Pictures of horns & systems, with descriptions by Thomas Dunker and other contributors

The following was submitted by Peter van Vegchel (vegchelp@iaehv.nl):

"My backloaded horns use one Fostex FE103 sigma speaker (10cm, single paper cone, full range speaker) each. After reading through a lot of references, I opted for a tractrix curve (good soundquality, reasonable length). Designed cut-off frequency is 50Hz, hornlength 1.9m, internal width 18cm. Overall dimensions are 120 x 24 x 60 cm (h x w x d). Excel was used for calculations, CorelDraw for designing the shape. I tried to make the horn contour as smooth as possible, hoping to reduce reflections. Each horn is made up out of 14 layers of particle board. The speaker is mounted in a 28cm sphere, made out of another 14 layers of particle board. The sphere is almost solid, with a small, symmetrical chamber for the speaker."
pvhorns1.jpg: the horns in my living room
pvhorns2.jpg: construction view
pvhorns3.jpg: myself with the jig I made for routing the spheres
pvhorns4.jpg: sideview
Peter van Vegchel

The Schmacks Horn.
Drawings and text submitted by Thomas Eberhard
(Thomas.Eberhard@labmed.ki.se)

CAD drawings:
Schmacks1
Schmacks2
Schmacks3

 These date back to the mid 50s I think. They are exponential (30 Hz)
backloaded basshorns for 8-10" drivers. The bass from these are far
superior to that of Lowther Accousta 115 and other small horns. At 350
litre's they are almost 3 times the volume of Accoustas 130 litre's and
this can be heard. The first time I heard them was with JBL 2110/075. They
sounded terrific even when played extremely loud. I also have heard them
with Lowthers at a different place and they sounded rather boxy (it could
have been bad damping of the chamber). Klang & Ton issue 8&9/1989 tested
the Schmacks horn with 25 different drivers Qes 0.16-0.45 Vas 21-50L and Fr
28-35 Hz. In all cases the frequency response measured in the horn mouth
the difference between the different drivers was 1-2 dB. That is 50-160 Hz
+/-3dB and -10 dB at 40 and 250 Hz. This is close to an octave better than
my Accousta 115 that was 6 dB down at 80 Hz in the horn mouth. The Schmacks
is I believe the best backloaded basshorn for 8"-10" drivers of reasonable
size. In my experience basshorns have to be this big to sound really good.
For small sizes Voight pipes can be used down to 60 L perhaps even smaller.
I found out this the hard way by building Schmacks scaled down to fit 6.5"
drivers and they sound far inferior. I have no expansion why the perceived
difference is greater then the measured one but I have a hunch that it is
room interactions. That is that the big horn get some help below the
cut-off by the half wave resonanses in the range of 30-45 Hz for room
diminution of 4-6m. The smaller (all dimensions reduced to 70%) have
already fallen below any help, that is the shelving in this range is not
perceived. Some suggestions.

1. There is room for some tweaking by adding two corner reflectors and some
cross braces to increase the stiffness of the enclosure. Especially the
free edges
that is three sides of the mouth and the back end of the last section of
the horn

2. Behind the driver chamber there is a tapered box made out of 4 pieces
keep the one closest to the chamber removable and use it to tune the
lowpass point.

3. Fill all spaces behind the corner reflectors with sand. Apart from one
that is used for xover and terminal. Inside the loudspeaker is the worst
place a crossover can be.

4. The chamber can be lined with felt and then some additional BAF can be
added between the magnet and the back wall. But be careful with the BAF
Klang & Ton measured a 5 dB loss in the horn when filling the chamber in a
backloaded horn!

5. Apart from such obvious candidates like the Fostex/Lowther fullrange 8"
also two way combinations are possible not only the magnificent JBLs but
also more humble drivers from VIFA SEAS and others.

6. It is possible to have the driver centrally placed by bifurcating the
first part of the horn but then also the baffle effect in the lower
midrange will change.

