Tweakers' Asylum

Posted by Scott W (A) on July 27, 2007 at 18:39:22

It all started when the big boxes arrived outside the house. After getting these Duos in place in the living room it was clear that this was a new musical experience. Over time however, I grew to believe the bass was not up to the level of the horns. These were the Pro217s not the 225s.

First came the Behringer Parametric EQ. This made a huge improvement as the room modes of the bass modules added nearly 20dB at 40-50Hz.

Next I decided to bypass the AG sub amps and drive them both directly with two Adcom 300W amps. I used the Behringer EQ as an active low pass x-over. I was pleased with the improvement in tightness this caused. I suppose having the amps directly connected to the woofers was the reason.

Even with these improvements the bass just wasn’t able to keep up with the horns especially when played in my large 16x24x17ft high living room at 95dB+ levels

I decided it was time to build my own super bass modules that would provide more than enough dB output to keep up. Two Dayton RSS 10” subwoofers per side in a hand built bass module sized to fit into the AG frames. Driving these would be a Crown K2 providing 1KW per side! Using a Marchand active crossover this power was directly coupled to the woofers. Well, plenty of bass now – but a hole in the sound at around 100Hz. I was clipping the Crown trying to get this hole filled!! The lights would dim on the beat.

Then I read about dipole bass.

I rebuilt the bass module boxes and re-installed the 10" woofers. I eq'd the system with the FBD and level set the horns to the bass. The performance of these dipole bass modules are amazing. No holes in the FR, the amp hardly works. The bass is tight, the room modes are far reduced, there’s absolutely no mud. This bass performance is the closest to real that I’ve heard. Now I can play realistic levels, 100dB+, any kind of music. Dynamics are simply incredible at this level.

It took a long time to get here but it was worth the effort. Now I have a music system with dynamics to spare from top to bottom. All the benefits of the AG horns together with the dipole bass – it’s the best of both worlds.

Current system
AG DUOS with Dipole bass modules
Crown K2 pro amp
Bryston B60 pre amp + driving the horns
Marchand active cross over at 150hz
Behringer FBD 24/96
Symetrix 303 line level converter (to pro level for the Crown)
Sansui TU317 tuner
Old Panasonic DVD player

Scott W