It was some of the same thinking that resulted in the EU alternative. There was some discussion whether there should be alternatives for other parts of the world also. The point is just to have some limits that are relative to the available cost/assortment of goods, so people don't go haywire and start comparing 100USD designs to 50AUD designs and vice versa.
Nothing wrong with adjusting for different budgets in relation to cost for continents/large sections of the world, but if we go down to small country level the point sort of vanishes.
The idea behind this friendly competition is, in my own personal view, to show skill in choosing the right drivers and other components needed, at as low price as possible, and achieving a high degree of performance that may rival more expensive designs.
In other words:
A sort of marathon effort for cheapskates of the audio world
Nothing wrong with adjusting for different budgets in relation to cost for continents/large sections of the world, but if we go down to small country level the point sort of vanishes.
The idea behind this friendly competition is, in my own personal view, to show skill in choosing the right drivers and other components needed, at as low price as possible, and achieving a high degree of performance that may rival more expensive designs.
In other words:
A sort of marathon effort for cheapskates of the audio world
Thanks ScottG I did wonder about free field. I guess the only way to find out would be to buy one and measure it myself They are only around $14 here in Aus.
BTW I stuffed something up with the sim above, not sure what but when I re-did the transformations on the traced curve I have a more prominent peak at around 350Hz which is very difficult to deal with. I think I messed something up in the baffle modeling. I did a few sanity checks and something wasn't right, so redid from scratch.
Tony.
They are only around $14 here in Aus. BTW I stuffed something up with the sim above, not sure what but when I re-did the transformations on the traced curve I have a more prominent peak at around 350Hz which is very difficult to deal with. I think I messed something up in the baffle modeling. I did a few sanity checks and something wasn't right, so redid from scratch.
Tony.
Just for grins, here is the MCM 55-2421 measured by Zaph:
http://www.zaphaudio.com/temp/MCM-55-2421-FR.gif
-and this is MCM's Clio measurement (look to PDF):
http://www.newark.com/mcm-audio-select/55-2421/8-high-excursion-woofer-120w-rms/dp/88C7835
http://www.zaphaudio.com/temp/MCM-55-2421-FR.gif
-and this is MCM's Clio measurement (look to PDF):
http://www.newark.com/mcm-audio-select/55-2421/8-high-excursion-woofer-120w-rms/dp/88C7835
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Below is a comparison between the traced curves of MCM 6.5" and 8" models 55-2970 and 55-2971 . Definitely something funky with their measurement setup! I'm not sure why they would post such horrid looking measurements when they could put them in a standard box with an IEC baffle and post comparible measurements to everyone else!
Blue is the 8"
Tony.
Blue is the 8"
Tony.
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It's probably just quick measurement from the "QC" pass/fail setup (..which is usually just clamping the frame and running free-air with a very near-field measurement). The T/S and Impedance trace is really the most important part of the data for most woofers/applications.
I wouldn't be at all surprised if many fullrange measurements from non-pro manufacturers just use as simulation for the lower end of their freq. response graphs. Of course many in the pro industry that actually do fullrange graphs are using a vented box as spec.ed at the bottom of their graphs.
I wouldn't be at all surprised if many fullrange measurements from non-pro manufacturers just use as simulation for the lower end of their freq. response graphs. Of course many in the pro industry that actually do fullrange graphs are using a vented box as spec.ed at the bottom of their graphs.
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I feel that this silk purse from a sows ear contest should be perhaps a junk box or very low budget affair.
I've a few drivers I got cheap 5 years ago? Can I use them?
Mission cp134 and cp168 I think around 17 euro each at the time...
Or I have some salvaged aluminium come 10" bass guitar drivers from a Hartke 4x10 cab and some Visaton frs5x which were may be 16 euro each. Passive xo from spares bin. Drivers suit vented box I suspect so I'd have to measure...
Hmm
I've a few drivers I got cheap 5 years ago? Can I use them?
Mission cp134 and cp168 I think around 17 euro each at the time...
Or I have some salvaged aluminium come 10" bass guitar drivers from a Hartke 4x10 cab and some Visaton frs5x which were may be 16 euro each. Passive xo from spares bin. Drivers suit vented box I suspect so I'd have to measure...
Hmm
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I think that it is great that this has got so many people thinking about building stuff in creative ways!
Personally if it inspires you, even if it doesn't qualify under the rules, I'd say go for it! Post the results and have fun. I've joined in even though it is unlikely I will actually build (though I'm becoming more tempted by the day). We could always spin off a new thread, "Junk box speaker builds with measurements"
edit: Scott, yes it always helps when the manufacturer details their actual test setup, without that info I guess it's just a pretty (or not so) picture
Tony.
Personally if it inspires you, even if it doesn't qualify under the rules, I'd say go for it! Post the results and have fun. I've joined in even though it is unlikely I will actually build (though I'm becoming more tempted by the day). We could always spin off a new thread, "Junk box speaker builds with measurements"
edit: Scott, yes it always helps when the manufacturer details their actual test setup, without that info I guess it's just a pretty (or not so) picture
Tony.
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I started cutting wood! Even with the 100 degree heat index... Got as far as ripping the tall panels and cross cutting the tops and bottoms and braces. No router action yet. These are apparently going to be 4' tall yellow speakers since that is what my son chose...
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Today I got 2.5 hours to throw the pieces I previous cut together with some glue and temporary drywall screws. I also routed the face, and immediately screwed up and did the tweeter to the same depth as the woofer. I will have to glue in a spacer ring to bring it flush with the face.
I also still need to cut the holes for the ports and terminals. I am going to give them a listen with just a 3.3uF cap on the tweeter just for giggles / to get a baseline measurement which could count as a contest entry I suppose!
I also still need to cut the holes for the ports and terminals. I am going to give them a listen with just a 3.3uF cap on the tweeter just for giggles / to get a baseline measurement which could count as a contest entry I suppose!
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First listening. I did not round over any edges yet, or do any painting, and the crossover is a single 3.3uf cap I un-solderd from old car tweeters... I have not added the port yet either. I can tell it is boomy in the 100-120hz range for sure. I would call it a bit fatiguing actually.
Internal dimensions:
46.5" X 8" X 10.5"
woofers in series wired full range, tweeter has the 3.3uF cap.
Next step is to get some measurements, see where it stands, and then decide on the port or not.
Please ignore my eldest of 4 kids in photos, they were having a dance party. Listening area was impromptu set them up in the loft, which is about as 'prepared' of a listening setup as I will ever have lol.
Internal dimensions:
46.5" X 8" X 10.5"
woofers in series wired full range, tweeter has the 3.3uF cap.
Next step is to get some measurements, see where it stands, and then decide on the port or not.
Please ignore my eldest of 4 kids in photos, they were having a dance party. Listening area was impromptu set them up in the loft, which is about as 'prepared' of a listening setup as I will ever have lol.
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Sorry, no.
Clearly you've spent far to much money on this project and can't cloth your children.
Integrated sub and full range
It's tough to get anything done in the summer.
I thought I'd try a design using an acoustic cross over. There's a 6.5"woofer (TC-6028 for $12) in a BP6 config and a small 3" full range (PC83-8 for $10) in a sealed chamber.
Some assembly pics and the initial separate driver tests.
It's tough to get anything done in the summer.
I thought I'd try a design using an acoustic cross over. There's a 6.5"woofer (TC-6028 for $12) in a BP6 config and a small 3" full range (PC83-8 for $10) in a sealed chamber.
Some assembly pics and the initial separate driver tests.
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