Boats/full range and hernias !!!!!

[kimbo1]

Guys (hey ,lets not be sexist- maybe girls ) I'm now on a 1940's wooden boat for my humble abode. Good life and love it, recommend it to anyone thinking of 'a change', but i digress !
Having built/modified all sortsa things hi-fi and, owning lowthers with pm6a etc, i'm rather into my sound. However, i'm off with stated op and, need a quick/cheapish fix.
So, bearing in mind my space issues and, the fact these have gotta be fast vis-a-vis build time. I'd like some full range horns, cornu is a thought but, best left for more time i feel. How about a half decent rear loaded, with minimal dimensions.
Uk based, so could do with drivers available here. Cabinet making not an issue but i stress.........time IS.
If not, i'm moving in a single leak sandwich for now

Whatcha got my fellow tinkerers?

Profuse thanks in advance

 

[xrk971]

You won't find a more compact back loaded horn that is easier and faster to build then than cornu. For a boat, something like a 16 incher will be suitable. And you can build it on a boat with nothing more thsn a razor and a hot melt glue gun.

 

[kimbo1]

Tis true, i've wanted to do these ever since i found them in the depths of cyberville!
Ok, so, has anyone got a pdf/jpg of the spiral so as i can download and get scaled/printed off ?
Driver choices for the 16" also please, think the original had monacor or tangband but i'm guessing.
Again thanks for all replies, much appreciated

 

[kimbo1]

apols, i was being lazy wasn't i !! I'll read more before asking questions.

 

[xrk971]

You will find the pdf's in the posts scattered throughout. There is a fully circular spiral and one that has straights and curves. For a 16 incher, you might try the circular spiral - easier to make. Probably closest build will be the one Cal or Prezden recently did. A 3 inch driver like just about any Tang Band W3-xxx should work, as well as Fountek FR88EX, Fostex FF85WK, Visaton FRS8 (3.3 in), Vifa TC7FD (2.5 in), or TC9FD (3.5 in). (Prezden, any tips for someone making a 16 inch cornu?)

 

[kimbo1]

Thank you my man. Ok, monacor sp30x is available along with visaton frs8.................think i'll plum for the monacor ( Sd 30cm/ Vas 1.13l/QTS .46) unless anyone has objections. Any ideas on throat width and spacing(depth) of forms? Presuming a tad wider at that overall baffle width? seems to run between 2.5-3.5 at 20" baffle and, approx 2" at 14 " baffle sizes.

I've spent almost the entire day trawling the relevant forum pages but no-one as yet, seems to have the 'magic' ratio. Correct me if i'm wrong though.

Thanks in advance as always

 

[xrk971]

Kimbo,
If you are set on the Cornu for your boat, you may want to consider posting in the Cornu thread - where more folks are likely to see it who can help. Setting the depth of the channels has basically been done in the past based on trying to get the throat area in the cornu to be matched to the driver Sd. If you wanted to get a throat size in a 16 in cornu to match the 30 cm^2 Sd, the depth will have to be 4.5 in which is a little on the thick side. If you think the driver can handle a reduction in throat area (have some driver compression) of 20% then you can go with a 3.5 in depth. For a 20 incher, a 3.5 in depth will give you a matching Sd and throat (1:1). There are other considerations: the 16 incher will have an upper cutoff freq of about 300 Hz whereas the 20 incher will be only 240 Hz. This is the cutoff at which freq above will be attenuated coming out of the horn mouth. You can modify this with volume filler in the driver chamber (adding volume filler will raise cutoff freq, adding a volume chamber below will reduce it). If you want, you can custom design your own channels to end up with a larger throat and this lets you play with cutoff freq independent of Cornu size. The above numbers assume you are using the original commercial cornu plan that Planet10 provided as pdf.

 

[Cal Weldon]

Kimbo, Make sure you have enough room to place these flat against a wall, it is very important. If you move them away, you lose that loading and with it, the bass. To get the bass back, you have to remove some of the damping material and it ends up sounding bloated. 20" square doesn't sound that big but sure is when you go looking for a place to put it.

Uh, put them I meant to say.

See y'all in the Cornu thread.

 

[owenhamburg]

why go for super speakers on a sail boat?

I cant imagine your boat, you should describe it better, The boat I am imagining is space limited and form of the boat follows function, and its mast and hull shape are not movable and based on the requirements of a sailing barge, or international sailing cruiser and about 15 meters long. In any case it will be constantly tipping up and down.

Due to the motion of a sail boat, I think suspended speakers should be ruled out before we start. I think gimbled speakers are overkill, and the benefits might be slight.

I would not be looking for HiFi in a boat, if I needed that I would go for headphones and not electrostatics. I would be looking lifestyle. I would instantly be thinking 4 ohm waterproof drivers for the cockpit, coaxial of any size or approximately 3 inch full range speakers. I would electrically cut off frequencies the speakers cant handle, to avoid them being damaged in a party mood. for example. Have you auditioned the Visaton FX 16 WP they might be nice for the helm.

Powered on Car/Truck 12/24V equipment and sadly I would go 12 V as its cheaper, and maybe class D as electricity is a drag in most sailing boats but probably just a car stereo. I recently put some cheaply made car coaxial speakers (though I paid about 60 UKP some 10 years ago) in a very old Heco home loud speaker boxes for use in my basement with my old Car stereo (was about 120 UKP 10 years ago). The sound was remarkably good when playing from an android device or CD and it ran off a single lead acid battery, I see a solid box being made in the future with wheels so I can take it easily with me, and maybe also so I can chain to a post for festivals.

By lifestyle rather than HiFi I mean more than 2 speakers of small full range sealed boxes, or better wall mounted speakers (like a giant open baffle) for ultimate HiFi in a boat, but I suspect very small sealed boxes in the right spot (close I guess) would be nicer. I would probably build 4-6 small coaxial or full range speakers dependent on taste placed for good sound 1 pair for each listening position and the speakers be quiet near to your ears in each listening position and targeted at not so loud music as the sound of the sea and wilderness is nice. I would probably later add a single 6.5" Bass driver probably in a small bass reflex enclosure to act as a subwoofer, or if your a bass head a Seas L26RO4Y from seas but I would not imagine trying to make lower than 50Hz I imagine you will not benefit due to the space.

I don't know if your boat is how I imagine?

On Visaton Startseite DE have a look at least the: FR 10, (and I am curious now about the HX 10)

and maybe some of the waterproof / high humidity solutions.

Waterproof Speakers

But I imagine any that's not made of paper should be fine, or disposable and cheap like the FR10 this is a big reason for favouring car door speakers full range or coaxial with a reasonable sized space behind them.

 

[xrk971]

Owen,
You have some good points about humidity and water resistance for boat applications. Polypropylene cone waterproof automotive drivers would be a good choice in that case. I will bet that Kimbo's boat is really just a moored floating apartment more than a sea faring vessel. The Cornu can be hard mounted to a wall and need not be hung or suspended as you say. It is light enough that even double sided tape can be used. Although wall mount clips and screws will allow easy removal. There is no reason that the Cornu can't be made out of polyfaced foam core with waterproof drivers, in which case it would be a waterproof speaker.

 

[owenhamburg]

You think he has flat square walls? I imagine the 1940's wooden boat without many.

Am I right in thinking the Cornu horn is based on the assumption of a flat wall for loading?

Regards

Owen

 

[xrk971]

Kimbo posted his boat room dimensions in the Cornu thread and indeed, there is one flat wall where he intends to mount the cornu's.