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AR LST Best tweeter replacements


Ibis
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Hi 

I am having restored a pair of LST speakers and have just had the report from the repair guy on the drivers see below. Im wondering what would be the best options for replacements on the tweeters, I would probably replace all and then sell on the working old ones. Any advice would be most appreciated Thanks in advance. 

 

I have today cleaned the speakers ready for investigation and have tested all the drivers: -

 

2 woofers tested OK for swept Impedance and frequency response

8 Mid-range tested OK for swept Impedance and frequency response

2 tweeters have open circuit voice-coils (and cannot be repaired)

1 tweeter has damaged diaphragm (and cannot be repaired)

5 tweeters have very low output (less that 75dB at 1 metre and reduced frequency extension) - (and cannot be repaired)

3 tweeter tested OK for swept Impedance and frequency response

The crossovers seem to be OK as far as I can tell at this stage.

 

So to get the speakers working again you will need 5 tweeters

 

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All of your tweeters can be rebuilt whether or not they are operating.  There are no replacements that do not require modifications.  Rebuild which preserves originality is also probably your least expensive route unless you are willing to mod and do the work yourself.  Mods will lower resale value and will not restore the original sound.

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1 hour ago, DavidR said:

Midwest Speakers has a drop-in replacement. I'm unable to hear a difference.

https://www.midwestspeakerrepair.com/shop/home-audio/tweeters/dome/mw-audio-mt-4121-75-inch-dome-tweeter/

The only speaker requiring a modification is the AR11 and 11B

The Midwest tweeter is not a drop-in replacement for the LST. The Midwest tweeter is nearly identical to the later cloth dome AR-11 type of tweeter, and more suitable as a drop-in replacement for later models than the LST. The LST and 3a shared the same earlier style of tweeter, which had different impedance and response characteristics.

The OP didn't mention if the tweeters are front or back-wired. Most LST's have front-wired tweeters.

I should add that the AR-11/11B and the AR-10pi are the least likely models to require modification when using the Midwest replacement.

Roy

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4 hours ago, Aadams said:

All of your tweeters can be rebuilt whether or not they are operating.  There are no replacements that do not require modifications.  Rebuild which preserves originality is also probably your least expensive route unless you are willing to mod and do the work yourself.  Mods will lower resale value and will not restore the original sound.

Thanks, this is very encouraging as I would really like them as original as possible. Im based in the UK, can you recommend anyone who can rebuild and what would the costs be? I would be willing to send to the US if this is the best option .  Thanks for your help 

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The Midwest note about adding a .1mH parallel inductor for the AR-11 is a head scratcher, seeing as how that model already has a .104mH parallel inductor on its tweeter. Are they saying that this tweeter needs another inductor for the AR-11?

I wonder if maybe it's the other (classic) models that need the inductor and not the AR-11...

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1 hour ago, genek said:

That's why I find what Midwest says questionable. If their tweeter was a bolt-in replacement for the one in your 10pi, then it would also be one for the 11, and should need that inductor for the 3a and LST.

Agreed, Gene...The Midwest tweeter is an excellent replica of the AR-11/10pi tweeter. That note is either a misprint or the result of misunderstanding feedback (some of which I provided). Any modern style tweeter, whether it be the original AR-11 tweeter, the Midwest AR-11 replica, or the HiVi tweeter require some sort of crossover modification (the simplest being a parallel inductor) to emulate the roll off characteristics of the original 3a/LST style tweeter. The Midwest note should be included for use with the earlier AR models, not the AR-11/10pi and later models.

Roy

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20 hours ago, Ibis said:

Thanks, this is very encouraging as I would really like them as original as possible. Im based in the UK, can you recommend anyone who can rebuild and what would the costs be? I would be willing to send to the US if this is the best option .  Thanks for your help 

I'm in the UK and had Chris1This1 restore all 8 of my AR-LSTs tweeters. The difference was quite remarkable. Follow his guidance on packing and be prepared to pay some cash to HMRC! Worth it though.

Mike

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