file FSP-MAGICBOX

12 years 3 months ago #3582 by tony.a.s.s.
Replied by tony.a.s.s. on topic FSP-MAGICBOX
Are you talking about one cab instead of two i.e. a cab that will cover what we perceive as sub bass and bass. I noticed that a frequency of 200hz was mentioned. Baring in mind, that the voice starts to come in at a liittle over 100hz I wonder what the thinking is to venture into mid range with a sub.

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12 years 3 months ago #3583 by deadbeat
Replied by deadbeat on topic FSP-MAGICBOX
200hz would be the target, of course we would run it slightly lower...but I have no qualms with slightly higher frequencies coming from a properly folded horn. The cabinet would attempt to be a one way bass cab with respectable range.

tommy, an aperiodic enclosure is one that has 'leaky' ports. It is an accepted way of making a sealed cab smaller. I think dynaudio and seas used them. They're very interesting.

[url=\"http://users.ece.gatech.edu/~mleach/beraneklaw.html\"]Beranek\'s law[/url]
\'bits of ply round a driver\'

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12 years 3 months ago #3587 by ajw
Replied by ajw on topic FSP-MAGICBOX

Deadbeat wrote: .

tommy, an aperiodic enclosure is one that has 'leaky' ports. It is an accepted way of making a sealed cab smaller. I think dynaudio and seas used them. They're very interesting.


Goodmans in the late 1960's early 1970's used to use them a lot. You could buy the "Lossy Panel" off them as you could from Dynaudio a few years ago.

The Dynaudio was in the form of a round vent. The Goodmans one was a rectangular panel set in the enclosure wall. It basically makes the enclosure behave as though it is of larger volume.

I am also with Tony A.S.S. ( at least I think it is his view) in that I would never allow any part of the vocal region to come out of a folded horn, "shudders at the thought".

Tony
Edited by: AJW

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12 years 3 months ago #3589 by tony.a.s.s.
Replied by tony.a.s.s. on topic FSP-MAGICBOX
Tony, They are my very thoughts. Long straight horns that we used back in the day were more acceptable, because there was no breakup of the smaller waves in the cab. Because of defraction, small waves break up and reflect back and forth in a folded horn
You also have the velocity of a bass speaker, that as well as trying to meet max excursion, would also be trying to make sense of the more delicate vibrations usually saved for a mid speaker that doesn't have to move much.

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12 years 3 months ago #3590 by ajw
Replied by ajw on topic FSP-MAGICBOX
It has always been my contention that a lot of people have become used to the muddy type of vocal sound that comes from using folded horns too high or even 18" drivers up to 200hz.
This then explains why when they listen to a well balanced system using 8" or 10" mid drivers to cover down to 100hz (which they are perfectly capable of doing as you know) they reckon that the sound is too thin!!!

The finest PA system I have heard to date is a line array that actually uses multiple 5" mid drivers down to 100hz and to my ears sounds amazing.

Tony

Edited by: AJW

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12 years 3 months ago #3591 by jsg
Replied by jsg on topic FSP-MAGICBOX
I think it will be hard to get any kind of horn loaded system to work well in singles or doubles. The best solution to acheive the specs is probably ported reflex using 15 or 18 inch drivers.
If you were to allow degraded performance in stacks of less than four, then ported horn looks more like it. I would look into porting into the throat, and I'd also consider the possibility of fitting a straight (unfolded) horn into the cabinet (using the space around it for the ported chamber).

Ars est celare artem

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12 years 3 months ago #3593 by chaudio
Replied by chaudio on topic FSP-MAGICBOX
Vocals through a folded horn? Turbosound, FK1 and Martin all used folded horns on the low mids up to 250 for Turbo and Martin and 440Hz for FK1.

I think part of the problem is because there tends to be a lot more gain on the bass cabinets in the system, if the crossover point is too high then you get too much of the low end of the vocal. I think it's a crossover issue more than purely a folded horn problem.

For dance music I'll happily cross over from bass to mid-tops up to around 160Hz but for live music no higher than 120Hz really. Unless you start running aux fed subs which could eliminate some of the problem.

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12 years 3 months ago #3595 by deadbeat
Replied by deadbeat on topic FSP-MAGICBOX
Thanks jsg,

The only thing with reflex is the efficiency...but you knew I was going to say that.
Plus this is a thought exercise for now.

Looks like the ported horn is the way to go.
A straight horn could be an option, it's how altec did it once (though I should add that that port was actually a mass loaded RLH on some of their models...). The cabinet i am envisaging that way would be a double driver, with a port or two in between the drivers.

So all the solutions we have involve loading the back of the driver to enable cuttoff frequency of the cab to exceed that of the horn. Now we just have to settle upon a loading, and porting seems to be the one.

Back to the side topic,
About subs in vocals, I agree, and the cab would be ideally crossed around or just above 100hz. When I meant slightly higher frequencies, I should have been more clear, not >200hz, but I mean just above 100, like 120.

I found these on john sheerin's website. They're quite interesting.

http://ldsg.snippets.org/HORNS/images/roundbend/5khz_straight.jpg
http://ldsg.snippets.org/HORNS/images/roundbend/5khz_round_8_v2.jpg
http://ldsg.snippets.org/HORNS/images/roundbend/5khz_reflector_8_v2.jpg

I am also of the opinion that mouth termination plays a big part in a HF horn, with regard to colouration due to reflection. But this is not sub talk, so I'll shut it.

BTW,
The finest PA mid highs I have heard... one came from (sealed cab) paper cones, and 1" driver loaded on a massive compression driver waveguide, in a install. The other came from an array of SH-50s.

TMS series cross over their BPH mids quite high, and the Blackline H3+ and FK1 tops do too. I'm not exactly a fan of them (well, the H3 was quite nice...)...there are better sounding cabs.

EDIT:
How could I not note that! The xover and amp....

Edited by: Deadbeat

[url=\"http://users.ece.gatech.edu/~mleach/beraneklaw.html\"]Beranek\'s law[/url]
\'bits of ply round a driver\'

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12 years 3 months ago #3609 by tony.a.s.s.
Replied by tony.a.s.s. on topic FSP-MAGICBOX
Picking up on a point made by chaudio, My MT 502 and 1200 were folded at the start of the throat, which brings me to the point. If the fold is smaller than the highest frequency required, there won't be a problem. It'd just this simple rule of defraction, and one everyone should be aware of when designing horns.

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12 years 3 months ago #3643 by jake_fielder
Replied by jake_fielder on topic FSP-MAGICBOX
Ported horn seems the best....

But do we port into the horn or straightto the outside? obviously the port output can never match the horn output if the port goes straight to the outside, if we port into the horn then it will be v difficult to modelbut thepotential output of the port will be higher.We need JaKe on the scene if we seriously wanna do this!

Also i have my prototype im building, if its rubbish i will have a play round and i'll port it in different places etc...

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