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Rotten
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Power Amp Recommendation for Infinity QLS

I recently inherited a set of humongous Infinity QLS speakers. They were sitting in my late uncle-in-law's living room since the mid-70s, when he bought them new. They look to be in good condition, albeit pretty dusty.

Can anyone recommend a moderately priced power amp with enough power to drive these? I'm new to the stereo world, but love '70s progressive rock and would have fun building a system. Thanks!!

Tedrick
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Re: Power Amp Recommendation for Infinity QLS

You can find a lot more information on these speakers at Infinity Classics, including owner's manuals. Like most early Infinity's, these are power-hungry speakers, so for rock I would think you would want at least 200 watts per channel. The amp should also be a high current design, and should be stable driving a 1 or 2 ohm load. You can find a lot of good used amps that will work with these. I might suggest Adcom, B&K, or Parasound, just to name a few. Personally, I like Adcom...a 200wpc GFA-555 can be had for $400-500 off Audiogon or eBay.

To make these speakers REALLY sing, you'll want to bi-amp them, but you can always build up to that later .

Good luck with the QLS's .

Jan Vigne
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Re: Power Amp Recommendation for Infinity QLS

Firstly, I hope you have a reasonably large room for these speakers. You'll need to sit in the far-field to get the best sound from my experience. And do not cram these speakers into a space, they need to be set up to work within the room.

I would start with a Citation 16s, recently reviewed in another magazine. Period sound which is not far from what today's manufacturers are selling in many aspects. Very high current and capable of low impedance drive. You should be able to find this for a reasonable price and it can still be repaired if necessary. The "V" shaped display will be very desirable in any listening room as many audiophiles still remember the look of this amp with the lights out.

Another amp to enjoy with the lights off would be a McIntosh MC2300. Play it loud and imagine you're Jerry Garcia with another 49 of these amps stacked behind you.

If the 2300 is a stretch monetarily, any used Mac amp of more than 150 watts should do the job though without the panache of the 2300. They can also be repaired and I wouldn't consider any amplifier that can't be serviced. More than a few amplifiers which were paired with the QLS met their demise trying to coax decent sound out of these boxes. More than a few of those amplifier companies are no longer in existence. Servicing an amplifier produced by a company no longer in business can be a frustrating effort.

The Mac and the Citation are different ends of the solid state spectrum. And, then, there are always MOSFET amps to consider. You might want to have an idea what end, or at least which direction, you want to head towards before setting out to buy an amp which merely plays along with the Infinity's. The Infinity's have a defintie character and it is best to play toward that sound rather than just stick an amplifier into the mix which fights what the QLS is trying to achieve. Bi-amping was the best way to make these speakers work. What did your uncle-in-law use? Who got the amp?

CECE
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Re: Power Amp Recommendation for Infinity QLS

check out E-bay search HAFLER get some P500 or dh500....then you can send them to AVA and make them into 21st century sonic bliss units www.avahifi.com

CECE
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Re: Power Amp Recommendation for Infinity QLS

Sumptin' like this...then ya run em in MONO, so each P500 is 1200-1400W of AVA bliss, throuhg AVA Ultra Hybrid phase inverter I use em they are superb. Watts, there is no substitute...anything less than about 4800W RMS capable is under powered IMHO. If ya want it REAL, it takes watts and cones.

mjalazard
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Re: Power Amp Recommendation for Infinity QLS

One caveat with Infinity speakers...most of the cones used in the 70's and 80's by Infinity used foam surrounds, which can decay. Carefully check all your cone drivers by gently pushing on the foam edges. If they crack or disintegrate, you will need to have them repaired.

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