Alpair 12P quicky


2011-01-30 5:56 pm
Hi All,

I asked for enclosure help previously and finally got around to finishing the Enclosures, thanks for the suggestions! It was suggested by a few that the Avebury might be the ticket for my room size, however, it was a bit to big to accommodate so I decided to try the Super Pensil!

Thanks for posting the plans, it is crazy how different a driver can sound in a proper enclosure. Myself and I'm sure everyone appreciates the sharing of information. Originally I had the 12P breaking in what was a 18 Litre BR tuned to around 58 Hz. They sounded nice and worked for the initial breakin period.

I then dropped them into the Super Pensil enclosure (no stuffing yet) and noticed an immediate improvement. Not small, for fear of exaggeration, I'd say an order of magnitude better. Granted the original box were farrrr from optimal and I'm sure once a proper enclosure is made, the 12P will sound great in BR. But it seems small differences in tuning and enclosure size for this driver has vast effect on sound quality.

Not even thinking of subwoofer. Usable low bass output is enough for me and the bass quality is astounding. I've only had around 200 hours on the drivers so they are in the breakin period right now.

Now for the nitty gritty. I opted for small BSC of around 3.5dB starting around 500-600 Hz. Implemented digitally right now till I have 800 hours on the drivers. It is difficult to properly measure in my room as my mic is not very good and the host of problems with in-room measurements.

Since it is still the breakin period, I should hesitate to mention this, but I'm running a small tweeter about 6dB down (in bassline SPL with respect to the 12P) in parallel with the 12P. 2nd order HP around 10k, no LP or anything on the 12P. I know I'm getting horrible combing and a host of other issues with this, but, it seemed to smooth out the area 10k+ according to my very bad mic. Small movements in mic position change the 'smoothing' result, some better others worse.

This is probably a case where eyes tell ears what to hear. In a blind ABX test I'll be the first to admit I might not be able to pick out the difference, but it does seem a hair smoother on the top end, when I say hair I mean hair. Gonna give it a few hundred more hours then remove the tweeter and assess BSC as this is probably just breakin stuffs.

By no means is the 12P deficient or subpar in ANY region. In fact my eyes and ears are having a tough time coming to grips with the quality of sound from this one driver. My eyes say no, my ears say yes. I'm not used to how nice these sound compared with ANY of the previous speakers in this room. I thought it was the room, but clearly it was other issues.

Using a computer as source, Jriver, and playing with JPLAY. Options to go directly to AVR used as pre or Emotiva firesale XDA DAC to AVR as pre via optical Toslink. Amplifier is Topping TP60. Need to upgrade the PRE in a bad way.

Thanks for listening all!


2011-01-30 5:56 pm

*** Update ***

Hi Jeff,

My experience with the 12P sounds a lot like your own.

Removed the tweeter, this seems not necessary now. BSC is -3 dB starting around 300hz. After repositioning in my room and changing the listening position, was getting too much low bass (60Hz and below). Will start stuffing accordingly but this is probably a room issue. These sound really natural.

Have to start building the 10.2 and 7.3 now. Too much to do, not enough time!