7. The throat area is 220 cm2 and this is just abut right for a 10" driver...

The Drawings
Key CAD Complete 1.0 (Macintosh) refuses to chamfer at other angles than 45
degrees so there are some odd ends in the drawings The Schmacks have been
presented in HH Klingers book about loudspeaker building, by Isophone and
several magazines as well, like Klang&Ton (Germany) and Radio&Television
(Sweden) they all differ slightly in measurement and the old ones dont have
corner reflectors but the folding geometry is the same. Small deviations
hardly matters as long as airtight seals and stability is maintained.

I cant give recommendations on specific drivers apart form the general
guide lines that high Qes drivers are unsuitable, they sound boomy and
uneven in bass both in horns and Voight pipes. Below 0.4 they are OK and
above say 0.6 unsuitable.

"horn01.jpg" shows one of my (Tom Dunker's) horns from the rear. Each horn is made up of a sandwich of fifteen 20 millimeter particle boards (not MDF, it was plenty of work with coarser particle board and each horn weighs 20 kg. less driver) Turning 30 pieces of particle board into two tractrix horns in this manner is no small job, believe me. The results literally speak (sing!) for themselves, however. I used an adapter (which actually was part of a lens assembly called 2031) to mate the JBL 2461 1" driver with the circular throat of the wooden horn. This is visible on the picture. There's a pretty serious time alignment problem in this setup, but when I thought of the WE 15A 'ram's horn' in the L'Audiophile systems I decided to chill out and hope for the best. I was not disappointed.

"horn02.jpg" shows one of my horns close up from the front. The mouth measures 24 cm x 48 cm, so the mouth cutoff is approximately 230Hz. The tractrix is purely Edgar style all the way back to where it measures about 12 x 12 cm, where it begins to approach a circular shape towards the mouth. The wooden part of the horn is 30 cm deep, and at this point it has a 6.5 cm diameter circular cross section which creates a smooth transition the 2031 adapter. This part of the throat was a lot of work, but I'm very happy with the final result. After I was happy with the smoothness of the bare particle board, I used latex spackle, then polyurethane varnish and finally black spraypaint.

Sato's Horn Pardon the name of the picture file which is misleading. Jean-Michel Le Cleac'h informs me that "the western electric type horn showed in the first image WE15A-01.jpg is not a WE 15 A. It is the replica of a smaller horn build by Mr. Sato, a japanese audiophile. In France we call that horn "Sato's horn". This horn is intermediary between the WE22A and the WE66A. In some papers it is improperly called 6368 but the original WE6368 is very different and smaller. The Sato's horn was described in the french review "La Nouvelle Revue du Son" N69 Juin-Juillet 1983, plans and schematics are on page 33. First intended to work with the compression driver Onken OM_255_ES it is more often used in France with the TAD_2001 (TAD is the professional part of Pioneer), the rear cavity of which is somewhat modified (enlarged) to lower the resonance frequency. The original Sato's horn is build in welded steel sheets except the mouth (high quality plywood). The exemplary of La Maison de l'Audiophile, presented during the Paris'Audiofairs in 1990, 1991 and 1992 is in baltic beech plywood (each wall is composed of two sheets of plywood separated by a thick layer of compressed sand)"

"lausys01.jpg"
The reporter's comment (in Norwegian below the picture) reads in English: "2.5 Meter tall horn loudspeakers in the demo room of the DIY magazine L'Audiophile. This was with VERY large margin the best sound I heard in Paris. It was also the biggest surprise! When a modern audiophile sees such speakers, an automatic reflex reaction is head shaking! But when you hear the SOUND of them, the head shaking turns into eager nodding, with an open mouth! A great example that 'hearing is believing'"
Jean-Michel Le Cleac'h again fills me in with these comments:
"This is a picture of the "RYU ONKEN" system presented in March 1990 by La Maison de l'Audiophile. 2.5m is actually the total height of the system, the big Sato's horn possess a mouth surface of 1 square meter. The compression driver was the Onken OM_255_ES."
Regarding the bass amplifier used to power the Onken W cabs: "The amplifier was in fact a 2 x 50 watts Kaneda with a regulated supply. May be some demos have been done with the Hiraga 20Watts?"
Details regarding midrange horns: "There was only one midrange horn per channel . It was the Le Dauphin's horn (baltic beech plywood + sand), a replica of the famous horn Onken SC_500 Wood. The compression driver in the midrange was the Onken OM_455_ES and for some demos the TAD_2001." The large horns on top of the Onkens are "Sato's horn" (close-up photo in "WE15A-01.jpg") and not original 15A's.
The tweeters:(Jean-Michel says)
"Those tweeters are the famous Onken's 5000T_ES."
4 Legend 300B single ended monoblocks each power one of the midrange/midbass horns and two 3.5W amps with WE 275 tubes power the tweeters.

