Power/Current: How much is realistic?

Rebuilding my system, Just got a pair Martin Logan 13A, B212. Just looking for insight on how much power/ current
would be enough without going overboard and throwing $$ away. I know i am only driving the panels. Had a Krell fpb-300, 400cx, 350mcx driving M/L Oddessy Descent i. Should i go up to 600watt?  Looking for that last amp without spending a fortune on something i do not need. Thanks, Mike
Looking for that last amp without spending a fortune on something i do not need. 

Yes but you went and got the ML anyway. Oh well. 
You don't need that much power, but an amp with low output impedance in the treble. Unfortunately most amps rise in the treble, so this can be difficult even with high current amps.

As others have recommended, the Sanders Magtech amps are designed for electrostatic amplifiers, and have copious power.  I'd definitely consider auditioning those, especially for the right price. :)

Sorry the first response was so bitchy.

In any case, a quick Google shows those speakers to be rated at 4ohms, which is pretty low. I don't know if there are any Stereophile reviews that show the impedance curve of your speakers, but that would help in deciding what amp you need.
Given a speaker with 4 ohm nominal impedance, I would look for something with a lot of guts. Say, D'Aggostino, Pass and Ayre. The new Vandersteen amps might be another choice.
Krell missed the bus when they let Dan D go and their products have never been the same. IMHO.
Guess some people dont like stats:(  I love em, Looking at the Pass, Never looked at Sanders I will take a  look at Sanders  I have had a Threshold S500 Just wanted some advice if i need 1000 watt or would lower be fine with the 13a . You know 25 grand vs.15grand  What about current? Thanks all
Sanders website has some very good info that i was not aware of.
Did not know anybody had lifetime warranty. Definetly look into them.

A low/moderate power tube amp with a really good power supply like Audio Research's VT-80SE would be awesome.  They can be had used for $3500.

To provide some perspective on this I did a calculation of maximum SPL (sound pressure level) at the listening position based on the following assumptions:

-- Amplifier power 600 watts, corresponding to the upper limit of ML’s recommendation for this speaker.

-- Sensitivity 5 db less than specified, because Stereophile measured the sensitivity of the 13A’s big brother, the 15A, as being 5 db less than specified. That amounts to 86 db/2.83 volts/1 meter, which for the speaker’s 4 ohm nominal impedance corresponds to 83 db/1 watt/1 meter. (Stereophile found the impedance specs of the 15A to be accurate, btw, so I assume that the similar corresponding specs of the 13A, namely 4 ohms nominal and 0.7 ohms at 20 kHz, are also accurate).

-- A listening distance of 3 meters.

-- An assumption that at the 3 meter distance the sound pressure level will have fallen off by 3 db per doubling of distance relative to the 1 meter figure, given that this is mainly a planar speaker. (That figure would be 6 db per doubling of distance for a box-type speaker).

The result is a maximum SPL at the listening position of 109 db, which is certainly enough volume for most of us, even on the brief dynamic peaks of well engineered minimally compressed classical symphonic recordings for which brief peaks can be vastly louder than average volumes.

Going down to 300 watts would reduce that to 106 db. Going down to 150 watts would reduce it to 103 db.

Also, keep in mind in considering various amplifiers that their 4 ohm power rating is what matters, not their 8 ohm power rating.

Also, given that like most electrostatics the impedance of the speaker descends to very low values in the upper treble region solid state amps (having high damping factors and correspondingly having near zero output impedances) will produce greater emphasis of that part of the spectrum than tube amps (which of course have relatively low damping factors and correspondingly have relatively high output impedances). Which is better comes down to individual preference, IMO, although of course high powered high quality tube amps don’t usually come cheaply :-)

Hope that helps. Good luck,

-- Al

my mcintosh mc602's manual says it's current is 150 amperes per chanell. is this true??? if it is, where doe's my amp stand with other's??
Was also considering AR tube end Personally never heard with M/L 
Also had AR Pre Ls25m2 with ss amp.Looking at options, but my ears will decide. 
Thanks Al for some insight
@g_nakamoto, amplifier current ratings are among the most useless and misleading of specs.  They usually represent how much current the amp can put into a dead short (i.e., zero ohms) for some unspecified miniscule fraction of a second.  And in some cases they may even correspond to that capability as measured at the output of the amp's power supply, not even at the output of the amp itself.

