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New Owner - AR LST-2's

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Hi all, I'm new here, from Eastern Canada..picked up a pair of AR LST-2's tonight..other than the grill cloth, they appear to all original?, all drivers working..cabinets are nice, but there is some slight "crackling" every once in awhile..not much, and not often..maybe 2-3 times in an hour..I see there are a few AR aficionados that might chime in with opinions/advice...Thanks

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On 1/6/2020 at 7:28 PM, nbman said:

The drivers appear to be original. The back-wiring and plugged front terminal holes are indicative of a very late version of this model...probably 1975.

Roy

 

 

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On 1/6/2020 at 7:14 PM, nbman said:

Hi all, I'm new here, from Eastern Canada..picked up a pair of AR LST-2's tonight..other than the grill cloth, they appear to all original?, all drivers working..cabinets are nice, but there is some slight "crackling" every once in awhile..not much, and not often..maybe 2-3 times in an hour..I see there are a few AR aficionados that might chime in with opinions/advice...Thanks

It’s a methodical process.....going thru each section of these wide dispersion speakers until you get to the source of the noise/ distortion.

 I’ve had 2 not so distant cousins to the LST’s ....The Allison:One and The Allison IC 20.....6 and 10 driver cabinets respectively.

The A1’s I bought new, so nothing to do but play, but the IC 20’s were a 25 year old (at acquisition time) labor of “love”.

The short story of how I got them ready to go back into service was to bring one system at a time (with my new hand truck) into my listening room and swapped it with the existing right loudspeaker. With the woofers removed, I evaluated the performance of each midrange and tweeter (all series wired) and isolated any noise/distortion issues.

With the aid of Millersound in Pennsylvania, I had the voice coils in 3 midrange drivers realigned,

a handful of questionable solder joints redone, and a rebuild of the (4) in my case woofers which included replacing the spiders and the surrounds.

Other detail work also done, but without getting totally lost in this since it’s a different system then what you have acquired, the point is, evaluating each section individually is the key (including the crossovers) to isolating the “crackling” noise.

 

Bill

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On 1/6/2020 at 7:14 PM, nbman said:

Hi all, I'm new here, from Eastern Canada..picked up a pair of AR LST-2's tonight..other than the grill cloth, they appear to all original?, all drivers working..cabinets are nice, but there is some slight "crackling" every once in awhile..not much, and not often..maybe 2-3 times in an hour..I see there are a few AR aficionados that might chime in with opinions/advice...Thanks

Reminds me of an lst post a couple of years back,  the problem was in the spectral balance control. I think it needed a deoxit hit or maybe a few rotations to work it out. 

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Congrats on a terrific set of speakers. They look well cared for.

When you're listening for the distortion, use a paper towel cardboard tube, and place it over each tweeter and mid and put your ear at the other end and listen as a way to find the offending driver.

since the surrounds look to be replaced, remove the woofers and check inside that everything looks ok on the crossovers, i.e., any loose wires etc..... The crossovers are pretty complex in these.

Glenn

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On 1/10/2020 at 11:56 AM, newandold said:

The short story of how I got them ready to go back into service was to bring one system at a time (with my new hand truck) into my listening room and swapped it with the existing right loudspeaker. With the woofers removed, I evaluated the performance of each midrange and tweeter (all series wired) and isolated any noise/distortion issues.

With the aid of Millersound in Pennsylvania, I had the voice coils in 3 midrange drivers realigned,

Bill

Bill,

I respect Millersound's work a great deal, but "realigning" this type of AR midrange is not something I've ever heard of, nor possible in my experience. Furthermore, it is not something known to be required of this type of mid in my 40 years or so of repairing AR speakers.

I know you have tried different speakers with the amp, but if you haven't already done so, simply swap the channels to see if the distortion follows the speaker wire from your amp or remains in the suspect speaker. Once you are sure it is the speaker and not the amp, it is just matter of repeating the problem until you nail it down. In this situation, I would be first suspicious of the electronics. If it is not the electronics,  listen closely to each driver, including the woofers. The LST type switches are seldom the culprit.

Before doing any of the above, by-pass or replace the fuse on the rear of each speaker. I'm not sure about the LST-2, as I have not seen many of these in recent years, but I recently found a number of old LST fuses to cause significant sound degradation.

Roy

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The culprit may simply be a dirty switch.  Try cleaning the switch with DeoxIT, and see that clears it up.  My daughter's vintage Pioneer integrated amp was occasionally producing a crackling sound, and it turned out it was a dirty toggle switch.

Sorry, I missed that Aadams already gave this advice,

Edited by AR55
Answer already given.

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2 hours ago, AR55 said:

The culprit may simply be a dirty switch.  Try cleaning the switch with DeoxIT, and see that clears it up.  My daughter's vintage Pioneer integrated amp was occasionally producing a crackling sound, and it turned out it was a dirty toggle switch.

