LSTs vs 3As...

[Mexicomike]

Finally got all the necessary new caps/resistors and I recapped my LSTs today. Then I A/B them against my 3As that I recapped a few months ago.

It took about 10 seconds to figure out that AR once again knew what they were doing. Clearly the speakers are of the same family but the LSTs exhibit just what I suppose one would expect it to do with 3 more each of mids and tweeters - it images much better and has more of an "there's no speaker here" quality. It's pretty impressive and it's better than I expected it to be. Frankly, although I had always wanted a pair of LSTs, deep down I figured they were really just a louder-playing versions of 3As. I never heard a set until I bought these and I was underwhelmed at first. But all that was the caps, one of which was split open. Recapping brought them back to life as they should be.

As would be expected, the LST is noticeably lower volume-wise than the 3A. I did my initial testing just using my AR amp that drives the 3As and it is clearly NOT the amp to use to seriously drive the LSTs but for my fairly quick medium volume A/B it was OK; I didn't push it too hard.

I have to thank John O'Hanlon more than I can possible express for all his help which included FAR more than just sending me recommendations/instructions - though he did plenty of that. Without his help I can absolutely state that these LSTs would still be sitting unused for want of new caps and expertise!

They were a gorgeous set of LSTs when I received them, beautiful cabinets, new original-style grill cloths and all the original AR drivers; now thanks to folks here and ESPECIALLY to John, they sound even better than they look!

If anyone is wondering whether LSTs are worth the price of admission, I'd have to say yes although obviously it depends on what that price is...

[Diamonds&Rust]

Finally got all the necessary new caps/resistors and I recapped my LSTs today.

It would be instructive for future fellow-travelers and valuable <and FUN!> for all of us to know what caps you used and if you decided to remove the 2500uFs entirely.

I don't think John would mind.

Bret

[dynaco_dan]

Finally got all the necessary new caps/resistors and I recapped my LSTs today. Then I A/B them against my 3As that I recapped a few months ago.

It took about 10 seconds to figure out that AR once again knew what they were doing. Clearly the speakers are of the same family but the LSTs exhibit just what I suppose one would expect it to do with 3 more each of mids and tweeters - it images much better and has more of an "there's no speaker here" quality. It's pretty impressive and it's better than I expected it to be. Frankly, although I had always wanted a pair of LSTs, deep down I figured they were really just a louder-playing versions of 3As. I never heard a set until I bought these and I was underwhelmed at first. But all that was the caps, one of which was split open. Recapping brought them back to life as they should be.

As would be expected, the LST is noticeably lower volume-wise than the 3A. I did my initial testing just using my AR amp that drives the 3As and it is clearly NOT the amp to use to seriously drive the LSTs but for my fairly quick medium volume A/B it was OK; I didn't push it too hard.

I have to thank John O'Hanlon more than I can possible express for all his help which included FAR more than just sending me recommendations/instructions - though he did plenty of that. Without his help I can absolutely state that these LSTs would still be sitting unused for want of new caps and expertise!

They were a gorgeous set of LSTs when I received them, beautiful cabinets, new original-style grill cloths and all the original AR drivers; now thanks to folks here and ESPECIALLY to John, they sound even better than they look!

If anyone is wondering whether LSTs are worth the price of admission, I'd have to say yes although obviously it depends on what that price is...

Hi there;

You may be surprised at the subtle improvement made by going up to an amplifier in the 200 plus watt at 4 ohm rating per channel from the AR amplifier's 60 watt plus.

A thousand watt or more per channel is not out of line, and I do not mean driving them really loud, just having adequate reserve power.

Just as you noticed in a brief period of time the difference between the AR-3A and AR-LST's, I found in less than one minute a substantial, mind you, mostly it was the gut massaging bass, was greatly improved.

My first amp was the AR amp and it was ok, well more than just ok, it was great.

That is, until I tried a Crown DC-300A and Double Dyna 400 amplifiers, and that's all she wrote.

