Saved LST cabinets

[roundhome]

Hello this is going to be a fun project. ok these are from the parts that were sold on Ebay 90.00 for the pair no Idea how they would be until they got here. last night they arrived. ok good new first. cabinets look vary nice will look good when done. grills all there and no holes cloth needs cleaned or replaced will check with local dry cleaner first. no emblems no knobs no cross overs, now the bad news he took 3/4 plywood and glued and screwed it over both side driver holes, front looks fine.

The good news is the black paint helped. Last night I took my time and took out the screws and drilled holes through the driver holes again then with a rubber hamer and chisle split the layers of plywood off until down to the last layer it came off with vary little damage to the driver face wood the paint stuck to the glue. so with a little wood filler and black paint the will be ready to put drivers back into. it looks like about 10 hours of splitting wood off of both of them .

I think I have most of the drivers maybe short a few tweeters and mids but will need to fined the woofers. I have one cross over from my LSt that was smashed in shipping so will start with that and make a list of coils and caps to get.

But was wondering if I'm going to use these as stacked LST and I don.t think they will ever be on the most wanted LST list. would one LST crossover drive both speakers? I don't think I would have a problem with the mids and tweeters but how whould you conect two woofers to work on this cross over?

happy working

Jim

[nfmisso]

>would one LST crossover drive both speakers? I don't think I

>would have a problem with the mids and tweeters but how whould

>you conect two woofers to work on this cross over?

Hi Jim;

Not without major modification.

With some calculation, and knowing the values of the original components for the crossover, it would not be hard to design a single crossover for the stacked pair.

Nigel

[roundhome]

Well so far so good I have all the plywood off one speaker with vary little damage to the face. now to fill in the small chps and paint it black again. the paint helped the glue stuck to it and it pealed off the wood. but all four terminal blocks were removed. will just have to hit up the guys that have cabinets that are so bad they can't fix them.

Till the next step.

Jim

[roundhome]

Update

looking good!!!!!!

all the plywood is off the small chips in the driverface are filled.

(example when you take out a woofer and some of the wood stickes to the sealant so not to bad.)

next sanded and flat black paint they now look vary nice. do a finish on th black walnut and its ready for drivers. also need to find crossover parts and the terminal boards for all the drivers. thats nine oval three terminal boards!

Any Ideas

Jim

I have enough mids and maybe tweeters. two woofers of the correct year and were off.

think its time to take the one LST crossover I do have and see if Ken still would like to take a crack at getting some specs off it.

then could make a crossover without the xformer.

also will any coils from other crossovers fit the LST specs?

[Pete B]

>Update

>looking good!!!!!!

>all the plywood is off the small chips in the driverface are

>filled.

>(example when you take out a woofer and some of the wood

>stickes to the sealant so not to bad.)

>

>next sanded and flat black paint they now look vary nice. do a

>finish on th black walnut and its ready for drivers. also need

>to find crossover parts and the terminal boards for all the

>drivers. thats nine oval three terminal boards!

>Any Ideas

>Jim

>I have enough mids and maybe tweeters. two woofers of the

>correct year and were off.

>think its time to take the one LST crossover I do have and see

>if Ken still would like to take a crack at getting some specs

>off it.

>then could make a crossover without the xformer.

>

>also will any coils from other crossovers fit the LST specs?

Hi James,

The LST crossover is really very similar to the AR-3a crossover,

where obviously the autotransformer is used rather than the pots.

The cap and inductor values are very close, the woofer inductor value

was used in one of the later variants, as was the slightly reduced

midrange cap from 50 to 40. The midrange inductor was increased

probably because the array of 4 mids could handle a more gradual

(lower Q) rolloff at the crossover point.

There is a switch setting that puts the woofer at the top of the autotransformer

leaving only the large cap in series, so it's reasonable to simply wire the woofer

as it is in the 3a.

The input cap and the winding inductance of the autotransformer

form a highpass filter that will provide some attenuation of LF

noise such as record warp. It can also provide some LF boost if

the Q is high, this would have to be measured or calculated.

I've done some work in this area from about a year ago when I was

speaking to a few people with LSTs. But have not had an LST to

measure.

The series/parallel connection of the LST drivers retain the

impedance of a single driver and so the AR-3a topology should

work just fine, using the slightly different LST component values.

I would probably use switched attenuators rather than the pots.

I would not try to run a pair of LSTs off of one crossover since it

will stress the autotransformer.