Sunday, February 7, 2016

High Efficiency Fully Horn-Loaded Speaker System Powered By Tiny Class D Amplifier

The tiny amplifier playing the music is a class D stereo audio amplifier, available from Parts Express, Part # 320-604. The New Folded Corner Bass Horn pair, plywood midrange horns, and Atlas Sound HR-3 horn tweeters provide the acoustic amplification.  For the Folded Corner Bass Horns, I am still using the 12 inch woofers and crossovers removed from the KLH CL-3As.  A recycled 12Volt, 1Ampere, switching supply that came with a Netgear router is providing electrical power to the amplifier.  The NAD amp provides pre-amplification for the phonograph through the "pre-amp out" RCA jacks.

The LP track "No Time This Time" by The Police playing through this high-efficiency stereo system was recorded using a Canon PowerShot S2 IS for audio and a Panasonic Lumix DMC-ZS40 for video.  The cameras are mounted to the same frame.  Occasionally, you can see the edge of the Canon S2 IS on the right side of the image. I use both cameras to take advantage of the complementary and mutually superior performance of both cameras at once.  One has superior audio performance while the other has superior video.

The New Folded Corner Midrange Horn with impedance measurement setup makes a cameo appearance in this video and will actually be playing in a future videos as soon as I have a stereo pair. Also appearing is a framed original watercolor painting of an Ampeg SB12 Portaflex bass amplifier.

Monday, February 1, 2016

A Hybrid Stereo System Combining Infinity Qe Acoustic Suspension With Sound Transformer Bass

The Infinity Qe speakers are connected to a Lepai 2020A amplifier and the Sound Transformer Bass Horns are connected to a Pioneer SX-4 receiver.  I set the iPod volume at 1/2 and adjusted the balance between the Qes and the Bass Horns.  I used some boxes I had on hand for back chambers for the MCM 55-3211 10 inch woofers driving the bass horns.

Hybrid Infinity Qe Pair With Sound Transformer Bass Horns
Hybrid Infinity Qe Pair With Sound Transformer Bass Horns
I made a recording using a pair of Sony microphones set on lamp stands.

Sony Microphone On Lamp Stand - Infinity Qe Upper Right
Sony Microphone On Lamp Stand - Infinity Qe Upper Right
Sony Microphone On Lamp Stand - Infinity Qe Upper Right
Sony Microphone On Lamp Stand - Infinity Qe Upper Right
Here is the Focusrite iTrack Dock set up with the Sony microphones directly connected to the unbalanced line level inputs. 

iTrack Dock And Sony Microphones On Lamp Stands
iTrack Dock And Sony Microphones On Lamp Stands
Here are the two amplifiers.

Pioneer SX-4 And Lepai 2020A
Pioneer SX-4 And Lepai 2020A
The Pioneer SX-4 rests on the throat section of the bass horn functioning as a table.

A Very Small Highly Efficient Stereo System

This very small stereo system consists of a highly efficient class D stereo audio amplifier, Parts Express Part # 320-604, playing an iPod track through a pair of Radio Shack Realistic Minimus 7 speakers.  The power supply is a recycled 12V, 1A, power supply plug-in transformer from a Netgear router.  This is the amplifier right out of the box with no embellishments.

Highly Efficient Stereo System
Highly Efficient Stereo System

Here is the system playing some Neil Young:

In the next post, I will be hooking this same small amplifier to the new folded corner bass horns to demonstrate how a very small, efficient, low-power amplifier can provide an even higher level of performance while playing through a highly efficient horn-loaded loudspeaker system.