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

Thanks!

 

Nice speakers

 

Hi. First of all, awesome speakers! I have almost finished constructing two towers and the center channel. I dry fit them together and put the drivers in because I just couldn't wait, and I have never heard speakers that sound so good. There is a few questions I have before I complete the construction. First, do you recommend stuffing or dampening the speaker? If so, with what materials? I have both fiberglass insulation and polyester stuffing on hand if you do recommend one of those. Second, do you have the detailed measurements for these speakers like you do for the others? Lastly, when you say "middle length cut to 5.5" do you mean the straight piece of PVC tube? I'm assuming you do, but I just want to be sure. Once again, thank you. They sound so great and I can't wait until they are fully built and ready for use.

 

Thank you,

The center channel can be stuffed with either the poly or fiberglass since it is sealed, as can the midrange chambers of both designs the woofer chamber of the towers should be lined rather then stuffed as you want a clear path from the woofers to the port. You can use the poly or fiberglass there as well if you keep if behind a thin breathable fabric on the walls of the enclosure. The area behind the midrange chamber can be lightly filled up with stuffing. Generally I would use poly there as it won't shed fibers which can then blow out the port like the fiberglass will.

I don't have detailed measurements of the Towers yet as I have yet to get one up onto my turntable, it would be quite a feat to get one 10' into the air.

Yes the middle straight section of the port tube should be cut the 5.5" long.

 

Hi Matt,

Easy question for you. I recently ordered 3 PCBs for MTMWW towers and a center channel. Rather than use the listed dimensions for the towers I wanted to go overboard on the design, which is broken into two pieces. The lower chamber being a space for the woofers within 2% of the rectangular speaker woofer chamber volume, and the top chamber volume within 1% of the standard volume. Do you see any potential problems with this design?

 

That's perfectly fine to do and I think it is a very neat way to build the cabinets.

Baffle width and driver placement on the baffle is probably the most important aspect to follow closely when modifying a design as small changes there can have noticeable impacts on the response in the mid range or treble.

Cabinet volume is far less critical, I'd say as long as it's within +-10% there will be almost no perceivable change in response from the drivers and even +-20% is acceptable.

 

Hello does anyone have any good atmos speaker designs that would match the nexus series currently have the nexus center and i wanna build the main left and right towers but i wanna make sure that i can do atmos with something matching before

 

Hey mate....I know this is from years ago but any chance you still have those Sketchup designs floating around or have a diagram with measurements? Liking the idea of the Centre and LR with the WTMW alignment.

 

Matt.....looking to build some HT speakers for my living room. Still deciding what to build but the Nexus is high on my list.

I think I prefer to do the WTMW Centre as well as WTMW L/R speakers but ideally would like the L/R ones to be ported instead of sealed like the centre. Would this change the XO at all doing that and I assume the volume would have to get a bit bigger and add port.

Have you ever worked out what the volume would need to be and the port details for such an arrangement? If not I'm sure I can figure it out with a bit of research. Never built anything ported but have build some custom sealed enclosures for car audio subs.

Excellent work!!

 

@Matt Grant

Hi! Yesterday I managed to make some outdoor testing of my Nexus MT.

Measurement is outside, gated to around 10ms, unsmoothed and NO EQ. If you see the scale is around +/- 3db which is OK.

The think is that it does not match your Nexus MT measurements. I think I don't have the latest XO version and it was a little windy when I took the measurements (would this affect high frequency measurements?)

I also uploaded On Axis with EQ, which is quite flat.

 

I will look for them and upload them.

 

If you can get a picture of the current crossover I can determine if something in your measured response correlates to the differences in the crossover design.

I've seen a bit of wind effect high frequency measurements but usually it's a broad shift in level.

I think you need to shorten the gate further, I still see lots of interference pattern from reflections in those measurements. When determining the ideal gate/window time I usually test it shortening the window time by 1-2ms increments, you should see a sizable jump in clearness when you manage to gate out the primary reflection.

That said I think some of the HF weirdness and sawtooth pattern is actually your mic boom, it looks like you have some damping material applied to it but there is a chance that's making things worse with the close proximity to the mic.

A few years back I modified how I was mounting my mic and ended up getting some thin aluminum tubing just larger then the mic and 3d printing a cone shaped adapter to mount the mic to the tube to minimize diffraction. The tube holds the mic around 2-3ft from mic stand which largely removed the HF hash I was getting before from reflections off the original clip and stand setup.

This is the setup I have for my UMIK-1 which is how most of my outdoor measurements have been taken, but the newer boom I built for my M23 is slightly longer:

 

Sorry for the delay.

No need to change the crossover on these when moving from sealed to ported or vice versa.

The woofers are fairly flexible in terms of cabinet volume, so the question is rather how large do you want the cabinets and/or how much extra bass extension do you want from them.

The sealed center channel cabinet design is about 1cuft internal. You can actually use the woofers ported in a cabinet that same size tuned to 35Hz which should give an extra 10Hz of extension over sealed but a ported cabinet gives greater benefits in the 1.5-3cuft range.

 

@Matt Grant

Thanks for your reply. Sadly, I don't have pictures of the XO but... I bought the PCBs from you on 7 September 2018, and XO was assembled in year 2019, so it's probably the old version.

I will try the following:
1-. Wait for less windy conditions.
2-. Use a smaller gate. I am OK with this, as I am only concerned in performance over 100Hz.
3-. Rebuild the mic rig/boom. Regarding your rig... when you rotate the speaker, shouldn't you rotate in the speakers axis? It seems that with your rig, when you rotate it, the distance between speaker and mic will change.

I also measured my Fusion 6 speakers, also designed by you, so If you have measurements for that, I can also compare them.

 

On that turntable the axis of rotation is aligned with the front of the baffle:

 

Do you sell the crossovers for the Nexus speaker pre- assembled or only the PC boards?

 

I can sell fully assembled crossovers for any of the Nexus designs, I just don't keep any in stock so there would be a short lead time needed to assemble them.

 

I would really like to get the crossovers for a set of your Nexus /Dayton cabinets you built at the beginning of this thread.
Please let me know what you need from me on my end to get them going. IE Deposit, address etc.
Thanks!
-John