Wednesday, November 30, 2016

Big Horn Speakers For Your Tiny House - 61 milliWatt In - 80dB Out!

The recording is "A Mighty Fortress" at Riverside Church, played by Virgil Fox on the Aeolean-Skinner Organ.



The sound amplification system we are trying out here illustrates how a high-efficiency loudspeaker system requires little electrical power to play at moderate volume levels in a medium-sized room.
Eight volts DC is supplied by a nearly discharged 9V battery.   Supply current is monitored using a Fluke 87 rms reading DVM set on 39.99mA range. 

Although it does not appear in this video, an analog sound level meter registers levels up to 80dB which is loud enough for demonstration purposes in this small room but louder than you would probably listen to normally.

The quiescent power supply current reads 21.44mA.  Peaks of about 29mA occur during this video and the DVM does not over-range.

The difference between 21.44mA and 29mA is 7.59mA.  At 8 Volts, this is 60.72mW.  So, as an approximation to be sure, in my listening room, I can get 80dB peaks with 61 thousandths of a Watt of power supplied above the "quiet" current.

Qualitatively, the "large hall" ambiance is audible almost anywhere in the room.  Loudspeakers like this can provide a convincing illusion of space much larger than your listening room and you don't need much electrical power to run them. You could even be "off grid". This video features a tiny class D stereo audio amplifier, Parts Express Part # 320-604.

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. 

Thursday, April 28, 2016

Progress On Construction Of The New Straight Midrange Horn

With the large flares of the New Straight Midrange Horn construction essentially completed, I begin construction of the smaller flares of the horns.  Using the same techniques employed on the Sound Transformer Bass Horns, a pair of flanges of the same dimension as the smaller flange on the larger flare are cut out on the table saw.  By beveling the edges of the square opening in the center, I will have the flange interior edge flush with the faired exponential expansion.  Four pairs of ribs are cut at the proper angle on the chop saw.  The ribs will be scribed to the exponential curve using a plywood pattern but only after they are fastened into position between the flanges.  To get the ribs to fit, it is necessary to cut away a bit at the small end of the horn.  Here is one of the horns set up for marking with the pattern.

New Straight Midrange Horn - Throat Flare Progress
New Straight Midrange Horn - Throat Flare Progress
After marking all four of the ribs for the curve as well as numbering the matching parts so they can be reassembled later, the rib curve is cut out on a band saw.


New Straight Midrange Horn - Throat Flare Progress
New Straight Midrange Horn - Throat Flare Progress
The series of small cuts to the line make it easier to "leave the line" without cutting away too much.  Here are the four ribs after cutting the curve.


New Straight Midrange Horn - Throat Flare Progress
New Straight Midrange Horn - Throat Flare Progress
Now, the horns are reassembled so the other two pairs of ribs can be positioned and marked.


New Straight Midrange Horn - Throat Flare Progress
New Straight Midrange Horn - Throat Flare Progress
All eight rub curves are sanded by hand to the line using a sanding block.


New Straight Midrange Horn - Throat Flare Progress
New Straight Midrange Horn - Throat Flare Progress
Here are the horns with all eight sanded ribs fastened in.  The cardboard trapezoid will be used to mark four plywood sides.


New Straight Midrange Horn - Throat Flare Progress
New Straight Midrange Horn - Throat Flare Progress
Here is one of the throat flares set on top of a mouth flare.


New Straight Midrange Horn - Throat Flare Progress
New Straight Midrange Horn - Throat Flare Progress
Tomorrow, I will cut the sides for the throat flare.

Monday, April 25, 2016

Latest Progress On Construction Of New Straight Midrange Horn Pair

Today, I cut out the last four flare sides and custom fit each one into its respective horn.  Following that, I "dry-assembled" the horns several times, refitting here and there, until I got a reasonably good fit for the joints.  After cutting out "throat square" blocks to hold the sides in place, here is what the horns looked like.


