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Old 23rd May 2014, 01:28 AM   #1
awgrant is offline awgrant  United Kingdom
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Join Date: Jul 2012
Cool DIY Ghetto soundsystem!

Hi folks,

Im in need of a little help with an interesting project that should make some of you laugh and some of you cry….

I am attempting to put together a whole bunch of very cheap speakers i find from Craigslist to create a suicide rig for Burning Man. Something in the vein of Click the image to open in full size.
The purpose is so i can DJ a techno set at my own camp in the middle of the desert.

The Equipment will take a beating with high daytime temperatures (100’s) and low evening temperatures possibly approaching freezing and also very dusty conditions!!!

So far the rig consists of

Click the image to open in full size.

2x Kenwood KL-A900 Speakers with after market DHD NTX-6615 (800W Max @ 8ohm) installed.

Click the image to open in full size.

2x JVC SP-MXKC45 (200W Max @ 6ohm)

Click the image to open in full size.

Philips FWB-R7 (100W @6ohm)

Click the image to open in full size.

Philips SW3900/17S Subwoofer (unknown watts @ 4ohm)

Click the image to open in full size.

($37 Craigslist )

I plan to make it a 2 way stereo stack, split into Low and Mid/Top.

I plan to use the Subs in the Kenwoods only, I will remove the rather nice horn loaded tweeters (Trio-Kenwood T14-079-05) to use as tops, and have the other drivers installed but not wired and the hole blocked up.
Click the image to open in full size.

The Philips/JVC speakers and Philips SW will be used as stereo mid/tops and the Horn loaded tweeters removed from the Kenwood’s and sat on top.

The Low will be powered by a Behringer A500 amp bridged into 600watt @ 8ohm Mono
The Mid/tops will be powered by a Behringer A500 amp 2 x 300watt @ 4ohm stereo
($150 approx ebay each)

I am considering using a stereo 2-way Behringer Super X Pro CX2310 active crossover, and as yet an unknown EQ.
($100 approx)

I am hoping you guys can point out anything i may have missed before i go and buy the amps etc.

Im am looking to achieve

a. the best sound,
b. the cheapest price,
c. the lowest power consumption. (running from a 2000w max Honda generator)

Also, I am no electrician so my understanding of ohms is limited, maybe someone could highlight the pitfalls of using differently rated speakers together on the same amp? Does the resistance balance out over all the drivers, i.e. does 2 x 6ohm and 2 x 8ohm create a 7 ohm resistance? And if so would the above amp kicking out 2 x300watt @ 4ohm be sufficient to power them?

I would love to hear what you all think of this slightly mad endeavor? Just remember i have to take it to BM with the intention that nothing will be in a fit condition to use again, hence a suicide rig! Thanks for your time.

Ali
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Old 23rd May 2014, 02:35 AM   #2
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Quote:
Originally Posted by awgrant View Post
Im am looking to achieve
a. the best sound,
LOL.. Good one.
Quote:
Originally Posted by awgrant View Post
b. the cheapest price,
Probably nailed it.
Quote:
Originally Posted by awgrant View Post
c. the lowest power consumption. (running from a 2000w max Honda generator)
Probably failed miserably on that one though, a single proper PA speaker would produce more sound with a fraction of the amplifier power than all this stuff.

Quote:
Originally Posted by awgrant View Post
Also, I am no electrician so my understanding of ohms is limited, maybe someone could highlight the pitfalls of using differently rated speakers together on the same amp? Does the resistance balance out over all the drivers, i.e. does 2 x 6ohm and 2 x 8ohm create a 7 ohm resistance?
Have a look at this link and plug in the impedances of the speakers you have. Note that putting a jumper from 1 speaker to the next is considered a parallel wiring. http://www.speakerimpedance.co.uk/?a...age=calculator

Last edited by conanski; 23rd May 2014 at 02:38 AM.
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Old 23rd May 2014, 02:42 AM   #3
awgrant is offline awgrant  United Kingdom
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Join Date: Jul 2012
Thanks Conanski, i suppose you fall into the cry category then is it?

Hey I understand that a super nice powered Mackie or an all out Void Incubus rig would sh*t all over what i got of course it would, but its supposed to be burnt at the end of the festival..... there is no way im burning a nice set of speakers! The amps will most lickly be fried either from the heat or after from the akaline dust!

SOOO the alternative is to get the 'best sound' for as little money as possible, any help would be much appreciated...... its a fun project not ment to be taken seriously.

And you would be surprised at how good a bunch of cheap band pass speakers can sound when given a clean signal.

Thanks for the reply anyways.
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Old 23rd May 2014, 03:12 AM   #4
awgrant is offline awgrant  United Kingdom
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Quote:
Originally Posted by conanski View Post
Have a look at this link and plug in the impedances of the speakers you have. Note that putting a jumper from 1 speaker to the next is considered a parallel wiring. Speaker Impedance
Great link, thanks

So some quick calculations for one top/mid channel would be as follows;

JVC = 200W Max @ 6ohm
Philips = 100W @ 6ohm
Kenwood horn = Unknown watts @ 8ohm

with a 300 watt amplification this gives the following results;

Parallel connection,

Total Impedance = 2.18181818182 Ω
Speaker A Power = 109.090909091 Watts
Speaker B Power = 109.090909091 Watts
Speaker C Power = 81.8181818182 Watts

Series connection,

Total Impedance = 20 Ω
Speaker A Power = 90 Watts
Speaker B Power = 90 Watts
Speaker C Power = 120 Watts

Looks like the total impedance of the 'in series' connection method would be too high for the 300 W 8ohm amp, am i wrong??