"kiowsk01.jpg"
Shows Peter Kiowsky of Avedoere (south of Copenhagen, Denmark) next to one of his huge 4-way horn speakers.

"kiowsk02.jpg"
The entire system.
The bass horns are straight front loaded horns. Mouth size is 80x90cm and the depth is 110 cm. Two Gamma 12" woofers are used in each bass horn. According to Peter the bass horns roll off around 60 Hz. Each bass horn is damped with sand and built from discarded furniture boards and other recycled materials. Each horn weighs 200 kg.
The midrange horns are interesting: Peter does not like compression drivers and has found that horn loaded conventional drivers are the best sounding in his ears. He has settled for a 2" Peerless soft dome midrange. Note the unusual elliptical shape and asymmetrically placed throat of the horns. Peter claims that these details can bring about big improvements in the critical midrange.
The (white) treble horns use a 1" Peerless soft dome.
The top end (above 10K) is covered by a Pioneer PT-R7 III ribbon tweeter.
Passive 3rd order crossovers are used, and the whole speaker system is powered by a 2 x 22W Hiraga Class A transistor amp, weighing over 50 kg. Total PSU capacitance of this amp is about 3.4 Farads.
Peter primarily uses vinyl records as the source. He uses Thorens TD 126 with a home made air bearing tangential arm and an Audio Technica AT-OC9 cartridge and an SRPP based experimental phono stage.

220cm/7'4" tall!
(Bodo Kalthoff)

The following nine pictures were submitted by Jean-Michel Le Cleac'h, who also has provided the descriptions.

ikeda.jpg
Mr. Kei Ikeda has been an enthusiast audiophile since 1919 and his auditorium is a museum devoted to audio.
Look at the two giants horns WE 15 A used in the high bass and low medium range in the main 4 ways system!
The low bass is reproduced by the big woofer you see behind the left shoulder of Mr. Ikeda , another room close to the auditorium is used as a rear load for the woofer . This woofer, IK38 inspired from a RCA duocone loudspeaker, was designed by Kei Ikeda for JVC.
You'll also notice the famous WE 59 A (or WE 540) loudspeaker known as "chinese hat" intended to works with the first Western Electric amplifier, the WE 25A.
Compare the huge mouth of the WE 15A to the smaller WE 6368, half visible behind books and a desk lamp up to the chair in the left part of the view.

Comment: Pictures "ikeda.jpg" and "takashir.jpg" were published in a paper with the title "On ne vit qu'une fois, de musique" in the No1. issue of "Stereoplay" (French edition) in October 1979 . That paper with some others in the same review and the famous papers of Jean Hiraga in "La Nouvelle Revue du Son" from the end of 70's and the beginning of the 80's , led to a deep change in the mind of the French audiophiles.

takashir.jpg
Shigemi Takashiri plays piano and 10 others instruments. His favorite leisure is to record and reproduce music in his auditorium.
Two Steinway pianos, some Japanese drums and percussion instruments are visible in the auditorium but the loudspeakers are difficult to locate through the collection of lamps and crockeries.
The Goto tweeters are at the same level as the ears of Mr Takashiri. Those tweeters are touching the high medium and low medium Goto horns, the throats of which go across the rear wall, the Goto compression loudspeakers situated in a small room behind.
But where are the bass loudspeakers? Look at the ceiling and you will see the two giant mouths of the concrete bass horns the cut-off of which is 20Hz.
Not visible are the turntable with 6 tonearms, the 6 tape recorders and the rest of the electronics.

