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Attempting to reuse old Bose Subwoofer for my first speaker build.  

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MilesOlson
(@milesolson)
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30/05/2020 4:33 pm  

Hello, I am a huge fan of 123Toid and his work with the DINAS and Voxel sub. I recently acquired two bose 181860 6" subwoofer drivers for free. I pretty sure that the impedance is 4 oms but I am not sure about the recommended watts and could not find it anywhere on the internet. I as also interested in the Lepai LP210PA 2x30W + 60W 2.1 Channel Mini Plate Amplifier and would not like to break it. I do not know if I want to put the subwoofers in the bookcase with a full range driver or put it in its own separate enclosure for the best sounds and easiest convince. This will be the first speaker I have built instead of bought. Any guidance or feedback would be greatly appreciated.

Thank you!

 

This is the speakers I have

Bose

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TVOR-Ceasar
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31/05/2020 1:42 am  

That's a hard part to find info on. Most places say it's 4 ohm, one says it's 2, another says possibly 6. 4 sounds about right. And there isn't anything relating to power other than 10-200 watts. That would be 10 nominal, 200 max. I base that on this page.

I'd say your amp choice is just fine. 

As for the box, well, that depends on your final choice. In order to get there, it would be nice to know at least the minimum T/S parameters, Qts, VAS, and Fs. Unfortunately I cannot find them for this driver. Do you know anyone in the area that has a DATS? If not, you could figure them out using the info on this page, using just your computer, Audacity, an amplifier, a resistor and a voltmeter. It may be tedious, but you can do it. Having at least those 3 numbers is a good start.

Of course, you could always base it on approximately 1/2 the volume of the Bose bass unit, and tune it by starting with a port sort of close to the original unit. From there it would be experimentation to see what works best.

-Charlie


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MilesOlson
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31/05/2020 1:51 pm  

@tvor-ceasar Thank you for all of this great information. This is my first speaker so measuring the loudspeaker parameters may be a little too difficult. I still have the original box and that 16x19x6 for two speakers with a front slot port 2 inches tall. Lastly, I found two more of the 181860 6" subwoofer drivers which makes me have four now. Would you recommend using all four, two, or just a single driver for the build? Also how would you you wire up the speakers?

1 Speaker
4 speakers

 I found this on the internet for wiring but I couldn't find anything for two speakers.


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TVOR-Ceasar
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04/06/2020 9:02 am  

Sorry for the delay, it's been crazy here with work and then yesterday a nasty storm came through that took out our electric and cell service. Yeah, it was bad.

'Nough of that.

Going with 4 ohms on your drivers, and the general specs on most amps that aren't specifically designed for automotive use, I'd say wire them in series to make them 8 ohms equivalent. If you were to wire them in parallel, they'd be 2 ohms equivalent, which could be too low for the amp. 

This link does a rather good and thorough job of explaining the wiring of multiple drivers.

In essence, if you look at your 2nd pic, use the top 2 for wiring. Amp + to 1st speaker +, then 1st speaker - to 2nd speaker +, then 2nd speaker - to amp -. That will be double both the driver ohm rating and power rating. That's the easy explanation. Reading that link above shows it can get a lot more complicated the further you go into multiple driver setups. For now, that would be the safest route for you to go.

-Charlie


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TVOR-Ceasar
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04/06/2020 9:10 am  

Also, isn't the Bose sub basically a sealed box with a port? When you take it apart to access the  driver, is there a sealed box in front (or behind) the driver and the ported box on the other side of the driver baffle? That's my recollection of their design from WAY back.

If so, that is what is called a Band-Pass design. If you can get the inside dimensions of the separate boxes (sealed and vented), and the approximate size of the port, I "MAY" be able to work it backwards to try to figure out some of the T/S parameters I listed in my first reply. Of course, they would be no substitute for actual measurements since I would have to make an initial assumption on at least one or 2 of the parameters and finesse it from there.

-Charlie


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MilesOlson
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04/06/2020 1:46 pm  

@tvor-ceasar I hope you are doing better now that the storm has went away. Thank you for all of this information. I measured the speakers with my own multimeter and got around 2.4 plus or minus .2. I feel like series would be the right call to be on the safe side for whatever the resistance is. I dissembled the bose unit around a year ago so I can not remember if it is a sealed box with a port. This is the exact speaker I disassembled. Also, I have another one of the subwoofer units that I could completely dismantle to find the interior design of it. Thank You!

BoseUnit

actually is. 


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TVOR-Ceasar
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05/06/2020 1:14 pm  

@milesolson

I've done a good bit of looking to no avail. Bose really doesn't publish useful info for people like us. There are only 2 things I've found that have any bearing on this whole topic, but even they aren't really helpful.

Link 1

Link 2

At this point, my initial feeling and advice is to stick with the box they came in, or rebuild one with the same internal volume and a similar port. Check your amp's subwoofer section for minimum speaker load and determine how to wire it from there. If you were closer, I'd offer the use of my DATS.

Oh, and since you linked that video (which I watched), it is a standard ported box, nothing exotic in design.

-Charlie


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123Toid
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05/06/2020 1:52 pm  

@milesolson and @tvor-caesar

Sorry I was on vacation.  I agree with everything that has really been said.  Bose typically does not publish specs at all.  In fact, they shut down people who take measurements of their speakers and post them.  It's really ca carzy thing. 

But most Bose subs use a transmission line. I would consider resuing the box you have and then adding a fullrange to the top.  Changing out the amplifier with something like the Lepai sounds like a good idea.  If that doesn't interest you.  Than I am all for experimentaton.  Without test equipment, it really would be just guessing.  Maybe try an isobaric and then shorten or tengthen the port until you like the sound. Most people use test equipment, but if you don't have it, this is how they did it back in the day.  Of course, depending on where you live, somoen might be able to test them for you.

 


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TVOR-Ceasar
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05/06/2020 4:06 pm  

@123toid

It's been so long I forgot that the TL was Bose's modus operandi. 

I concur with the full range or a small 2-way that can go down to at least 100 Hz. The big consensus of most enthusiast / audiophile / reviewers is that the stock Bose systems usually have a gap between the bass module and the satellites (see the second link I shared above), and having the small full range speaker cover enough audio territory is a good idea.

Nick, how was the vaca? My 1-1/2 day vaca without electric and connectivity was... interesting. 🙂

-Charlie


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123Toid
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06/06/2020 2:06 pm  

@tvor-ceasar

Haha, sounds like fun.  Mine was good.  I had a friend from Il, actually come down here to visit. He is thinking about moving here, so I showed him around.  Luckily we had electrictiy the whole time 🤣 


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