Building (2) 10" Portable System, parts purchased - diyAudio
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Old 9th February 2013, 02:19 PM   #1
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Default Building (2) 10" Portable System, parts purchased

EDIT: First pictures up on page 4, along with a change in some components

So I don't know if this is the right spot, apologize if it isn't. A couple times a year my friends and I take a trip to his hunting camp (we don't hunt) and there is no power except for gasoline generators. Usually this results in one or a few of us running our car batteries dead playing music over the course of the May 24 weekend. So I decided to build a system to take with me to run off battery.

Goals
107+db output
40 Hour Uninterrupted playback with reserve to also power an MP3 player
Fit in my car for transport
Under $200(CDN) (not counting enclosure)
Sound quality better than the iPod docks etc. that my friends usually bring, which are tinny and don't disperse far.

Background - I mostly browse Diyma since I spend most of my time on my car. I currently have a Car PC setup with (G530, Win 8, SSD, Delta 1010LT) - Mimo 720S - Iogear Wireless KB - ID XS28, Scan 18w/4434G00 (Active) - IDMax 12D4v3 IB - PPI P900.4 - Kenwood XR4S
It runs full active with 64 band parametric EQ per channel, and also was tuned with a calibrated EMM-6.

First off, I am not expecting SQ anywhere near my home, car, or recording setup.

The parts I purchased, taking into account price first, efficiency second, SQ third.

MCM Audio Select 10'' Die Cast Woofer with Paper Cone and Cloth Surround - 100W RMS 8ohm | 55-2961 (552961) | MCM Audio Select
3.5mm one way xmax, 96db (across the usage range, -3 is like 90hz, that's fine for this)

MCM Audio Select Piezo Horn Tweeter | 53-800 (53800) | MCM Audio Select
95db, easily replaceable if they are completely useless ($5 total)

http://www.ebay.ca/itm/230608705311?...#ht_3790wt_906
Basic tripath, with some decent components

Special Price 10W 12V Module Polycrystalline Solar Panel-in Solar Cells, Solar Panel from Electrical Equipment & Supplies on Aliexpress.com
10W, fits the dimensions of the top of the box perfectly

http://1000bulbs.com/pdf/ubD5745-spec.pdf
18aH should be good for 40+ hours while powering an iPod with the solar panel getting 2-3 sunshine hours a day

WinISD says approx 110-112db peak at 1m with 15w rms input. This is with 0.66cu ft per driver and tuned to 72.89hz.

I am going to slightly modify this value however and run 0.8cu ft per driver which nets me (compared to 0.66) -0.2db 100-200hz, +1 db 70-125hz tuned to 73hz.

Sketchup so far for 0.6 cu ft, which I will change Box 0.6cu ft Dual 10 by wy2sl0 - 3D Warehouse

I designed the battery/amp compartment into the rear 1/4 of the box along the entire width.

Any comments would be grateful. I just ordered this week so I am thinking this should be done in a month or so, and start getting parts in the next 3 weeks.

Last edited by wy2quiet; 20th February 2013 at 06:22 PM.
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Old 9th February 2013, 05:07 PM   #2
DUG is online now DUG  Canada
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Sounds like a great project, post pictures when you are done.

But you may not get quite the power you were expecting.
Attached Images
File Type: jpg TA2020.JPG (56.9 KB, 197 views)
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Old 9th February 2013, 05:55 PM   #3
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Running the tweeter and woofer together will net approx a 4 ohm load, and will output 15 or so watts per channel. Even at 8w RMS that is only a 3db decrease which is above my 107db requirement :-)

Thanks, I will post pictures.
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Old 9th February 2013, 08:36 PM   #4
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Quote:
Originally Posted by wy2quiet View Post
Running the tweeter and woofer together will net approx a 4 ohm load, ...
No. It doesn't work like that.
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Old 9th February 2013, 10:44 PM   #5
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Originally Posted by Saturnus View Post
No. It doesn't work like that.
Goes to show you what I know. I have used actives as long as I can remember, I have never even made a passive!

Glad I read up. Ok well -3 db is ok, as I said. If it ends up NOT being, I will buy another TA to run each set of drivers seperately. I am thinking it should be ok, it is not like I am trying to run at concert levels.

