LWE Servo speakers

[troystg]

Well I will be starting my prototype system shortly and figured I'd throw up a thread for guidance.

I will be looking for the best way to design the final enclosures (woofers front or side firing) and the electronics section to isolate the electronics from vibration. Or possibly a seperate module behind the speakers, but then longer wire and additional connections.

Mr. Erath is still alive and just finished my amp (the latest revision of his Servo technology) and I will be making my effort on the "ultimate Hi-End" design this spring / summer.

The current plan is active bi-amped speakers using Mr. Erath's Negative Feedback Controller (NFC for short, also referred to as his servo since that was the original concept / application).

Parts:

Amps - Hypex UcD 180's, AD rev for top, basic for bottom
Servo - Mr. Erath's NFC for electronic crossover and correction.
Passive Crossovers - Meniscus Leap tested and designed. Gorgeous crossovers built as I would build myself as an ultimate DIY effort.
Tweeters - SS Revelators, 9900 (Soft domes not the ring radiator)
Midrange - B&W Kevlar mids from my WONDERFUL 805's the kids finally killed. Poor things were constantly knocked over by my loveable but spastic kids happily dancing.
Woofer - Parts Express Reference 10" Aluminum woofers, two per speaker.

All wiring is Teflon insulated Silver plated stranded from Steve@apex.jr along with other miscellaneous parts.

Power supplies are the impeccable boards from BrianGT's Pass labs A30 clone GB and Hypex soft start boards.

Currently the amps and servo are in an external Par-metal series 20 enclosure and the speakers will be passive in 4 boxes until everything is tested and proven. Then the final version will be one enclosure perside with an electronics section on the bottom. Only power, signal XLR connection and 12v trigger will be on the lower rear.

For those not familiar with LWE speakers, Mr. Erath has been building Active speakers since the 60's.. I think he has just a little experience.. His LWE-1A was once called the Ferrari of speakers in the 60's..


EDIT: I put this in the Solid State forum because the main focus is the electronics (the servo in particular) and how to fold that into the enclosures without the vibrational energy coupled to the electronics.

Also they are to be true "actice" speakers.. The drivers and passive XO is pretty much set and sounding nice as a passive system in a sat / sub combo now with conventional amplification..

[troystg]

I know this is on the verge of a commercial post and I understand if any moderators choose to edit the content appropriately.

I am posting only to show that this new product from an old Engineer is what my previous post is being built around.

This IS Mr. Erath's "new design" and I am fortunate to get to build "bleeding edge" (all things relative) technology speakers as a DIY hobbyist.

I just hope the finial product is good because I will have no funds to start anew on something else.. I guess this is a giant leap of faith..

I hope to be able to work on the amp in two weeks from today.. I have a couple of small projects to complete before I can get started on this one again.



Propaganda for the Trout but relative to my speaker..

