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Compact 2 way fullrange cabinet

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Post Options Post Options   Thanks (0) Thanks(0)   Quote Monkeys Quote  Post ReplyReply Direct Link To This Post Posted: 01 February 2020 at 10:50pm
Originally posted by Xoc1 Xoc1 wrote:

Originally posted by Monkeys Monkeys wrote:


12" would be too big. I want to keep the box size below 30l.
Unit would operate primarily as a battery powered Bluetooth speaker (looking at getting a pair of Lutkevelds boards


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 driverClap



What, really? So what is the quoted 45w per channel referring to then??
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Post Options Post Options   Thanks (0) Thanks(0)   Quote APW Quote  Post ReplyReply Direct Link To This Post Posted: 01 February 2020 at 11:13pm
24 volt battery
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Monkeys Quote  Post ReplyReply Direct Link To This Post Posted: 01 February 2020 at 11:38pm
Originally posted by APW APW wrote:

24 volt battery


Oh, right. Yeah ok so they will do that quoted power if powered by 24v DC, that's fine.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Monkeys Quote  Post ReplyReply Direct Link To This Post Posted: 02 February 2020 at 12:04am
Originally posted by studio45 studio45 wrote:

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. 


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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Post Options Post Options   Thanks (0) Thanks(0)   Quote Monkeys Quote  Post ReplyReply Direct Link To This Post Posted: 06 February 2020 at 10:47am
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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Post Options Post Options   Thanks (0) Thanks(0)   Quote Monkeys Quote  Post ReplyReply Direct Link To This Post Posted: 10 February 2020 at 11:05am
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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Post Options Post Options   Thanks (0) Thanks(0)   Quote Monkeys Quote  Post ReplyReply Direct Link To This Post Posted: 11 February 2020 at 10:28am
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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