yoshikat.jpg
There are two 5-way loudspeakers systems in the auditorium of Dr. Idemiya Yoshikatsu .
The two sytems share the concrete bass horns each of which works with two woofers, Goto SG 38 W.
The first system uses:
In the low midrange, MB-90II horn with an YL D-7500 (Yoshimura Laboratory) compression driver.
In the high midrange S-300A (Goto) horn with a SG-555PS (Goto) compression driver.
In the low part of the high frequency range the S-500 (Goto) horn works with the SG-370 Goto compression driver and in the upper part there is a tweeter SG-17T (Goto).

The second loudspeaker system uses:
-In the low mids the JBL PRO 2202.
-In the high mids the JBL PRO 2440 with a 2355 horn.
-In the highs the JBL 2420 with an home-made horn and.
-In the upper range the tweeter JBL 2405.

kobayash.jpg
5-way loudspeaker of M. Tatsuo Kobayashi.
f < 150 Hz : 2 x 416 8A loaded by a concrete bass horn,
150 Hz < f < 650 Hz: compression driver Onken ES 255 Esprit with a concrete bass horn,
650 Hz < f < 2800 Hz: compression driver Onken 500MT with a wooden multicellular horn,
2800 Hz < f < 8000 Hz: compression driver Onken OM 455 with a multicellular horn SC 500 Wood, f > 8000Hz tweeter Onken 5000T.

Comment: That system has inspired the French society: AII Ingenierie SA in building their reference sytem in their auditorium in Chatou (near Paris). AII Ingenierie SA designed the Eurythmie 33 and Eurythmie 11 (the last one is also sold under the label Jadis).

roggiero.jpg
A beautiful 5 ways horn system owned by Mr. Roggero in the south of France. Mr. Marcel Roggero has designed himself the concrete bass horns and the whole auditorium that received a very complete acoustical optimisation (constant reverberation decay at each frequency...).
Mr.Roggero wrote a paper describing his whole system in "L'Audiophile" No.30, Septembre 1994.
You may find in the paper some schematics about the concrete horns and of the auditorium.
Six Altec 515 for each of the giant concrete bass horn that are perfectly integrated in the auditorium. The entrance door of the auditorium is between the two bass horns.
The effiency of those bass horns is very high (108 dB/1W/1m), the cut-off frequency is 18.5 Hz.
Low medium (200Hz to 1350 Hz): Onken 255 ES with 15 cells horn Onken MS 200 Wood.
Medium-high (1350 to 7000 Hz): Onken OM 455 ES with 4 cells horn Onken SC 500 Wood.
High range (above 7 kHz) tweeter Onken 5000 T. Above 8500 Hz there is a slow relay by a ribbon tweeter Pioneer PT-R7-III working up to 100 kHz.
rogmedhi.jpg shows close shot of the mid/high horns and drivers of Roggero's system.
roggamps.jpg shows the array of amplifiers used for Mr. Roggero's system. The bass horns are powered by a MacIntosh MC2600 (2x600W).
The low mids (Onken 255ES/MS200) are powered by an SE 845, with WE310A and WE300B drive stage.
The mids (Onken OM455ES/SC500) are powered by SE 300B amps with 310A drive stages.
The highs (Onken tweeters and Pioneer ribbons) are powered by an SE amp using the 6EW7 (triode + power pentode), where the triode section drives the pentode output stage.

