LST-2 tweeters

[Guest dogmeninreno]

AB Tech is offering some 4 ohm replacement tweeters for the LST2. I questioned them and Carlos says they used to make these 8 ohn units for AR by adding a 4 ohm resistor in series with the 4 ohm tweeter. Anyone ever tried this or better yet A/B between an original and a resistor unit? Something doesn't seem right here? Dale

[frankmarsi]

I'm looking for LST tweeters. I have newer tweeters on my 3as a factory replacement circa 91. Let's talk, maybe we'll get somewhere.

See web site

http://www.frankmarsi.CityMax.com/

E-Mail: mailto:: FMARSI@earthlink.net

[dynaco_dan]

Hi there

I would check out ebay, etc for AR5 tweeters or a destroyed ARLST/2 cabinet.

Something don't sound right with the added 4 ohm resistor in series.

If that comment is true, then adding a 4 ohm resistor to a true 4 ohm tweeter, actually 2.75 +/- ohms, and you have a lot of loss through the resistor.

That is very poor engineering to say the least.

I have, still un-packed, a AR tweeter with a power resistor either hot glued or epoxied across the rear of the magnet. I believe it had a label on the back saying it was a replacement unit. Until I find it I am willing to bet it is a 8 ohm tweeter.

The resistor when soldered parallel to the tweeter would give 4 equivalent ohms, I'm sure.

If I remember correctly the resistance is down around 5.75 +/- ohms for the 8 ohm tweeter and 2.75 +/- for the 4 ohm tweeters.

When I first saw it I immediately thought, how smart, now only one tweeter to stock, it also serves two purposes.

It certainly would make better business sense making an 8 ohm speaker and attaching the resitor.

This also may have been a trial project. You never know. Eh?

Good luck.

>AB Tech is offering some 4 ohm replacement tweeters for the

>LST2. I questioned them and Carlos says they used to make

>these 8 ohn units for AR by adding a 4 ohm resistor in series

>with the 4 ohm tweeter. Anyone ever tried this or better yet

>A/B between an original and a resistor unit? Something doesn't

>seem right here? Dale

[Guest dogmeninreno]

>I'm looking for LST tweeters. I have newer tweeters on my 3as

>a factory replacement circa 91. Let's talk, maybe we'll get

>somewhere.

>See web site

>

>http://www.frankmarsi.CityMax.com/

>

>E-Mail: mailto:: FMARSI@earthlink.net

>

>

I seem to recall reading that the AR2ax had 8 ohm tweeters in their later models also. 3/4" units...Dale

[dynaco_dan]

You are correct Dale, thank you.

The 2ax's also used the 3/4" 8 ohm tweeter.

My memory is not as good as it once was.

Now where was I?

I never owned 2ax's and so I don't remember if they used the larger old style tweeter in early production units or not.

They also may have been manufactured with the wires on the front and also rear terminals, the same as the 4 ohm tweeter.

Good luck again.

>>I'm looking for LST tweeters. I have newer tweeters on my

>3as

>>a factory replacement circa 91. Let's talk, maybe we'll get

>>somewhere.

>>See web site

>>

>>http://www.frankmarsi.CityMax.com/

>>

>>E-Mail: mailto:: FMARSI@earthlink.net

>>

>>

>I seem to recall reading that the AR2ax had 8 ohm tweeters in

>their later models also. 3/4" units...Dale

[mluong303]

>>I seem to recall reading that the AR2ax had 8 ohm tweeters in

>>their later models also. 3/4" units...Dale

Happy Holiday to Dale and all AR Fans

If AR-2ax did use 8 Ohms version of the 3/4" paper dome tweeters such as the one used in AR-5 speakers, does this mean AR actually made two versions of 1 3/8" Orange hard dome alnico V magnet tweeters? 8 Ohms for the early version of AR-2ax in compare to the 4 Ohms units for the AR-3 and AR-2 speakers at that time. I did not remember AR did any change in the crossovers for earlier and later AR-2ax at all.