New Straight Midrange Horns - Sides Dry-Assembled
New Straight Midrange Horns - Sides Dry-Assembled


New Straight Midrange Horns - Sides Dry-Assembled
New Straight Midrange Horns - Sides Dry-Assembled

With all of the sides marked for proper positioning, I applied adhesive to the joints.  It is necessary to keep the adhesive away from the square blocks so they will come out tomorrow after the glue dries.


New Straight Midrange Horns With Adhesive Applied
New Straight Midrange Horns With Adhesive Applied
It will get quite cold in the barn attic overnight so I have moved the horns inside so the glue can set under more ideal conditions.


New Straight Midrange Horns With Adhesive Curing
New Straight Midrange Horns With Adhesive Curing
Tomorrow, I will start on the smaller portions of the horns.



Sunday, April 24, 2016

Still More Progress On The New Straight Midrange Horn Pair

Because the Lauan plywood is 1/8" thick, I can cut out the horn flare sides with a utility knife.  As in the Sound Transformer Bass Horns, the first two sides for each horn are trapezoids and fairly simple to cut even without a straight edge.  Here is an image of two of the trapezoids ready for fitting.  The only dimension that needs to be trimmed is the length.  Each end of the side needs a beveled edge that I can easy machine with a sanding block.


New Straight Midrange Horn With Two Trapezoids
New Straight Midrange Horn With Two Trapezoids
Here is a horn with trapezoids in position.


New Straight Midrange Horn And Two Trapezoids
New Straight Midrange Horn And Two Trapezoids


New Straight Midrange Horn And Two Trapezoids
New Straight Midrange Horn And Two Trapezoids
The next thing to do is to fit a corrugated cardboard pattern for the other two sides.  Here is the cardboard pattern being fitted by scribing, cutting, and sanding the edges until the pattern fits.


New Straight Midrange Horn - Fitting Cardboard Pattern
New Straight Midrange Horn - Fitting Cardboard Pattern
The cardboard pattern will be used to mark the first side on the Lauan panel.  The first plywood side will be cut slightly larger than the cardboard pattern for a more accurate fit than can be achieved with the cardboard.

More Progress On New Straight Midrange Horn Pair Construction

I cut two smaller square flanges for the smaller end of the horns.  The square hole in each flange is too small to be cut out with the table saw so I used a scroll saw with the shoe set to an angle to match the flare angle.  I made the square hole a little smaller than it needs to be so I can fair it to the horn sides after they are in.


New Straight Midrange Horn With Small Flange
New Straight Midrange Horn With Small Flange


New Straight Midrange Horn With Small Flange
New Straight Midrange Horn With Small Flange
I am playing some music here through the original Sound Transformer Horn Stereo Pair and have to turn the volume way down because I am standing right in front of the horn while attaching the small flange.

Thursday, April 21, 2016

Progress On New Straight Midrange Horn Pair Construction

Today, I cut the plywood square frames to make the large flanges for the pair of New Straight Midrange Horns.  All I had to do is set the table saw fence for the right width and carefully lower the plywood squares onto the blade to start the cut at the right position so as not to overcut each of the four edges.  I completed the cutting with a scroll saw.  Here are the two horns, each with eight ribs tacked in place so I can position the smaller flanges and correctly align everything before drilling and screwing the flanges to the ribs.


New Straight Midrange Horns - Ready For Small Flange Alignment
New Straight Midrange Horns - Ready For Small Flange Alignment


New Straight Midrange Horns - Ready For Small Flange Alignment
New Straight Midrange Horns - Ready For Small Flange Alignment
Tomorrow, I will cut the smaller flanges.  I have already purchased a Lauan plywood sheet for the curved walls of the horn.