There was no turning back to a smaller amp after that.

These may be older classic amps but they are readily available and affordable, along with a few other brands.

Vern

[Mexicomike]

Totally agree re the Amps; I have a 300WPC Moscode 300 and a 270WPC McIntosh 70270 standing by to take over LST duties. But the amps are downstairs and the LSTs are upstairs and for my initial test, I didn't feel like carrying either the speakers or the amp(s) in up/down. I still have to figure out where the speakers are going to end up.

Re the caps: One LST had 2500uF of caps orginally, the other had 5000uf. They are now both 2500uF each made up of 2 1000uF and one 500uF Bennic cap:

http://www.madisound.com/catalog/product_i...products_id=124

http://www.madisound.com/catalog/product_i...products_id=109

additionally,

2 ten watt, 20 ohm resistors are soldered in parallel across the terminals of the caps

http://www.madisound.com/catalog/product_i...products_id=201

The Midrange caps are one each Solen 40uF with a 33 Ohm non-inductor resistor in series

http://www.madisound.com/catalog/product_i...products_id=751

I don't have the links for the resistor - looks just like the 20 ohm-er listed above

The tweeter caps are a 6.2 uF Daytons with a 33 Ohm non-inductor resistor in series (same as my 3As)

Don't have the link for the cap

Woofer caps are 150uF Dayton NPEs made up of one 100uf and one 50uF cap in parallel with a .47 Ohm non inductive resistor in series (Same as my 3As) - don't have the link for the cap/resistor. Again, the resistor looks just like the 20 ohm-er, above

Note that the LST woofs/tweets are the same crossover specs as the AR 3A's but, by original design, the mids are not. When I first ordered the caps, I didn't notice that the specs were different and I mistakenly bought 50uF caps instead of the correct 40uF caps, ASSUMING that since the drivers were the same, the Xovers were too. But they are not. That is totally clear in the crossover schematic but, of course, one has to actually LOOK at the schematic to see it .

I will be glad to answer any other related questions but please don't ask me any technical questions on why I chose the specific caps/resistors - I used what folks here who are far smarter than I am re these issues recommended. If you disagree with the recommendations, don't talk to me about it! EVERY single bit of what I did component-wise is someone else's "intellectual property."

I am very pleased!

One thing that may be helpful for LST work...

I'm sure a lot of folks know this but often with the new original-style grill cloth, the cloth sometimes looks a bit wrinkly in spots, no matter how well you attach it to the frame. If you spritz a little bottled water (to avoid any discoloration by minerals in the water) on the cloth after it's installed on the grill and then dry it with a hair dryer, it will tighten beautifully to an absolutely perfectly flat and brand-new from-the-factory surface. This, of course will work with any of the AR speakers grills. HOWEVER, the LST front grill frame has a large unsupported opening on the upper section. Doing the water/dryer thing can pull the upper frame support down and make the grill sag away from the upper speaker edge which doesn't look very good. One of mine did that, the other did not. The solution is very simple - just put a little wooded brace the same thickness as the grill frame and maybe 3/8" wide vertically in the middle of the big "hole" and the upper part won't sag. The little brace is in the middle and well clear of any radiation pattern of the tweeters. The grill side of the little brace should be painted black, the back side doesn't matter.

[Carlspeak]

Dear MexicoMike:

Your description of the cap/resistor combinations in series or parallel configurations raised a question in my mind. I don't remember seeing all those resistors (except one 0.5 ohm) in the original schematic and, on a pair of LST's I worked on recently.

Could you let us know what wisdom within your friend's intellectual property prompted the inclusion of the reistors?

[Mexicomike]

Carl,

You are right, of course, there are no resistors used this way in the original crossovers. I don't feel even remotely qualified to answer the question from a technical viewpoint but there are references to resistors in the AR3 restoration paper on the site. It is my understanding that some folks who have done a lot of testing have observed that resistors bring the capacitor operation more in line with that of the original caps AR used in the speakers. As I understand it, current caps have a different characteristic than the old ones which, without the resistors, will produce sound somewhat different than intended by AR.

