Hypercube Loudspeakers

[xrk971]

Nice looking H'cube there!

 

[gmad]

Thanks. Still need to buff them out a bit more before the clear-coat. I'm thinking not too glossy since I left the tape on too long during glue-up and the surface got slightly marred. Should turn out pretty well though.

 

[ultrakaz]

I haven't tried foamcore myself but here's how I might make the 13 pieces needed for each enclosure:


-choose an edge length (x) for the square baffle plate and cut one of these

-cut 10 rectangles with dimensions (x) X 1.414(x)**

-inscribe a rhombus in each rectangle by drawing lines connecting the midpoints of adjacent sides and cut these out

-cut two of the rhombi in half to create the four triangles


X, perhaps you have a better method. I think the possibility has been mentioned of creating a "net" and using a special v-shaped scoring tool. I guess once the RD is made we could just truncate one of the pyramids...


**alternately, and with less wasted material, you can cut a few rhombi from a strip with a width of .8165(x) by making parallel 70.53 degree cuts spaced apart by .866(x) (the edges of the strip become the edges of the rhombi).

Hi gmad, Sorry if I missed it but what bevel angles (for baffle, triangles and rhombis) did you settle on?

 

[gmad]

The bevel angle of the rhombi is 60 deg. The triangles, being half of a rhombus, will have one edge (the edge that connects to the baffle) with no bevel (90 deg.). The square baffle should have 45 deg. beveled edges and the thickness should ideally be .707 of the other pieces.

 

[ultrakaz]

The bevel angle of the rhombi is 60 deg. The triangles, being half of a rhombus, will have one edge (the edge that connects to the baffle) with no bevel (90 deg.). The square baffle should have 45 deg. beveled edges and the thickness should ideally be .707 of the other pieces.

Thanks!

 

[mattsmith]

 

[gmad]

Thanks, mattsmith.

I have been wondering how you've been getting along with these. That shot of the taped-up "net" is crazy.

My Pluvia Seven set is on hold right now while I experiment with different paints. I had a problem with the tape marring the surface (leaving it on for 24 hrs. probably didn't help things). Not an issue if sandable primer and a coat or two of paint is to be used, but I suppose I could hold each piece in place (one at a time) and use super glue. As for painting, I like hanging the enclosures by the baffle and painting down towards the bottom (rear) point to help control drips. However, I haven't gotten satisfactory results yet from the low voc paints. There is one more I may possibly try before switching to oil based.

 

[xrk971]

Mattsmith,
Beautiful precision work there. Very nice Hypercubes. Your photos are oversized and don't display well. In the future please downscale to 1024 wide max landscape format.

So how does it sound? Did you use any stuffing?

I missed what driver this is.

 

[mattsmith]

Mark Audio CHR-70A 4"

Sound is good. Still listening to them after a year. Have a sub to fill in lows. Building a new pair with Tang Band W8-1808 8" speakers. Should be about twice as big (duh) and do better lows. If that is not enough I'll probably just build a pair of powered subs to go under the new speakers. End up with a hypercube snowman

 

[gmad]

That's good news; I look forward to hearing more about the new project. xrk971 built a 2-way and I think was pleased with the performance. The 1808s should provide plenty of output without a sub but you may need a bit of eq to get the balance right. Also, note that the W8-2145 is now available and may give similar performance for half the price. Good luck.

 

[xrk971]

That's good news; I look forward to hearing more about the new project. xrk971 built a 2-way and I think was pleased with the performance. The 1808s should provide plenty of output without a sub but you may need a bit of eq to get the balance right. Also, note that the W8-2145 is now available and may give similar performance for half the price. Good luck.

Ah yes. Down memory lane. Almost forgot about those. They look cool too.

http://www.diyaudio.com/forums/full-range/265915-hyperfast-hypercube-based-2-way.html

 

[gmad]

Pluvia Seven Hypercubes w/stands

I've been listening to these for a couple of days and I'm impressed. The stands are angled at 22.5 degrees. I was worried at first that the speakers would want to slide off, but with urethane bumpers they are very stable. The stands can also be configured to hold the speakers in their alternate orientation, but I think the way I show it here is more stable. The brass thumbscrews make it easy to get the bases level (especially important when your house is over 130 years old).

