High Current Monoblocks

Punishen1, I have no need for more than 900 watts per channel into 4 ohms, but the Magtech is outstanding. I also have never compared it with the ESL. Since that amp is primarily for electrostats, I would expect the Magtech would be better suited for other drivers, as Sanders doe say.

You omit another strong reason to buy the Sanders, it is inexpensive and a true quality product.

Also Sanders warns that you may need a 240 volt supply for the monoblocks into lower impedances.

I'm in agreement that you should seriously consider the Sander's ESL or Magtech monoblocks. They're ridiculously powerful, relatively small and light, put off very little heat, have a ton of amps behind them and almost zero distortion. If you haven't looked into them by now, you really should. I have his ESL amp and it's an absolute dream! Transparent, neutral, and smoothe, with a punch that you wouldn't expect from such a light component. They drive my Martin Logan Summits like they're nothing, and those badboys can dip down to 1ohm.

Power to spare, great sounding, and absolutely bulletproof. On top of that, Roger Sanders gives his equipment a lifetime guarantee and he's a super cool guy that will work with you PERSONALLY. How many big-name manufacturers can you say that about?

Good luck and happy listening!!

Josh

More practical implication of high current amp is that they can deliver needed power in difficult lower impedance load. Ohm's law says when the load impedance goes down by 1/2 (say from 8 Ohm to 4 Ohm), it requires twice as much current in order to maintain the same voltage. High current amp will be able to maintain the voltage when the impedance drops to 4/2 Ohms, thus "double down" on the power. Current limited amps will supply constant the amount of current in 8/4/2 Ohm load, thus the power supplied will decrease as the impedance drops.

I used NuForce REF 9 V2 SE's with an ARC LS26 with outstanding results. They have plenty of muscle for my very demanding Aerial 10T's and are as transparent an amp as I've ever heard, by a wide margin. I would give them an audition.

Peter_s, Ohms law is how an amp's amps would be calculated.
If you know the impedance...and for the case of a simple calculation, it would be the DC resistance, you would use probably 8 ohms. Find out your amp's power supply voltage. This will usually run maybe.....50 volts......I don't think I'll get much argument for that choice..So the calculation would be I=E/R or 50/8 is just over 6 amps. Power, in watts is P=IE or 50*6 or 300+ watts, RMS.
So much for 'hi-current'. This says nothing about a bunch of other factors.
1. What is safe operating range for the output devices of the amp.....mainly referring to SS, here. Heat sinks count!
2. What is the total energy of the amps PS storage? This is usually expressed in 'joules' and can be translated into more familiar measures.
3. What is the speakers capacity? both sensitivity and max power handling count, here.
4. What kind of load is the speaker? Highly inductive or capacitive? Speakers are not correctly represented by 'impedance'..... google 'Power Factor' to see that large phase angles reduce the available power delivered. Better amps are better at this, no question, but in no case can exceed the physics limits.
5. Google 'Smith Chart' for a graphic representation of impedance vs phase angle vs frequency.

The short answer of why you don't see continuous current ratings is that it is a small number, and as we all know, size matters. Amps is inherent in the 'watts' data, anyway.
As for 'burst' or 'short term' capacity, I am open to arguments about how much and how useful. But, Don't forget, even my power hungry Magnepan panels have only a 4 amp fuse, in the mid/tweet, from 600hz up. If my panel can handle 7 or 8 amps, total than how much power is that, really? I stop turning it up when my ears begin to bleed. My 500/side @4ohm ICE amp is way more than enough and since it is dead quiet, huge dynamics, too.

Dodgealum; the only requirement it does not meet is not being monoblock design; sorry forgot to edit the above post.

Dodgealum; would a moscode 401hr fit your requirements with power,current and the physical size requirements?
It would also give you options of tube rolling that would not break the bank.

I'm curious where one sees the specification for how much current an amplifier can deliver. I've always seen watts, never amps. Thanks, Peter

First, amps are almost ALL voltage amplifiers, not current.
Also, imdepance may not represent the true 'load' of these, or any other speaker for that matter.
Phase angle, the amount that current leads or lags voltage is what really determines the 'load' an amp sees.
That is why lower powered amps with more tolerance for such loading can actually sound louder / better than a 'more powerful' amp driving the identical load.

Since there's a bit of interest here on this thread, there is yet another great review on Audiocircle just posted praising the synergy between the Modwright and Lou's speakers. See the recent post to the thread by VinylLady.

Grant - I wondered the same thing when I read that.

