Flirting with a round-earth classic of all time (LS3/5a)

Posted by: Anders on 28 January 2002

Hi,

Having been reading a lot lately in various publications (particularly in the HNR) about the venerable LS3/5a, I took the plunge and bought a pair without prior auditioning! Before I comment on the sonic results, I will discuss some practical issues with the speakers.

The pair I bought was the classic Rogers 15 Ohm version in rosewood (made ca 1986-87) and they were delivered with the AB-1 “base extender”. The LS3/5a’s is very much a Linn Kan copy (actually it is the other way around) with identical dimensions and similar frequency response (down to approximately 70 Hz). The AB-1 was designed as a stand-substitute for the LS3/s and has consequently the same footprint. The AB-1 base extender increases the usable base to approximately 55 Hz. In addition, it makes the combined amplifier load much easier to drive.

In the LS3/5a community, the set-up of LS3/5a in combination with the AB-1 is a widely discussed topic. Originally, the AB-1 was intended to fit between the amplifier and the LS3/5a. The crossover in the AB-1 cut off at 110 Hz thereby limiting the signal passing through to the LS3/5a. In addition to the base extension, the idea with the AB-1 is that the LS3/5a would perform better in the mid-band by letting it free from the lower frequencies.

In this set-up, the AB-1 and LS3/5a connect in series with the amplifier. However, there are two shortcomings with this set-up as users with highly resolving front-end equipment quickly recognise. Firstly, the AB-1 is a poor stand for the LS3/5a as it lacks rigidity and adds vibration to the speaker. This significantly impairs the fantastic sound stage of the speakers. Secondly, the addition of the AB-1 crossover in the signal-path reduces the quality of the signal to the LS3/5a and consequently reduces the transparency. These two shortcomings made several LS3/5a connoisseurs disregard the AB-1.

For some time, an alternative set-up of the LS3/5a and AB-1 has been used and discussed to some lengths among LS3/5a users. In short, the alternative set-up has the following elements:
- use a separate high quality stand for the LS3/5a (I use the Linn Kan II stand)
- position the AB-1 approximately 6-8 inches behind the speaker stand
- connect the LS3/5a and the AB-1 in parallel to the amplifier thereby effectively by-passing the internal AB-a crossover (parallel means feeding the LS3/5a directly from the amplifier and then using a jumper cable from the speaker terminals taking the signal to the AB-1)
The improvement is significant! In this way one preserves the outstanding transparency and soundstage of the original LS3/5a while adding the weight of the AB-1 (which is not unsubstantial).

So, how does this set-up sound?

Driving the LS3/5a + AB-1 with my CDSII/52/500 (all on Mana) in my 14 x 12 feet room results in a full-range “wall-to-wall” 3D sound with lot of PRAT! I was totally stunned! Most LS3/5a users drive them with valves but to my ears, Naim electronics and BBC sound seem to be a match made in heaven! The realistic presentation of acoustical instruments, like strings and guitars, and voices were spooky. I have never heard a cleaner and more natural mid-range in any set-up (and I have heard a lot).

The speakers strength is obviously on lighter acoustical music but even on highly dynamic orchestral pieces like Schedrin’s Bizet Suite (Pletnev, Deutsche Gramophon ) the speakers made a credible presentation of the event. The only negative aspect I could think of is that the speakers need a lot of juice driven by solid state (valves seems to be another story altogether – many people run the off Quad II’s). I think a 250 is the absolute minimum to drive them to get this kind of performance.

So, if you have the opportunity to test a pair of LS3/5a at home – do it (it may be now way back).

Regards

Anders

Posted on: 28 January 2002 by JohanR
Ah! In my youth, around 1979, I had a pair of LS3/5A, Chartwell 15 ohms. Later sold them to my brother.
Yes, I remember the bass as sounding the same as Kans, but not the rest.
After your report here Anders, I think I should contact my brother and getting them back! Worth the try, anyway.

/JohanR

Posted on: 28 January 2002 by Tony L
I have always been irritated with the way that the LS3/5a has been branded a "round earth" speaker, I prefer to look at is as one of the few pieces of decent hi-fi that idiot mainstream reviewers have actually recognised as such.

