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Family Feud Basra Style

Saturday, December 13, 2014 

Gunfire is pretty common here, perhaps even more common than in Oakland though usually for the same reasons: celebrating holidays, sports victories, weddings, that sort of stuff.  It is kind of fun to listen to and watch tracers and stuff, but usually the villa is also celebrating in an obvious way; when you hear gunfire you also hear cheers, at least at night.

This evening the house was quiet, but the gunfire sure wasn’t.  The guys tell me it was a tribal feud in the neighborhood, quite close from the sound of it.  This is a low-fi recording from my phone.

Posted at 17:13:13 UTC

Category: Audioplacestravel

Power Adventures In Iraq

Friday, December 12, 2014 

Plugging things in here is always an adventure. Most of the outlets are the horrible giant British style so they have interlocked grounds, but most appliances are European style, so plugging things in means either using something to jam open the ground interlock, breaking the interlock tabs with force, or dispensing with the plug entirely and just stuffing bare wires in the holes.

When using the latter method, it turns out the British plugs are actually kind of useful because toggling the ground tab with a screwdriver uses the interlocks to bind the wires in place.  You just hope the ground pin is wired to ground, not hot.  Usually it just isn’t wired to anything.

Most appliances and power strips here come from China and are the sort of manufacture China was famous in the US for about 30 years ago: taking something out of the package usually breaks it.  The wires inside are so thin it is amazing they survive and grounds are never, ever actually connected.  I have cables that on the inside have a ground insulator but no ground conductor inside the insulator.  Awesome!

But we just rewired the new villa and even though the ground isn’t wired (of course), the outlets are new and seem like they’re decent quality.  And we even got British style plugs to dispense with the highly problematic and very melt-prone plug adapters.  All seemed good until….

Uh oh.  Maybe it just needed to create a little vent….

outlet_going

 

Nope.  Melt down.  Good thing these have a built-in fuse…  (which is still fine, though encrusted in melted plastic).

outlet_gone

Posted at 15:27:24 UTC

Category: phototechnologytravel

Regional Energy Drink

Monday, December 1, 2014 

I’ve run across this energy drink in dramatic packaging.  Energy drinks aren’t really my thing, but I thought I’d try it: slightly orange tasting fizzy water, mildly sweet with that slightly weird energy drink taste.  But the bottle is fun:

Bomba Bottle Image

It is made in Hungary and seems to be distributed more to the East than the West, at least as far as my travels have indicated.  I have seen it in a lot of Middle-Eastern markets, but not in many European ones.

The lid release mechanism is kind of thematically clever.

Bomba Pull Top Image

I suspect this would be a particularly problematic beverage to forget in your carry-on luggage.

Posted at 18:29:45 UTC

Category: funnyNeutraloddphotoreviews

Speaker Build

Friday, November 28, 2014 

In December of 2002 (really, 2002, 12 years ago), I decided that the crappy former Sony self-amplified speakers with blown amplifiers that I had wired into my stereo as surround speakers really didn’t sound very good as they were, by then, 7 years old and the holes in the plastic housing where the adjustment knobs once protruded were covered by aging gaffers tape.

At least it was stylish black tape.

I saw on ebay a set of “Boston Acoustics” woofers and tweeters back in the time when ebay prices could be surprisingly good.  Boston Acoustics was a well-respected company at the time making fairly decent speakers.  36 woofers and 24 tweeters for $131 including shipping.  About 100 lbs of drivers.  And thus began the execution of a fun little project.


 

Design Phase: 2003-2011

I didn’t have enough data to design speaker enclosures around them, but about a year later (in 2003), I found this site, which had a process for calculating standard speaker properties with instruments I have (frequency generator, oscilloscope, etc.)  I used the weighted diaphragm method.

WOOFER: PN 304-1150001-00 22 JUL 2000
80MM CONE DIA = 8CM
FS  = 58HZ
RE  = 3.04 OHMS
QMS = 1.629
QES = 0.26
QTS = 0.224
CMS = 0.001222
VAS = 4.322 (LITERS) 264 CUBIC INCHES
EBP = 177.8

NOMINAL COIL RESISTANCE @ 385HZ (MID LINEAR BAND) 3.19 OHMS
NOMINAL COIL INDUCTANCE (@ 1KHZ) 0.448 MHENRY
TWEETER: PN 304-050001-00 16 OCT 2000
35MM CONE DIA
FS  = 269HZ
RE  = 3.29 OHMS
QMS = 5.66
QES = 1.838
QTS = 1.387
CMS = 0.0006
VAS = 0.0778 (LITERS)
EBP = 86.7

NOMINAL COIL RESISTANCE @ 930HZ (MID LINEAR BAND) 3.471 OHMS
NOMINAL COIL INDUCTANCE (@ 1KHZ) 0.153 MHENRY

Awesome.  I could specify a cross over and begin designing a cabinet.  A few years went by…

In January of 2009 I found a good crossover at AllElectronics.  It was a half decent match and since it was designed for 8 ohm woofers, I could put two of my 4 ohm drivers in series and get to about the right impedance for better power handling (less risk of clipping at higher volumes and lower distortion as the driver travel is cut in half, split between the two).