 

[BYRTT]

Beatifull, enjoy and please spoil us later with some over avarage artistic curves .

Imagine improvements for one boundary distance and a lower frq reach now ?

 

[gmad]

Thanks, BYRTT!

Good eyes. The drivers are just 20" (508mm) from the floor which is a bit lower than what I was used to, and you're correct, there is noticeably more low freq output than with my previous setup. However, the close floor proximity doesn't seem to work as well when EQing from the listening position (I'll have to work more on that in the future). For now, I'm using nearfield measurements as the basis for EQ, which is something I've wanted to try for a while anyway. The speakers are tuned for flat response with a Qtc of .5 (-6dB at 65Hz) which is plenty of bass for me with room gain. I do plan to post some graphs. I would like to try to have my mic professionally calibrated first, but that might be a little while...

 

[xrk971]

Friction mount at 22.5deg? Yowza. An small earth quake will roll them off please bolt them down.

Nice looking speakers and stands.

 

[perceval]

Earthquakes?

In my corner of the world... All the time! But in New York?

Could use some of those very sticky sorbothane pads.

 

[wesayso]

I've been listening to these for a couple of days and I'm impressed. The stands are angled at 22.5 degrees. I was worried at first that the speakers would want to slide off, but with urethane bumpers they are very stable. The stands can also be configured to hold the speakers in their alternate orientation, but I think the way I show it here is more stable. The brass thumbscrews make it easy to get the bases level (especially important when your house is over 130 years old).

Beautiful fit and finish.

Thanks, BYRTT!

Good eyes. The drivers are just 20" (508mm) from the floor which is a bit lower than what I was used to, and you're correct, there is noticeably more low freq output than with my previous setup. However, the close floor proximity doesn't seem to work as well when EQing from the listening position (I'll have to work more on that in the future). For now, I'm using nearfield measurements as the basis for EQ, which is something I've wanted to try for a while anyway. The speakers are tuned for flat response with a Qtc of .5 (-6dB at 65Hz) which is plenty of bass for me with room gain. I do plan to post some graphs. I would like to try to have my mic professionally calibrated first, but that might be a little while...

Have you ever considered taking multiple measurements at the listening spot (in a tight square) and averaging them (with (A+B)/2 in pairs) to use as a base for FIR/EQ? This way getting most of the room anomalies like reflections filtered out while dealing with the tonal differences?

 

[gmad]

Friction mount at 22.5deg? Yowza. An small earth quake will roll them off please bolt them down.

Nice looking speakers and stands.

I know, I know... but they really are stable. I promise. Thanks for the compliment.

Earthquakes?

In my corner of the world... All the time! But in New York?

True, but a 2 yr. old child can strike anywhere...

Beautiful fit and finish.

Thanks so much. I took inspiration from your towers.

Have you ever considered taking multiple measurements at the listening spot (in a tight square) and averaging them (with (A+B)/2 in pairs) to use as a base for FIR/EQ? This way getting most of the room anomalies like reflections filtered out while dealing with the tonal differences?

I could try that. I decided to use this as an opportunity to learn a bit. Still never tried the MMM....

 

[ultrakaz]

I've been listening to these for a couple of days and I'm impressed. The stands are angled at 22.5 degrees. I was worried at first that the speakers would want to slide off, but with urethane bumpers they are very stable. The stands can also be configured to hold the speakers in their alternate orientation, but I think the way I show it here is more stable. The brass thumbscrews make it easy to get the bases level (especially important when your house is over 130 years old).

Hey gmad, great work. I'm always tempted to build a pair myself when I read updates to this thread. The only thing holding me back is my lack of understanding on how the shape makes it sound "better" than a conventional box. I get the stiffer structure, but it seems like you wouldn't get the benefit of a proper baffle and a get a more irregular/undpredictable response (boost in certain frequencies). Perhaps, I'm just missing the point and it is more about the unique shape.

 

[gmad]

Thanks, ultrakaz.

Matthew Kennedy (who is a lot smarter than me) wrote a technical briefing which can be found here: Technology Briefing

I'm not sure what you mean by "benefit of a proper baffle". According to Olson's research, a sphere (no baffle at all) is supposed to be best. Interestingly, he seems to have found that the next best baffle shape is a truncated pyramid...