More about LWE and Louis Erath:
LWE loudspeakers were an early (1965-73) line of compact, motional feedback loudspeakers designed by a geophysical engineer named Louis W. Erath of Houston TX. Most LWE loudspeakers employed a back-EMF-based negative feedback network which dynamically enhanced bass and transient response enabling over-sized 15" woofers in a small cabinet to behave as if they were in a more suitable, larger enclosure.
The flagship model, the "LWE-I" was one of the first compact "super-speakers" with extended bass response; possibly the very first loudspeaker using motional feedback to make it into production. It received rave reviews from audio magazines (Audio 11-68, Stereo Review 9-70) for having achieved a near flat frequency response all the way from a low 22hz up to 20khz which, at the time, was unheard of for a speaker of such a small size (25" H, 17" W, 12" D).
First Manufactured and sold by Louis himself (1965-68), the LWE brand and technology was later licensed to Acoustron Corp (1969-73), a manufacturer of college language lab systems.
Acoustron went out of business (1973) after suffering financial losses in the language lab end of their business.
Acoustron licensed 140 LWE dealers nationwide, many of them McIntosh? dealers as their amplifiers worked well with the LWE circuitry.
Soon after Acoustron's demise, many LWE dealers closed out their remaining stock at a discount, some telling their customers that there was "a fire at the Acoustron plant" which was untrue - there was never a fire.
The LWE negative feedback network electronically models the attributes of an "ideal speaker" ; this network is connected in series with the actual speaker and the voltage characteristics between the two are compared in real time. Any difference between the two is sent back to the amplifier as an inverse corrective voltage and fed into the input of the amplifiers designated negative feedback output stage; thereby creating an immediate, dynamic voltage correction for the real speaker at a specified frequency.
The negative feedback network incorporated an state-of-the-art transformer for the era: a toroid-wound over powdered-permalloy core that was previously used only by Bell Telephone in their loading coils and in certain military electronics. The feedback network also used a photo resistor and light bulb to attenuate the amount of bass boost (negative feedback) at higher volume levels.
Vintage LWE speakers are characterized by their near exclusive use of CTS (Chicago Telephone Supply) drivers with Electro-Voice T-35 tweeters (used in some models), 3/4" plywood cabinets with walnut or birch veneer, and 3/4" MDF baffles and backs,
The first LWE-Is were sold with a companion solid-state stereo amplifier that mounted in a compartment on the back of either speaker, but this was quickly abandoned because many japanese-made all-in-one receivers were starting to flood the market; therefore a "clip-kit" solution was developed so LWE dealers would have a library of diagrams of how to connect the LWE negative feedback network to these systems.
The demise of Acoustron combined with the difficulties in marketing and supporting a loudspeaker that needed a modified amplifier along with Louis' busy career in geophysical instrumentation pretty much ended the LWE loudspeaker.
CM Labs briefly resurrected the LWE technology for their CM15 Servosound Feedback Speaker System in 1974, going so far as to modify their amplifiers (CM911) to include 6-pin cinch-jones connectors so their feedback speakers (or LWE speakers) could plug right in.
Louis W. Erath Continues to design and build loudspeakers and is presently (01-2007) marketing an updated motional feedback loudspeaker system called the "Trout".
Louis turns 90 this year.
A Yahoo users group of LWE users sharing information:
[LWE Users Group on Yahoo]
Erath loudspeaker models:
Vintage LWE loudspeaker models:
LWE-I
25" x 17" x 12"
Speaker Complement
One 15" Woofer
One 6" Mid-Range
One 5" Horn-Tweeter
Nominal Impedance 4 OHMS
Frequency Response 22 - 20.000 Hz (± 5dB)
Power Handling Ability 50 Watts (Program Material)
Sound Pressure Level 96 dB/per watt @ 1m
Room gain control for adjusting negative feedback
Mid and High level controls.
Phase control for 0 -180 degrees on some models.
3/4 inch plywood cabinet with walnut or birch veneer.
3/4 inch MDF baffle, back and amplifier compartment.
The LWE-I was one of the first compact super-speakers with extended bass response; possibly the very first loudspeaker using motional feedback to make it into production. It received rave reviews from audio magazines (Audio 11-68, Stereo Review 9-70) for having achieved a near flat frequency response all the way from a low 22hz up to 20khz which, at the time, was unheard of for a speaker of such a small size (25" H, 17" W, 12" D).
