AR LST autotransformer, do I leave it or remove it?

[giovanni56]

I was recently asked:

"I would like to ask you something: is it very complicated to bypass or eliminate the autotransformer?" 

To which I replied as follows, thinking it might be potentially useful to publish this for Ar LST owners.

"They are two different things, if by bypassing you mean a temporary way to engage or disengage the transformer in the circuit e.g., with an additional multistage selector that opens and closes connections I see it as complicated, it could be done, but I do not recommend it. Another thing is to intervene by electrically disconnecting the transformer and related components and then connect the filter section and the speakers directly to the terminals permanently, less difficult than the first, then the difficulty depends on the degree of preparation of the person intervening to carry out the modification, if intervened "amiocuggino" but also some improvised pseudo technicians the probability of making mistakes would be high, because the connections and disconnections to be modified are different, it would be easier to recover all the components of the filter, only capacitors, inductances and resistors and rewire it American style well knowing that this involves an extremely more radical modification than the first two. Another aspect the mids and tweeters of the Ar LSTs are connected together in series/parallel to obtain the impedance of the single mid or tweeter, however the emission level of the four components is higher than the single one, therefore eliminating the trafo (which in normal use from pos 1 to pos 6 modifies the impedance of all three ways of the case and therefore their emission levels), it would be necessary to attenuate them to obtain a correct frequency response that otherwise would be unbalanced on the mid-high frequencies; "ammiocuggino" would do it "by ear," then he would surely say they sound outstanding."

What do the experts think?

[Aadams]

1 hour ago, giovanni56 said:

What do the experts think?

Gionvanni,

Roy Allison agrees with you.

 

[newandold]

21 hours ago, Aadams said:

Gionvanni,

Roy Allison agrees with you.

 

I enjoyed your response taking me down a memory lane trip with RA chiming in on the subject.

unfortunate that I’ve never had the opportunity to hear a pair of LSTs for myself

[frankmarsi]

"ammiocuggino" would do it "by ear" then he would surely say they sound outstanding."

I too do it by ear, I do not have tools to measure FR.

I’ve set up my speakers in a position that most in the know would agree with; against the ‘front-wall’ facing into the listening area of 26 by 12.5 feet. As I stated in a post here over 10 years ago, when I first carried these heavy transducers into the new living room, I went against years of learned true-isms of that knowledge on a lark and placed the LSTs 1/3 away from the front wall and into the room.

The sound? it sucked, period. They did not sound anything like AR-LST’s. It was a waste of time and also meant I had to move these heavy weights another time with their dedicated stands. I so lovingly moved them to their correct position, against the front wall! There’s no, ifs, or buts they sounded their best that way, period.

These days, I see AR-LST’s on ‘y__t_be’ with folks listening to them mid-room, or even 2/3 into the room and the sound is anemic and severely lacking in the great bass reproduction these are capable of.  It seems more then ever mis-information and misguidedness is almost taking over the world.

Regarding the ‘transformer’ “AR” decided upon using was a good decision and the correct one in terms of what AR had decided for a mass market of consumer purchases and a generalization for ease of use. And when I saw a transformer used in the 10pie, I knew AR was into something great.

In my use of the LST’s I find myself setting the transformer’s switch setting to the number ‘2’ or flat or neutral setting, which is the standard setting without any attenuation. This setting I deemed best and probably because of using huge wattage going into each speaker certainly answers the bass strength needs. Also, using AR’s for over 50 years as my sole choice of speakers, I’ve never wanted to go to that silly place some others might enjoy unknowingly as a fake exaggerated bass sound, the web is flooded with those types.

I learned all those years ago that AR provides accurate bass and to spoil that aspect of their sound quality is something only a novice would do. And as a bass guitar player in the late ’60s into the early’70s, rhythm guitar player before that 1964 to 1967 in multiple rock-bands I certainly was attune to such matters. Also, in all of my audio-life, I aways pursued realistic and a natural amount of quality-bass and that in of itself is what drew my to AR speakers initially. Back in the mid - late ’60s to the ‘knowing’, AR bass was the one to pursue.

So, in closing I suggest to look at my posts and the 2 videos, I have room filling sounding bass that is inescapable as natural and realistic sounding bass. So, “giovanni56” that’s why I in my listening room I set the transformers at the #2 setting as I found setting #3-5 too heavy sounding. As I mentioned, it’s achieved with high wattage because typically the bass frequencies demand it and in the flat #2 setting the bass is full bodied while remaining accurate.

Pace a tutti !!!

FM

 

 

 

 

 

 

 

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