More recent pictures of this installation here!

sakai.jpg
This 4-way active system belongs to Mr. Yoshiaki Sakai.
It is a complete 4 Way Onken system.
Bass range (< 250 Hz): Big Onken bass reflex (Jensen type load) 360 liters with a 416 - A Altec 38 cm woofer.
Low medium: 250 Hz < f < 1000 Hz: compression driver Onken ES 255 Esprit with a 15 cells Onken horn MS 200 Wood,
Medium-high (1000 Hz < f < 8000 Hz): compression driver Onken 500MT with a 4 cells Onken horn SC 500 Wood,
High range (f > 8000Hz): tweeter Onken 5000T.

kobayas2.jpg
This system belongs to Mr. Kobayashi.
The mixed type "horn-bass reflex" Onken enclosure has an efficiency of 105 dB/1W/1m at 50 Hz..Each bass reflex possess two Onken 515 B loudspeakers (inspired to Eijiro Koizumi by the Altec 515 ).
This enclosure is inspired by the big Altec 211 but the Onken has a shorter horn and Jensen-Onken type vents.
Low medium (250Hz to 1500 Hz): Onken 255 ES with 15 cells horn Onken MS 200 Wood.
Medium-high (1500 to 8000 Hz): Onken OM 455 ES with 4 cells horn Onken SC 500 Wood.
High range (above 8 kHz): tweeter Onken 5000 T.

Brian Weafer (bweafer@the-wire.com)submitted:

VOLKS-4.JPG (and SKELET1.JPG) was built by Bill Woods in 1976 for as a high quality P.A.system. Two horns were built driven by a low Qts, high Bl 15" woofer. The flare is for a free space (no additional loading required) 70 Hz Tractrix straight axis contour. This horn is made like an airplane and only weighed 120 pounds. The rear chamber was 1.5 cubic feet. At the time the designer (Bill Woods) lived only 30 miles from Mr. Voigt, inventor of the tractrix who kindly provided critical assistance durning the engineering phase. A Phillips 9710m 9" wide range speaker had the highest fidelity sound. The horn was 7 feet long and 5 feet by 5 feet at the mouth.
DUAL4.JPG (and CONSTR1.JPG) was a large straight axis 60Hz Exponential flare housing dual 15" woofers. Built into the ceiling of an art gallery. This horn was used with two satellite 15" reflex systems. This system was used for experimental multimedia live performances and was tri-amped with an active network. The horn was built in 1978 and was 7 feet long, by 4feet by, 7 feet at the mouth. It was destroyed some years later when the building was sold.

Here are some more pictures of horns built by Bill Woods. They don't really fit in with "amateur/DIY", as you'll see from Bill's own descriptions. This is PA/Sound reinforcement pro stuff, but it looks great.

"Here is more stuff I have built - a folded bass horn that starts as a circle and ends as a square. This design was originally made by RCA for the 1939 Worlds Fair. Their version was a 3 foot cube, co-axial horn with mid/tweeter in center of horn . You can see the RCA horn in the Audio Anthology sound reinforcement book from AES Vol. 1--Vol 26 page "F 2". It was called the "Twin Powered" speaker. This is the most efficient speaker I have ever measured (110 dB 1w/1m). To my knowledge, this is the only way you can co-axially mount the mid horn in a bass horn of reasonable size. I built about a hundred of them for the PA business."

MOULDS.JPG
SHOP2.JPG
WALL.JPG

"Version of JBL "Ranger Paragon" based on the Arnold Wolf industrial design of Richard Ranger's patented reflection array system. This speaker is a beatiful design from a visual standpoint, but like the Hartsfield and the Klipsch-suffers from coloration in the 120Hz-800Hz range. This unit was built in exchange for a fireplace and was loaded with RCA electromagnetic 15" theatre woofers and JBL top end. It was driven by the 12 watt Advent reciever. The woofer flare was 50 Hz and the reflection concept worked well."

