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Suitcase Soundsystem

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fergatron1 View Drop Down
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    Posted: 09 March 2012 at 3:32pm
Hi,

I'm making a three way sound system in old suitcases, I'm looking at using an alpine mrx-v60 (4 x 50W + 200W @ 4Ohm) and a 12v 30Ah LiFePO4 battery.

I want heavy bass, reggae roots stylie. The bass bin is an old trunk with internal dimensions of 990 x 530 x 600mm. I'm currently thinking of using either a PDN.15sb40 or PDN.18sb40 for weight and efficiency. I am intersted in the G sub design because it potentially leaves me with storage in the trunk space for the other suitcases for transport. Could I make something similar but with one driver? 15 or 18?

The mid range will be boominator style in a suitcase. Maybe using 4 x PDN.10MH25, or PDN.12MH25.

For high I'm looking at 4 x beyma cp21f in an an old radio, although they might be a long stretch from the mids...

I am a first time builder, any advice/help is appreciated. I am building it at the Artspace Lifespace College in Bristol. I can offer free drum kit lessons for anyone that wants to come and help me. The system will be on the Swindon Battle For the Winds Machine at Weymouth in July, I have till June and £1600 to complete it. I will eventually build a cargo trike for it after July.

Thanks

Fergie

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nomercy82 View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote nomercy82 Quote  Post ReplyReply Direct Link To This Post Posted: 19 March 2012 at 2:23pm
Build DM2s. Your suitcases are not, acoustically sound. so if you tried to load them up with speakers they would not hold the weight correctly, and would deform as the speakers tried to push and pull air around. Look at the bracing on a G-sub. It's extensive, and I have 2.  There's no  bracing in a suitcase, 2 DM2s will outperform anything ever built into a suitcase, gradnted they are larger, you'll have full range in 2 boxes. 
Building a system in Pennsylvania.
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fergatron1 View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote fergatron1 Quote  Post ReplyReply Direct Link To This Post Posted: 19 March 2012 at 6:17pm
Ok, thanks for the suggestion, but the suitcase's are a crucial part of this build, as its a part of a range of musical instruments all built into old suitcase's. I have been thinking/learning more since the last post, and here is the current design idea:

Firstly see the pic of the trunk, the suitcase and the radio at the bottom of the page.

The design includes two modes of setup, one omnidirectional to be used on a trike type thing, and the other directional for stationary use.

Starting with the trunk I'm planing to have one pd.18sb40 mounted on the bottom (for transport/omni-directional mode where it will be raised on a vehicle), and the whole thing turn on its side for static directional setup.

I plan to build a plywood box inside the trunk. The baffle with the driver will be raised 20mm off the bottom of the trunk, and a circular design will be cut into the trunk in front of the driver to act as a grille. The total internal height of the box is 600mm, I plan to make the enclosure height 300mm, giving me an ecnclosure volume of 143l (minus port volume), as well as providing space above the sub enclosure to carry the suitcase and the radio, battery and amp (thinking about mono 300Wrms car amp on 12v for sub.) I have modelled this on winISD to find port lengths and tuning etc using a 5" port, but I am aware that my box shape will be different to the model...

As for the suitcase I am thinking of a 3 way design, again all fixed to a plywood structure behind the actual suitcase with a grille cut into the suitcase. I will be the same on both sides, with each side containing 1 pdn.12mh25, crossed arounf 1.5khz with a compression driver (unknown, maybe jbl 2470, maybe jbl 2418h, maybe beyma smc8060) and a jbl 2405 (of which I got excited about and bought a cheap pair and diaphrams last night!) The pdn12 goes on one half and the mid and hi go on tother. (see pic) I plan to put a 4 x 100WRMS amp in here so as to create a modular system (2chan for pdn12s, one for mid, one for top)

For the omni-directional use this will be as pictured with the suitcase closed inspired by boominator design. Then for the directional setup (this is where it gets even more crazy) I'm planning on opening up the suitcase and standing it on end, the 2 baffles will be at a 45 degree-ish angle so the sound will fire over a 90 degree-ish area, and (inspired by a wee pc speaker call "mini-X") I plan to use adapted air sac of an accordian to provide an extendable ported enclosure for the 12s. :)

The current plan for the radio is just to gut it and stick my roland mobile cube in there and have it as a special rotating microphone speaker. This system is designed to facilitate musical interaction n stuff so a I figure the seperate system would give microphone freedom and limited feed back potensh.

There is still the option of putting the jbl2405's in it instead, but it might present me with some phasing issues.

I have chosen the pdn18 and the pdn12 for their efficiency, I understand that all the designs on this site will outperform this one but the fact thats its in these old suitcases is as important as the sound. Saying that I do need to make a fairly loud noise.

So to conclude, any suggestions to improve the bass trunk design (given the parameters), and suggestions for a suitable/affordable compression driver with or without horn? (bearing in mind the 5" space for each.) I may have used technical words (like baffle) in the wrong places; sry...

And as before if anyone around bristol wants to help me build this monstrosity I will learn you some drumming in return!

 many thanks

mike

Feel free to laugh, it'll only make it better!



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nomercy82 View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote nomercy82 Quote  Post ReplyReply Direct Link To This Post Posted: 19 March 2012 at 7:14pm
On the bass trunk I would brace it up like it's a G-sub, thoroughly caulking the insides with something like liquid nail from there I would calculate the internal volume of the trunk and subtract the volume of my braces, this is your Vas parameter. Then I"d go into WinSID, and play with drivers until you find something suitable for your frequency range. GRills mounted directly to the suitcase itself, and an 3/4 inch ply wood backing to add some support for the drivers. 