I have always had a soft spot for the LS3/5a, as I posted on another thread recently my first hi-fi speaker was the Jim Rogers JR149, which is effectively a 3/5a mounted in an oversized aluminium baked bean tin (with nice wooden ends). I am by nature one of those people who regret selling everything, and I regret selling these more than most bits of hi-fi I have owned. They were unquestionably not to blame for the problems I had with my system at that time, but in those days blaming the speaker was the thing to do. Applying perfect 20/20 hindsight puts the blame firmly at the door of the old Lenco 75 front end I had at the time.

The 3/5a is from memory not perfect, the Kef T27 tweeter is not the most refined of soft domes, and does definitely have a bit of a sizzle at the very top (I probably couldn't hear that now!), and the crossover gives the bass a little lift to add some warmth. The thing it gets right is the midband, and it gets that really bloody right. These are the two main differences between the 3/5a and the Kan - all Kans have a more modern tweeter, either Scanspeak or Hiquphon units, and use the rear wall to give the bass lift, not the crossover. I have never directly compared a 3/5a with a Kan, I suspect that would be a very interesting proposition, and almost certainly one with no clear winner.

If the current crop of valve obsessed mullet system using hi-fi reviewers are to be believed, it would seem that the LS3/5a favours a heavy mass loaded stand rather than the open frame approach such as the one for Kan II. Open frame stands seem to be intensly unfashionable these days, as do systems that play music. By saying that, you really don't want to know what awful things I had my poor 149s on, the word 'castors' may have been involved, but lets just leave it at that. I later used them on Celestion SL6 stands, but these were still pretty wobbly wooden things.

On the few occasions I have heard the AB-1 subs I have been decidedly unimpressed. I suspect subbing 3/5as is probably a great idea, but not with these feeble passive things - I reckon a well sited REL would work wonders, and allow a decent stand to be used for the speaker.

I would love to hear a pair of 3/5as again in my system, or even better the JR149. I did visit the LS3/5a room at last years London show, and got to hear the very first pair. They sounded really good, and certainly brought back memories of my old 149s.

Tony.

Posted on: 28 January 2002 by JohanR
Andrew L wrote:

"but in those days blaming the speaker was the thing to do. Applying perfect 20/20 hindsight puts the blame firmly at the door of the old Lenco 75 front end I had at the time."

I know what you mean. I had a Era MK 4 (realy, realy, crap french recordplayer and modified by myself so it was probably even worse). It was later replaced by an Ariston RD 80, still the biggest, by a great margin, improvement in my HiFi.
Remember the JR 149, they was on my shoppinglist when bought the 3/5A:s.

/JohanR

Posted on: 28 January 2002 by JohanR
Got hat wrong, should be Tony L wrote:

Sorry /JohanR

Posted on: 28 January 2002 by Tony L
quote:
I had a Era MK 4 (realy, realy, crap french recordplayer and modified by myself so it was probably even worse).

I vaguely remember them, kind of a subchassis job bit with a plastic platter or something really weird about it. I seem to recall they were partnered with SME 3009s quite often.

The Lenco probably had more in common with a Garrard than anything else - big heavy platter that was idler driven. Could do any speed between about 14 and 80 rpm! Here's one identical to my old one right down to the type of plinth. I stuck a Grado F1+ in it as it claimed to work with all manner of silly arms, and boy is that a silly arm.

Tony.

Posted on: 28 January 2002 by JohanR
When the Era:s came out in the late 1960:s they where claimed to be an improvement on the AR. I have owned an early 2-motor AR, they were not!
The platter was of aluminium and the bearing was an inverted one, like Pink Triangle. So far, so good, now the weird stuff begins. The bearing was attached to the chassis via rubber. This filtered out a lot of the rumble generated and, of course, a lot of the music to!
And the origianal arm was to complicated to try to explain here.

Lenco L75 was popular here to in the early 1970:s. Everybody had one (except me of course).

/JohanR