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It's tuff to love a speaker box........


frankmarsi

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Hi Roy and all at CSP, sorry for such a late reply here.

This method seems easy enough so I can finally get to complete my LST

'Refurb'. Question now is what are the values for the two components, the resistor and the coil? Can I actually accomplish this with one value of a single set of components or must I actually have a 'coil-resistor' pair for each tweeter?

Secondly, where can I get these components cheap enough? Best to use silver solder or 60/40? Thirdly, my LST cabinets have the 'rear-passage' cross-over panel, would it be best accomplished to enter from here, or go from the front?

All and any input from any and all out there is much welcome.

Must be somebody's friend, Frank Marsi

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For solid state soldering, I prefer 63/37(361F) solder since it melts at a lower temperature than 60/40(370F). Lower temp generaly means a longer life for solid state.

In a crossover consisiting of caps, inductors and a few resistors, it may not make a difference. As for the silver based solder, the silver content is so low I doubt it matters. Real silver solder has a very high melting point and is unsuitable for electronics.

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Hi Frank;

Using a solder 60-38-2 with the 2% being silver, is a nice flowing solder.

I am not talking about the expensive imported siver bearing solder.

Most all electronic shops carry a 1/2 - 1 pound roll $20.00 +/-, or smaller rolls in a plastic bag.

Also just 60-40 is adequate, as long as the solder that you do use is flux core, NOT ACID CORE, nor using rosin paste.

With your removing the rear panel gives you greater access to the crossover and wiring.

You could try working through the tweeter opening but the rear is much easier, Frank. LOL LOL

A small 25 - 40 watt pencil type soldering iron or soldering station is much more controllable than a heavy duty hand held gun type.

Heat is your worst enemy, too little and you have a cold, poor solder connection.

Too much heat and you can overheat the item your want to solder and destroy it.

If soldering on a circuit board, too much heat can lift the pads even.

Always helpful to practice on a scrap piece of wire before the main project to get the feel of everything.

Remember that the coils are insulated wires and require a sandpaper or equal to remove the coating prior to soldering.

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>'Refurb'. Question now is what are the values for the two

>components, the resistor and the coil? Can I actually

>accomplish this with one value of a single set of components

>or must I actually have a 'coil-resistor' pair for each

>tweeter?

>

Frank, as I recall the new tweeters put out far more sound in the lower frequencies than you like. Thus, the migration to a 2nd order filter that includes a coil as well as a cap.

You would use one filter (coil + cap) for each speaker. The cap would merely replace the existing cap. The coil would have to be wired in parallel with all 4 tweeters.

Values for a Butterworth at 5000Hz would be 6 mf for the cap (so you can use the existing cap) and then 0.18 mH for the coil. Here is one the won't "break the bank" and I'm certain there are others:

http://www.partsexpress.com/pe/pshowdetl.c...r=255-208&DID=7

Hope this helps ...

Regards,

Jerry

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Thanks Jerry, finally a easy remedy to my LST woes. Remind me to beat-up on K.K. later, after I meet him first, he may be bigger than me, besides he's a major value to this site, I don't wanna hurt him with my realistic, but plastic cap-gun just yet.

Unfortunately due to the late '60s (love and peace and sex and drugs)I sometimes have difficulty grasping certain things. Now....Lucy.......please splane to me? Is it one coil per tweet and one cap per tweet also?

Now...Lucy...... can you please 'free-hand' me a little diagram show each of all the elements involved here? I would appreciate it immensely and you too will be an honored guest to listen to my dream system when all is finally hooked-up,and you won't even be charged for admission-it's on me.

If this works well, I will forever be grateful to you and all those who love you and America too.

A former friend of this site, abandoned and "pushed aside, tossed by the tumbling tide" * Hendrix 1967

Who was that lunatic? Frank Marsi

To Vern; I though 'acid-core' was the same as flux? Actually how stupid have I become since I've past 50? Has the AR syndrome displaced other minute traces of intelligence I may have possessed before letting myself become so absorbed with the AR phenom?

As some one's wife if this is true, will ya.

FM

P.S. Don't forget to check-out the special offers: List in the pages called: "THE PERSONAL REVIEWS", at the end of page 3.

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>Hi Roy and all at CSP, sorry for such a late reply here.

>This method seems easy enough so I can finally get to complete

>my LST

>'Refurb'. Question now is what are the values for the two

Hello Frank:

I appreciate your frustration at the delay in replying -- no secrecy here! Roy wanted to implement the change in a pair of AR-3a with AB-Tech tweeters to see how Ken's measurements and computer synthesis sounded to his "golden ears." His first pass listen is quiet positive, but I will let him describe that in his own words. To answer your questions:

>Question now is what are the values for the two

>components, the resistor and the coil?

-> C = 6 uF and remains unchanged

-> L = 0.07 mH

-> R = 15 Ohms at 20-W or greater.

NOTE 1: In another reply to this post mention is made of a 0.18 mH coil value. Ignore that value, it was not anything that originated from Ken's detailed study.

