Carnival float sub

[peterdevon]

We had our first carnival yesterday and it has been decided that we should have a sub, I was considering one of these with a Pulse SPA1300 and a Behringer crossover. The problem is we cannot get a box of the recomended dimensions under the float, will it make a big difference if we keep the volume the same size but change the shape. Bearing in mind it is not a concert and hopefully anything will be an improvement on the JBSound 15" speakers current bass response.

[abbotsmike]

If you are prepared to DIY, then I'd recommend a ported or tapped horn of some description. If you are running off of generator power, then you will need much less to get the same noise as the horns are a lot more efficient. How big/small does it need to be?

[peterdevon]

We have an 18KVA generator, we are restricted to about 535mm high, 900mm wide and any depth

[Dave SA]

I'd recommend heading over to the speaker plans forum and asking the forum there.

 

Link

[Bobbsy]

I'd have to agree with Dave SA. Yes, the dimensions and internal design of a speaker cabinet can make a huge difference to the eventual sound and you will need people experienced in these areas to comment on your preferred shape/design.

 

Bob

[audiomik]

You could have a look at:

http://www.speakerplans.com/index.php?id=184sub

 

Which has dimensions close to what you've given, as well as it is designed for the Fane 18XB speaker - without any of the more complex woodwork of Horn designs.

Have a look at the Berry CX3400 crossover, which has limiters and a 25Hz High-pass filter built in, and use the Pulse SPA1300 Amplifier in bridge mode to drive the Fane.

The Amplifier will need to be run so that it doesn't clip, but the increased output is OK as the power rating of the speaker will be unlikely to be exceeded given the crest factor in audio signals.

 

Hope this is of use to you

Mik

 

We have an 18KVA generator, we are restricted to about 535mm high, 900mm wide and any depth

[peterdevon]

Thanks Audiomik thats perfect for what we want, I have searched for hours on google without a decent result, I will order some ply!

 

A concurrent post has been automatically merged from this point on.

 

From what I read about the Behringer cx 3400 it has

 

Individual Limiter on each output for optimal loudspeaker protection

 

Switchable 25 Hz Low cut filter on each input for low-frequency driver protection

 

and it is cheap

 

One quick question, does an amp with XLR input require a di box between it and a rca output of a cd player or ipod

 

You could have a look at:

http://www.speakerplans.com/index.php?id=184sub

 

The Amplifier will need to be run so that it doesn't clip, but the increased output is OK as the power rating of the speaker will be unlikely to be exceeded given the crest factor in audio signals.

 

Hope this is of use to you

Mik

 

We have an 18KVA generator, we are restricted to about 535mm high, 900mm wide and any depth

[audiomik]

re: "One quick question, does an amp with XLR input require a di box between it and a rca output of a cd player or ipod"

 

Simple answer is no, wire the signal as unbalanced directly to the amplifier input, you'll find the Rane Note at:

http://www.rane.com/note110.html

useful as a reference document on how to make the connecting cables, but be aware of your source signals not necessarily being the correct levels for full output of the Amplifiers.... if you are using the Berry X-over as the input: then it has +/- 12dB gain on it's inputs which should correct for this.

 

For an iPod, or a CD player, to work in mono: you also need to have the left and right signals 'summed' using series resistors - think this is covered in another thread.....?

 

If you get any problems with ground loops picking up hum or other noise, PM me and I can send you a couple of 600ohm 1:1 audio transformers to break the ground connections as in the Rane Note.

 

hope this helps

Mik

 

PS: check prices for the Fane driver at: http://www.bluearan.co.uk/index.php?id=FAN...de=manufacturer

[swampman]

That Fane speaker or the Beyma equivalent which is nearly as good (had to buy two recently in haste - they "wobble" a bit sooner) can be "shoe-horned" into compact boxes albeit at a reduced power level and used with care. What I am getting at is that it's specific build allows for a compact box volume which other 18" speakers of lower wattage and lighter build will NOT tolerate - the cheaper alternatives will wobble to bits. I re-built some compact subs for a recent event which required very discreeeeete bass enhancement (anything too visible would lead to the inmediate comment "its tooooo LOUD" - Live music for a mainly British church event! ). They measure only 60*55*45cm approx. if I remember correctly, and most of the front is speaker and porting. In use they are usually turned facing against a flat wall at about 4-6" which gives them additional loading.

Good luck with the float

[Jivemaster]

Search this forum for "Eminence book" (use the google box and click the "search the Blue Room" ) There are lots of suggestions for boxes and for drivers. If you can locate the whole of the Fane book of Speaker Cabinets then you will find designs for the Fane range. If you can locate the Eminence book you will find specific designs for their range AND some charts assisting you to design the cabs to suit several drivers.

 

All designs tend to miss out the importance of rigidity to a bass box. Often they are heavy simply because they are made of thick ply wood and have lots of internal braces to stop the box flexing as the driver works.

[peterdevon]

Box is made and speaker in, what is the best (or cheapest) material for sound deadening the box?

[noiseman]

Box is made and speaker in, what is the best (or cheapest) material for sound deadening the box?

Water or lots of jelly will deaden the sound the best :D

For control of internal reflections, Loft insulation is cheap as are cheap hollow fibre pillows just don't add anything too dense as this could reduce the box volume which is critical to subs.

[peterdevon]

Just ran it empty for one minute and it's OK but a bit boomy close up, apparently it sounds great 250m away in a conservatory, she wanted to know where the rave was!!

 

I'll put some loft insulation in tomorrow and see how it sounds in the centre of town on saturday

 

A concurrent post has been automatically merged from this point on.

 

Oh and a quick one, want cut off frequency would you use with a sub, I presume more you take away from the other speakers the better?

[audiomik]

Assume that you mean the crossover frequency by referring to the 'cut off frequency'?

For the '184 Sub' use 80Hz as there are discussions elsewhere regarding panel vibrations/resonances at 100Hz and above.

 

100mm Fiber-glass loft insulation is fine for this design - the Plan shows where to place it,

 

Have fun on Saturday

Mik

 

(Edit: revise XO frequency)

 

Just ran it empty for one minute and it's OK but a bit boomy close up, apparently it sounds great 250m away in a conservatory, she wanted to know where the rave was!!

 

I'll put some loft insulation in tomorrow and see how it sounds in the centre of town on saturday

 

A concurrent post has been automatically merged from this point on.

 

Oh and a quick one, want cut off frequency would you use with a sub, I presume more you take away from the other speakers the better?

[Jivemaster]

If it's a horn loaded box then don't put wadding inside it, if it's a ported or closed box then staple loft insulation or a duvet to the inside surfaces.

 

Crossover probably in the region of 120Hz. this takes some power away fron the mid n top box without putting any of the quirks of crossovers in the prime speech band Try about wqual power amps into the subs and the tops but this will need to change a bit perhaps.