Sorry, I missed that Aadams already gave this advice,

Dirty switches in electronic equipment often cause the sound you describe, which is why my first recommendation was to check out your associated equipment. It is not, however, a common problem with the more passive switches in LST and LST-2 speakers. I hope it is that simple.

Roy

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20 hours ago, GD70 said:

since the surrounds look to be replaced

Glenn,

Mind if I ask what you saw that makes you think that? I know you have tons of experience with these speakers...Thanks.

Also, I did find the culprit I believe..not the speakers at all. In a way, Roy was right. It was in the electronics. Not the amp, but the DAC. I use a NAD DAC2, and usually have the laptop in the audio room, but when I brought these home, my wife was using it in another room, I was eager to listen, so I just hooked them up and let it go from there. As far as I can tell, the signal must have been spotty causing the static..Several hours yesterday with various sources, and all is well. Clean, clear and sweet. Now for some stands...

Thanks

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4 hours ago, nbman said:

Glenn,

Mind if I ask what you saw that makes you think that? I know you have tons of experience with these speakers...Thanks.

Also, I did find the culprit I believe..not the speakers at all. In a way, Roy was right. It was in the electronics. Not the amp, but the DAC. I use a NAD DAC2, and usually have the laptop in the audio room, but when I brought these home, my wife was using it in another room, I was eager to listen, so I just hooked them up and let it go from there. As far as I can tell, the signal must have been spotty causing the static..Several hours yesterday with various sources, and all is well. Clean, clear and sweet. Now for some stands...

Thanks

Glad to hear you were able to isolate the noise issue.

Congratulations on your very fine acquisition! (And I like that woodwork in your room also!)

Extraordinary....to grab LST’s at that age and be able to just plug and play without issues! (Very cool)

Best of luck with them

 

Bill

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On January 12, 2020 at 7:10 AM, nbman said:

Glenn,

Mind if I ask what you saw that makes you think that? I know you have tons of experience with these speakers...Thanks.

Also, I did find the culprit I believe..not the speakers at all. In a way, Roy was right. It was in the electronics. Not the amp, but the DAC. I use a NAD DAC2, and usually have the laptop in the audio room, but when I brought these home, my wife was using it in another room, I was eager to listen, so I just hooked them up and let it go from there. As far as I can tell, the signal must have been spotty causing the static..Several hours yesterday with various sources, and all is well. Clean, clear and sweet. Now for some stands...

Thanks

Age. Original surrounds by now are cracking apart, or just about completely rotted and gone. If you look closely, you can see some glue on the cones that squeezed out when the new surrounds were glued in place. Also, please check where the woofer screws are pinching the surround edges. I'd fix that by making sure the surrounds are firmly glued flat in those areas.

Good to hear you figured out what the static issue was. If you make stands, ideally, you want the tweeters ear level when seated in your listening position. 

Glenn

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12 hours ago, GD70 said:

Age. Original surrounds by now are cracking apart, or just about completely rotted and gone. If you look closely, you can see some glue on the cones that squeezed out when the new surrounds were glued in place. Also, please check where the woofer screws are pinching the surround edges. I'd fix that by making sure the surrounds are firmly glued flat in those areas.

Good to hear you figured out what the static issue was. If you make stands, ideally, you want the tweeters ear level when seated in your listening position. 

Glenn

Thanks, I'll check that..

Got some stands done up, I think they'll work nicely..

2020-01-16%2012.13.17.jpg?dl=02020-01-16%2012.13.05.jpg?dl=0

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Love the stands you made! Curious what you think of the sound ones sitting on them. 

Are you planning to stain to match the cabs?

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I left them as they were. I'm ok with the contrast of the lighter stands and the darker cabs, plus they match the log wall as well.

They sound great at ear level. Using them as my zone 2 speakers.

Going to look into those surrounds though..since you pointed it out, it's been bugging me. You think that extra glue that squeezed out is having any effect on sound quality?

Thanks

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Nice score !

Are those DQ10's and NHT 3.3 with the LST-2s in the first picture in the 2nd post above?

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11 hours ago, DavidR said:

Nice score !

Are those DQ10's and NHT 3.3 with the LST-2s in the first picture in the 2nd post above?

Yes they are DQ-10's, but not NHT..Paradigm Monitor 7's

 

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2 hours ago, nbman said:

Yes they are DQ-10's, but not NHT..Paradigm Monitor 7's

 

NICE !

I'd like to visit some day. lol

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On February 7, 2020 at 11:35 AM, nbman said:

I left them as they were. I'm ok with the contrast of the lighter stands and the darker cabs, plus they match the log wall as well.

They sound great at ear level. Using them as my zone 2 speakers.

Going to look into those surrounds though..since you pointed it out, it's been bugging me. You think that extra glue that squeezed out is having any effect on sound quality?

Thanks

The bit of extra glue won't have any effect on the sound, just your eyes! I wouldn't worry about it, but check the surrounds lip by the screws. 

Glenn

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