midbass horn braces - solid? - or windowed?

Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.
would it make the most sense just to have two solid braces in this little folded horn ? (it will use one 10" speaker) - one friend says a mix with solid for the first part then window as it nears the mouth - what do you horn guyz say ? I can see use for the holes at the bottom - to grab it for moving ;^)

JdCAGS5.png
 
Last edited:
The advantage of windowed will be a lower weight. Multiple windowed braces like you have drawn have the same weight as a single solid brace, but support the walls at more locations which is better. Furthermore, a solid brace will be unnecessary stiff anyway.

Near the throat the pressures are higher (stiffer bracing required) and dimensions are smaller (less weight loss for windowed), so solid braces will be OK.

Make sure the windowing reduces weight as much as possible without weakening the braces too much. Circular holes may look pretty but are not optimal in both aspects. Connecting opposing walls with rectangular strips is better. Also, do not forget to brace the mouth including the side panels.
 
Last edited:
................ Circular holes may look pretty but are not optimal in both aspects. Connecting opposing walls with rectangular strips is better...............
Circular holes are probably not optimum for minimising weght to stiffness.
But they are very easy to manufacture and get pretty close to optimum with repect to spreading the stress along the two adjoining boards/panels for minimum weight and minimum peak stress in the bracing panel.

Close to minimum weight and easy to make is good enough for a panel that cannot be seen.

I do not believe that constant section "rectangular strips" are better. If one made a strip type of the same weight as the circular holed type I would expect the stresses in the panels and in the brace to be higher. Higher stress is possibly a good indicator of higher strain. Higher strain equals higher movement.
 
Last edited:
re: "straight horn" - my Edgarhorn 100Hz hyhpex with 80sq.in. throat and 400sq.in. mouth, haven't been used for well over a decade - they were good from 100-500. A recent folded horn (RCA-Fan help) works well - just want a new toy - anyhow, a Karlson with K-tube on top is more fun for its size than all of my horns. I agree that John Inlow's little 8pe21 horn should be great. If I had good health, were younger, then that would be investigated.


the 70Hz horn is very stiff from 5/8" Baltic birch - I hope the mini University Classic is sufficiently stiff too

8qag2Xo.jpg


in-room response with cheap Community 12" speaker - I've not tried a 12pe32 but have been told it won't go higher (?)

tHPM6Kx.gif


outdoor response of Edgarhorn 100 with 2220H and K43. The sine spectrum is for K43, 2220H had
10dB more distortion but went higher.

tMDIfqH.jpg


I have FH1 - prefer a K12. Prefer a K12 to my Klipschorns.
 
Last edited:
Hi freddi,

A Mini University Classic, that's cool. :)

You should need only one center brace (slightly offset) in the general horn path, but the mouth needs a bit more because of the long unsupported edges. Maybe one long dimension brace, and two short dimension braces, or external bracing?

Regards
 
hi tb46 - and it may be graced by everyone's favorite midhorn - the "Cobraflex" - would two solid braces hurt anything response-wise? (so far the consensus = "no") - its about 20" wide inside. btw- RCA-fan says that chamber formed by the throat pieces will resonate and cause a notch in the 500Hz region.
 
Hi freddi,

Isn't a Cobraflex a little large for this? You shouldn't need that much low end extension?

Could be RCA-fan is on to something, but, you can only prove or disprove that by experimenting. Another reason to slightly offset braces from the center line.

Regards,
 
Cobraflex has a very small composite mouth area and quite a long path - they do hobble to below 250Hz with some drivers - I've run out of existing midhorns which will sit on top and crossover at ~400 to 500Hz - lets see - this mini UC will be ~21.5" or so wide - a Cobraflex is 18" wide by 10.375" deep (without driver) - I could use an Altec 811 or Emilar EH500.

I think an X15 or 115BK with K-tube on top might be lots cleaner below cutoff than the little horn - 115BK outdoors with an EV15L had about 3% distortion at 20vrms down to the mid 50's IIRC

Karlson's K12 is a nice size and good performer with something like Kappa12a

A really good "K10" would punch hard enough - on the cheap, Delta10a

btw - I've seemed to have lost the "X15A" you drew so nicely

rough guess of 115bk vs mini-UC
CIYoIF0.gif


115BK - no damping material in the cabinet
nAZR20x.jpg

CslJdC4.jpg
 
Last edited:
Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.