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new 15" folded bass horns undercreation.. |
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dubsuction 
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Joined: 18 August 2004 Location: United Kingdom Status: Offline Points: 269 |
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 Posted: 08 October 2004 at 3:49pm |
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definatley man ....right all, high-pressure sub plans soon come........ |
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peace+respect-always
**HIGH PRESSURE SOUND SYSTEM** www.highpressuresound.co.uk |
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roborg
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Joined: 05 July 2004 Location: United Kingdom Status: Offline Points: 1026 |
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Posted: 08 October 2004 at 8:12pm |
It's a seriously good idea to put wheels on the cab (or at least use a wheelboard) A minimalist approach that works seriously well is to put two wheels recessed in the back of the cab, i've done this with some 1850ish cabs plans the wheels are recessed in from the bottom, but protrude slightly out the back, that way the cab rests upright by itself & theres no danger of it going walkees down a hill. You can move it easily by tilting it back slightly. The slight protrusion of the wheels out the back of the cab lets you go up & down stairs really easily too, the cabs will still pack correctly too, as the protrusion sits inside the mouth of the cab behind it. have fun! Rob |
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What I cannot create, I do not understand
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freddyi
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Joined: 22 September 2004 Status: Offline Points: 936 |
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Posted: 08 October 2004 at 9:21pm |
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HI Rob - my jaw literally dropped on those images, absolutely beautiful work and way cool cooling system for driver vent.
infra is - uh "interesting" -in my imagination ~ like an infrasonic whistle and not seen anything exactly like it before - might this make a nice home subwoofer? what does this infra do in the real world with regards to tradeoffs vs bulk vs LF and what kind of drivers does it prefer? would you have some sine spectral plots/HD & FR of its performance? - only horn woofers I have are Bruce Edgars 1/8 size 40Hz 'Monolith" and a K-horn bottom being dim/fried and highly math "challenged" - I struggle enough with odd Karlson type which are debatable whether they even "work" - from observation do think K provide some means of cone excursion reduction over a region vs reflex - but don't know how this holds up with higher mass.high BL drivers do you know anyone who looked at Karlson? - know one guy with math and engineering degree who is working on them from Poppe-K-coupler view trying to adjust losses to fit with Leach terminology but his belief system with regards to original Karlson claims is far more intense than mine. Best, Freddy (sorry to eat bandwidth) |
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Timber_MG
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Joined: 27 March 2004 Location: South Africa Status: Offline Points: 1454 |
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Posted: 08 October 2004 at 10:08pm |
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That cooling system does look intriguing. I didn't realize that you'd
done it with the bass-horns too until freddy commended on it now. In
simple terms you have a ported rear chamber at a very low frequency, so
it would still remain to be seen what effect this has. How hot has the
air coming out the vents become on testing?
Your use of castors is a very elegant solution to the problem of attaching wheels without increasing the packing dimentions. I might do something similar to that if you don't mind? Martin |
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staiper
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Joined: 26 February 2004 Location: Croatia Status: Offline Points: 550 |
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Posted: 10 October 2004 at 6:59pm |
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I have make similar cooling solution on very small (15" unit) 4th order cabinet and it works OK .. "Cooling" vent is placed on the back side of the cabinet and seems that do not affect the sound probably due to very low tuning of that "port" and small diameter (5cm).
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Timber_MG
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Joined: 27 March 2004 Location: South Africa Status: Offline Points: 1454 |
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Posted: 10 October 2004 at 8:20pm |
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But that's then a bandpass of 6th order with a rear volume tuned very
low. Could anyone comment on how such a "port" would affect the
performance of a horn in it's passband if the tuning frequency is well
below the passband? Presumably it would mean that the rear chamber can
no longer present the right amount of compliance to the system, or is
that only the case if the vent is tuned nearer to fc?
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roborg
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Joined: 05 July 2004 Location: United Kingdom Status: Offline Points: 1026 |
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Posted: 11 October 2004 at 12:37am |
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@freddi, thanks dude!
@timber, I've not really felt any hot air coming out of the vent when the speaker is running, mainly because the fan i use blows enough air thru that even with a 1Kw sine it'd probably only get luke-warm!  (fingers crossed) The t-junction of the tube is sealed against the back of the speakers vent with a rubber pipe seal that by shear fluke fitted perfectly in the vent. Also a bit flukey is the T-piece jams nicely under the speaker & the bottom of the rear chamber (so the pipe seal makes a really good seal with the speaker vent)
I reckon the rear chamber is really not too coupled to the cooling tubes at all (except thru the cone support material & round past the voice coil. There might be a slight effect due to the pressure differences on the dust cap tho, but I certainly didn't notice any audible difference. When i can get more time on my hands i want to get a pc+smaart & a good mic & measure delays, differences in response with/out the cooling & how much power-compression i get etc... The castors are really essential for me, i have to move these around by myself most of time, they turn those monsters into ballerinas when going round tight corners or up & down stairs! cheers, Rob |
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What I cannot create, I do not understand
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dubsuction
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Joined: 18 August 2004 Location: United Kingdom Status: Offline Points: 269 |
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Posted: 11 October 2004 at 10:22am |
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yeh i reckon they're going to get some wheels soon.......they're not too bad with two to carry though,.......might put some off road wheels on fi the free parties we used one of these subs in a corner of the room at our session on friday....with the two 18" reflex subs we already have and it sounded and felt heavy! .....cant wait to stack the 4 together and let em rip!!! .....still waiting for me to stop faffing about and get the plans up..... soon come...............
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peace+respect-always
**HIGH PRESSURE SOUND SYSTEM** www.highpressuresound.co.uk |
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Timber_MG
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Joined: 27 March 2004 Location: South Africa Status: Offline Points: 1454 |
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Posted: 11 October 2004 at 10:56am |
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Did you try it with just the single cab in the corner and compare it to the 18s (which I assume was in another corner). Would be interrested in how these cabs perform and if these things could get measured it would be well cool. At some time you should invest in a LMS to set the delay between the horns and Tops (which need sorting out next) Martin |
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dubsuction wrote: