Guest Posted March 7, 2003 Report Share Posted March 7, 2003 My uncle Joe introduced me to AR when I was young boy. The year was 1974 and he had picked up a pair of LST-2s along with a Luxman Amp, tuner and Thorens turntable. Being the son of a dairy farmer from the woods of Maine, I was in awe of my big city uncle and his stereo system. That experience soon led to a Stereo Review subscription and dreams of a Boston loft stocked with the finest audio equipment. So after 27 years, moving the hell out of Maine, two kids and a pair of PSB Golds, old uncle Joe called me up one day and asked if I had any interest in his “old ARs.” “The woofers are rotted, some of the tweeters are blown and the cabinets are scratched all to hell…you want em?” Well, to make a long story short, they’re now sitting on a workbench in my basement. The woofer surrounds have been replaced, beige grill fabric from Dale in Reno has been applied and the cabinets look fantastic after a lot of elbow grease. Now the real work begins. We’re all familiar with the sources of AR replacement drivers. The challenge, as far as I can tell, is all available AR replacement tweeters and midranges are 4 Ohm and the LST-2, along with the AR5, use 8 Ohm drivers. I have two questions (please forgive my ignorance):1) If 8 Ohm OEM tweeters and mids are not available, is it possible to replace all 12 original 8 Ohm tweets and mids with the available 4 Ohm drivers with or without crossover modification? It’s obviously a significant investment but one I’m willing to make if it’s feasible. 2) What do you make of the reply from the folks at Simply Speakers? Does this make sense to anyone?-----Original Message-----From: ALSAM1@aol.com [mailto:ALSAM1@aol.com]Sent: Wednesday, March 05, 2003 10:29 AMTo: info@simplyspeakers.comSubject: ACOUSTIC RESEARCH 1210084-0 TWEETER-3/4" DOME Can you tell me if these are 4 or 8 Ohm? Thank youSubj: RE: ACOUSTIC RESEARCH 1210084-0 TWEETER-3/4" DOME Date: 3/5/2003 9:36:05 PM Eastern Standard TimeFrom:info@simplyspeakers.comTo: alsam1@aol.com Hello, All older AR units are 4 ohm. Please give us a call or e-mail if you need more information.We will be happy to help you.-----Original Message-----From: ALSAM1@aol.com [mailto:ALSAM1@aol.com]Sent: Wednesday, March 05, 2003 9:51 PMTo: info@simplyspeakers.comSubject: Re: ACOUSTIC RESEARCH 1210084-0 TWEETER-3/4" DOME I have a pair of LST-2s (circa 1974) and understand they are 8 Ohm. Thanks anyway.Subj: RE: ACOUSTIC RESEARCH 1210084-0 TWEETER-3/4" DOME Date:3/6/2003 3:18:04 AM Eastern Standard TimeFrom:info@simplyspeakers.comTo: alsam1@aol.com Hi, The cabinet impedance will be 4 ohm. The midrange and high frequency units are 8 ohms each but do not determine cabinet impedance since the WOOFERS determine this specification. If you need replacement tweeters, these are the correct units. Part #1210084-0. Price is $79.50 each. Please give us a call or e-mail if you need more information. We will be happy to help you. Link to comment Share on other sites More sharing options...
Guest Brian_D Posted March 7, 2003 Report Share Posted March 7, 2003 It sounds like the folks at Simply Speakers have their heads up their rears. "Woofer impedance determines cabinet impedance..." this is, at the very least, simplifying things beyond reason. There are far too many factors to say this. I would definitely ask for an explanation, or discount these people as anything but driver salespeople.In answer to your question, changing the DC resistance of your drivers will shift the crossover point of the circuit. You must replace the drivers with others of the same impedance, or you must compensate. (putting a resistor in series will increase impedance, parallel will decrease it... you should get a speaker building book, it will explain the law of ohms to you... Vance ####asons "Speaker building cookbook" is awsome)Good luck!Good greif... his name is spelled dee ie cee kay. D i c k a s o n. Link to comment Share on other sites More sharing options...
administrator Posted March 7, 2003 Report Share Posted March 7, 2003 Ok ok .. this has been a busy morning. I'm going to kill the "bad word" filter. It was on by default. Mark Link to comment Share on other sites More sharing options...
ar_pro Posted March 7, 2003 Report Share Posted March 7, 2003 The LST-2 is a superb design that's definitely worthy of proper restoration - you owe your uncle a nice bottle of wine!It's imperative to replace the damaged tweeters with the correct parts - the crossover's performance is contingent (among other things) upon the designed impedances of the drivers. To be honest, I would suggest a long-term surveillance of eBay for LST-2 or AR5 tweeters & mids - you'd then have *exactly* what you need, and what this system deserves!Check out Parts Express (catalog or website) for a quick primer on how driver impedance changes a crossover's parameters - it's useful info when it comes to restoring vintage systems. Link to comment Share on other sites More sharing options...
Guest Posted March 8, 2003 Report Share Posted March 8, 2003 Brian,Good thing there's an "e" in you name;). Thanks for the reply. Inserting resistors in the path sounds like a simple and fairly inexpensive option. Is there any reason to think the sound of this configuration would be substantially different than that of an original driver - tweeter or mid? Link to comment Share on other sites More sharing options...
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