And the parallel connection calculations show suitable watts but the impedance is 2ohm's, who would this effect the speakers/amp?
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Old 23rd May 2014, 03:20 AM   #5
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I don't understand the "Why ? "
Simply, why you would want to go somewhere-and that's a load !-and use it and incinerate it ?!
Meaning that the transportation will burn gasoline and produce TONS of Co2



Ok, you are a villain living at the desert border and you take a walk and deposit your junk, No ! You live abroad and make plans to go to a certain place playing certain music with...whaaat ? Lol
That makes sense.

So a little sense of history: Give ghettoblasters a life ! I've never heard of a ghetto-blaster powered with a generator.
But...I see that low voltage goes with low Z loudspeakers
And the headroom is defined by ...deciBels
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Old 23rd May 2014, 03:41 AM   #6
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you can wire two speakers in parallel and third one in series with them.
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Old 23rd May 2014, 03:43 AM   #7
awgrant is offline awgrant  United Kingdom
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Quote:
Originally Posted by picowallspeaker View Post
I don't understand the "Why ? "
Simply, why you would want to go somewhere-and that's a load !-and use it and incinerate it ?!
Haha, yeah i get what your saying, why.... why the hell not? Go to a festival party, celebrate and express oneself. I'm an artist and i intend to use everything at my limited disposal to express the music i love to the people i love.

Quote:
Originally Posted by picowallspeaker View Post
Meaning that the transportation will burn gasoline and produce TONS of Co2


Burning man is all about burning visit this link for more info, Burning Man :: Welcome Home

Quote:
Originally Posted by picowallspeaker View Post
You live abroad and make plans to go to a certain place playing certain music with...whaaat ? Lol
That makes sense.
I thinkit makes sense too, thanks!

Quote:
Originally Posted by picowallspeaker View Post
So a little sense of history: Give ghettoblasters a life ! I've never heard of a ghetto-blaster powered with a generator.
But...I see that low voltage goes with low Z loudspeakers
And the headroom is defined by ...deciBels
No Ghetto blasters here my friend, these are the finest 90's Jap imports money cant buy, LOL! Heck its in the desert, there is no power apart from what you create yourself, hence the generator.
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Old 23rd May 2014, 03:55 AM   #8
awgrant is offline awgrant  United Kingdom
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Quote:
Originally Posted by MisterTwister View Post
you can wire two speakers in parallel and third one in series with them.
OH your good!

Ok now i got to figure the maths out...

Speaker A 6ohm
Speaker B 6ohm
Amplifier 300 watts

Speakers is Parallel
Total Impedance = 3 Ω
Speaker A Power = 150 Watts
Speaker B Power = 150 Watts

So to calculate speaker C, im a little confused?
Do i use the combined watts to calculate ie. 300w or is it halved, ie 150watts?

Result A using 300w;
Total Impedance = 11 Ω
Speaker A/B (parallel) Power = 81.8181818182 Watts
Speaker C (in series with the parallel circuit above) Power = 218.181818182 Watts

Speaker C gets a heck of a lot of watts

Result B using 150w
Total Impedance = 11 Ω
Speaker A/B (parallel) Power = 40.9090909091 Watts
Speaker C (in series with the parallel circuit above) Power = 109.090909091 Watts

Speakers A/B dont get many watts

Hum... have i done this correctly, help?
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Old 23rd May 2014, 04:22 AM   #9
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I was saying Lol from a technical POV
Now some hints
The two big aluminum woofers & enclosures ( leave the back opened so you can insert the mid-tw unity for ease of transportation ) are the sub units.
I guess they could work ( give appreciable sound in their pass-band range ) till 500 Hz...but who knows, and it depends upon the choice of the associated mid-woofer driver, which might not be one of your list.
This unknown driver ( yes : you have to dismantle all your speakers with hammers and screwdrivers and bring the drivers naked ) should tame the beast of the sub, so no 20 watters allowed.

the mono-bi-multiamplifying of the whole rig and the Low Tension supply is
another practical "mountain to climb".
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Old 23rd May 2014, 04:42 AM   #10
awgrant is offline awgrant  United Kingdom
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Join Date: Jul 2012
Thanks Pico, not 100% sure if i understand you but; here goes. The aluminium 17inch woofers from some bad car install (i bought them like that) will run in mono together in parallel, all the other drivers in those speaker boxes will be disconnected.

So the amp which runs at 600watt @ 8ohm output, doing the maths now looks like it will be slightly under powered.

Total Impedance = 4 Ω
Speaker A Power = 300 Watts
Speaker B Power = 300 Watts

The mid tops all have their own passive crossovers, so all im doing with the active cross over is removing the lowest frequencies allowing (hopefully) lower distortion/higher db's.

What did you mean about leaving the back open on the speakers, that doesn't make much sense to me, they have twin ports already?! Can you explain, thanks?

Also i think you may misunderstand about the voltages, 120v is standard US mains voltage which will be the same output of the generator/transformer so it will run in the same way as a home HIFI system.

Thanks for the comments, really appreciate hashing this out with you guys
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