Let me clarify the 'current' needs of the DA-1.1 etc. First they have a very stable curve @ 6ohms with a brief dip to a little over 4ohms @ 150hz and below that a rise to about 10ohms. As speakers go this is very smooth and easy for most amps to handle. I've found that amplifiers with much less than 30amps don't give the dynamics that these speakers can produce, but more is not always better. Depending on the amp 60 amps may not sound any better than 100amps, there are just too many factors.

thanks,
Lou

I kind of get it. Someone correct me where I'm off in my metaphor. The single most difficult task in the system is the transfer of electrical energy into mechanical energy at the speaker. The amp/speaker interface is critical as a poor match can absolutely ruin an otherwise fine system. The energy that it takes to move the speakers parts may vary over the spectrum of sound from high to low (at one point it may take very little energy to move them, while another may demand tremendous reserves from the amp). This can otherwise be seen in the impedence curve of the speakers in question (where it dips down low the amp will have to put out significantly more power). An amplifier with a specific amount of power to offer can deliver that power, or rather make that power available, in different ways. To make it simplistic for anyone to understand, lets say the demands of your speaker are that of a burning building that can go from a trickle of smoke to a raging fire and back again. Lets say the amps we compare both have 10 battalions of fire fighters to offer up, no more. A high current amp would have all ten battalions at the scene of the fire at all times, even if the fire were just smoldering. A different type of amp would only send a single battalion to that smoldering scene, and send the others there as needed and they would leave immediately back to their stations once their need was filled. Of course going to and from the station takes time, whereas the high-current version has all its resources right there at the site of the fire at all times. I guess this is also a metaphor for a Class A amplifier. Can someone explain to me in simplistic terms the distinction between a "high-current amp" and a Class A amp?

I would followup on Mofimadness by saying that I have one of the Sanders Sound Magtech amps. It is stereo but has 500 watts into 8 ohms. I have never had such a powerful and clean sounding amp. There are mono block versions with 1600 watts into 8 ohms briefly before your mains are drained. I cannot imagine why anyone would ever need such power, however.

Hi Everyone.

I'm with Dodgealum - I get glazy too when I read all this tech stuff. But, I try to learn.

I read on another Forum that "headroom" can be described as the difference between RMS (continuous power) and dynamic (peak) power. Like, 100w RMS vs. 150w dynamic. He then went on to say that in some applications lower headroon is preferable and in other applications more headroom is better. This totally confused me.

Mike

i recently had the rotel rb-1092 in my system. delivers the power you are looking for at 500x2watts. i thought this was a very nice sounding amp with my B&W 804S. you could always get a pair of the rb-1091 rated at 500x1 if you must have mononblock(s) :)

several of either amp for sale on AG and ebay.

Jax--thanks for the link. I get so "glazy" when I read these things. Yikes, maybe I'm not cut out for this hobby! Not to speak for Lou but my impression is that his current (pardon the pun) favorite amp for the Daedalus line is the Modwright, while the Claytons are a close second. The JC-1's were something he recommended a while back for his older designs--I'm not sure he would put them in the same category now.

Why do I need a high current design? Great question! I'm a little perplexed as well since the DA-1.1's are very efficient (as noted by Tvad) and do not, as far as I'm aware, present a difficult impedance dip (though I do not have specs on this). My understanding about amplifier matching is based primarily on my conversations with Lou who seems to prefer high current designs. Maybe I'm getting too hung up on this criteria, which I do not really understand fully. Also, I'm generally agree with Brauser about staying in the family to avoid problems with synergy. I thought about the new ARC SD135, which puts out 60amps of current, but amps like the Claytons, even at 50wpc Class A, put out 100amps. This is all a bit of a mystery to me and, unfortunately, I'm not in a position to listen to a whole bunch of amps to really discern for myself whether the pursuit of "high current" is really all that important relative to other qualities of an amplifier. Thanks for the suggestions everyone.

I would add the Tube Research Labs Samson monoblocks to the list you are considering. These amps are not as small as the Nuforce, Claytons, or Channel Islands amps, but they are smaller and lighter than many of the Class A behemoths such as Plinius and Pass Labs. I have an ordinary rack, and they fit comfortably in it, albeit not side by side. They run absolutely cool to the touch, and the sound is utterly astonishing--to say they have "serious control of the bottom end while being musically correct" is an understatement.

Grannyring wrote an outstanding review on these amps that I recommend and agree with. Needless to say, I'm deliriously happy with mine.

Good luck in your search!

Here's a good explanation of "high-current" (see the "best answer" at the top of this page). As I understand it, it basically means that the amp has a whole lot of idle power immediately available on tap when it is needed (as in Class A designs - read HOT). The KWA I use, as some other designs, are Class A for the the first 'X' watts and then A/B for those after. Still, it runs pretty dam hot in high-bias (around 140 degrees F). Sound is outstanding though.

Dodgealum - thanks for that clarification. I'm surprised that Lou likes the Parasounds - I've only heard those amps sounding mighty cold and sterile to my ears...never heard them with his speakers though. I've not heard the Claytons at all. Indeed, the KWA does run hot and is large. I've had the Bel Canto Ref. 1000's for a while and enjoyed them (original version), but after living with them for many months I ended up going back to tubes for the added level of presence they offered. I heard the new Ref's at CES and they sounded great there but cannot recall the speakers they were using and obviously could not compare to anything directly. Another amp I liked a whole lot is the Ayre V5Xe, which deserves consideration, it is a bit smaller than the KWA and does run cooler as I recall. Never compared the two head-to-head so couldn't comment, but enjoyed both very much. Good luck - nice speakers!