Wednesday, April 20, 2016

New Project - A Pair Of Matching Straight Midrange Horns

I built the New Folded Corner Midrange Horn with the intent of eventually building a second matching one for stereo. However, I have decided to build a pair of Straight Midrange Horns with the same flare rate as the original New Folded Corner Midrange Horn. The main reason for this is that I want to compare the New Folded Corner Midrange Horn with a Straight Horn version. The second reason is that the New Folded Corner Midrange Horn is so efficient, being corner placed, that it is several dB louder than the New Folded Corner Bass Horn with the KLH CL-3A woofer. The third reason is that I want to apply the same construction technique to a stereo pair of Straight Midrange Horns that I used with the Straight Bass Horns, otherwise known as the Sound Transformer Stereo Pair. I decided to build all of the parts at once for two Straight Midrange Horns. Here is the progress so far.

Pair Of Matching Straight Midrange Horns - All Sixteen Ribs Cut Out On Band Saw
Pair Of Matching Straight Midrange Horns - All Sixteen Ribs Cut Out On Band Saw

The band saw curved cut requires some attention to "leave the line" and not take too much.  Actually, before cutting the curved sides, I cut both ends of the identical ribs at the correct angle on a chop saw.  I used pine scraps I have had here for quite a long time.  After cutting the sixteen ribs, I clamped four at a time and sanded the curves to remove variations due to a "wandering" band saw cut.  Here is the setup using clamps and a sanding block.


Pair Of Matching Straight Midrange Horns - Four Ribs Clamped For Sanding
Pair Of Matching Straight Midrange Horns - Four Ribs Clamped For Sanding
These ribs will hold the sides of the mouth flare of the Straight Midrange Horns.  The mouth flare length is one-half of the Straight Midrange Horn total length.  The mouth flares will have a square flange at each end.  The smaller, narrower "throat" portion of the Straight Midrange Horns will also have a flange at each end.



Monday, April 4, 2016

New Folded Corner Bass And Midrange Horns Play - "Walking On The Moon"

Here is a recent recording of the New Folded Corner Bass and Midrange Horns playing "Walking On The Moon" by The Police.  A Sony F-97 measurement microphone captures more of the bass than the camera microphones do.  A crossover removed from a Pioneer CS-88A loudspeaker has been converted from four-way to three-way.  The magnificent Pioneer SX-1280 receiver provides amplification, although it does not have to provide very much as you can see in the video.  The output meter for the right channel doesn't read above 0.1 Watt.


Thursday, March 31, 2016

Wednesday, March 30, 2016

New Folded Corner Bass And Midrange Horns Play - "I Got Rhythm"

Here is an amazing 1949 rendition of George and Ira Gershwin's "I Got Rhythm" played on Steinway piano, Hammond Organ, Vibrachord, and Novachord.



There is a lot of sound on this 78RPM record!

Thursday, March 24, 2016

New Folded Corner Bass And Midrange Horns Play 78RPM Records

The New Folded Corner Bass Horn, New Folded Corner Midrange Horn and Magnavox horn tweeter provide a great way to hear what is recorded on old 78RPM records!
 
Elac Miracord 10 Turntable Playing 78RPM Record
Elac Miracord 10 Turntable Playing 78RPM Record
 
Here is a photo of the whole setup for monaural playback through one channel of a Lepai 2020A.  The phono preamp is a rewired Heathkit model AA15 amplifier.

New Folded Corner Bass And Midrange Horns With Magnavox Tweeter
New Folded Corner Bass And Midrange Horns With Magnavox Tweeter
The Magnavox tweeter through a series 4uF capacitor filter provides the treble response.  The signal is divided midrange/bass by a simple LC network.  The next photo is a close-up showing the hookup and the Lepai 2020A amplifier.

New Bass And Midrange Corner Horns With Magnavox Tweeter And Crossover
New Bass And Midrange Corner Horns With Magnavox Tweeter And Crossover
Here is the Elac Miracord 10 Turntable atop the Heathkit AA-15, rewired as preamplifier only.


Elac Miracord 10 Turntable - Heathkit AA-15 As Preamplifier
Elac Miracord 10 Turntable - Heathkit AA-15 As Preamplifier
I will be posting some videos of this "High-End" system playing several 78RPM records, some of them more than 100 years old!

