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Old 1st February 2012, 04:34 PM   #31
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Here's the model with it based on driver 1 and then on driver 2-I'm hoping driver 1 measured correctly and driver 2 was messed up by me!
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File Type: jpg B139 variant 1.JPG (112.8 KB, 158 views)
File Type: jpg B139 variant 2.JPG (118.0 KB, 155 views)
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Old 2nd February 2012, 09:37 AM   #32
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Baby was ill last night, so no chance to re-measure the drivers, hopefully will get time tonight!
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Old 4th February 2012, 04:07 PM   #33
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Right, remeasured the drivers, but didn't have the time to do added mass/known volume so have just got a fresh comparison between the drivers and also measured them mounted isobarically face to face. Looks like I didn't botch the measurement as both came out pretty much the same as before Will get them both hooked up for some burn in and see if it brings them more in line with each other-otherwise I'm just going to have to accept they'll be a little offf from each other or use some different subs: got a pair of REL 8", pair of IDQ10's and a Pioneer flat sub that would all give the right load for the amp I'll be using.
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File Type: jpg B139 wt3 TS.JPG (59.3 KB, 127 views)

Last edited by TheBaronGroog; 4th February 2012 at 04:19 PM.
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Old 4th February 2012, 04:31 PM   #34
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Quote:
Originally Posted by TheBaronGroog View Post
...got a pair of REL 8"...
The clearout ones that were on ebay about five years ago? If so, so have I. Strangely, currently in an isobarik BR of about 30 litres.

Not using them at the moment though, as the old Maplin mosfet amp I powered them with self destructed...
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Old 4th February 2012, 04:47 PM   #35
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They may have come from there a friend had 8 of them in his ML, now he has 8 Focal 5" subs and I had the two REL and the IDQs off him-Yuri on talkaudio and Diyma, not sure if he frequents here. Not done enaything with them except pull the specs with WT3! Was planning an underbed enlosure for them-they may now make it to the living room...
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Old 22nd February 2012, 11:19 AM   #36
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I've decided to go ahead with this and just see what the output is like, got a friend with CNC facilities so will get him to do the cutting and then get the glue and screws out

Thanks for everyones assistance, will post some pics of the build process as and when it starts!
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Old 20th November 2012, 04:10 PM   #37
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Default B139 tapped horn

Hi
I have just unpacked two new B139s that I bought back in 1980 (no jokes please) to build the Linkwitz system. The satellites were built but not the bass unit because we went overseas. I have been reading about tapped horns on this forum and others and am keen to have a go. I have relevant skills having built the Pro9TL decades ago, bandpass units and various sealed boxes. I can configure and set up Brutefir on Linux and design active filters. I have never built a tapped horn and so far have read tutorials and downloaded Hornresp.
I am very keen to hear how this project has been developing since the last post. There are some clear limitations of the B139 but I am more interested in depth than power. My units are matched SP1044 units with an fs of 25 and power of 100 watts. I will need to measure them properly before finalising the design. I am not really interested in an isobaric design.
Any pointers?


Kind regards
Martin
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Old 29th March 2013, 06:34 PM   #38
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Hi guys, hope you're all well

I've been on a little audio/forums sabbatical, while starting a new business and moving home, so I put the building of this little project on the back burner for a while.

The business is now open and doing well, the home is finally moved into and the pile of audio equipment needs assembling into a working system-with a bit more space to play with

I've been granted free reign over the size of the subwoofer - provided I can put the flat screen on it I'm good to go!

I've played around with Bjorno's design, increasing dimensions/volume, but haven't really succeeded in doing anything other than lowering the F3-but also the SPL. I'll be teaming this with a set of 3-way floor standers (6.5" MB, Ribbon and Tweeter), so don't need it to go as high or flat, but would like it to go lower and maintain or increase SPL-what say you? Possible?
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Old 29th March 2013, 06:53 PM   #39
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Martin,

As you can see I've not built mine yet-though very keen to start! They are very similar to a 6th order BP in theory and in SPL response to a standard ported box-however as they're using both sides of the cone you have effectively double the x-max, so while on the same power the TH may only be as loud as the BR you are only using half the x-max, so you can turn it up some more.

Good thread:
why is a tapped horn more efficient than ported?

Mine will be part on an active system, I scored a Sonance 12ch amp on ebay and will be running everything actively-however I am currently having to look at a bit of a Heath Robinson approach regarding the sub-woofer crossover. I have a decent 3-way active crossover which will handle the floor standers, and I was going to use a cheap car audio 2-way on the "low" out put of the three way to split it again-how hard is it to design and build a simple active crossover?
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Old 29th March 2013, 07:07 PM   #40
OllBoll is offline OllBoll  Sweden
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Just saw this thread and the ideas and thought of one thing since you haven't built it yet:

If you still plan to use dual drivers then you could invert one of them to reduce second order distortion at the lower frequencies, Danleys for example do it in several of their designs.
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