NOTE 2: The resistor is not needed for the AR-3a. Ken added it here as the tweeters are driven from a transformer.

>Can I actually

>accomplish this with one value of a single set of components

>or must I actually have a 'coil-resistor' pair for each

>tweeter?

The answer is: "your choice." Two access panels or eight tweeters :-) If you are uncomfortable with removing the crossover access panel in each cabinet, then use four coils and four resistors and remove only the four tweeters. I would guess, and Ken can verify, that 10-Watt resistors would be sufficient, if four resistors are used. The 20+ Watt resistor would be for the case of installing one resistor and coil. Circuit diagrams with the two options are shown in the attached figure. It is the same one Roy posted, but shows a magnified portion of the diagram.

>Secondly, where can I get these components cheap enough?

Frankly, (pun intended) you will find Parts Express shipping charges are about the same as the parts! 18-gauge air core inductors cost about two bucks and resistors about a buck. You might ask Minh if there is a local place and avoid shipping, but then again that's two subway fares ... :-)

>to use silver solder or 60/40?

What you refer to as "silver solder" is not what a plumber would call it. You are referring to the 96%-4% Tin-silver solder sold in Radio Shack and Parts Express for a two or three bucks. It has a very low melting point and is sold for two reasons: for those who do not wish to breathe lead oxide vapors, and for soldering silver-plated copper wire (which you do not have). Tin-lead solder, either 60/40 or 63/37 cannot be used on silver-plated wire as silver diffuses into tin and leaves voids making the long-term resistance high or possibly open. That is not the issue here, you have no silver-plated wire! You can use either tin-lead or tin-silver, depending on your concern for breathing in lead vapors.

>Thirdly, my LST cabinets have

>the 'rear-passage' cross-over panel, would it be best

>accomplished to enter from here, or go from the front?

Your choice -- panel and tweeters both need sealing putty.

>All and any input from any and all out there is much welcome.

>Must be somebody's friend, Frank Marsi

Please ask if you have more questions! Eventually, someone will answer -- most of these guys have paying jobs and/or families!

Cheers,

2651.txt

post-100900-1188423253.jpg

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It is probably appropriate to remind those not skilled in circuits that the four tweeters are in a series-parallel arrangement. Thus wiring a 0.07 mH coil in parallel each tweeter is the same as attaching one in parallel with the wires driving the entire array. Ditto for the resistors.

Cheers,

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Hey Frank,

John has covered the essentials, although I doubt the part about my "golden ears"...more like "olden ears" (like most of the rest of us :-)).

I've been playing around with the .07mh coil in a pair of 3a's for about a week (see pics), and for all practical purposes it seems to be worthy of the effort. It certainly is MUCH better than without. (Those 8 AB Tech tweeters must have been making your fillings fall out!) It should be noted that Ken mentioned the 15 ohm resistor as an afterthought as a possible addition for the LST. Having tried it in the 3a, it was certainly not needed in that model.

My only quibbles are some sibilance or high frequency diffraction issues. I have been experimenting with some felt diffraction rings and different room placements to try to figure it out. The diffraction rings may work better than the 15 ohm resistor should the tweeters need a bit more taming. They really suck some life out of the tweeter. I'm trying to determine if it is too much. It should be noted that earlier versions of this tweeter had foam on the faceplate.

As for parts, I am putting together a Parts Express free shipping order (over $99) very soon. You are only 3 hours south of me, so I could order your stuff and send it to you more cheaply. Also, the .07mh coils will need to be unwound from .10mh coils. The Parts Express 18ga Jantzen inductors are the easiest to work with, and I can adjust them to the proper value for you.

I also like the Kester "44" 63/47 solder for non-silver wire. It is very easy to work with. At our age I wouldn't worry about a little lead solder exposure unless you plan on snacking on it or smoking it :-).

Send me an email if I can be of assistance.

Roy

post-101150-1188442512.jpg

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Johnieo and RoyC and Jerry and Vern and rrcrain, this info is great and seemingly what I’ve been after all these months/years. I’m away this week-end , when I return I’ll be in touch. Thanks much for all.

FM

P.S. The more simple the diagrams and schematics, the better.

Values and such particulars as possible up-graded wire specs and etc. are major to me at this point so keep those "cards and letters coming", as I intend to win this battle of "replacement tweeters for AR speakekers" once and for all! Thank you, God bless you.... and America too! On a serious note; I'm often hesitant about keeping things too original if there's enough dialog to 'show' and that I can brag of it's 'naturalness' and 'electrics' making things better; I'm strongly 'in' then too.

FM

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>Frank,

>

>The only thing that would be a likely improvement is the

>replacement of the old crossover capacitors. I would leave the

>wiring as is.

>

>Roy

I agree with Roy, but would add one detail. Check the old wiring and replace anything that is corroded.

My comments on soldering were based on 6 years as an electronics bench tech and certified mil spec solderer. That was life time ago or so it seems.

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