See the following thread:


-- Al

Guess i will look for regulated power supplies. All this knowledge you need to know.Yikes
@fruitloopsr, as you may realize lots of people successfully use power amplifiers having unregulated power supplies in conjunction with electrostatic speakers, the comments at Mr. Sanders’ website notwithstanding. Not to mention that there aren’t very many power amplifiers that have regulated supplies, at least for their power stages.

Also, one further comment regarding the possibility of going with a tube amp. The output impedances of various tube amps vary widely, and I believe it would be preferable to limit your considerations of tube amps to those having relatively low output impedances, meaning damping factors of at least 8 or so. Most and perhaps all Audio Research tube amps are among those which meet that criterion.

-- Al

Let me ask Anyone have tried the combo of Pass or Sanders amps with M/L 13A if so what do you think?
my mcintosh mc602's manual says it's current is 150 amperes per chanell. is this true
No. Not unless it can make well over 22,500 watts!! And that is giving it the benefit of the doubt- that it can drive 1 ohm.

@almarg I think ML specs their speakers the way they do because they are panels rather than point sources. In that regard a microphone placed 1 meter from the speaker will not pick up all the energy that the speaker radiates. If Stereophile measured it at 86 dB, 10 feet away from the speaker the sound pressure effectively is as if a point source were being used that is 5-6dB more efficient, so 91dB might be practically more accurate. This is why so many panel speakers seem crazy inefficient, but in reality aren't that hard to drive.

Thanks Ralph (@Atmasphere). As you saw I factored in a loss of 3 db per doubling of distance, rather than the 6 db loss per doubling of distance that would apply to box-type speakers acting essentially as point sources. But even so, per your comments I was probably being overly pessimistic in my SPL estimates.

So the 109, 106, and 103 db SPL numbers I calculated for powers of 600, 300, and 150 watts, at a 3 meter listening distance, should be even higher!

Thanks again. Best,
-- Al
I own a Sanders designed innersound electrostatic Amplifier.  It is an older version of his current amplifier, though not as capable as his current Magtech. I have used it to drive quad ESL 63 speakers and it is a wonderful, very capable amplifier. I believe it would be very capable of driving your Martin Logan electrostatic speakers. It can completely dump the current into a challenging load in an electrostatic loudspeaker.
Was considering Pass x600.8 or x260.8 Would i ever use that power with these panels. Would there be a difference in sound or just a waste of power.
I was always under the impression that it’s not really possible to overdrive speakers that require high current to drive like the Martin Logan’s or Dynaudio’s - at least that’s what I have been told over the years.
While you probably would not use the excess power, I was of the understanding that it imparts a greater ease to the sound because of the high reserves available. Perhaps @atmasphere can correct that if untrue.
I was a Krell user up to the FPB cx era and am now a Pass Labs X 0.8 user. The sound is pretty different so if you really like the bass slam that Krell gives you you won’t find it with the Pass Labs. You probably won’t even find it with current D’Agostino’s.
Thanks for your input .Now i just want to research options for class D 
Ok do not crucify me. I did some research on it here and i get dizzy with it
Any comments or just stay with what i know..
I was always under the impression that it’s not really possible to overdrive speakers that require high current to drive
This is in need of correction- you can overdrive any speaker if you have enough power!
Now i just want to research options for class D
I would certainly give them a try. Class D is different from regular solid state- its artifacts are not the same. There can be difficulties with low impedances on account of the output filter of the amplifier; you'll have to check with the manufacturer on that. But the low impedance at high frequencies may not be much of an issue as there is not nearly as much power up high.

