Hi-Fi/HT speakers

I believe the speaker Erich is speaking of is the newly revamped 88-special and these two designs are very different animals.

The new 88-Special is nearly 10dB more sensitive then the Nexus Center and also has greater power handling so it is a far more dynamic speaker and can play at output levels well in excess of what the Nexus center is capable of.

It does have a more narrow dispersion and while this can improve intelligibility the sound-stage will tend to be more focused and less spacious then the wider dispersion dome tweeter on the Nexus.

The weaknesses of the new 88-special will be much more limited bass extension and a slightly more uneven frequency response.

Overall it's far more suited to home theater use when you need to fill a large room without strain even on normal AVR power.

I should note that the 88-special is a much taller speaker if that is an issue (this is the original version but the cabinet is the same):

 

Hi Matt,

Is there a thread that I could learn more about the 88-special? I've mined around on here for about a month and have found references to it but nothing in the way of dimensions et al. Is there enough to embark on this as a pure DIY, did you create a unique crossover board for this?

Thank you,
Mark

 

I think I have settled on a short throw projector for my application and am trying to get a grip on the real estate involved and can I make this work with the projector.

 

Hi Matt,
I originally built these towers, center, and atmos about 3-4 years ago and you helped me immensely. I am looking to rebuild everything to make it a bit more pleasing to the eye. I originally built it all as typical black boxes, I've enjoyed them the entire time. I have since upgraded everything around them and still think they sound great. Actually as the electronics around them improve so does their sound. I am planning to build the towers as boat hulls, for lack of a better description, I am going to change a few things I wanted to run by you to get your thoughts. 2.163 seems the optimal space for the dual woofers, 12 for the port, except I want to make it downfiring. I'm also going to do a wmtmw configuration to get the tweeter at the height I watch movies at. I just wanted any thoughts you might have. Thanks again for 4 years of great sound.

 

I don't envision any major issues from those changes.

 

Is 12" the correct length for the port if using 4" pvc instead of the precision port? Will that leave the port too close to the back wall?

 

If using 4" PVC without flared ends I'd make it about 10.5" long.

 

Sorry I should have mentioned I am going to flare the wood on the outside port end using a 1.5" roundover but that shouldn't matter much right?

 

Also, I just finished assembling the crossovers using your pcb's. Those things are awesome, make the crossover SO much simpler for a dummy like me. Worth every penny!

And big thank you for the designs. Bummer I have to wait till March till parts express can ship some back ordered parts.

 

In that case either way should be close enough being a couple Hz difference between the two, which is probably unnoticeable in room.

 

Hello Matt Grant

I just stumbled upon this website, and it’s great!

I especially like the Nexus MTMWW Tower speaker design, this appeals to me on a number of levels; the aesthetics of the design, the DIY factor, the frugality of the components, and from what I’ve been reading the sonic performance. Oh and the color scheme isn’t bad either.

All of the DIY aspects of the project, carpentry, crossover wiring, as well as component purchasing, are well within my skill set, unfortunately my weakness will be the sonic piece, too many years of loud engines, loud machinery, and the use of headset coms for extended periods of time.

I’ve read all 236 posts, with a lot of attention paid to post #6.

I think I’ve identified the few revisions to this design, but I would like to be sure before starting the project.
• Is the 2018 revision for the crossover the most recent?
• Is the 2018 Parts Express BOM still correct for item description, (ignoring the pricing)?
• I saw no revisions to the carcass, it appears from my reading that the dimensions are somewhat fluid, but if I missed something…

I’m sure I’ll have questions as I progress through the project especially regarding the ‘tuning’ of the units, for now that can wait.

It’s time to fire up AutoCad and generate some 2D drawings of the MDF carcass, as well as a 3D model to confirm fit up.

I’m excited to start.

Thank you for your work designing this speaker.

 

Yes the 2018 crossover revision for the MTMWW tower design is the current model. The build info on those first 6 posts has been kept updated with the latest and greatest crossover revisions and cabinet designs.

Just be aware the posts following might reference older info.

The only dimensions on the cabinet that are critical are the baffle width and to a lesser degree the driver spacing. The cabinet height, depth, shape and even internal volume can be customized to a certain extent with minimal impact on the overall sound.

 

Hello Matt Grant

Excellent. I'll try to restrain myself, and stick to the first six posts.

Do you have any of the crossover PCBs available for purchase? Not a big deal if not, the circuit is simple enough to reproduce on a hobby PCB, or I can draw them up and etch them myself.

Thanks again for your efforts, and prompt response.

Cheers

 

You don't have to disregard all posts, anything you see posted after 2018 for the MTMWW tower design will obviously be relevant as that's the last time I made any updates on that design. It's really just the first few posts after the main design info posts that reference some of the older outdated crossover schematics.

I do have PCBs available for them on eBay.

 

Hello Matt Grant,

Copy that, I remembered seeing a link to eBay, and ordered the PCB's last week.

Cheers

 

Hello Matt Grant,

I received the PCBs for the crossovers. Thank you.

I have a question regarding the horizontal stiffeners, one above the HF driver, and one below the HF driver. Are theses stiffeners full width, which would divide the MTM chamber into tree discrete volumes, or are these stiffeners just a short block to tie the baffle to the back plane of the MTM chamber?

Cheers

 

They are just short blocks that tie the baffle and rear wall together, they do not partition off that section into separate chambers.