Perhaps the folks who assisted me will chime in here and explain the function of the resistors in this application; I certainly can't and I don't feel right in posting content from emails I received without approval from those concerned.

[johnieo]

Carl:

I belive Mike meant to say 0.33 Ohms in series with the polypro caps; not 33 Ohms!

AR went through many iterations of the big cap in series with the transformer. One early version had four polarized 2,500 uF caps installed as back-to-back pairs to simulate a 5,000 uF non-polar, then they reduced the value to a single 2,500 non-polar, and later added a 10 Ohm resistor in parallel to prevent problems with some amplifiers. The two parallel resistors total 10 Ohms at 20 Watts. As Ken Kantor commented, the 10-Ohm resistor prevents the load from becoming purely reactive at very low frequencies; a problem that occasionally caused instability in "DC coupled" amps with servo loops. A reasonable option especially if one is experimenting with a selection of early amplifiers.

Hope this clarifies these details,

Cheers

[Mexicomike]

Thanks John, I should have posted a disclaimer re possible TYPOS! It is .33 Ohms of course, not 33. I can't guarantee there aren't other similar typos!

[Diamonds&Rust]

Thanks John, I should have posted a disclaimer re possible TYPOS! It is .33 Ohms of course, not 33. I can't guarantee there aren't other similar typos!

Thank you for all the specificity. Now we just need your ear's opinion after you get one of your monster amps on them.

(re: 33 vs .033 Ohm resistors; I assumed I knew what you meant, but I was hoping it was not your mis-reading 0.33 and installing 33.0... I really hoped that.)

Bret

[Carlspeak]

Carl,

You are right, of course, there are no resistors used this way in the original crossovers. I don't feel even remotely qualified to answer the question from a technical viewpoint but there are references to resistors in the AR3 restoration paper on the site. It is my understanding that some folks who have done a lot of testing have observed that resistors bring the capacitor operation more in line with that of the original caps AR used in the speakers. As I understand it, current caps have a different characteristic than the old ones which, without the resistors, will produce sound somewhat different than intended by AR.

Perhaps the folks who assisted me will chime in here and explain the function of the resistors in this application; I certainly can't and I don't feel right in posting content from emails I received without approval from those concerned.

Yes, the low value caps in series with new caps to simulate the assumed higher ESR of the older caps makes sense.

[Mexicomike]

I did a lot of listening comparisons with the LSTs and the 3As in the same position and a/b with the 300WPC Moscode. First, and no surprise, both speakers are much tighter-sounding with the Moscode and seem much better controlled. Again - with 300WPC vs 60WPC, this is no revelation and we all know that already. I used CD, MP3 and LPs and rock, classical, and jazz

It was interesting that by varying the setting of the LSTs control, I could make the sound quality essentially identical to my 3As. But with both speakers at max treble/flat settings (full treble/mid on the 3A, 2 on the LST), the LST had clearly more high energy that seemed to delineate many instruments, like bass, when you wouldn't necessarily assume that to be the case. On some tracks you could hear the pluck of a bass that was not so apparent on the 3A. I did test tones down to 31.5 HZ and LST/3A were essentially the same in the low end as one would probably expect.

One notable difference that I mentioned yesterday is the LSTs much greater sense of "air" regardless of its control settings. Again, no surprise based on the additional drivers and angled placement. However, at higher levels on some CD and LP sources, the LST at setting 2 was decidedly "shrill" where the the 3A sounded less so. That was even more pronounced on MP3 stuff. Switching the setting to 6 tamed that. But just as with the 3A, LSTs can be unpleasant in the treble with poor sources. It makes me wonder about people saying ARs are subdued - they have always been able to produce more treble than my ears can deal with.

When pushed to high volume levels the difference between the two becomes very pronounced with the LST having a sense of presence, soundstage and authority that considerably exceeds the 3A. However, at low to medium volume setting, the difference is much less and almost disappears though the LSTs' presence is discernible even at low levels.

