Tuesday, May 24, 2016

New Folded Corner Bass Horn New Straight Midrange Horn Super Tweeter

The New Folded Corner Bass Horns and the New Straight Midrange Horns now have a pair of Eminence APT-150 Super Tweeters.  This is a bi-amped system with line-level RC low-pass filters for the bass and RC high-pass filters for the midrange/tweeter.  The midrange and tweeter horns are powered by a Lepai LP-2020A+ amplifier and the folded corner bass horns by a Pioneer SX1280 receiver.  Here are Chester and Lester playing "It's Been A Long Long Time".  The preamplifier is an NAD 3020 Integrated Amplifier with "Y" RCA connectors in the pre-amp outputs.



The audio recording was made using the Tape App running on an iPad Air controlling an iTrack Dock with the high quality Focusrite preamps built in and a matched pair of Behringer C-2 condenser microphones. 

Watching the FFT of this system's response to a white noise track, I find that the smoothness of response vs frequency between 300Hz and 400Hz is improved without the line level low pass filters.  It appears as if the bass horn and woofer together function as a low pass filter.  The high pass filters provide some protection for the midrange and tweeter combination from low frequency energy and do not appear to have a significant effect on the smoothness of response around crossover.

Wednesday, May 4, 2016

New Folded Corner Bass Horns With New Straight Midrange Horns

The New Straight Midrange Horns are now fitted with small two inch drivers originally taken out of Boston Acoustics Unity enclosures.  The back chambers, recycled from the New Folded Corner Midrange Horn, are made from short lengths of PVC pipe.  Here are pictures of the left and right horns.

New Folded Corner Bass And Straight Midrange Horns - Left Channel
New Folded Corner Bass And Straight Midrange Horns - Left Channel


New Folded Corner Bass And Straight Midrange Horns - Right Channel
New Folded Corner Bass And Straight Midrange Horns - Right Channel
I tried making passive crossovers for each channel.  However, the midrange horns are even more efficient than the bass horns and I would have had to pad them down to get a good balance between the bass and midrange.  Instead of padding, I made a couple of line level crossover networks and now the horns are bi-amped.  RC low pass networks for the bass horns and RC high pass networks for the midrange horn allow independent control of the bass and midrange/treble amplifier gains.  Once a balance is achieved, the overall gain adjustment on the preamplifier allows the levels to "track" and stay in balance at any volume level.

Midrange and treble networks are plugged into a Lepai LP-2020A+ Amplifier.

High Pass Networks For Midrange And Treble - Lepai LP-2020A+ Amplifier
High Pass Networks For Midrange And Treble - Lepai LP-2020A+ Amplifier
Bass networks are plugged into the AUX input on a Pioneer SX-1280 receiver.



Low Pass Networks For Bass - Pioneer SX1280 Receiver
Low Pass Networks For Bass - Pioneer SX1280 Receiver
The bi-amp arrangement is also pretty handy when you want to raise or lower bass output relative to midrange and treble.  I have found that the bass level on some recent recordings is way too high so it is great to be able to adjust the bass level without altering phase as a result of the adjustment.