AR LST and LST-2 cloning

[teknofossil]

Some of you intrepid people have expressed interest in cloning the LST series loudspeakers from AR. Not sure where the drivers will come from but I will do my best to provide some basic plans. Complexity of such things as cabinetry joinery and the like will be left up to the builder. So, here is the first plan, sheet #1. I added some mahogany wood grain for some visual interest. Next sheet should come tomorrow. LST plan is in the works. If anyone has access to a LST system or a cabinet and would like to assist in the project please contact me. I would like to thank Glenn Davis for his assistance measuring his Model LST-2 systems.

[owlsplace]

Some of you intrepid people have expressed interest in cloning the LST series loudspeakers from AR. Not sure where the drivers will come from but I will do my best to provide some basic plans. Complexity of such things as cabinetry joinery and the like will be left up to the builder. So, here is the first plan, sheet #1. I added some mahogany wood grain for some visual interest. Next sheet should come tomorrow. LST plan is in the works. If anyone has access to a LST system or a cabinet and would like to assist in the project please contact me. I would like to thank Glenn Davis for his assistance measuring his Model LST-2 systems.

Looks like a fun project.

[teknofossil]

Some of you intrepid people have expressed interest in cloning the LST series loudspeakers from AR. Not sure where the drivers will come from but I will do my best to provide some basic plans. Complexity of such things as cabinetry joinery and the like will be left up to the builder. So, here is the first plan, sheet #1. I added some mahogany wood grain for some visual interest. Next sheet should come tomorrow. LST plan is in the works. If anyone has access to a LST system or a cabinet and would like to assist in the project please contact me. I would like to thank Glenn Davis for his assistance measuring his Model LST-2 systems.

Below is the second drawing. This is somewhat of a generalized plan as I don't have dimensions of some of the cabinet interior panel components. So builders will have to use their best judgement. I don't know if there is any horizontal bracing along the back wall given its relatively large surface. If anyone knows or perhaps is willing to remove their LST-2 woofer and the fiberglass filling and have a look, please report your findings. This drawing provides a general plan for location of the side panels on the top and bottom panels.

[GD70]

There is no bracing on the back panel or anywhere else. Just the panels glued at the joints.

There's lots of pics in my restoration thread which should be helpful.

Glenn

[teknofossil]

There is no bracing on the back panel or anywhere else. Just the panels glued at the joints.

There's lots of pics in my restoration thread which should be helpful.

Glenn

Just what I want to hear Glenn. I forgot about the photos of your project. Thanks.

-T

[teknofossil]

Here is the woofer / tweeter/midrange baffle. If anyone actually builds a clone you may want to wait until you have the actual drivers in hand if you are going to use the recommended tweeter replacement. AR used "T-nuts" on the driver mounting holes which I believe are 10-32 thread.

[Steve F]

There are lots of DIY’ers in the speaker hobby realm. We all dream of our ‘perfect’ speaker; we build it in our heads, we imagine what drivers we’d use, the ideal crossover components (especially the capacitors), how we’d do the cabinets (whether ourselves or by a good friend we have who’s a woodworking whiz), what accessories we’d incorporate (depending on how important we thought such things were), like bi-amp terminals, spiked feet, etc.

Most home-built efforts fall pretty short of excellence, unfortunately. There are several culprits:

- Choosing ill-suited drivers, not knowing whether a woofer is best-suited for sealed or ported use, picking it because it looks “gutsy” or impressive. Midranges and tweeters, again, that “look” impressive, but aren’t good choices to blend with the other drivers or have wildly mismatched sensitivities, etc.

- An alarming lack of the engineering ability needed to properly match the woofer to the enclosure, especially in ported systems.

- Poor or shoddy crossover design.

- Worst of all—the lack of good, consistent, reliable measurements during the development process.

Granted, computerized design programs for the hobbyist have made things better. If you do a lot of proper planning and research, these days, the well-informed hobbyist can likely come up with a decent speaker. Probably the biggest obstacle is the cost of a really professional-level test microphone, which can easily run into the $1000’s.

When I was in college in the ‘70’s, I was friendly with another “stereo nut” who loved to “roll his own.” He was also a very good woodworker. One September he said to me, “Come to my dorm room and see what I made over the summer.”

It was a pair of so-called LST’s. Dimensionally perfect down to the fraction of an inch, the subtle overhangs and every panel angle, they sure looked impressive. For drivers, he used the very popular (at that time) and perfectly good Philips drivers: four of their 1” hard mylars across the top, four 4 ½-inch cone mids and one of their best 12-inch woofers (intended for sealed enclosures). Everything countersunk to be flush with the baffle. Nicely done, for sure, and very impressive-looking, to say the least. (He used a conventional crossover, not an autotransformer.)

They sounded…..okay, at best. Okay, nothing more. Decent bass, kind of colored mids and definitely veiled highs. If anyone remembers those hard, translucent-yellowish 1” Philips mylar domes, “veiled” was not exactly one of their sonic traits. Words like spitty, harsh, edgy, brash, etc. come to mind. “Veiled” does not.

These were the classic examples of what usually goes wrong with even the best-intentioned home-brew speakers. There were probably some glaring errors in his crossover and he likely never even knew it because he couldn’t do repetitive, accurate, subtle measurements. He probably did all the tuning by ear, relied on test records and A-B’d the speakers against what he considered to be dependable references. It’s amazing what you can convince yourself you hear.

Fast-forward 40 years to 2016. Today’s hobbyist could potentially do better, but there are no guarantees. Most home-made speakers sound best in our imaginations.

Steve F.

[michiganpat]

Steve,

with the tools available from a measurement and crossover simulation standpoint, you may be selling the DIY community short. over at Parts Express's techtalk forum there's a number of fantastic designers developing very, very good speaker designs.

That said, making something like the LST with multiple drivers on multiple planes would be a very difficult beast, especially developing the crossover/autotransformer network, as I'm sure there's some magic in there to avoid comb filtering and other phenomena that start to happen when using multiple higher frequency drivers....

if someone really wanted to make an LST looking speaker, I think I'd make it a conventional 3 way with all drivers on the front baffle.....or maybe go with the mid/tweet on the front baffle, and a pair of smaller diameter woofers on each side baffle (say, 2 6 1/2" per side), and utilize the nature of the off axis response as a natural low pass to simplify the on-axis low pass response, much like AR did with the Holographic Imaging series (canting the woofers back allowed them to run them without an electrical low-pass to achieve a 12db/octave rolloff)....might make off axis listening pretty funky, though....