New to LSTs

[jnolan5784]

 

I am relatively new to this, and have been searching for a pair of LSTs for some time. This is the first pair of LST's I have seen much less heard. I restored my father's pair of early 3a's, and have been so impressed with the results that I wanted to get into it more. 

This pair came from the estate of the original owner. The foam has been recently replaced. The best I can figure from the serial numbers (2700's), these were likely 74-75 vintage, although they might be later than that due to the rear wiring. It's my desire to keep these all original and do everything I can to make them sound the best that they can. A couple of questions:

1. Given that I do not want to go with external tweeters, what is a good amp wattage that will let them shine, without jeopardizing the integrity of the original tweeters. I know this depends on a lot of things, but I listen to classical, vocal, etc and am conservative on the volume. I tend toward McIntosh, but am not afraid to spend what is necessary to get good results. 

2. Placement is always key, and against the short wall firing down the long axis is where I plan to put them, but are there any plans for stands available out there, and what is an optimal height off the floor. I am handy with woodworking, and was planning on building my own. 

3. Any other advise on such things as fuses, settings (1-6, I think most people have them at 5 or 6), banana plugs/spades, wire gauge, or any impressions on this pair. 

Thanks so much, I have really learned a lot from everyone's comments. 

[ar_pro]

You might want to contact Frank Marsi, who is the resident expert on the LST. He uses Phase Linear amplifiers with his system, which I believe is what Audio magazine utilized in their 1972 review of the speaker, with excellent results.

The knurled nuts that AR used will give a very solid connection with soldered ring terminations on your speaker cable, but they're less convenient than bananas if you need to disconnect the speakers. For a banana connection, you'd need to buy or fabricate an adapter.

Do you have the owner's manual, as well as the various reviews and product literature for your new speakers?

[lakecat]

Congrats...those looked well cared for. I have found with mine is the higher I got them...the better it sounded. They were designed as studio speakers. Remove the fuses in back and replace.

[frankmarsi]

1-24-2022

@ lakecat:  I too have found the higher I got them...the more I liked  the way they sounded.

Although I do agree with that, it may also hinge of the placement of couches, chairs and other furnishings.  I intend at some point to raise the bottom of the two I have stacked from 16” (bottom of speaker), to 21 inches (bottom of speaker). I vaguely recall the original steel stands I had them on in the 1990’s were about 21” also. I put them on lower stands in my new living room because I felt maybe the stacked double LST’s wouldn’t come across so imposing in the new room. Well, either way, there’s no way I can distract from their imposing appearance in any room, they’re just big as far as AR speakers are from the original ‘classic-period’. Mind you, after the LST production run was over, in came the AR-9. And, like my AR-LST’s, they too are most obvious to any one when first walking into a room.

@ jnolan5784, as I have been on this forum since 2004 and I have repeatedly discussed how I use them and where I place them.

All I can say is for you to do a search of my posts found on this forum and I’m sure you’ll find the answers you’re looking for. My information is basically what I learned in the late 1960’s and early 1970’s and have made that information my credo. 

So basics are for AR-LST speakers are: Correct placement against the ‘front-wall’  for best dispersion and bass reproduction.

High wattage is a prerequisite also as these speakers require much more raw power than the AR-3a or similar models do. Though, volume levels is like driving a car, go too fast and you’ll learn what is possible and not.

For several years I drove my four LST’s with two Phase Linear PL-400 amplifiers that at 4 ohms supplied a healthy 400 watts per-channel and although it was enough for most listeners without question, I personally wanted the absolute maximum wattage I could push into them as I felt they would benefit from. In 2009 I purchased two Phase Linear Series II PL-700 amplifiers and they supply a very healthy 700 watts per-channel without any hiccups and bring these speakers to another and higher-level of realism.

Always maintain them with the correct FNM-2 ‘slo-blow’ fuses in place, and as mentioned above, newer fuses may make a slight difference though if unavailable ‘fast-blow’  4 amp fuse will do but, if you enjoy high listening levels you may be changing fuses frequently.

Do not get caught up in the newbie habit of toeing-in or toeing-out as AR has addressed that initially when these speakers were designed. In fact, the whole concept that AR addressed initially with the designing of hemispherical dome tweeters put that to rest with the advent of the AR-3’s tweeters and midrange from the 1950s on. Just looking at the LST's will certainly prove that point even further.

Regarding the transformer’s settings: I use setting # 2 as this is the ‘flat’ setting. Setting number one will reduce the bass and highs a bit while setting 3 through 6 will slightly increase the bass and treble respectfully. I find when using high power amplification, this will vary and offer stronger bass response. A transformer was also included on the AR10 and offered more options in sound and placement than the AR-11. I only wish that AR had continued to use this or similar methods in all of their speakers.

FM

 

161

 

[jnolan5784]

Thanks so much FrankMarsi.  Been reading a few prior posts - how did the capacitor replacement go with the LST's? Did you end up changing tweeters? If you did replace the capacitors, can you share what you replaced and how that changed the sound. I have replaced the fuses, and am now contemplating having all the tweeters rebuilt by Chris. While I am in them, I thought that the caps should be done as well. They sound really good now, and I can't detect any drivers that aren't working - but they are 40+ yrs old.