Audio Physic Avantis and DIY improvements

[jeffreybehr]

After enjoying a pair of (ugly) DIY open-baffle line-arrays for a few years, I decided I didn't have the energy to build good-looking ones, so I investigated a pair of speakers, the Audio Physic Scorpio, I heard and enjoyed at the '06 CES. Found them but also found a pair of the next-up-in-the-line Avanti IIIs close enough to listen to and bring home. These have turned into a fairly substantial improvement project.

Mine are in ebony...

...and sounded quite good--and LOTS different than my OBLAs.

First thing I did was discover that all 3 sections of the 2 crossover boards are driven by separate cables all the way back to the binding posts. I separated the bass cable and drove that separately with an old-but-good Hafler 9120 poweramp (with level controls). Last week I started using a pair of Marantz MA-500 monoamps driven by the middle section of a dbx DriveRackPA digital speaker-management system I had been using with the OBLA system. (The MR/treble runs diredt from the preamp to the poweramps and NOT thru the dbx.) That allowed much experimentation with lower crossover points and some eqing, and this week I removed the original bass-only crossover boards and wired the bass drivers, four 16-ohm Peerless 7"ers, directly to the same kind of 11g. bass cable I've used on several projects.

Last week I removed the MR/treble crossovers from the boxes...

...and rewired the tweeter and MR drivers with hi-quality Audioquest speakercable. I've temporarily wired a pot in series with the input of the tweeter section--the pot is now soldered to the board --to adjust its output; eventually probably I'll wire a rotary switch with various resistors to have treble output adjustable in perhaps-several levels.

Late this week I made the biggest improvement yet--I removed the hi-pass caps* from the 2 MR x-over sections** and 'replaced' them with 1-each new coupling caps in my 12-watt tubed monoamps***. I chose for this new coupling cap a lower hi-pass filterpoint to get a bit more lower-MR and upper-bass energy from the system. This was a resounding success. The sound is now a bit warmer but not at all thick, and a layer of obfuscation and grittiness has been removed from the sound. WOW!

I've ordered some custom-configured long spikes--of 8mm/1.25 thread--that'll go thru my carpet to the concrete below from Brass and Granite Audio ( Speaker Spikes Floor Cones Audio Tweaks Stands ). Yet to do is replace the 2 caps in series with the tweeter and improve some other x-over parts, but I'm VERY happy with these speakers.

I thank Jeffrey Glowacki of Sonic Craft for again assisting in pointing me in new directions and keeping me out of trouble.

Comments and suggestions are always welcome.



* 55uF of inexpensive plastic-film caps
** the lower of the 2 MR drivers handles lower MR only...about 200 - 500Hz; the other handles 200Hz - c. 2.5KHz.
*** Music Reference EM7-12 SET mono poweramps

[jeffreybehr]