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Is my amp up to driving Maggies?

67.103.110.13

I'm wondering whether my aging but trusty Arcam A85 integrated amp is up to the task of driving Maggies, specifically the LRS. Specs in the manual list power at 85 watts into 8 ohms continuous power, both channels driven. It's 140 watts into 4 ohms, one channel driven. But here's what Stereophile's John Atkinson found in his review several years ago:

"Fig.7 shows how the A85's distortion rises with output power under continuous drive with both channels driven. The nominal clipping point (1% THD+N) is quite a bit higher than specified, at 120W into 8 ohms (20.8dBW) and 200W into 4 ohms (23dBW). However, into 2 ohms with one channel driven...the A85 turned itself off at 200W output." (See link.)

According to his findings, it seems to me the amp would be up to the task, but I'm hoping some of you more experienced Maggie vets could confirm or deny that. THANK YOU.

https://www.stereophile.com/content/arcam-diva-a85-integrate (Open in New Window)

Follow Ups:

RE: Is my amp up to driving Maggies? - triamp 19:46:34 09/15/21 (0)
Amplifier power and loudness are logarithmically related. That is to say, in order to make a speaker play TWICE as loudly, you need TEN TIMES the amplifier power. This is just physics and the nature of human perception. Which is to say that there is not a lot of audible difference between, say, an 85 watt amplifier and a 120 watt amplifier.
So that is one thing to keep in mind.
Another thing to consider when selecting an amplifier to drive Magnepan speakers is something that Wendell Diller ( of Magnepan ) told me: magneplanars like amplifiers that have good current delivery capability. The ability of an amplifier to deliver current into a reactive load like a speaker is dependent on several things, most of which you can't find any information about anywhere for a given amplifier. The two things you CAN learn about amplifiers are their power output capacity, and their output source impedance.
Generally speaking the greater the power output of the amplifier, the better it will work with Magneplanar LRS- but keep in mind that physics tells you ten-times-the-power-for-twice-the-loudness, so you want an amplifier that is reasonably powerful.
And, again speaking in general, the lower the source impedance, the better the amp will work with Magneplanar speakers. ( lower source impedance translates to higher damping factor, and generally speaking, higher current delivery ability) The stereophile review noted that this Arcam amplifier has an output source impedance of 0.25 ohms, which is good. But if you compare that to an amplifier like the Benchmark AHB2 ( https://www.stereophile.com/content/benchmark-media-systems-ahb2-power-amplifier-measurements ) at 0.09 ohms, you can make an educated guess that the Benchmark would sound a little better. But, at this level the improvement between an amp with a 0.25 ohm output source impedance and one with 0.09 ohm will be fairly subtle, everything else being equal.
My guess is that your Arcam amp will work just fine for "normal listening levels" with the LRS, but that some other amps will be slightly better, but unless you go to a hugely powerful amp you are not going to find major differences.
I think that room placement, room volume and structure, wall and floor treatment ( if any ) and listener position will make a much larger difference in sound quality than trying to move up the ladder in terms of amplifier capability.

Science doesn't care what you believe.

Edits: 09/16/21 09/16/21
RE: Is my amp up to driving Maggies? - pictureguy 14:30:39 09/15/21 (0)
What do you have to loose?
NOTHING....ypu already own the amp.

I drove MG-1s with a Kenwood integrated of 80x2@4. Every heard of a KA-7100? Just not at nose-bleed levels. The extra 3+db when I went with a Carver Cube was appreciated, though.....

You can recoup some power by low-cutting the panels and using a sub.....
Too much is never enough
yup - farfetched 09:29:53 09/05/21 (2)
currently using a 55w ss brit integrated myself. On the LRS's. The only thing it bristles at is really loud. But that is not what I do except rare days. I listen to a lot of piano, classical, violin.

You will definitely want a good powered sub to handle <40hz. But I say go for it unless you got some huge room that will soak up watts.
/ optimally proportioned triangles are our friends
- RE: yup - Mcmusicman 17:03:43 09/06/21 (1)
  If you want to get the most out of your Magnepan panels, ask the vendor of any amplifier you are considering to give you the capacitance specification.
  You are looking for 80,000 or more AuF. This is more important that Watts for a number of reasons. While Current (A) is needed, the capacitance to handle dynamic passages will differ greatly among manufacturers that do not want to spend the money in the build. Some examples that get there and get there well: Pass 250, Bryston 4B3, Parasound JC5 just to name 3. Good Luck.
  
  Edits: 09/06/21
  - RE: yup - farfetched 17:22:38 09/06/21 (0)
    it's an audiolab 8000a, which was refreshed in 2001. It needs another refreshing. My music life goes in swings. This is a quiet spell. I have a BAT vk-500 (w/ the extra capacitor boards) in drydock.
    
    / optimally proportioned triangles are our friends
Thank you, everyone - hesson11 12:41:18 09/04/21 (0)
I appreciate your responses. In broaching the topic of Maggies and amplification, I knew I probably shouldn't expect unanimity! But your replies will certainly help inform my decisions. Thank you!
My experiences driving LRSes - Mike K 11:20:30 09/04/21 (0)
When I got my LRSes, I drove them with a Rogue Audio Cronus Magnum II. At
first I thought everything was fine, but eventually I came to think the
amp was straining a bit. So I bought a PS Audio Stellar stack. And the
strain disappeared completely. Rogue - 100wpc @ 4 ohms; Stellar M700s -
700wpc @ 4 ohms. Very big difference in favor of the Stellars. Draw your
own conclusions.
Whether or not you can observe a thing depends upon the theory you use. It is the theory which decides what can be observed. - Albert Einstein
RE: Is my amp up to driving Maggies? - FX35 10:47:51 09/04/21 (0)
"Is my amp up to driving Maggies?"

Maybe... probably, but so will plenty of other cheap amps. Being able to drive Maggie's is one thing, making them "sing" and reveal their full potential is a totally different ball game. Driving Maggie's with that amp will make some noise, but thats about it.
RE: Is my amp up to driving Maggies? - Joe Schmo 08:01:14 09/04/21 (0)
I have used that exact amp with 1.6s. It will work fine. When I switched from the A85 to a high power amp with a massive power supply (Krell FPB-200) however, the improvement in performance was nothing short of astonishing. By comparison the A85 sounded bright with a very thin bottom end, less dynamic slam and overall a flat, less detailed sound stage. Maggies love power! As Wendell has recommended before, a good rule of thumb is a powerful class A/B solid state amp the doubles in output power down to a 2 ohm load is the ideal amp for Maggies. I now use a Pass Labs X150.8 with 1.7i speakers and that combo is sublime! The A85 will get you going fine, but consider something with more power and finesse down the road to get the best from them. Good luck and enjoy!
-Joe

They're not that big!
if you keep it within reason - mbnx01 15:46:11 09/03/21 (0)
You'll be fine. No Black Sabbath concerts, got it?

PS: That's a real nice amp.

'A lie is halfway around the world before the truth gets its boots on'. -Mark Twain
RE: Is my amp up to driving Maggies? - G Squared 12:33:15 09/03/21 (1)
My amp is rated 200/400 WPC 8/4 ohms. Good headroom in my set up where I roll the input to amp that drives the LRS below 70 Hz. Running them full range my amp has just enough gas.
Gsquared
- Thank you, and I should add... - hesson11 15:40:04 09/03/21 (0)
  Thanks for the enlightening info.
  
  I should have added that I seldom push my speakers beyond the low 70s dB. Thanks again.

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