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THE TROUT LOUDSPEAKER
By LWE
The TROUT Loudspeaker is a two-way system using an 8" mid-woofer and a magnetic planar transducer as the mid-tweeter. It uses the LWE feedback system for driving both speakers. The LWE feedback system was introduced in the sixties and was sold thru HIFI dealers nation-wide. This feedback system reduces harmonic distortion which is normally generated in dynamic loudspeakers. It also improves their response to transients. In the LWE-1, only the woofer was included in the feedback loop. The new circuits allow all speakers in the TROUT to be enhanced by the amplifiers feedback loops. ...... The special crossover network and the feedback network are also mounted on this panel. This arrangement is advantageous because of the close interconnection between the speakers and the electronics. The back-panel also has on it the powerline cord, the power switch, the power fuse, the led "on" indicator light, two banana jacks for an external woofer (if used), its on-off switch, the tweeter fuse, the input phono connector and the mute switch, (the amplifier must be muted when connecting or disconnecting the phono input plug) Four three-position slide switches are
in a group labeled "room-gain controls". The use and function of these switches are described below. An external woofer is available to use when the TROUT is used in a
very large room where more bass power may be needed.
History of the development of the TROUT Loudspeaker:
In 2001 and 2002 I experimented with big multi-cellular horns and drivers for residential sound rooms. I used a two-by-four Altec theater horn with a 25 watt driver. This combination is so efficient (better than 120 db at 1 meter with 1 watt) that the power required for a normal sound level in my listening room was only 10 to 15 milliwatts. At this low power level the inherent distortion generated by the horn and driver is minimal
and the sound in the mid-range is magnificent. I combined this horn with an LWE type of feedback woofer (which has low distortion due to the negative-feedback circuit.) and a
JBL ring-radiator driver on a "baby-cheeks" horn for the highs. The JBL ring-radiator type of diaphram does a good job of keeping the distortion low at high-frequencies. I
was so impressed with the sound of this low-distortion system* that I decided to try to design a low-distortion loudspeaker in a more practical form. There was no question that
I could obtain high performance from a good 8" mid-woofer for the lows and mids, since I had accomplished this in the LWE-8 feedback bookshelf speaker which I produced in
the sixties in Houston. The upper half of the audio spectrum was where the problems would lie. I experimented with various horn and dome tweeters; listening and measuring 1 distortion. The horn tweeters ( except for the ring- radiator type of diaphram mentioned above ) and the dome tweeters such as are in common and widespread use today are plagued with so many forms of distortion that I eliminated them from consideration. The typical one inch dome has break-up distortion at the higher frequencies, {break-up is where the dome is driven by a voice coil mechanically connected to its periphery and the dome is not rigid enough to move as a unit but develops standing waves in its surface} This can be corrected at great expense by using exotic materials such as vacuumdeposited diamond. The voice coil moving in the magnetic field can cause distortion due to field non-linearity.{This non-linearity causes the force delivered to the dome to vary over the voice coil excursion.} This can be corrected at moderate expense by using an under-hung voice coil structure. The Doppler-effect distortion (the high-frequencies are
being radiated from a surface which is moving at the lower frequencies of the tweeter range) can only be minimized by increasing the area of the dome to reduce its velocity
from the lower frequencies in the tweeter range ,however this increases the break-up problem. The same is true for distortion which is caused by the non-linearity of air at high values of compression, {since atmospheric pressure is about 15 lbs/sq in this limits the sound pressure in the negative direction however in the positive direction air can be compressed to hundreds of pounds per sq. inch.} Distortion in the tweeter in any form can
be most disagreeable because it creates inter-modulation between the high frequencies of the sound of the violins and other high instruments . The only good solution is to use a
surface with a large area, which is driven by a uniform force over its entire area. The electrostatic loudspeaker is an example of this. The disadvantage of electrostatic loudspeakers is that they require a high dc voltage for polarization and a high audio
voltage for driving. In recent years the development of the neodymium magnetic material has enhanced the design of magnetic planar transducers for the mids and highs which
eliminate most of the tweeter problems at moderate cost. The TROUT uses an 8" magnetic planar transducer for the mid-tweeter and an excellent 8" woofer for the midwoofer.
The quality of the reproduced sound exceeds that of the horn system described above.
*see my article on this horn loudspeaker in the March 2002 issue of the Audio Express magazine.

The ROOM GAIN CONTROLS on the amplifier panel on the back of the TROUT cabinet are for the purpose of balancing the loudspeaker output to the room in which they are used. The controls consist of four slide switches, each having three positions
indicated by "MAX", Medium (not marked) and "MIN". The switch marked "LOWs" controls the lower half of the audio spectrum (20 hz to 1 khz) and would normally set in the "MIN" position. If the sound is too brilliant, this switch may be moved to the center
position or high position. This alters the response by raising the lower half of the spectrum by plus 4 or plus 8 db. The switch marked "MIDs" is normally used in the "MIN" position. Moving this switch to the medium or max position enhances the midrange response and brings voice and lead instruments forward. The "HIs" switch is normally used at MIN. The highs may be enhanced by setting it to Medium or Max positions. The HI-HIs switch is normally set to the Mid position. It may be moved to the
Max position to enhance the very upper part of the spectrum, that is from l0khz to 20khz.
The MIN position of this switch filters out this part of the spectrum.
OLD EARS: Human hearing will typically suffer a loss of 10 to 20db above 10 khz after the age of 60. The Room-gain switch marked "HI-HIs" set in the max position will boost the sound in this region by about 10 db and tend to compensate for this loss. The cymbals in an orchestra will sound more natural, however it should be set in the mid position for younger ears.

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Now with all that said... It was edited too!!

I have no affiliation with Mr. Erath. I am simply a local dipsh17 who grew up listening to the incredible systems he and Mr. Gerald would put together. I knew one day I would eventually earn enough money to actually buy one. Well the last few years I reached that point and bought the last revision of his servo system. It was good, but because of "domestic" issues it was not allowed to reach it's full potential. When I found out about this new version and it ability to incorporate the electronics into the actual speakers lessening the "domestic disturbance" I jumped on it.. Since that time I have done away with the domestic issues and with that all "spare" finances to leisurely pursue this project.

So as you might expect the actual build of the cabinets for the drivers is VERY slow going. I have all the pieces (amps, LWE circuit, drivers, xo's, etc.) but the actual woodwork will be expensive both financially and time wise.

I will try to post a proposed enclosure design and ask for opinions.. Most importantly are the sonics and the isolation or electronics.