Adventures in Auto Equalization (or "Taming the Beast: The hard way")

Some of you may remember my love / hate relationship with my MartinLogan speakers. I loved their looks, hated their sound (it was the Scenario model). People told me they were the highest bang for the buck, the most revealing speaker for the price, etc. All I heard were shrill, bothersome, piercing, screaming mids, no low end, and no air. Kinda like a horn speaker, only worse.

I changed the amplifier (tubes, hybrid, transistor), the preamp (tubes, hybrid, transistor), the cable (CAT5, zip cord), the interconnects (Radio Shack, Audioquest), the room (added lots of pillows). Nothing helped.

Enter the ugly duckling: The Behringer Ultra-Curve Pro 8024. A little DSP with an RTA, Auto-EQ, room correction, parametric equalizer, feedback destroyer, and 31 point EQ. People love to hate this piece of gear, especially when used in the analogue domain. I think it has something to do with the price (something like $179, $249 with the optional digital interface).

I had the Behringer for quite some time, and used it to calibrate my subs, or as a simple RTA. I used it to check my Margules speakers recently, and found out they had a filtered high end (so I'll take them to have their crossover modified).

My parents have the MartinLogans now, but I thought "maybe the Behringer can tell me something about their behaviour"...

Long story short. I ended up interfacing their CD player digital output to the Behringer, and then ran a frequency sweep. The speakers' frequency response was HORRIBLE. I'd say frequencies below 400 Hz were attenuated by some 9 dB's, while the same thing happened to those above 4,000 Hz. I was appalled - how on earth could MartinLogan sell such a speaker?!?!? Maybe they voiced them for small ensembles...

Anyway, I then proceeded to run an Auto-EQ on the room. 2 minutes later, the Behringer had apparently smoothed out the speakers' response. I played a bit with the subwoofer output, ran the Auto-EQ two or three times more, smoothed the EQ settings, and applied a "House Curve" to boost output a bit from 100 Hz downward.

The results? My parents' system blows me away now. It blew them away, too. The system now sounds absolutely stunning. Gone is the horrid midrange, replaced by a smooth frequency response from about 35 Hz up to 15 KHz (+-3 dB or less, according to the Behringer). The sound is smooth, fast, rythmic and... well, it's just about perfect. And that's with strictly mid-fi equipment (a Parasound HP850 preamp and an Adcom GFA-5400 amp). I really can't believe the change.

I'd get an UltraCurve for myself, if I didn't listen to so many SACD's (the UltraCurve works in the digital domain, so I'd have to add an A/D - D/A section to my playback chain).

And, since the DSP is connected to the CD players' digital output, the sound isn't degraded that much. It certainly does 100X more good than harm in my parents' system...

The Behringer's bang for the buck is out of this world, IMHO. Highly recommended.

 

"Stunning....!"

...good call, Javier.