I will probably run the 10 up to about 2.5-3k and then cut them. I have more reading to do about piezo wiring, although I see their impedance graph sort of works as an automatic lf attenuator.
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Old 9th February 2013, 11:19 PM   #6
sreten is offline sreten  United Kingdom
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Hi,

The 8 ohm drivers will extend battery life over 4 ohm drivers,
at maximum volume. Read up on piezo's, they don't work
like normal tweeters, e.g. you use series caps for attenuation
and series R for response shaping, just doing it right will make
a big difference to the apparent treble quality you end up with.

rgds, sreten.
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Old 10th February 2013, 02:46 PM   #7
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I read up on them, thanks. I will be using an 8 ohm resistor across the leads, and HP them at 3khz, LP on woofer the same.

Believe it or not this took me hours of changing different designs and dimensions to make sure everything fit, in a box as SMALL as possible and getting flat response (from the enclosure).

Here is my final design

Tripath Boom Box by wy2sl0 - 3D Warehouse
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Old 10th February 2013, 03:07 PM   #8
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Quote:
Originally Posted by wy2quiet View Post
You've basically just copied my Boominator design. That's fine. You have however forgotten the very basics of the design.

You can't use 12mm plywood for a cabinet design like yours. There´s far from sufficient bracing to prevent a serious amount of loss in the bass region due to cabinet vibrations. You need to go at least 15mm (18mm baffle) to compensate.

The Boominator works so well because it's bipolar. Your design will sound very thin in comparison unless you bafflestep it by dampening above about 382Hz with a -6dB bafflestep filter.

Should also note that the Boominator is only 40% bigger but houses 4x 10" drivers. Which makes a huge difference.

Last edited by Saturnus; 10th February 2013 at 03:10 PM.
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Old 10th February 2013, 03:25 PM   #9
JMFahey is offline JMFahey  Argentina
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Quote:
I will be using an 8 ohm resistor across the leads, and HP them at 3khz,
You needn't do that
Piezos crossover at around 3.5KHz (depending on model) all by themselves.

Just curious, can't you get same woofers (or equivalent) in 4 ohms versions?
That way you'll get 15W RMS out of each of them.

Note: if you want more usable *clean* power, you may add , say, a TDA2003 chip amp and biamp a "real" (meaning VC and magnet) Tweeter.
I do exactly that in my commercial "Callejero" ("Street Guy") amplifiers, powered from 12V 7A batteries.
Loud and clean .
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Old 10th February 2013, 05:55 PM   #10
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Quote:
Originally Posted by Saturnus View Post
You've basically just copied my Boominator design. That's fine. You have however forgotten the very basics of the design.

You can't use 12mm plywood for a cabinet design like yours. There´s far from sufficient bracing to prevent a serious amount of loss in the bass region due to cabinet vibrations. You need to go at least 15mm (18mm baffle) to compensate.

The Boominator works so well because it's bipolar. Your design will sound very thin in comparison unless you bafflestep it by dampening above about 382Hz with a -6dB bafflestep filter.

Should also note that the Boominator is only 40% bigger but houses 4x 10" drivers. Which makes a huge difference.
First off, yes thank you. I obviously got a huge amount of inspiration from your design. I however didn't want to use 4 drivers, 1) to do something different, and 2) since it will be sitting close to a wall more than likely most of the time anyways so I don't want reflections. Looking at the response graph of the speaker I do understand that a P.A speaker is considerably lower below 300 since it shows efficiency in its midrange. Doing what you are saying however, is essentially destroying the efficiency of the speaker, wouldn't it? If I was running active then I could simply -5db everything from 380hz+, but doing it at a speaker level is post-amp and is just destroying effciency and wasting power. Not very good. I don't see why a speaker (which many I have used before have similar) with a response graph such as the one I chose would sound so differently? Bass is not going to be any better than a speaker that is trying to play fullrange essentially, but that is what you expect when you run passive and without a dedicated subwoofer in a P.A setup. In saying that I have read up on baffle diffraction a bit and I see the problems in the original FR measurements of speakers, and real world FR patterns. Am I wrong in what I said about your idea killing efficiency?

I should more than likely switch to a 3/4" plywood design you are right.
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