I know it totally depends on the music and it may not be to everyone's taste but at high volume playing Bon Jovi's "Living on a Prayer" the LSTs were stunningly "real." When the bass line starts you can hear the "pop" of the strings and when the snare drum comes in the impact is almost scary. It's really a "you are there" experience.

This should not take anything at all away from the 3A. After all, the LST was double the AR3A's price when they both were made as I recall - and maybe one way to characterize the LST is to say that it's really nothing more than a "maxed out" AR3As and it shows how good the drivers in the two speakers really are.

In any case, it's a definite "upgrade," just as AR intended.

[Guest pbda]

Many thanks, Mike, for your excellent comments. Having done a similar comparison with my LSTs and 3as I concur with your views. I've been meaning to get my LSTs to Carl for a recap, and your posts will spur me to action.

Carl, it would be interesting to know your thoughts on Mike's recap compared to the one that you and I discussed a couple of months ago.

[Carlspeak]

Many thanks, Mike, for your excellent comments. Having done a similar comparison with my LSTs and 3as I concur with your views. I've been meaning to get my LSTs to Carl for a recap, and your posts will spur me to action.

Carl, it would be interesting to know your thoughts on Mike's recap compared to the one that you and I discussed a couple of months ago.

Except for Mike's use of resistors, my approach to recapping isn't much different. Although I use different cap brands in some cases. I don't see much need for the 0.33 ohm resistors. The 10 ohm resistors in parallel with the 2500 uF caps are only necessary if you have one of those problematic amps. AR did it routinely only because they didn't know what amps their LST"s were going to serve.

[Mexicomike]

I approached the LSTs with the idea that I wanted them to be as AR intended them. So it was never in my mind to eliminate the 2500/5000Uf caps. Once I understood their purpose, it seemed to me to be a good thing that they stay there because I had no idea if any of my amps would have a problem with the transformer without the caps and, if I ever sold the LSTs (can't imagine such a thing!), I wanted them to function as original for the next owner. It is my understanding that these caps have no effect on the sound at all since they are not part of the crossover frequency splitting process. Therefore, again - AS I UNDERSTAND IT - eliminating them doesn't help anything sound-wise and since they prevent any possible amplifier instability, it seemed like a good idea for them to stay.

Obviously what someone does with their own speakers - including bi/tri-amping, new non-oem drivers, etc. - is a personal choice but I wanted the LSTs (and my 3As) to be totally oem (with the exception of the the new caps) and functioning as closely as possible to the originals as AR made them.

I should add, if it wasn't apparent in earlier posts - the difference between my LSTs with the original caps and the new caps are almost beyond comparison. The LSTs, when received, were totally blown into the weeds by my 3As. Obviously the condition of the caps may vary from unit to unit but replacing the caps is a must to ensure they are performing as they should.

[Diamonds&Rust]

I don't see much need for the 0.33 ohm resistors.

Most of us don't, either. We can argue about the specifics of "why" all day long, but the practical result of using the resistors is to cause losses in the system that compensate (inexactly) for losses in the old capacitors that don't occur in the new capacitors. We have been calling this "ESR" although it really isn't ESR, but a combination of things; ESR, capacitive reactance, inductance, etc. True ESR, even in the old caps, is insanely low.

The conceptual problem I have with adding a resistor is that resistance is broadband whereas some of the losses in the original capacitors were frequency dependent...and there are other things which may or may not be audible that go-on when you add resistors or change things.

Assuming that the speakers were designed, then "voiced" at some point (using ears), the final tweaking would have been made by ear. So losses in the original caps **could** (and I stress the "maybe" part of could) have resulted in different values being used (by trial and error) or maybe a small inductor change here and there, or goosing the resistor value on the parallel circuit. Who knows? We would have one engineer for the LST, another for the 10pi, and another for the AR9, who would all have to come and tell us these things.