Peter_s...The "Double down" criteria is a good test of a decent power supply.
Another criteria which might be more appropriate for music is "headroom". I think this word describes the ability to deliver an undistorted waveform when the peak (brief duration) voltage is well above what the amp can deliver continuously. In practice this would mean high "rail" voltages that will "sag" if a correspondingly high output voltage is required continuously. Don't like that "sag"? No problem. Just give me another $1000 for a bigger power supply,and more output transistors, but if you don't listen to continuous ear-splitting sine waves it will gain you nothing (except audiophile bragging rights).

I would stay with something from ARC. There 'is' such a thing as synergy in a system. It's rarely achieved mixing multiple brands together. ARC spends a lot of time tweaking there designs by listening to them with other componets from there own line of product designs. Call ARC and ask their oppinion. Leonard usually handles those types of calls and is a 'straight shooter'.

I think Spectron amps are switching and provide high current - is this correct? I know nothing about their sound.

But I want to throw out a general question about high current. I've always judged this solely by how wattage changes with speaker impedence. The closer the amp comes to doubling its power when impedence is halved, the better it is at not being current restricted. An amp that doubled its power with half the impedence would not be current limited, and should be a great candidate.

Are there other measures of how well an amp can deliver current while playing music? What are they?

Thanks, Peter

Sanders Sound System ESL Mono amps. He also has a new amp for "regular" speakers.

What do you mean by "high current"?

An amplifier's power output can be limited by: (1) the maximum voltage it can produce, or (2) it's ability to deliver current to the speaker so that the output voltage can be maintained.

Musical signals are characterized by infrequent "spikes" of high voltage. These only require high current for a brief time interval. For music reproduction it is better to run out of current than voltage. The "continuous" power rating that FCC specs require are actually less sensible than the scorned "music" power specs that the industry dreamed up some years ago.

I am all in favor of a "robust" power supply, but I don't need a welding supply.

Fitting your criteria so far.. Diminutive in size, gigantic in performance--check out FM 111.

Thanks everyone. Jax--I have spoken with Lou a number of times about amp matching for my DA-1.1's. As you say, he really likes the new Modwright and he is also a fan of the Clayton's and the Parasound JC-1's. The problem is that none of these amps meet certain practical requirements that I must adhere to. Whatever amps I choose either have to fit inside my entertainment center (ideal) or on the floor behind my speakers (less ideal but if physically small this would work). The amps Lou recommends are either to large or run too hot (or both). The best bet for me would be a small switching amp that runs really cool but the problem is there don't seem to be many (any?) that put out the kind of current my DA-1.1's like to see. I've given some thought to the Bel Canto Ref 1000mkii's, the CIAudio M500mkii's (neither put out serious current) and even the Monarchy S70Pros (which run hot but are physically smallish) but none of these are ideal. I've even thought of the Odyssey Monos built in the smaller case but these, I'm told, run pretty warm as well.

So I feel like space and design limitations are making this very difficult. I'm currently using an ARC 150.2 which is a Tripath switching amp--it sounds very good but only puts out 20amps of current according to ARC specs. While this amp would be a great choice in many systems (it drove my Harbeth Compact 7's wonderfully) Lou feels it is not really giving me the best that the DA-1.1's have to offer. Also, while I've enjoyed the 150.2 I can't resist the notion that I may be able to get better sound from more advanced switching technology or going with a Class A or tube design. I also have to keep system matching in mind so whatever I get has to be driven properly by my LS26 (therefore not a too low an input impedence).

At the end of the day, what I think I want are:

1. Physically small monoblocks that run cool but put out gobs of current and can fit side by side on a regular 19" rack shelf; or

2. A stereo amp that meets the same criteria above; or

3. Physically small monoblocks (tube or solid state--heat not a factor) that can fit on the floor behind my speakers.

All of the above should be NEUTRAL in sonic character, have serious control of the bottom end and be musically correct in presentation.

My own lack of expertise may be keeping me from seeing available options so I'd really appreciate hearing back.

I would think a pair of Odyssey mono extremes SE's would do a good job; Give Klaus a call at Odyssey Audio;one of the good guys in Audio like Ralph from Atmasphere.

I apologize. I meant to say "I couldn't be happier"

I just sold a pair of Electrocompaniet Nemo monoblocks that are very high current amplifiers for Dan Wright's new KWA150, and I could be happier. They drive my Maggie 3.6R's effortlessly.

Without knowing a price range, it is hard to make a recommendation. But, the Parasound JC-1s are top notch and extremely high in the quality-to-dollar ratio. I understand that they get even better with modification.

Seems I may have stated this before on another thread, so pardon me if I'm playing the broken record here - check into Modwright's new KWA 150 - a great pairing with Daedelus. See my input and disclaimer on this Audiocircle thread along with the input of others on that relatively new amp. I heard the Modwright+Daedulus pairing in Amboy at Dan's shop and it was a great combination (RA-1's there). Yours are larger speakers, but I can't help but think it would be a great match given Lou's response - check in with him if you have not already.

Cary Audio MB500's, stellar.