I'd stay away from the  accordion as a port though. the last thing you want in your system is something shaking. Afraid I won't be much of a help with the tops as I just buy mine. I I can say that neodymium us usually your friend. and Eminence though not the best can and does produce a considerable bit of sound and are easier on your wallet.

Just an idea, but for your bass trunk you could put a commercially made set of subs  that fit into the trunk, in the trunk, and just cut holes in the trunk. Completely based on nothing that last bit, but the idea popped into my head.
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amlu View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote amlu Quote  Post ReplyReply Direct Link To This Post Posted: 19 March 2012 at 8:25pm
just stay away from liquid nails. evil stuff stinks of solvents. stick to wood glue :)
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Post Options Post Options   Thanks (0) Thanks(0)   Quote fergatron1 Quote  Post ReplyReply Direct Link To This Post Posted: 19 March 2012 at 10:37pm
Wow! thanks

 I have thought about using a ready made sub, all I found that could work is this 'In Phase XTBL 15':

http://www.caraudiocentre.co.uk/product_m-in-phase-xtb15l_p-21486.htm

It says 98dB sensitivity but I don't know whether I can trust it. Also it weighs 26kg, price is £200 (affordable), and it will fit in the trunk with enough room for the others and save me alot of work.. (maybe less fun though ; )

So the 8.5kg pdn 18 still seems attractive, although I don't know how heavy it'll be plus the bracing (thanks), and don't know whether my building method will work.

Any other efficient ready made subs for 12v?
What do you reckon of that 'In Phase' thing? ...meh..

Would it be crazy to have pdn18 crossed with pdn12, crossed at 1.5khz to a beyma smc8060 crossed with a jbl 2405?

And if not too crazy what might be suitable crossover points?

Thanks for your help, sorry about all the questions...

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Post Options Post Options   Thanks (0) Thanks(0)   Quote nomercy82 Quote  Post ReplyReply Direct Link To This Post Posted: 21 March 2012 at 4:17am
That in Phase will do the job, I'd guess and say it get's a C.  PD and JBL get an A in my book. Wood glue is the right way to go.

The 2405 is SUPER POWERFUL from my reading on it you want to cross it high talking about 7 or 8 kHz.  Really adds some sizzle to your music.

What I would do is model your system's boxes separately in Win SID. To see the SPL vs Frequency graphs, then from there cross them with a 24 db Octave slope at where they start to trail off.  I usually cross subs are 100 hz though.
Building a system in Pennsylvania.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote fergatron1 Quote  Post ReplyReply Direct Link To This Post Posted: 26 March 2012 at 2:11pm
Ok thanks.

Currently I am interested in a 'less is more' approach, by using the pdn12 straight to the 2405 without a crossover...

http://www.precision-devices.com/asps/uploads/super/70.pdf

The pdn12 has a smooth roll off around 5-6khz, and the jbl is suggested crossover 6.5khz..

The reason for considering this design is that this system is designed to provide music for freestyle microphone caddies and muso's etc, where the mic will run through a roland microcube in the radio on top, so the sound in this system will be mostly bass and percussion. I want the music sound to provide 'space' for the vocals so I might eq the vocal range down a bit anyway. (not sure how yet ;)).

So the current setup idea is having two pdn12's and one 2405 on each side of the suitcase and the one pdn18 for the sub. (thanks for the xover suggestion).

What do you think?

The questions that follow on from this is choosing the right amp and power distrubution.

Most of the time this system will be at a reasonable level for a group of say 20-40 people to be dispersed all around the system. Then occasionally I will need it to get quite loud, like slightly too loud to stand next to it for parades/showing off etc... ; ). I am aware of the exponential nature of watts and spl and also that a high power amp will be less efficient, but I have no actual experience to base it on..

My first suggestion was the alpine mrx-v60. This is a 5 channel amp with 4 x 50w @ 4/2 ohms and 1 x 200w @ 4ohms rated at 14.4v. Currently I will be using a 12v battery so I wont get the full 14.4v. The 2405's are 8 ohms so I think i will need to run them in parrallel on one channel, then sending a channel to each pair of pdn12's and the 200W channel to the sub. This leaves one channel spare, and I'm not sure how loud it will be.

Could I use an 8 ohm load with one channel on this amp so have a channel for each 2405?

The sensitivities for the drivers are 2405 105dB, pdn12 100dB (no 4.98%), and pdn18 98dB (no 3.29%).

I originally looked at usung a 41hz kit but the website doesn't seem to be responding. I'm open to using other voltages/amps but keen on a Lithium ion battery.. any suggestions/thoughts?

Thank you! for getting this far, its very much appreciated..
super-forum!


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Post Options Post Options   Thanks (0) Thanks(0)   Quote nomercy82 Quote  Post ReplyReply Direct Link To This Post Posted: 28 March 2012 at 3:08pm
That smooth roll off you describe at the 5 kHz mark is closer to a swan dive off a cliff. I'd strongly advice you to use a crossover. Have you considered adding another suitcase that could be used as a rack?  you'll keep the asthetic, enhance sound quality, as a well as be a tad louder.

I am far from knowledgeable on care stereo equipment, as my system run on 2 separate 13 A circuits.
Building a system in Pennsylvania.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote fergatron1 Quote  Post ReplyReply Direct Link To This Post Posted: 28 March 2012 at 5:22pm
haha ok nice analogy. Well its a good job I couldn't get any, they're out of production. So instead I got excited again and have gone and bought 4 Beyma 122Nd...

http://www.beyma.de/fileadmin/seiten/download/pdf/Beyma_professional/122ND.pdf
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