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Multi-Way Conventional loudspeakers with crossovers

silk purse from sows ear contest?
silk purse from sows ear contest?
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Old 15th June 2018, 06:39 PM   #1
Jared is offline Jared
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Default silk purse from sows ear contest?

I was curious if anyone would be interested in making a communal thread / contest to make the best measuring speakers possible, for some absurd low driver price limit. I thought a contest like nature might be that extra bit of accountability for people like myself to actually get something done in a timely manner. How about setting up a initial set of rules / judgements of:
- use USD or EU, convert your currency. (if you are in US or EU, you cannot convert)
- $30 limit USD (or 37 EU) prices per speaker (drivers, active/passive crossover components, DSP, purchased radius ports)
- $ free no limit wood, pvc ports, screws, glue, wire, stuffing, terminals (goal is to take cheap components and design / build good enclosures)
- DSP not allowed unless it is part of the budget (SGTL5000 type chips make this feasible actually).
- amp not part of contest UNLESS you go for DSP, then your entry takes RCA input instead of speaker level input
- prize = bragging rights within this thread.
- deadline = 9/1/18 2.5 mo should be plenty of time.
- judges = anyone who submits a design with photos / simulations and a 1W/M REW response curve. You may vote a single time for someone else's project.
- 2 categories, simulated as well as IRL.
- do NOT include shipping costs, Taxes, VATS, Customs, anything else.
- do NOT include incidentals like wire, terminals, glue, caulk, screws etc.
- use best guesstimate for winding your own coils
- NO External dimension or volume limits on enclosures.
- use 1/24 smoothing in REW plots.
- out of budget entries welcome for 'close but no cigar, still ineligible but thanks for helping us learn!'
- You may enter multiple designs even reusing exact same components.
- NO driver minimum, CAN be single full range driver in a 4x8 sheet of plywood if you can make that sound good and convince peers to vote for it!


possible judging guidelines, but remember this is peer with 1 vote, not something scientific:
- Mathematical formula for judging 20-20k, add a point for each db higher or lower than reference at each standard graph axis label in REW: (20, 30, 40, 50, 60, 70, 80, 90, 100, 200, 300, 400, 500, 600, 700, 800, 900, 1000, 2000, 3000, 4000, 5000, 6000, 7000, 8000, 9000, 10000, 20000) meaning the lowest score aka flattest response wins.
- Another formula that does not focus so much on the lower frequencies, maybe octaves? 20,40,80,160,320,640,1k,2k,4k, 8k, 16k ??

Extra imaginary internet points for:

- dumpster diving!
- creative reuse of things ( unwind a motor into an inductor for example)!
- inventing creative cheats!
- money left over
- not using buyout drivers
- high peak SPL
- HD plots that are actually good
- painting it red or gold
- using OSB instead of decent wood

Last edited by Jared; 20th June 2018 at 02:02 PM. Reason: edit #3 add in more feedback, trying to keep spirit to original idea
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Old 16th June 2018, 03:33 PM   #2
Pano is offline Pano  United States
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silk purse from sows ear contest?
Fun idea, but if all the speakers aren't measured with the same setup, it could be difficult to judge.
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Old 16th June 2018, 05:11 PM   #3
Jared is offline Jared
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Yeah, I would expect some people would use REW and the laptop mic.. Not really expecting a great scientific comparison from this, but a cheap way to get some feedback / provide peer feedback, and focus on the engineering under our control vs throwing the $ at the engineering that we cannot really control. Maybe it would encourage some mini meetups for testing if logistics aligned.
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Old 16th June 2018, 08:47 PM   #4
PeteMcK is offline PeteMcK
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Great Idea, doesn't have to be a competition, just a thread... I love making up systems from drivers I've found on the side of the road, & have a shed full of dodgy drivers...
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Old 17th June 2018, 02:44 AM   #5
wolf_teeth is offline wolf_teeth  United States
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$20/cab for speakers including xovers? That's really likely that it can't be done, at least at retail cost.

$50/cab is more reasonable.

Later,
Wolf
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Old 17th June 2018, 03:30 AM   #6
wintermute is offline wintermute  Australia
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silk purse from sows ear contest?
This would not be possible for me. I doubt I could find any drivers for the $20, I could do bipolar electros for caps, and coils I could wind myself (how would I work out the cost, my magnet wire I bought ages ago). If I had to buy coils then again would be very difficult to meet the cost.

The shipping alone would be more than the budget, if I were to buy something from OS where the prices are more reasonable

You could have two categories. One for actual builds, and one for simulated builds I'd be able to participate in the second, provided I could find some cheap drivers that had FR and impedance curves published.

edit: perhaps shipping could be excluded from the cost, that would make the playing field more even.

Tony.
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Last edited by wintermute; 17th June 2018 at 03:32 AM. Reason: add comment about shipping excluded.
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Old 17th June 2018, 06:42 AM   #7
haiqu is offline haiqu  Australia
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I'd enter the system I'm currently listening to except that I don't have specs for either driver and my measurement system is in the back of the truck somewhere. Taiwanese 4" woofer with 40yo used Jordan 50mm as a tweeter. Sounds excellent.
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Old 17th June 2018, 08:18 AM   #8
TMM is offline TMM  Australia
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Given that half of the judging frequencies are below 700Hz, the winner is probably not going to be the person who builds the flattest speaker but the person who knows how to measure below 700Hz without significant room/environmental effects.
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Old 17th June 2018, 02:57 PM   #9
bbutterfield is offline bbutterfield  United States
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Quote:
Originally Posted by TMM View Post
Given that half of the judging frequencies are below 700Hz, the winner is probably not going to be the person who builds the flattest speaker but the person who knows how to measure below 700Hz without significant room/environmental effects.
That's a good point that the measurement conditions would probably have to be standardized. Also, the set of measurements would have to be standardized as well. For example, should this include off-axis measurements, or on-axis only? If off-axis is included, do you do both vertical and horizontal?
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Old 17th June 2018, 03:48 PM   #10
phivates is offline phivates  United States
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$20? This would be an audio dish prepared from leftovers, with maybe a trip to the Dollar Store for foam board. Wait - my retired art teacher spouse has some!
This is why I saved all those drivers and crossovers and boxes.
OK I'm off topic. Again.
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