I don't use the resistors because it seems to me that erring on one side of a compromise is just as bad as erring on the other.

But I don't think I have to be right and I really have no problem with using the resistors, either.

The differences are really very small and a matter of "tilting" the response one way or another, or *maybe* causing a *tiny* hump or resonance... it's just that using resistors may be as bad as not-using them. The sound at our ears is probably more dependent on the flooring, their height above the floor or distance off the wall, or the furnishings in our rooms.

AR did it routinely only because they didn't know what amps their LST"s were going to serve.

Probably. In theory it shouldn't have hurt anything in best-cases and should have helped in worst -- as you say. It just became one-more-thing to go bad, though. Now it's become a difficult thing to replace.

It *would* have to be in LSTs, 10pis, and AR9s, wouldn't it? It couldn't have been the 4 or a 16... no, that would make the restoration decision far too easy.

Bret

[RoyC]

Most of us don't, either. We can argue about the specifics of "why" all day long, but the practical result of using the resistors is to cause losses in the system that compensate (inexactly) for losses in the old capacitors that don't occur in the new capacitors. We have been calling this "ESR" although it really isn't ESR, but a combination of things; ESR, capacitive reactance, inductance, etc. True ESR, even in the old caps, is insanely low.

Bret

I agree with Bret and Carl on this issue. Having spent a fair amount of time experimenting with small series resistors, and discussing (at length) the results with John and Bret, I have concluded that *if* after living with new caps for awhile, the sound continues to seem too bright or gritty, the addition of a small series resistor before the tweeter cap may have a "smoothing out" effect. Interestingly, very subjectively speaking, ordinary wire wound resistors seemed to be more effective than higher cost "non-inductive" types...which would support Bret's comments above. I do not believe adding .33 ohm resistors will have any detrimental effects on Mike's LSTs, or any other old AR beast, but they are seldom required for a successful restoration.

Roy

[Diamonds&Rust]

...and discussing (at length) the results...

LOL

I think my eldest child was in the fourth grade when we started this. It's almost time for him to choose a college.

We've beat this horse so long that I was recently given a bad fright. I finally turned off the stereo, closed the laptop, put my textbooks away (which have been constant lounge-chair companions so long I felt funny putting them on a shelf) and turned on The History Channel.

They were showing something about a mummy that was returned to Egypt recently - apparently a Pharaoh that's been out of the country for a while, uh, traveling. As a director *must* do whenever Egypt is mentioned, they showed a scene of the Giza plateau with some tourists riding camels around in the foreground looking as though they were actually experiencing something. There was a Fez involved, and tassels... But I digress.

Anyway, in the background were the pyramids.

It's been so long since I looked-up from capacitor discussions and dissections and physics principles explanations and my notepad that I could swear the pyramids looked older than they did the last time I saw them.

What did I learn? Well... you can either use a 0.1 to 0.3 Ohm resistor or not, depending on how you feel about it, and if you have any resistors laying around you would rather use than store for another project some other decade.

My car almost qualifies as an antique, now. My "new" integrated amplifier is two years older than I thought, I should probably change the oil...uh, tubes... I meant tubes. Not only is it 2008, but it's closer to 2009.

I'm scared to death to look in the mirror.

Bret

[Mexicomike]

JULY 8, 2008 MEXICO CITY 8:43PM

My Wife (comes up stairs to ask): "What's that rumbling?"

Me" "AR LSTs!"

My Wife: "Holy $h1t!"

Me: "Yeah!"

After more listening testing I have to say that these re-capped LSTs are the best speakers I have ever owned. I thought my set of Nestorovic 5AS speakes were the best speakers I had ever owned and they were...until now. I no longer have the Nessies (my ex-wife does) but I still have all the discs and same amplification equip that I used with them and the Nessies could never throw a soundstage like the LSTs can.

