Unnamed Design by Lutkeveld (Development Thread) |
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lutkeveld
Young Croc Joined: 23 September 2013 Location: The Netherlands Status: Offline Points: 517 |
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Posted: 29 May 2016 at 9:55pm |
Welcome
This will
be the thread where I dump my progress on my, yet unnamed, project. It is
somewhat similar to the Boominator MICRO, but different in a lot of ways. The
main point of this thread is to give people some insight in the design
workflow, as well as giving input and asking questions. The goal is to make the
design fully open-source. Every step
will have instructions with pictures and explanation. Along the way I will post
some YouTube videos and Instructables on certain steps to provide a little more
knowledge than just the information needed. It’s great to see more people get
into DIY audio, so I hope this design will help many people get started. Most of the
design is already complete, so this thread is partly a backlog of updates. However,
the devil is in details, and there’s still a lot of choices to be made. Feel
free to suggest/correct/add things. First step
will be driver selection |
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lutkeveld
Young Croc Joined: 23 September 2013 Location: The Netherlands Status: Offline Points: 517 |
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Driver
choice
Selecting
the woofer is the most difficult task, so that’s the first choice. Tweeter
choice will depend on which woofer is selected. Parts Express has a great
selection and can thus be used as a tool for driver selection. Since I am
aiming for a small enclosure (<10 liters) I’d rather go sealed. Decent bass
extension is wanted and the driver needs to preferably be light weight and low
cost. This leaves me with the following requirements: - Medium
Vas (3-10L) - Medium Fs
(<65Hz) - High Qts
(>0,45) - Low
weight magnet, preferably neodymium (<500gr) - Low price
(<50$) - 4 ohm
impedance A quick search returns the Dayton ND140-4. Great fit, especially considering the low price of 31 dollars. Sensitivity isn’t too high at 88.4dB @2.83V/1M. I have chosen to exchange some loudness for bass extension, with the reasonably powerful amplifier it will get loud enough either way.
As you can
see in the frequency response graph the response starts to get nasty around
4kHz, probably due to the aluminum cone breaking up. This means filtering has
to take place at 3kHz or below. This will be an important parameter when
selecting the tweeter. The tweeter
should be: - - Low
cost (<20$) - - High
dispersion - - Easy
to mount The last
requirement already disqualifies anything that has to be flush-mounted since I
will be laser cutting the enclosure. The Dayton
ND20FB seems to offer what I’m looking for. It flush-mounts from the back in a
12mm baffle. My baffle will be double 6mm, so that would work. The
resonance frequency is a bit on the high side, but the tweeter won’t see more
than a couple of watts and will be actively filtered with a >2nd
order filter. I don’t foresee much trouble there. DaytonAudio is really great in providing the files needed for simulation (FRD, ZMA,
TSP). Here are the links to the ZIP folders for both drivers: It’s always best to measure them yourself, which I’ll be doing in another post, but this is a great starting point. Next stop
will probably be the amplifier :) Edited by lutkeveld - 29 May 2016 at 10:09pm |
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Ganon
Registered User Joined: 07 May 2014 Location: Denmark Status: Offline Points: 114 |
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Remember when you calgulate your spl with 2.83v at 4 ohm, it's the same as 2Watt/1meter, not 1 watt.
So the spl is more like 85,4db 1W/1M :) |
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cookie-dj
Young Croc Joined: 09 May 2014 Location: Warwickshire Status: Offline Points: 977 |
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Have you simmed any mainstream drivers for this project? (e.g eminence, p audio, rcf etc).....
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You can't polish a turd!
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chemacky
New Member Joined: 18 February 2016 Status: Offline Points: 6 |
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Subscribed. Can't wait to see it unfold, keep up the good work.
Some teaser pics of what you're brewing up would be great! Cheers, and good luck!
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lutkeveld
Young Croc Joined: 23 September 2013 Location: The Netherlands Status: Offline Points: 517 |
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I know, thanks for the headsup Ganon :)
Cookie-dj, I have looked at a lot of drivers but the ND140 is the only driver that has the T/S parameters I want and doesn't cost that much. There were some more expensive woofers that would work, but the ND140 is the best fit for my project. Chemacky, a small teaser: Oh, and I just posted an Instructable on my amplifier design: Next step will probably be on the rendering and lasercutting (fusion360). Edited by lutkeveld - 06 June 2016 at 7:38pm |
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DJ-Dulux
Registered User Joined: 24 August 2009 Location: Kenilworth, UK Status: Offline Points: 378 |
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This could be interesting, subscribed. Looks smart and commercial....
Dupe... |
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Dupe...
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cookie-dj
Young Croc Joined: 09 May 2014 Location: Warwickshire Status: Offline Points: 977 |
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What were the more expensive drivers? Looks really promising
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You can't polish a turd!
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chemacky
New Member Joined: 18 February 2016 Status: Offline Points: 6 |
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Just a little nudge to see how this is shaping up. Haven't heard anything in quite a while. :)
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davey t
Young Croc Joined: 11 March 2004 Location: Bristol UK Status: Offline Points: 1428 |
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Your output filter looks a bit suspect. If you are just making this for your own use and cables are short then just get rid of all the output filtering - it will extend your battery life a lot.
You'll need to add an electronic bass boost to extend the low end of that sealed enclosure. What is your signal source, power supply, crossover etc? David
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Minirig portable soundsystem movement
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slaz
Old Croc Joined: 27 November 2009 Location: London E2 Status: Offline Points: 2713 |
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Is htis gonna be battery powered ? Aimed at indoor or outdoor use ?
If battery power, I'd suggest removable battery compartment (a la soundboks) - opens options for the user to get extra battery life (by buying extra packs) and also possibly to choose mebbe 6S LiPo for full beans volume (would need good heatsink I guess - mebbe even forced cooling) or similar physical size 4S pack for ~double the runtime .... any auxiliary circuitry would need to tolerate ~15-30V supply I suppose. Also, personally I favour the "ghettoblaster" form factor with a carry handle ..... just the job for this size/weight - and lends itself quite nicely to carrying (and playing) on the back of a bike, for example. |
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REMEMBER....POLITICIANS AND DIAPERS SHOULD BE CHANGED OFTEN AND FOR THE SAME REASON
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barrymossel
New Member Joined: 14 April 2016 Status: Offline Points: 8 |
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Any news on this lutkeveld?
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