I had run across some AR tweeters rated at 4 Ohms but when take a reading I got 5 to 6 Ohms DC resistence. Why is that?

Is there anyone can tell for Sure what the original Western Electric 755A driver was rated at? 4 Ohms or 8 Ohms? Also the Altec 755A that used in the AR-1 speakers to mate with the Alnico V magnet 4 Ohms woofer, are they rated at 4 Ohms or 8 Ohms? If you are Lucky enough to own even a single Western Electric 755A unit and measure the DC resistence, very likely you will see 6+ Ohms. For all the one who are rich enough to purchase the AR-1 speakers and gutted out the Altec 755A drivers for the pride of ownership, any DC resistence reading aboue 2.8 Ohms? I had heard of some units that measured as low as 1.3 Ohms.

4 Ohms vs 8 Ohms already puzzle me enough and NHT comes up with the 6 Ohms tweeters in their design like some of the Euroupian made drivers. What is the advantage?

Any knowledgable answers will be appreciated.

[dynaco_dan]

Hello there.

AR did make 4 and 8 ohm tweeters in both designs.

To look at them they would appear identical physically but the 4 ohm would measure about 2.75 ohm and the 8 ohm about 5.75 ohm.

On installing the wrong model, such as placing the 8 ohm version in an AR3a, the level of the highs would be down. Conversely if the 4 ohm version was installed in the AR5 the highs would be brighter.

I expect that some sellers were born after the end of the golden era and have only read most data that they know.

I've seen on ebay where the seller has stated their tweeters were removed from an AR3a and can be used in the AR3, 3a, 2ax, AR5, LST, and LST/2. In fact they were incorrect.

There has been written on this site about the AR2ax changes and how marketing determined that a change in model number may affect sales.

Tom or Steve may want to comment on this.

So, if you have a reading of 5 - 6 ohms you have an 8 ohm version.

Good luck.

Merry Xmas and all the best in 2005 to everyone.

>

>>>I seem to recall reading that the AR2ax had 8 ohm tweeters

>in

>>>their later models also. 3/4" units...Dale

>

>

>Happy Holiday to Dale and all AR Fans

>

>If AR-2ax did use 8 Ohms version of the 3/4" paper dome

>tweeters such as the one used in AR-5 speakers, does this mean

>AR actually made two versions of 1 3/8" Orange hard dome

>alnico V magnet tweeters? 8 Ohms for the early version of

>AR-2ax in compare to the 4 Ohms units for the AR-3 and AR-2

>speakers at that time. I did not remember AR did any change in

>the crossovers for earlier and later AR-2ax at all.

>

>I had run across some AR tweeters rated at 4 Ohms but when

>take a reading I got 5 to 6 Ohms DC resistence. Why is that?

>

>Is there anyone can tell for Sure what the original Western

>Electric 755A driver was rated at? 4 Ohms or 8 Ohms? Also the

>Altec 755A that used in the AR-1 speakers to mate with the

>Alnico V magnet 4 Ohms woofer, are they rated at 4 Ohms or 8

>Ohms? If you are Lucky enough to own even a single Western

>Electric 755A unit and measure the DC resistence, very likely

>you will see 6+ Ohms. For all the one who are rich enough to

>purchase the AR-1 speakers and gutted out the Altec 755A

>drivers for the pride of ownership, any DC resistence reading

>aboue 2.8 Ohms? I had heard of some units that measured as low

>as 1.3 Ohms.

>

>4 Ohms vs 8 Ohms already puzzle me enough and NHT comes up

>with the 6 Ohms tweeters in their design like some of the

>Euroupian made drivers. What is the advantage?

>

>Any knowledgable answers will be appreciated.

[Steve F]

>There has been written on this site about the AR2ax changes

>and how marketing determined that a change in model number may affect sales.

>

>Tom or Steve may want to comment on this.

As I have written on this site previously, the AR-2ax was changed in 1970, quite extensively.