Saturday, March 19, 2016

The Sound Transformer Plays Some Bass By Stanley Clarke

Here is the Sound Transformer powered by the Fisher 35A Home Music Center made by Fisher Radio Company.  What great sound!



The tracks are "Play That Bass 103" and "Are You Ready For The Future".

Thursday, March 17, 2016

Avery Fisher - Model 35A Home Music Center - High Quality Stereo

Here is another video of the Fisher 35A Home Music Center playing a little Count Basie.   When this Pablo Today record came out in 1980, the Fisher 35A was practically new.  It is essentially still new.



I wonder if even Avery Fisher realized how long this product would last.

Wednesday, March 16, 2016

Avery Fisher Interview 1976 - Stereo Fireplace

There is a Rolling Stone interview from 1976 in which we learn that Avery Fisher had a very large vintage Western Electric Horn Loudspeaker built into a fireplace.  The link to the article takes a long time to load for some reason.  Perhaps the fireplace speaker looked like the one pictured below or one of the ones at this link:

Western Electric Horn Loudspeaker
Western Electric Horn Loudspeaker

Avery makes mention of Jethro Tull in the article.  I did not know this when I uploaded a youtube video of the Sound Transformer playing an excerpt of "Thick As A Brick" by Jethro Tull.  This video is thirteen minutes long.



If only we could have heard this band through a system like this back in the day.  Well, we can hear it now through the Stereo Fireplaces :)

Sunday, March 13, 2016

The Sound Tranformer Plays Some Cachao

Here is the Sound Transformer playing something by Cachao.  This recording has some amazing bass and percussion and you really feel like you are there listening to live music. Thanks, doctor, for the referral :)  Cachao is great!


The Klipsch Shorthorns With New Folded Corner Bass Horns

Here is a recording of a portion of  "Thick As A Brick" by Jethro Tull played back through the Klipsch Shorthorns with the New Folded Corner Bass Horns separately amplified and filtered using the bass network in crossovers recycled from a pair of Pioneer CS-88A loudspeakers.  This is a thirteen minute video.  Two digital cameras are used, one for audio and one for video.



Thursday, March 10, 2016

Pioneer CS-88A Loudspeaker - The Crossovers Recycled

Here is a Pioneer CS-88A I found at the local transfer station a few months ago.  There was a pair of them but one had the woofer missing.  Some of the tweeters had gone "open circuit" and one of the crossovers needed some repairs.  The cabinets were in good condition, particularly the wood grilles.


Pioneer CS-88A Loudspeaker
Pioneer CS-88A Loudspeaker
Before taking the CS-88A apart, I decided to test the response in the bass region using the SWTP function generator and the iPad Air running an FFT app.  Here is the setup for testing.

Pioneer CS-88A Loudspeaker - Bass Response Test Setup
Pioneer CS-88A Loudspeaker - Bass Response Test Setup
 During this testing, I could hear buzzing from the woofer at several test frequencies.  Tapping the bass cone gently stopped the buzzing temporarily.  Apparently, the voice coil is rubbing the pole piece intermittently.  The only drivers working perfectly in this speaker are the two midrange drivers and the "super" tweeter in the upper right.  The bass output of this loudspeaker rolls off below about 70Hz while placed at the floor boundary.  It would probably have more bass placed in a corner.

These Pioneer cabinets have a removable back panel making it easy to get them apart.

Pioneer CS-88A Loudspeaker - Back Panel Removable
Pioneer CS-88A Loudspeaker - Back Panel Removable
 Here is the back panel removed.

Pioneer CS-88A Loudspeaker - Back Panel Removed
Pioneer CS-88A Loudspeaker - Back Panel Removed
 Here is the four-way crossover.  This one appears to be in good condition.  I had to replace a 3uF capacitor and solder a couple of high-wattage resistors back into the crossover I removed from the other speaker.

