Compact 2 way fullrange cabinet |
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Monkeys
Registered User Joined: 30 August 2012 Location: Melbourne - Aus Status: Offline Points: 429 |
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Posted: 11 February 2020 at 10:28am |
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Can anyone please advise if there appears to be anything wrong with this design? Apart from the obvious lack of efficiency for an "ideal" 12v system etc. I am OK with that, I just want to know if the cabinet design and sim etc looks OK.
Would it be possible to reduce the port resonance to say around 2khz without too much issue? I have read that damping the port can significantly reduce port resonances. This would be ideal for me if it is possible since it would mean I could get away with a smaller box.. |
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Monkeys
Registered User Joined: 30 August 2012 Location: Melbourne - Aus Status: Offline Points: 429 |
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Ok I am thinking I will go with the Seas Ca22RNY, but in a larger cabinet size of 36L internal volume. I plan to crossover to the tweeter at 1.5khz. The tweeter I am looking at is the Wavecor TW030WA11
I've modeled the CA22RNY in WinISD in a 36L box, tuned to 53hz, with a 6.8cm diameter and 5.77cm length port. This gives the following results: Sensitivity of 91.5db F3 of 50hz and F9 of 40hz 1st port resonance is 2979hz Maximum rear port air velocity at 50w is 26 m/s. Response curve shows a hump at around 70hz up to 92.5db. Can anyone see anything fundamentally wrong with this design? The port length seems fairly short, shorter than it is long, is that right?
I would have preferred to go with a lower tuning frequency to get slightly more bass extension but since I am planning to cross over at 1500hz, I need to get the port resonance up to around double that (or greater). Is this really necessary? Edited by Monkeys - 10 February 2020 at 9:35pm |
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Monkeys
Registered User Joined: 30 August 2012 Location: Melbourne - Aus Status: Offline Points: 429 |
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Ok, update and advice pleas? I have done some further research in an attempt to find some middle ground and gain efficiency, without compromising too much on box size and bass extension.
I have come to the conclusion that I think will use a high efficiency 8" bass-mid driver, in a 25L (internal) volume box. This should get me around 90-92db efficiency and a fairly flat response to 50hz with the right driver. I have narrowed it down to 4 driver choices, which I would appreciate any advice on. Beyma 8P300Fe/N - Pros - Best efficiency (92.5db), Looks very durable and heavy duty (should be resistant to power compression?), reviews say it can be crossed around 1500-2khs with the right tweeter on a waveguide. Cons - Slightly lower bass response than most of the other options (90db from 50 - 100hz), quite expensive ScanSpeak Classic P21WO20 Pros - Very good bass response, flat to 50hz. Tried and tested classic driver, great sound quality based on reviews Cons - Lower efficincy (89.5db) SEAS - Ca22RNY
Pros - Quite good efficiency (91.5), smooth bass rolloff from 100hz. Great reviews, relatively affordable Cons - Very light construction, looks like it may not be very durable? Peerless - HDS-P830869 Pros - Best bass response, nice hump at 50-100 hz. Easily the cheapest Cons - Lower efficiency (90.5db), nomex probably not be the most durable? Unsure about crossover frequency. Any advice on the above greatly appreciated =) |
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Monkeys
Registered User Joined: 30 August 2012 Location: Melbourne - Aus Status: Offline Points: 429 |
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I do appreciate all the advice, I really do. I'm not sure that I'm making clear the priorities for this project though. And I do understand that what I am suggesting is going to require significant sacrifices in efficiency and loudness for the sake of a bit of low end. I have a fairly massive 240v rig (12 x Punishers, 4 x MKB12's, 6 x TSE111's, 2x TMS4's) and access to generators already =P I'm really not looking to throw parties with the speakers from this project, I would use my rig (or part thereof) for that. This project is meant to be an attempt to make a really nice bluetooth speaker. To be able to have some easy, fairly compact, high quality, portable speakers which will take seconds to set up, will still produce a fairly full range sound (albeit at reduced volume). They don't need to be able to play for days on end, 8 hours at max volume (100ish db) would suffice, I think... If I really need them to run for longer than that I can bring an extra battery or a small generator. Thinking, more a portable studio monitor rather than PA speaker? |
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Monkeys
Registered User Joined: 30 August 2012 Location: Melbourne - Aus Status: Offline Points: 429 |
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Oh, right. Yeah ok so they will do that quoted power if powered by 24v DC, that's fine. |
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APW
Young Croc Joined: 13 November 2012 Location: Kent, UK Status: Offline Points: 1174 |
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24 volt battery
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Monkeys
Registered User Joined: 30 August 2012 Location: Melbourne - Aus Status: Offline Points: 429 |
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What, really? So what is the quoted 45w per channel referring to then??
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Xoc1
Registered User Joined: 15 October 2012 Location: Devon UK Status: Online Points: 399 |
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When you Say Box size 30L are you talking External volume or internal Volume - Box minus walls drivers. ports etc? The Lutkevelds boards are Class D but do not have DC DC converters so will not do anything like 50w More like 7 watts RMS on a 12volt battery into a 8 ohm speaker. or 15w in to a 4 ohm driver |
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studio45
Old Croc Joined: 16 October 2007 Location: United Kingdom Status: Offline Points: 3864 |
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You have to sacrifice low end and box smallness for 12v use, because efficiency is KING. There's no point building a rig that needs so many batteries to play all day, and such big heavy amps, that you can't take it anywhere without a big van. You might as well build a 240v rig and buy a generator.
If that really worries you, you can always build a separately powered subwoofer system and bring it out when necessary. But that will *not* be every party.
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Studio45 - Repairs & Building Commotion Soundsystem -Mobile PA
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Monkeys
Registered User Joined: 30 August 2012 Location: Melbourne - Aus Status: Offline Points: 429 |
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12" would be too big. I want to keep the box size below 30l. Goddamn physics! I'll have to compromise further somewhere in the design, I can't decide wheter to sacrifice low end, or efficiency (and as a result, loudness). To elaborate further on what I'm aiming for, the unit would operate primarily as a battery powered Bluetooth speaker (looking at getting a pair of Lutkevelds boards). I'd like it to produce a high quality relatively full range sound at low-moderate volumes, that would be it's use day to day. But with the option to operate as a compact PA speaker, at which times efficiency on battery power could become non-essential since I could arrange to bring additional batteries to power it for longer periods.. Hmmm. Getting WinISD as we speaker =)
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smitske96
Young Croc Joined: 16 February 2016 Location: The Netherlands Status: Offline Points: 1092 |
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It will do 50 Hz, just not loud enough But Marjan is right, if you want something happening down low, 12" would be the minimum for me.
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MarjanM
Old Croc Joined: 10 February 2005 Location: Macedonia Status: Offline Points: 7816 |
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It wont do 50Hz.
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Marjan Milosevic
MM-Acoustics www.mm-acoustics.com https://www.facebook.com/pages/MM-Acoustics/608901282527713 |
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