Bill Woods

From William Eckle (wmeckle@primenet.com):
Right side of Bill's system
Left side of Bill's system
"Next to the floor are a pair of NHT 1259 subwoofers in 100 liter cabinets driven by a pair of Adcom 555IIs in bridged mode fed from a Sumo Deliah II electronic crossover set at 80 Hz 12 db/octave for low out. High out is set at 100 Hz at 6 db/octave, and feeds a pair (per channel) of Marchand XM9 boards set at 400 Hz and 5000 Hz respectively. The Marchand boards are powered by a Welborne PS-1 power supply and are housed in custom cabinets with controls. The XM9 boards are each 24 db/octave.
The low out from the XM9 board feeds a Joe Curicoized Dyna Mark IV power amp which feeds an Altec Lansing Model 414 12" driver in an Edgar 100 Hz horn finished in red oak. The mid out from an XM9 board feeds 1/2 a Van Alstineized Dyna Stereo 70, which feeds an Altec Lansing model 755C 8" driver mounted on an Edgar # 4 horn, finished in red oak. The high out from the XM9 board feeds the other half of the Stereo 70 which feeds an Altec Lansing model 3000H sectoral horn housed in it's red oak cabinet.
With the exception of the subwoofer and it's crossover and power amp, all other parts of the 3 way system described above are late 50s and 60s vintage drivers and amps (though updated by parts replacements).
Note the pictures were taken before any attempt at positioning the horns, testing various crossover points and adjustment of levels. This proceedure will be ongoing for several months (ain't this hobby fun ?).
This (hopefully) will provide an insight to younger folks the kind of stuff we had in the 50s/60s. All the vintage gear was accumlated over several years and was bought (and modified) very reasonable."

Ed Billeci (tube@teleport.com) sent the following two pictures - he describes them himself:
"The Altec system uses a concrete reinforced A-7 cabinet, modified with a box on the back to accept the huge magnet of the Electrovoice 15-W woofer.
The midrange is handled by the Altec two cell horn, #203-B. This uses the 288-C driver, 24 ohms.
The highs use the Altec 805-B horn, (eight cells), with the 288-16K driver, having the "tangerine" phase plug.
Super tweeter, (not shown) is the JBL 2404 "baby cheek".
The crossover for the bass is active, using 845 push-pull, while the horns have passive crossovers, driven by W.E. triodes.
The crossover points are 8 kHz for the tweet, 2 kHz for the 8 cell, 400 Hz for the two cell, and the active crossover is a 12 dB unit, starting in at 300 Hz on the A7 cabinet only.
The Lowther "Acousta" cabinets are The original design, using 3/4" plywood. The entire interior is lined with 1/8" cork, and the interior horn folds are all radiused.
I alternate between a pair of 2-C's, and 6-A's. ( they both have their strong points. Bass for the 2-C's, and highs on the 6-A's. I might try rolling off the 2-C's at 5~8 khz, and add the JBL tweet. This would eliminate peaks, give better HF response, and better HF dispersion."

Dirk Wright (wright@uspto.gov) sent me these four pictures of his system, which he describes best himself:
dwr_left.jpg
dwr_sys1.jpg
dwr_sys2.jpg
dwr_sys3.jpg
"I designed these 70 cycle straight horns myself, with some help from Bruce Edgar. Technically, they are quarter sized hyp-ex, with an "m" factor of 0.6. I use the Electrovoice EVM15L lead guitar driver. The throat has the same aspect ratio as the mouth, which is 1.25:1. The aspect ratio is important in a horn, and a good one is about 1.5:1. An aspect ratio of 1.5:1 wasn't practicle for my application, since I wanted to sit the midrange horn on top of the bass horn. This meant the the max height for the bass horn was a little over 2 feet. Aspect ratio is defined as the ratio of width to height. It doesn't matter which side is width and which is height. I felt that the throat should have the same ratio to reduce the distortion of the sound waves. I have no proof of this, but my memory of fluid machanics lead me to that conclusion.
After doing a bunch of research, I came to the conclusion that this type of horn would be best, and that I could live with a lower cutoff of 70 cycles. An advantage of quater size straight horns is that you don't need a pair of good corners, as in the 1/8 sized ones, and that the rolloff is slower(less steep) for a straight horn than it is for a folded one. The actual horn part is 42" deep, but with the cabinet and backchamber added in, the overall depth is 4 feet. A further advantage of using a straight horn for the bass is that all three drivers can be "time-aligned"(tm). This is critical for good imaging in horns, and is the main reason that most klipsch products don't image well. The most critical alignment is between the tweeter and midrange, since most of our spacial information is processed in our brains from 500Hz and up. Aligning the bass too is a "benny", and improves imaging even more.
I use the standard #5 Edgarhorn that takes the dynaudio D54 midrange driver, and the tweeter is a Peerless PR120. I intend to replace the tweeter someday, but I've been busy with other things.
I use a third order LP crossover for the bass, because all of the breakup mode harmonics from the lead guitar driver pass through the bass horn. The midrange has no crossover, since it appears to have very steep acoustical rolloffs. The tweeter has third order HP crossover with a notch filter. Both crossovers have zobel networks. Crossover points are 400 and 5K Hz. I used MathCAD to run the numbers. Most of the information anyone needs to design a bass horn is in the "Show Horn" article in Speaker Builder.
I got hooked on horns when I heard a pair of home made Klipshorns. The bass is what blew me away. so natural, so real. I didn't care that they didn't image, tha bass is what squeezed my lemon for me. I went home to my cone and dome system, and immediately thought to myself "this SUCKS!!!!!!" So, I started working on a horn system. It took about a year to get it all together, and about another year to pay for it. I have about 2500$ invested, since I paid a cabinet maker to make them for me. I wanted my wife to be pleased with how they looked, so I had to hire an expert woodworker.

