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

In this bedroom system I keep the amp(s) under the bed and generally leave them on 24/7.

@peter_s Would you want to do that with a Class A amp?

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+ 

@mspot is correct about 24/7 powered up.

@mijostyn gives accurate information about the LS 3/5A characteristics.  I just do not know how crazy loud or how much bass you will demand for a bedroom system from an understandably small monitor meant for near field moderate levels.

Thanks All.  I agree that a Class A amplifier left on 24/7 under my bed is a bad idea!  The bedroom is small, and mostly I'm trying to TAME bass nodes.  That's a benefit of the Weiss 501 - I am able to use the built in DSP for that purpose.  With my current Raidho XT-1's, I also tune the bass by adding a small KEF subwoofer. 

I would like to also be able to use my LS 3/5A's in the bedroom system. I think they sound very good with the AGD Audion (that's why I kept them), but I am dealing with a little bit of sibilance.  So the question is: is the sibilance a characteristic of the Falcon Gold Badges or is there something about the amp/speaker combo that can be improved (no sibilance with the AGD's driving my Raidhos).  I was thinking that maybe it is the impedance matching, or maybe the LS 3/5A's were designed for an amp with less high frequency extension.

@celtic66 - you nailed it.  Small bedroom, lots of bass reinforcement... don't need much output.  Perhaps that changes the amp matching discussion just a bit...

@mijostyn if I ever use these speakers in a "normal" sized room, your approach sounds good.  Right now my room is 8x12 - pretty small.

But the theme here is very consistent - lots of current needed!