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.