From Mark Winquist (mtw@kih.net):

bass5.jpg

Built by Mark Winquist

"I built the bass horn of these Klipschorns from Speaker Lab plans. Originally I went by their plans which utilized the normally sealed volume of the top and bottom reflectors but later I sealed them off. bass1.jpg shows the SL version being built. This view shows the 4 upright pieces used in SL plans. The current Klipschorns has 2 wood pieces running the full height of the horn the same depth as the 4 pieces shown in the picture. I found out later that the Klipsch method is better for 2 reasons; (1) it better supports the side walls and stops resonance, and (2) the woofer that I used did not need the additional volume. bass2.jpg, bass3.jpg, and bass4.jpg show the construction phases.

I also made another modification that Bruce Edgar recommended by enlarged the first and second reflector. He claimed it would help the high end of the bass horn. I have no comparison but I would say it made a lot of difference. The response curve I saw from Klipsch shows a dip in response starting at around 300 Hz. My Klipschorns are a little hot between 300-500 Hz. In fact it makes the low end sound a little weak. I really don't know if this was a good modification or not but it did do what he said it would do. The carpet lining the horn mouth shown in bass4.jpg was later removed. This helped the low end some. Bruce said this would stop high frequency peaks that can be a problem sometimes. Bruce also recommended the EVM15L which I used for a while and later replaced it with K-33-E Klipschorn woofers (made by Eminence) which further improved the low end. According to all the horn calculations the EV woofer should have worked better. In my opinion the high Q of the K-33-E improves the bass response because the horn is not acting like a horn at the low end and it relies on the high Q sealed box response to help the low end.

I built the Midrange horns from a Speaker Builder article by Bruce Edgar using the JBL LE5's. I am very pleased with this horn. Bruce recommends crossing it over at 5000 but I have found that it sounds best crossed higher. The response is a little uneven above 5000hz but it images much better. Currently I am using it without a tweeter. The PR120I1 that I was using didn't mate well with these mids. I constructed the mids horns a little differently than Bruce did in his article. It was very easy and I recommend this method. It makes mounting of the mids in the Klipschorns much easier also. mid1.jpg shows just how easy plywood bends when you cut 1/8 inch kerfs in the back of 3/4 inch oak cabinet plywood. mid2.jpg, mid3.jpg, mid4.jpg, mid5.jpg, and mid6.jpg show the construction in process. Finally I made a modification of my own and made the bass and midrange sections separate. This saved a little wood and made them easier to move and modify if necessary.

imaging.JPG shows the midrange section removed and sitting on a few boxes in front of the bass horn. This improves imaging quite a bit. They also sound good on top but if I had the room I would use them sitting in front."