Yep, Sounds reasonable . Think i will shy away from class D 
Do not think i want to go thru trying and returning amps. I will look for a dealer around here for Pass .Not any for Sanders  
Be sure to check out CODA Power Amps. They are high current, heavy duty transformers, double down to 4 or 2 ohms. Good looking to boot. Punch way above their price point. The Sanders amps are a good choice as well. Just slightly to the warm side of neutral. Read reviews on these too.
Absolutely. I have owned JRowland, Edge, Audio Research, Unico and SimAudio power amps. My current CODA CSX in silver 330W x 2 into 8 Ohm Load 660W into 4 Ohm Load
2 Ohm Load Stable
Class A operation to 25W
5 Hz to 100 kHz
.04% from 10Hz to 20kHz driven into 4 to 8 ohm loads.
Damping factor: 150
50k Ohms unbalanced 1k Ohms balanced
3.0 kVA toriodal transformer, high speed rectifiers and 80,000uf capacitance and a 10 year warranty!

Best amplifier by far for my system and taste has been the CODA CSX REGARDLESS of price. I hope this data helps. Tom
"2 Ohm Load Stable"

 So is a a 1980’s 20w NAD 3020 integrated.

Doesn’t mean it can "drive" the loads of speakers with 2ohms impedance

Quoting this "meaningless manufactures statement", "2 Ohm Load Stable" hoping readers/customers are gullible enough to think the amp can drive without a sweat a pair of Wilson Alexia’s, all it means is the amp won’t blow up seeing 2ohms.

A more meaningful quote would be:
"this amp can double it wattage for each halving of impedance down to 2ohm and remain stable"

Cheers George

Hang on, I have a 3020 and 3 ohm Apogee Stage... be right back.....

Here's two amps "both 2ohm stable", "both 20w into 8ohms"

Nad 3020 (20w-8ohms)

Mark Levinson ML2 (20w-8ohms)

To a "certain volume level" which will drive and sound better into the Apogee's horror loading?

Cheers George

A big Thanks to all who posted I just pulled the trigger on a pr. of Coda Tm monos. Will let you all know how they sound with my  M/L 13a's.
 Another shout out to tom6897 Thankx
Congrats, those should work very well.
I have just recently received a 7X pre and a 15.5 amplifier from Coda replacing my .8 Pass Equipment and could not be more pleased.
As much as u can afford, more is always better.
 Had low power, mid and high power, high power amps are always better at crescendos, power chords, maintaining the current.
Just waiting for the new Coda 07x Pre to come in.  Doug is making a new run now, Pretty busy after that review. Stay in touch.
Why? Is there something wrong with them?

The comment was as usual provocative, specifically to provoke thought. You said,
Rebuilding my system, Just got a pair Martin Logan 13A, B212. Just looking for insight on how much power/ current
would be enough without going overboard and throwing $$ away. I know i am only driving the panels. Had a Krell fpb-300, 400cx, 350mcx driving M/L Oddessy Descent i. Should i go up to 600watt? Looking for that last amp without spending a fortune on something i do not need.
So you start with "rebuilding my system" and end with "without spending a fortune on something I do not need." But then you went and bought ML. Why? If you didn't know it then, I sure hope you do by now, because just look at the can of worms you opened with that one choice. Pages and pages of mind-numbing technical mumbo-jumbo and why? ML.

When there are all kinds of great efficient easy to drive speakers. And note, NOT saying anything bad about ML per se. People have a hard time with this. So I'll say it again. Because I know they have their fans. Not saying anything bad about ML. Heck the first speakers I built were ESL. But that was how I learned a lot of the crap above. Its not that there is anything "wrong" with them. Its just that they limit and greatly compound your amp choices. Which is kind of inconsistent with not "spending a fortune on something I do not need." You created the need when you bought the speakers.

That is all.
No There awesome Just thought u were bias to them I have always owned Ml from cls2z and up to these 13a  Never had problem driving them just looking for what was to much power to invest in Now i have monos that probably to much power but did not cost a fortune.And no problem  being up there with megabuck amps Had big Mirage,Infinity just no comparison to my ears.Sound like a box. Unless i had boatload of funds.Love your posts,Like i said i tried those bdr cones,SR migs still evaluating. Thankx for insight.