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Amp for LST


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Hi Steve;

I purchased an Adcom 545 mkII on ebay from a guy in Utah - affliated with a dealer, with no problems. Before bidding on ebay, read the feedback of the seller carefully, especially the Complaint and Neutral.

With Adcom, at the worst, you can send the amp to Adcom for repair/upgrades. It may cost you, but you will not be totally up the creek.

Based on the reviews and the speed at which Adcom removed it from the catalogue, I would avoid the 5800. Someday, I plan to get a 5802 to go with my AR9 speakers. If you can afford it, that is the way I suggest you go.

In the mean time, I am vertically bi-amping them with a pair of Onkyo TX8500 receivers (ca.1977). If you are on tighter budget, I would consider vertically bi-amping a pair of Adcom 545 mk II or 5400 amps. Buy one now, buy a second when the budget allows.

See the AR9 literature on this site for AR's discussion on bi-amping.

You could also horizontally bi-amp, using your Pioneer's amp for the mids and tweeters, and an Adcom 545 II or 5400 for the woofers. The Adcom's power supply is much better equipped to handle the classic AR woofer than any reciever.

Nigel

nfmisso@home.com

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Hi, I have a pair of LSTs that I am currently powering with a Pioneer receiver rated at 100w/ch. I am thinking of moving them to the basement where I will be able to listen to them a litte more "fully". I have hesitated to crank these speakers up to whewre they are really room filling for fear of clipping. I have blown tweeters on AR speakers befors, and I listen to Jazz and Clasical, not rock.

I have a good receiver with pre outs I can use but am wondering about amplifier. The LSTs are fairly inefficient, the basement is large carpeted and pretty dead. Adcom seems a good moderate cost approach. Do any have opinions on the 5400 (125w/200@4ohms) versus the 200w versions (555, 5500) the 250 w version (2800) and the 300w (2802). It seems a good deal can be had on the 2800 for around $600, but I hear that they have some problems with mechanical hum and fan noise. The 2802 is pricey as yet. The 5500 is also $600+ used. The 555 is $300-400 used but seems to get a bad rap as being harsh. I am not looking to spend $ for the sake of spending or impressing anyone. Is the 555 almost as good as the others for all practical purposes? And would a 5400 even be sufficient to fill the room (not earsplitting, you all know the difference) with enough margin to avoid clipping.

Final question, how risky is it to buy these on ebay or audiogon. If you get one that has a lot of hum or some other problem you have a time consuming mess on your hands. Better to buy new or used from a dealer???

Thanks Steve

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Maybe a big ballsy old Dynaco 400! You want a high power amp to do the LST's justice. I let a friend of mine use my pair and he has a big SoundCraftsman amp. He said it was the first set of speakers that had no problem with all his wattage. If I remember right the LST's will take 1000 watt pink noise bursts- pretty impressive!

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I saw an Adcom 555 for sale locally a couple of days ago and bought it reasonably to see if this made a difference. It did. The speakers seemed to open up with this amplifier. Very nice.

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Steve,

For driving the AR 12" woofer, you need an amp that's biased to run well at low impedences. Impedences can drop as low as 2.8 ohms at some frequencies with the 12"... a real torture test for most amps. I was a big fan of AR back in the olden days when I worked in the audio business. I had the opportunity to run my AR 10pi's with a lot of different amps, and the best sounding solid state amp I ever encountered for the AR was the Harman Kardon 16a. Thrives on low impedence, completely dual power supplies, extended frequency response, massive heat sinks, and a really sweet sound.

There's a real clean looking 16a up on eBay right now and it's going for around $350. I'm sure it would sound awesome with your LSTs.

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