First-generation 2ax's had an alnico magnet woofer with cloth surround, the CTS 3 1/2" midrange (which was also used as the tweeter in the AR-4), and the 8-ohm version of the 1 3/8" dome tweeter. Crossover frequncies were 2000 and 7500Hz. They also had an older-style grille cloth, with the square "AR Inc" logo in one corner and a gold, script "a" in the other corner.

Second-generation 2ax's (above serial number 125,000) used a new woofer (the same as the one in the AR-5, with the foam surround), the same 3 1/2" mid as before, and the 8-ohm 3/4" dome tweeter (also borrowed from the AR-5). Crossover frequencies were lowered down to 1400 and 5000Hz. The logo was changed to the one-piece brass with red lettering, the same style as the AR-3a.

As you can see, except for the actual midrange driver itself, everything else changed--the woofer, the tweeter, the crossover, the grille cloth, and the logo. Companies have changed model numbers for a lot less than this, yet AR stuck with the "2ax" designation--probably because the market equity of the 2ax was very strong and AR didn't want to risk losing it. Sort of like when Ford introduces a new Mustang or Honda introduces a new Accord. It may be a completely new car, but the company retains the name for the sake of market continuity and customer familiarity .

Steve F.

[Guest ARDave]

Hi Guys:

First time post. I have a pair of AR-LST-2s my father purchased new in 1977 or 1998. They are serial numbers 9592 and 9601. The cabinets are in very nice condition. Of course the woofers need to be refoamed. The tweeters in one are dead. I carefully removed and checked each one with my ohm meter and they open. They are marked 200013-2 "Made in the USA". If I remeber correctly tweeters in the other cabinet were replaced in 1991 or 1992. These tweeters are good and are also marked 200013-2 "Made in the USA" They measure just under 6 ohms. The good tweeters look a slightly different. The terminals on the front face stick up perpendicular to the flat face plate of the tweeter. On the original tweeters the terminal are bent back against the face plate.

So the question is what to do with these. Anyone have good working 20013-2 tweeters for sale. Should I buy 3 new tweeters with resistors from AB Tech? Should I consider selling my three good tweeters and buying six of the new tweeters with resistors from AB Tech?

After I get done fixing these I have a pair of AR-3a my dad purchased new in 1972 to restore.

[frankmarsi]

>Hi Guys:

>First time post. I have a pair of AR-LST-2s my father

>purchased new in 1977 or 1998. They are serial numbers 9592

>and 9601. The cabinets are in very nice condition. Of course

>the woofers need to be refoamed. The tweeters in one are dead.

>I carefully removed and checked each one with my ohm meter and

>they open. They are marked 200013-2 "Made in the

>USA". If I remeber correctly tweeters in the other

>cabinet were replaced in 1991 or 1992. These tweeters are good

>and are also marked 200013-2 "Made in the USA" They

>measure just under 6 ohms. The good tweeters look a slightly

>different. The terminals on the front face stick up

>perpendicular to the flat face plate of the tweeter. On the

>original tweeters the terminal are bent back against the face

>plate.

>So the question is what to do with these. Anyone have good

>working 20013-2 tweeters for sale. Should I buy 3 new tweeters

>with resistors from AB Tech? Should I consider selling my

>three good tweeters and buying six of the new tweeters with

>resistors from AB Tech?

>After I get done fixing these I have a pair of AR-3a my dad

>purchased new in 1972 to restore.

Hi there! I've purchased the AB-Tech 4 ohm tweeters and they measure about 4.2 ohms. They have a higher output and sound more like the AR 1991 version tweeter replacement. I use these replacements on my AR-LST's and AR-3a's. When I finally get to re-doing my AR2ax's, I'll probably use these also, but with a 4 ohm resistor in series with hot glue. For the amount of extra output, better power handling, and for the money I can't think of a better option.I have mixed both original and replacements in the same cabinets (LST) and live with a nice blend of new and old, although I may switch to all new at some point. To para-phrase another member: I love my classic car, but I had to buy newer tires to drive it. Any opinions out there? While I'm here, anyone have 2 circa '71-'72 '3a' woofers for sale?

frankmarsi@verizon.net