Pioneer CS-88A Loudspeaker - The Four-Way Crossover
Pioneer CS-88A Loudspeaker - The Four-Way Crossover
I have already tried these crossovers out on the New Folded Corner Bass Horns.  They work really well.  Essentially, I am "bi-amping" through the low pass woofer network in this crossover, which appears to cut off at about 300Hz, to remove midrange and treble from the signal applied to each of the New Folded Corner Bass Horns.  With this setup, I can adjust the level of the bass region separately.  The Klipsch Shorthorns are powered with a separate amplifier.  A preamplifier feeds both of the power amplifiers so, once the balance is set, it remains in effect and "tracks" according the preamplifier volume level.

The Sound Transformer Pair and the New Folded Corner Bass Horn put out significant acoustic power down to about 45Hz.  This is with the amplifier(s) set for "flat" frequency response without any bass boost.

I think bass players would be flattered to actually hear how their playing sounds when played back through a horn-loaded system like the Sound Transformer Pair or the New Folded Corner Bass Horns.

Tuesday, March 8, 2016

Sound Transformer vs Infinity Qe - Bass Response Compared

The Infinity Qe loudspeaker is a very high quality transducer throughout the audio range.  I set up an experiment to compare the response of a pair of Qe speakers versus the Sound Transformer pair in the bass region from 32.7Hz (C1) to 220Hz (A3).  I used a FFT program running on the iPad Air to visualize the response at each musical note in the scale.  I tuned each note approximately with a SWTP function generator using the Fluke 87 in frequency counter mode.  Here is the plot.


Sound Transformer vs Infinity Qe - Bass Response Compared
Sound Transformer vs Infinity Qe - Bass Response Compared
The top trace in dark blue is the Sound Transformer fundamental response level in dB (relative) at each musical note.  The pink trace is the Sound Transformer second harmonic level.  The yellow and light blue traces are for the Infinity Qe speakers.  The Qe is relatively free of second harmonic distortion throughout the frequency range tested.  The Sound Transformer has significant second harmonic distortion below the cutoff frequency of 41.2 Hz (E1) but starts to clean up at around 49Hz (G1) and remains so all the way to 220Hz (A3).

Comparing the top dark blue trace of the Sound Transformer with the yellow trace of the Infinity Qe, you can see that both the horn and the Qe don't have much output below E1.  The Sound Transformer begins to put out a level 19dB higher than the Qe at G1.  The Qe doesn't start putting out until 73.42Hz (D2) where it is still 12dB quieter than the Sound Transformer.

Much of what we are seeing in the unevenness of the traces would appear to be due to "room effects" and the fact that the microphone is located at one point in the room so it does not really represent a collection of the total energy released into the room.

The second harmonic, being the octave, can be considered still "musical" even though it really was added by mechanical nonlinearity somewhere in the setup.  Also visible in the FFT response curves for both Sound Transformer and Infinity Qe are the higher harmonics.  It is perhaps a stretch to claim that the higher harmonics contribute to the "musicality" of a speaker.  However, acoustic musical instruments naturally emit the fundamental and harmonics and they are regarded as musical.

All of the above is "steady state" testing with a pure sine wave as input.  The Sound Transformer is "louder" than the Qe by about 20dB in the frequency range of interest.  This testing does not reflect the overall impression of the listener regarding actual music including the impact of transient information in a musical performance.  Based on listening testing so far, the Sound Transformer sounds much more alive and has a stronger impact than any other speaker I have compared it with.

Sunday, March 6, 2016

The New Folded Corner Bass Horns Get New Tops

I made more permanent back chambers for each of the New Folded Corner Bass horns using some plywood scraps a had here.  You can see one of the new back chambers in the photo below.  The old back chambers were 34 liters.  The new ones are about 50 liters.