Some early models (pre-Acoustron) have a recessed compartment on the back of the speaker with two t-nuts on either side that hold a LWE stereo amplifier inside, suspended in a rack-mount fashion.
Amplifier compartment inside dimensions: 9-5/8 T x 15-3/8 W x 3-1/2 D
measured from opening: 8-3/4 T x 13-3/4 W x 4 D.
LWE-I Compartment Amplifiers:
Model 274 - 60 watt, solid-state, stereo amplifier aluminum rack-mount-style housing for mounting inside rear compartment in early LWE-I loudspeakers. With two two female 6-pin cinch-jones output connectors for connecting LWE speakers, two screw-jacks for extra speakers, two female RCA input jacks, three 3 amp fuse holders and a 1/8 jack for adjusting idling current.
Model 288 - same as above but with 80-100 watt power output, added external heat-sinks, larger transformer, directly coupled design, modern components including silicon transistors.
LWE-II
34" x 24" x 16"
Speaker Complement
Two 15" Woofers
Two 6" Mid-Range
One 5" Horn Tweeter
Nominal Impedance 4 or 8 OHMS
Frequency Response 20 - 20,000 Hz (± 5dB)
Power Handling Ability 100 Watts (Program Material)
Sound Pressure Level 110 dB/per watt @ 1m
Room gain control for adjusting negative feedback
Mid and High level controls.
LWE-III
22 1/2" x 15" x 9 1/2"
Speaker Complement
One 12" Woofer
One 6" Mid-Range
One 3 1/2" Tweeter
Nominal Impedance 4 OHMS
Frequency Response 25 - 17,000 Hz (± 5dB)
Power Handling Ability 40 Watts (Program Material)
Sound Pressure Level 93 dB/per watt @ 1m
Room gain control for adjusting negative feedback
Mid and High level controls.
LWE-IV
48 1/2"x 36 1/2" x 20"
Speaker Complement
Four 15" Woofers
Four 8" Mid-Range
Four 6" Mid-Range
Two 5" Horn Tweeters
Nominal Impedance 4 OHMS
Frequency Response 16 - 20,000 Hz (±5dB)
Power Handling Ability 200 Watts (Program Material)
Sound Pressure Level 120 dB/per watt @ 1m
Room gain control for adjusting negative feedback
Low-Mid, High-Mid and High level controls.
Option for bi-amplification:
Phase/Bi-Amp Control: -0- -180degrees- -Bi-Amp-
Extra 4-pin cinch-jones plug for Bi-Amp option: 20hz-150hz
LWE-VI
19" x 10" x 9"
Speaker Complement
One 8" Woofer
One 3 1/2" Tweeter
Nominal Impedance 8 OHMS
Frequency Response 29 - 15,000 Hz (± 5dB)
Power Handling Ability 25 Watts (Program Material)
High level control - 3 positions
LWE-VII
22 1/2" x 15" x 9 1/2"
Speaker Complement
One 10" Woofer
One 3 1/2" Tweeter
Nominal Impedance 4 OHMS
Frequency Response 28 - 18.000 Hz (± 5dB)
Power Handling Ability 35 Watts (Program Material)
Room gain control for adjusting negative feedback
High level control.
LWE-VIII
90" x 49 1/2" x 23"
Speaker Complement
Eight 15" Woofers
Eight 8" Mid-Range
Eight 6" Mid-Range
Three 5" Horn Tweeters
Nominal Impedance 4 OHMS
Frequency Response 16 20,000 Hz (±5dB)
Power Handling Ability 400 Watts (Program Material)
Sound Pressure Level 113(?) dB/per watt @ 1m
Room gain control for adjusting negative feedback
Other controls?
Sits on four rolling casters.
The Largest LWE speaker ever produced.
Only four units made, all for Dr. John Hill of Houston, TX. After his murder, all four speakers were sold to Home Entertainment Inc. audio store in Houston.
[Movie based on murder]
FOLKSPEAKER
31" x 23" x 15"
Speaker Complement
One 15" Woofer
Two 4" Mid-Range
Two 3 1/2" Tweeter
Nominal Impedance 4 OHMS
Frequency Response ? Hz (± 5dB)
Power Handling Ability ? Watts (Program Material)
Sound Pressure Level ? dB/per watt @ 1m
An inexpensive loudspeaker Erath developed after Acoustron went out of business, but discontinued after lawyers from a certain german car company told him to stop using the name. No negative feedback network on this one.
