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Best Amplifier for LS3/5a

Happy New Year All!  Seeking advice from LS3/5 enthusiasts!  I have tried a number of these speakers (Graham, Harbeth, Falcon and KEF LS50's (if that counts)) - and to me the Falcon Gold Badge really stood out. It's been a while now since I did the comparison, so I don't remember all the details - but I felt that the Falcons were the most musical, engaging, open and did NOT have bloated bass (important for a small room)!  I've held on to a pair for my bedroom system, but I don't think that my current bedroom amps (AGD Audions, which I love with my current Raidho XT-1 monitors) are the best match for them.  I get a bit too much sizzle on the top and some associated sibilance.

Herb Reichert (Stereophile) seems to love these speakers, and his review notes that the Parasound A21+ was too dry with these speakers, but he really liked the Line Magnetic LM-518 IA.  That's not going to work for me!  In this bedroom system I keep the amp(s) under the bed and generally leave them on 24/7.  If possible, I prefer a balanced design, as I want NO HUM in my bedroom and my DAC/Pre (Weiss 501) has both balanced and RCA outs.

Based on the intended setup, I think balanced solid state would make the most sense. Amp selection might be influenced by the speakers having 15 ohm input impedance.

Any suggestions?  Thanks, Peter

peter_s

Showing 3 responses by mijostyn

mijostyn's avatar
mijostyn
8,223 posts
 

Hi Peter,

I have set up, must be over ten LS3 5A systems. I worked in a high end store when the Rogers was released back in the late 70s. 

The LS3 5A is VERY inefficient, like 83 dB/watt @ 1meter. If you are not using subwoofers I would recommend a 200 watt/ch SS class A amp. HOWEVER the only way to use LS3 5As is with stereo subwoofers and a two way crossover, preferably digital. You want to cross at 100 Hz. Taking that bass away from the LS3 5As lowers distortion DRAMATICALLY and increases headroom also dramatically. You can also get away with a smaller amp, a 100 watt class A amp, tube or SS will do fine. I would use a Pass XA100.8. Another great amp would be the Parasound JC 1+ 

mijostyn's avatar
mijostyn
8,223 posts
 

@peter_s 

Then you use small subwoofers. You are doing this as much to lower distortion as to add bass. The LS3 5A was envisioned as a monitor for remote set ups. Imagine a couple of guys in a van like the Rolling Stone Mobile Studio. 

mijostyn's avatar
mijostyn
8,223 posts
 

@peter_s 

The solution is to get a stand alone two way crossover either analog such as the JL Audio unit or digital such as the MiniDSP unit. You connect the preamp outs to the crossover then the crossover to the amplifiers and on to the speakers and subs. This is not an imaginary tweak. This is a seriously big improvement. You will gain at least 10 dB in headroom (twice as loud) and lower distortion in the Falcons by an estimated 50%. 

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