I was planning to buy a sheet of 3/4" mahogany plywood and cut it in two to make two covers for the New Folded Corner Bass Horns.  The idea is to eventually make the horns into a pair of attractive furniture pieces.  Well, I already had some southern pine tongue-and-groove flooring left over from a flooring project so I decided to take the chop saw outside and cut some of these ten foot flooring boards into pieces that would fit together to make the tops.  Here are the pieces I cut for one of the horns.


New Folded Corner Bass Horns - Southern Pine Tops
New Folded Corner Bass Horns - Southern Pine Tops
Even though the tops are not completely constructed yet, I decided to take the old 1/4 inch plywood top off so I could try out the tongue-and-groove flooring boards.  Here are the first two boards in place.


New Folded Corner Bass Horns - New Southern Pine Tops
New Folded Corner Bass Horns - New Southern Pine Tops
I added two at a time until they were all assembled.


New Folded Corner Bass Horns - New Southern Pine Tops
New Folded Corner Bass Horns - New Southern Pine Tops


New Folded Corner Bass Horns - New Southern Pine Tops
New Folded Corner Bass Horns - New Southern Pine Tops


New Folded Corner Bass Horns - New Southern Pine Tops
New Folded Corner Bass Horns - New Southern Pine Tops

New Folded Corner Bass Horns - New Southern Pine Tops
New Folded Corner Bass Horns - New Southern Pine Tops
The bass output from the horn is much stronger with this cover even temporarily installed like this.  That is a Klipsch Shorthorn on top in the next photo.


New Folded Corner Bass Horns - New Southern Pine Tops
New Folded Corner Bass Horns - New Southern Pine Tops
After I get new armature brushes for my table saw, I will complete the Southern Pine Tops for both New Folded Corner Bass Horns.





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.

Thursday, January 28, 2016

The 1965 New York World's Fair - DuPont "Wonderful World Of Chemistry" Show

One of my inspirations growing up was experiencing the New York World's Fair in 1965.  The one show I remember most is the DuPont "Wonderful World Of Chemistry".  It was at this performance that I first heard a really high-quality and high-power music amplification system.  Up until that time, movie theater sound was about the best I had heard.  When the music started playing, featuring brass instruments and heavy percussion and bass, at first I thought there must be a jazz orchestra somewhere "behind the scenes".   However, there was also a chorus and spoken dialogue and the sound seemed to be coming from different directions from one moment to the next.  So I knew it had to be a recording playing back through a really powerful and "live sounding" multi-channel sound system.  Fortunately, a recording of this event can be found at archive.org.

Up until this experience, I had for a long time been interested in listening to recorded sound but I never realized that recorded sound could sound as real as this.

There is more information including links to tape recordings of the event made by Ray Dashner and Bradd Schiffman.



A Stereo Sound Transformer Setup Using GE S-1201D Speakers

A while ago, I posted about the Merry Barn, operated by Howie Davidson, and record hops Howie would host at what was the Old Gym at Lincoln Academy, in Newcastle, Maine.  I decided to try out a stereo pair of the old GE S-1201D speakers on the sound transformer.  Here is an image of the old Califone portable speaker cabinets that clipped together for transport.  You can see Howie's clothesline that provided a handy carrying handle for easy transport.


Califone Portable Speakers Clipped Together
Califone Portable Speakers Clipped Together
If you unclip the two halves, you have two open-baffle boxes, each with a long lamp cord for connecting to an amplifier.



Califone Portable Speakers With Open Baffles
Califone Portable Speakers With Open Baffles
Here are the two GE S-1201D speakers removed from the baffles and ready for installation into the sound transformer:




Pair Of GE 1201A Speakers
Pair Of GE S-1201D Speakers
And here is the stereo sound transformer with the GE S-1201D speakers installed.  The amplifier is an old Pioneer SX-4 receiver.


Stereo Sound Transformer With GE1201A Speakers
Stereo Sound Transformer With GE1201A Speakers
Here is a vintage setup if there ever was one:  speakers from the 1950s and a pair of bass horns based on 100-year-old technology.