HTTP://WWW.ALLELECTRONICS.COM/MAKE-A-STORE/ITEM/XVR-21/2-WAY-CROSSOVER-INFINITY/1.HTML
CROSS OVER FREQUENCY 
3800HZ CROSSOVER
LOW-PASS: 18DB, 8 OHM
HIGH-PASS: 18DB, 4 OHM

Eventually I got around to calculating the enclosure parameters.  I’m not sure when I did that, but sometime between 2009 and 2011.  I found a site with a nice script for calculating a vented enclosure with dual woofers, just like I wanted and got the following parameters:

TARGET VOLUME 1.78 LITERS = 108 CUBIC INCHES

DRIVER VOLUME (80MM) = 26.25 CUBIC INCHES = 0.43 LITERS
CROSS OVER VOLUME = 2.93 CUBIC INCHES = 0.05 LITERS
SUM = 0.91 LITERS
1" PVC PORT TUBE: OD = 2.68CM, ID = 2.1CM = 3.46 CM^2
PORT LENGTH = 10.48CM = 4.126"


WIDTH = 12.613 = 4.829"
HEIGHT = 20.408 = 7.82"
DEPTH = 7.795 = 3"

In 2011 I got around to designing the enclosure in CAD:

There was no way to fit the crossover inside the enclosure as the drivers have massive, magnetically shielded drivers, so they got mounted on the outside.  The speakers were designed for inside mounting (as opposed to flange mounting) so I opted to radius the opening to provide some horn-loading.

I also, over the course of the project, bought some necessary tools to be prepared for eventually doing the work: a nice Hitachi plunge router and a set of cheap router bits to form the radii and hole saws of the right size for the drivers and PVC port tubes.

Build Phase (2014)

This fall, Oct 9 2014, everything was ready and the time was right.  The drivers had aged just the appropriate 14 years since manufacture and were in the peak of their flavor.

I started by cutting down some PVC tubes to make the speaker ports and converting some PVC caps into the tweeter enclosure.  My first experiment with recycled shelf wood for the tweeter mounting plate failed: the walls got a bit thin and it was clear that decent plywood would make life easier.  I used the shelf wood for the rest of the speaker: it was salvaged from my building, which was built in the 1930s and is probably almost 100 years old.  The plywood came with the building as well, but was from the woodworker who owned it before me.

I got to use my router after so many years of contemplation to shape the faceplates, fabricated from some fairly nice A-grade plywood I had lying around.

Once I got the boxes glued up, I installed the wiring and soldered the drivers in.  The wood parts were glued together with waterproof glue while the tweeters and plastic parts were installed with two component clear epoxy.  The low frequency drivers had screw mounting holes, so I used those in case I have to replace them, you know, from cranking the tunage.

I lightly sanded the wood to preserve the salvage wood character (actually no power sander and after 12 years, I wasn’t going to sand my way to clean wood by hand) then treated them with some polyurethane I found left behind by the woodworker that owned the building before I did.  So that was at least 18 years old.  At least.

I supported the speakers over the edge of the table to align the drivers in the holes from below.

The finished assembly looked more or less like I predicted:

Testing

The speakers sound objectively quite nice, but I was curious about the frequency response.  To test them I used the pink noise generator in Audacity to generate 5.1 6 channel pink noise files which I copied over to the HTPC to play back through my amp.  This introduces the amp’s frequency response, which is unlikely to be particularly good, and room characteristics, which are certainly not anechoic.

Then I recorded the results per speaker on a 24/96 Tascam DR-2d recorder, which also introduces some frequency response issues, and imported the audio files back into Audacity (and the original pink noise file), plotted the spectrum with 65536 poles, and exported the text files into excel for analysis.

Audacity’s pink noise looks like this:

Pink_Noise_Spectrum

It’s pretty good – a bit off plan below 10 Hz and the random noise gets a bit wider as the frequency increases, but it is pretty much what it should be.

