# inConcert Miles with 12inch: what options are my options?



## erwinbel (Mar 23, 2010)

Hi,

Now that we actually started the HT construction, it is time to decide on the five main speakers. Money no object, I would buy the B&W CT 8.2 at €15,000 each or the largest PMC... So let me try to make something cool with a far more modest outlay. The inConcert Miles designed by Tangen has been on my mind for some time. Atledreier has built them:

http://www.hometheatershack.com/forums/diy-speakers/43341-tangen-avdesign-inconcert-miles.html

This uses a AMT tweeter with waveguide [TPL150H] and two 15" mid-woofers [15P80Nd] from Beyma and a passive crossover @ 900Hz. Internal gross volume is 210 liter. Beyma recommends 40-150 liters for each 15P80Nd. 

After browsing the scandinavian forums (where the speaker originates) I have noticed that most folks think the tweeter should be crossed higher (1200, 1600 or even 2000 Hz) to sound its best. One could add one or two 10" or 8" making it a three-way. But BEF from Norway added a 12" "midrange" instead. This makes me think: why not simply trade in both 15P80Nd for two same breed 12P80Nd? It keeps things simple (two-way), they play just as loud, I can raise the crossover to 1200 Hz probably, the cabinets are smaller... Only downside is probably some 10 Hz higher low frequency output. But that's no biggie since they are part of a surround set with two subs. The original Miles was meant as a full range speaker from 30 Hz. I am looking for superior output between the crossover (50-80 Hz, tbd) and 150 Hz. 

I would use an active crossover in the form of the miniDSP 10x10 HD which would deal with all five bi-amped speakers.

Beyma recommends up to 60 liter internal net volume for (each) 12". This seems not very large since they mention up to 150 liter for one 15". I am looking for advice. Should I keep it at 60x2 = 120 liter net or go larger? Size is not an issue, it is a big room (28 x 22 feet). Can someone also help me determine port length and size, please? The online calculators give me impossible results.

12P80Nd
View attachment 12P80NdE.pdf


TPL150H
View attachment Beyma_TPL150H_inConcertMiles.pdf


inConcert Miles designed by Tangen


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## RTS100x5 (Sep 12, 2009)

I've seen several designs with similar drivers but with an Infinite Baffle design - You might do some research in that direction... The concept is said to eliminate the acoustical interactions between driver and enclosure... and would greatly simplify the build process and lower cost .... 

http://www.jamo.com/speaker-types/floorstanding/?sku=R909


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## erwinbel (Mar 23, 2010)

Ahum... I already own a pair of the Jamo R909...


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## fusseli (May 1, 2007)

The Original Miles is a cool looking speaker! Bet they sound great. Based on the frequency response on the driver's spec sheet I think you should be okay going with a higher crossover. You can easily shape the peak around 2kHz out of the response. I think the only issue is playing that 12" up that high, directivity (and your polar response) will be an issue. Not sure of a way to quantify the problem though, sorry.

I tried the 12P80Nd in 30L ported, tuned at 60Hz, and that's the best I see according to the specs you provided. Going to a larger volume or lower tune would not benefit anything, the driver's fs is too high and Qts far too low. The specs resemble a PA driver. These will not make excessive bass, but they will play stupid amounts of SPL before bottoming out (with the proper protective HPF). The model does not get anywhere near 30Hz.


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## erwinbel (Mar 23, 2010)

Thank you, Russ!

However I cannot open the files (I have Mac OSX) after downloading.


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## erwinbel (Mar 23, 2010)

After advise from BEF - who added a midrange to the two-way Miles - and Stig Erik Tangen - who designed the Miles, I am now leaning towards making a three-way Miles straight away, starting with a center speaker to see how it sounds. It's more complicated than I would prefer: I will need two miniDSP 10x10 HD for five speakers, fifteen (!) amps (five active three-channel speakers) and even bigger cabinets. 

This would look something like this:
http://www.hifisentralen.no/forumet/album-nr-231/
Difference is I would make a single box with a different midrange and the color would be matte black as it's for a HT. I can just squeeze all four drivers behind the 140 cm height of the Seymour AT screen too.

Tangen advises the Beyma 12G40 as a dedicated midrange in a 30 liter sealed box. It's actually a low frequency driver but Tangen claims _"that a 12" integrated better with the TPL, because the dispersion of the TPL is quite narrow around the XO (1.5 - 2 kHz), and the dispersion of a 12" matches well, much better than a smaller driver I think."_. I don't know why he didn't recommend the 12P80Nd, although maybe it's because the 12G40 is a lot cheaper and he also added that is has very low distortion and clean sound.

Beyma 12G40 spec sheet
View attachment 12G40E.pdf


That may all be very well, but now that quote "narrow dispersion" has got me worried... ! I know I very much like the sound of the AMT tweeter as also found in my Emotiva _airmotiv 5_, but when you listen to the airmotiv off axis, the treble quickly looses its sparkle. I was counting on the horn of the TPL150GH (Beyma's claim is 80° dispersion) to deal with this. 

I am now browsing the forums on the subject of coaxial drivers. These combine a midrange and a tweeter in one which has obvious acoustical advantages. Adding a pair of large high output woofers would get me an alternative Miles. The coaxial would have to be of very high output capacity also. 

B&C:
http://www.bcspeakers.com/products/coaxial-neo/12-0/12cxn76

BMS:
http://bmsspeakers.com/index.php?id=bms_4593nd

But I doubt these will sound as nice as the AMT breed of tweeters. Any comments?

BTW: HAPPY NEW YEAR ALL!


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