Also, re the bass. When I tested the LSTs/3As the other day I used a 31.5 test tone. It was the lowest I had and both speakers sounded about the same BUT, they are actually quite different with certain musical material. The selection that caused my wife's trip upstairs was the song "Rain" from Madonna's "Something to Remember CD." There is a deep bass drone that sounds great on the 3As but is just stunning on the LSTs. I don't know why the bass response should be different but my 3As are the original Alnico woofers and the first series of inductors where the LST uses the later woofers with different inductors. Or maybe the cabinet volume makes a difference?

I know I'm gushing a bit much but these things are truly amazing...especially for the price, whatever you pay! Nessie 5AS's are now listed for $10,000+ !!!

[rrcrain]

regardless of the cap or wire or inductors used, one single theme emerges time after time when a pair of high end AR speakers is fully restored with rebuilt crossovers. It's expressed differently by different people but the bottom line is the effort was worth every penny.

[genek]

Finally got all the necessary new caps/resistors and I recapped my LSTs today. Then I A/B them against my 3As that I recapped a few months ago.

It took about 10 seconds to figure out that AR once again knew what they were doing. Clearly the speakers are of the same family but the LSTs exhibit just what I suppose one would expect it to do with 3 more each of mids and tweeters - it images much better and has more of an "there's no speaker here" quality.

I auditioned LSTs when they were new, and I preferred them to the 3a. If I had had a listening room that could properly exploit their shape I would have spent the money rather than getting 2ax's (which I also preferred to the 3a). But it's been over 30 years since I heard them, and in all those years I've *still* never had a listening room that could properly exploit their shape. That's life.

[dynaco_dan]

I auditioned LSTs when they were new, and I preferred them to the 3a. If I had had a listening room that could properly exploit their shape I would have spent the money rather than getting 2ax's (which I also preferred to the 3a). But it's been over 30 years since I heard them, and in all those years I've *still* never had a listening room that could properly exploit their shape. That's life.

Hi there;

I have written previously of my experiences with the AR-3A's and the demo of the AR-LST's in my home.

I owned the AR-3A's for several years prior to that one time in-home demo.

Prior to the AR-3A's I owned AR-4X's, which I always felt were great, up to this point.

The AR-3A and AR-LST shoot-off was using my AR amplifier and records.

The turntable combination was AR turntable with Rabco SL-8E tonearm and Stanton 681EE and A stylus.

The records were stock Blood Sweat and Tears, Chicago, Simon and Garfunkle, etc and some direct to disk recordings.

There was at least 5 of us crammed into our living room.

The differences then were like night and day in favour towards the LST's, no doubt in my mind.

The LST's were a little more authoritive, a large step up in sound quality, from the AR-3A's.

Could be the balance as we used position 2 only throughout the demo and all amp controls were flat.

The LST's were $800.00 CDN each here if I remember correctly.

The AR-3A's were $399.00 CDN each here.

My comment at that time was, "I felt that they were twice the sound quality of the AR-3A's".

I had low WAF back then and they went back to the store.

Sadly today they go for sometimes 4 - 5 times the value, depending.

Some that go on sale are a sad sight to see.

My big bros last year, when I asked him for his opinion, as he has owned almost every speaker that AR ever made at one time or another.

His comment was, the AR-2AX was the best and he also had Dynaco A-25's for about 1/2 hour, that was long enough for him.

The living room I had was about 12' x 15' x 8' high.

It was a gyproc, large window and fireplace room, so it was average in acoustics, no special sound damping devices.

If I had never heard the LST's I would not miss them.

Because I did, I got the bug 20 years later to buy, used of course, and locally, I have 2 pairs of them now, an early rear access and later front access pair.

Other than some re-finishing of the one pair and replacing blow tweeters I have not dug into re-capping or anything else, YET.

I say, YET, because if and when it is needed or I win the lottery, I may do it.

I am certain that more than one divorce has come out a purchase of a pair of AR-LST's. LOL

I thank everyone here for their comments and opinions to every effort to improve or just maintain AR speakers.

Thank you.

Vern