First, I tested one of my vintage ADS L980 studio monitors.  I bought my L980s in high school in about 1984 and have used them ever since.  In college I blew a few drivers (you know, cranking tunage) but they were all replaced with OEM drivers at the Tweeter store (New England memories).  They haven’t been used very hard since, but the testing process uncovered damage to one of my tweeters, which I fixed before proceeding.

ADS L980 Spectrum

The ADS L980 has very solid response in the low frequency end with a nicely manufactured 12″ woofer and good high end with their fancy woven tweeter.  A 3 way speaker, there are inevitably some complexities to the frequency response.

I also tested my Klipsch KSC-C1 Center Channel speaker (purchased in 2002 on ebay for $44.10) to see what that looked like:

It isn’t too bad, but clearly weaker in the low frequency, despite moderate sized dual woofers and with a bit of a spike in the high frequency that maybe is designed in for TV and is perhaps just an artifact of the horn loaded tweeter. It is a two way design and so has a fairly smooth frequency response in the mid-range, which is good for the voice program that a center speaker mostly carries.

And how about those new ones?

New Speaker Spectrum

Well… not great, a little more variability than one would hope, and (of course) weak below about 100Hz.  I’m a little surprised the tweeters aren’t a little stronger over about 15kHz, though while that might have stood out to me in 1984, it doesn’t now.  Overall the response is quite good for relatively inexpensive drivers, the low frequency response, in particular, is far better than I expected given the small drivers.  The high frequency is a bit spiky, but quite acceptable sounding.

And they sound far, far better than the poor hacked apart Sony speakers they replaced.

Raw Data

The drawings I fabricated from and the raw data from my tests are in the files linked below:

Speaker Design Files (pdf)

Pink Noise Tests (xlsx)

Posted at 21:05:03 UTC

Category: AudioFabricationHowTophototechnology

Burnt Outlet

Saturday, March 8, 2014 

Occasionally electrical systems here just catch on fire for no apparent
reason.

burnt_outlet.jpg
Posted at 07:39:27 UTC

Category: -

Cactus Farmer

Wednesday, December 25, 2013 

A few years back, when I was in 3rd or 4th Grade, my brother and I went to visit David and Jesse Lenat at their Cactus Farm. While we were exploring the green houses, their dad, Richard, gave us each a cactus to take home.

Mine lived in a small pot near the window through the rest of grade school and high school and then my mom cared for it through college. It grew into a little cluster of pencil thin green, spiky pads over the years.

After I graduated, moved to California, and got an apartment in SF; I was home for Christmas one year and took one of the pads wrapped in tissue to California. It grew well there and now produces big, bright yellow flowers every year.

This Christmas, I stuffed two tiny buds into glass bottles and brought them to Iraq and planted in the yard with one of the cat’s help (paw in the background).

20131223_122142.jpg
Posted at 03:01:17 UTC

Category: catsGeopostphotoplaces

Yard Berries

Monday, November 4, 2013 

20130804_111745.jpg
Posted at 11:19:54 UTC

Category: photo

Iraq

Friday, November 1, 2013 

destroyed tank.jpg
Posted at 12:51:24 UTC

Category: photoplacestravel

A Friendly Arrival in Iraq

Wednesday, February 20, 2013 

I got through immigration in record time, no complications at all. Only a few questions about the power supply in my luggage at customs.

I thought I would get a cup of coffee from the stand an acquaintance operates at the airport, but I arrived as they were having breakfast. As this is Iraq, that meant I had to join them for a jovial breakfast of eggs, fresh tomato, cucumber, potatoes, and meat pastries while they told me funny stories about each other in a mixture of Arabic, English, and Spanish. They would not let me pay anything, a really pleasant and friendly welcome into the country.

But I couldn’t stay long, I had to take a taxi out to meet my friends at the arrivals lot, where the in car is a B6 Land Cruiser.

basra Airport Meeting.jpg
Posted at 20:23:39 UTC

Category: photoplacestravel

Visiting the Burj Khalifa

Saturday, February 2, 2013 

Dubai is an interesting contrast to Iraq. The first time I went through DXB from BSR it was more than a little culture shock. Getting out of the airport only amplifies the experience.

Dubai DSC03683.jpg

Jared and I had dinner at the Mall of Dubai and before eating had a little walk around the fountains – the largest dancing fountains in the world at the foot of the tallest man-made structure in the world.

Dubai DSC03693.jpg

Dubai is an good place to spot cars. Obviously the gold accented rolls is more pose-worthy than the $450k GTO. Then again they were probably posing with the license plate number which I think was 1, and therefore cost as much as 20 Ferrari GTOs.

Dubai DSC03695.jpg
The fire fountains:

Dubai DSC03692.jpg

Posted at 17:58:15 UTC

Category: mapphotoplacestravelvideo