 

Hi Matt,

I have been gathering all of the components to build an entire Nexus HT setup. I was wondering, do you have any subwoofer designs tat you recommend to be used with the nexus speakers? I was hoping there would end up being a Nexus subwoofer to complete the lineup!

 

I had planned to build a test a pair of subwoofer cabinets that I dubbed the Bassic-10 and Bassic-12. These were just to be a simple easy to build cabinet that could be used with a variety of inexpensive subwoofer drivers.

The 12" was to be 18" wide x 20" deep x 22" high (~3.2cuft, tuning: ~20Hz):


The 10" was to be 14" wide x 20" deep x 18.5" high (~2cuft, tuning: ~25Hz):

Unlike the VBSS they do not require EQ beyond a highpass and they could be powered either through an external amp driving multiples or singularly with a plate amp.

They can be made front or rear ported, the 10" using the 3" precision port kit at full length and the 12" using the 4" port kit at full length.

You could use the Dayton SD270A-88 in the 10" or the SD315A-88 in the 12", those drivers would match the look of the Nexus designs though a single SD270A-88 in the 10" sub would actually have a little less bass output capability then one of the Nexus towers.

There are also other drivers that are a better value and more capable in those the cabinets, like the GRS 10SW-4HE and 12SW-4HE.

 

Thank you for the quick response. I will absolutely consider those designs. Probably lean towards the 12 inch. I appreciate the help!

 

Hey Matt, I was wondering if you happened to have a cut list for the various designs in the Nexus series. I have seen some designs online that have them and it is totally fine if you do not. Just figured I would ask. Thanks in advance for the help.

 

Nexus Cabinet Cut Lists:

Nexus TM:
Using 1/2" material for the cabinet and 3/4" for the baffle, Overall Cabinet Dimensions - 10"H x 7"W x 9"D:
Baffle(3/4") / Back (1/2"): 10" H x 7" W
Sides (1/2") x2: 10" H x 7.75" W
Top/Bottom (1/2") x2: 7.75" L x 6" W
If using a window style brace, same size as top/bottom.

Using 3/4" material for entire cabinet, Overall Cabinet Dimensions - 10"H x 7"W x 10.5"D:
Baffle/Back (3/4") x2: 10" H x 7" W
Sides (3/4") x2: 10" H x 9" W
Top/Bottom (3/4") x2: 9" L x 5.5" W
If using a window style brace, same size as top/bottom.

Nexus MTM
Using 1/2" material for the cabinet and 3/4" for the baffle, Overall Cabinet Dimensions - 16"H x 7"W x 10.5"D:
Baffle(3/4") / Back (1/2"): 16" H x 7" W
Sides (1/2") x2: 16" H x 9.25" W
Top/Bottom (1/2") x2: 9.25" L x 6" W
If using a window style brace, same size as top/bottom.

Using 3/4" material for entire cabinet, Overall Cabinet Dimensions - 16"H x 7"W x 12"D:
Baffle/Back (3/4") x2: 16" H x 7" W
Sides (3/4") x2: 16" H x 10.5" W
Top/Bottom (3/4") x2: 10.5" L x 5.5" W
If using a window style brace, same size as top/bottom.

Nexus Center:
Sized for 3/4" cabinet material, Overall Cabinet Dimensions - 10"H x 26"W 12.5"D:
Baffle/Back (3/4") x2: 10" H x 26" W
Sides (3/4") x2: 8.5" H x 11" W
Top/Bottom (3/4") x2: 26" L x 11" W
Front to Back Braces (3/4") x2: 8.5"H x 11"W - Openings should be added behind midrange chamber)
Mid/High Chamber Back (3/4"): 8.5"H x 6.5"W - This one gets sandwiched between the other two braces to form the sealed midrange chamber.

Nexus MTMWW Tower:
Sized for 3/4" cabinet material, Overall Cabinet Dimensions - 46"H x 10"W 15"D (not including baseplate/feet), Rectangular Cabinet, no sloped back:
Baffle (3/4"): 46" H x 10" W
Back (3/4"): 46" H x 8.5" W
Sides (3/4") x2: 46" H x 14.25" W
Top/Bottom (3/4") x2: 13.5 L" x 8.5" W
Window Brace (3/4") x3: 13.5" x 8.5" - Two should be full window braces and are placed below/between the woofers, the third above the woofers forms the bottom of the midrange chamber and should only have openings behind that chamber.

Internal Midrange Chamber Back (3/4") x1: 14.75" H x 8.5" W.

Another window brace could be added behind the midrange chamber, in this case it would be: 9.75" x 8.5", otherwise you can add stick bracing there.

 

Hi Matt,

Thank you very much. This is great. I really appreciate you taking the time to write this all up for me. Extra points for the different dimensions using different thicknesses for the TM and MTM. I was debating which thickness to go with so this helps a lot. Having the list and the 3D drawings available helps so much to plan out how much material to buy. I am looking forward to starting on the cabinets in the next week or so. Again, I really appreciate it. I'm looking forward to any new designs you come up with. I'd love to see a design with some high end drivers. Just to see how crazy you could make it haha

 

Matt, your pcb's take care of reversing polarity correct? Sorry, I've misplaced the instructions that came with them. Just wanted to double check before I hook everything up finally.

 

Yes the PCB has the polarity markings already flipped for the midrange/tweeter so they can be wired up as marked on the board.