The End Of Big Iron?

Once upon a time you could buy a 1,000 wpc, a 900 wpc and a 750 wpc monoblock from Krell. You could buy a 1,000 wpc monoblock from Pass Labs. Now, 575 wpc is the biggest you can get from Krell and 600 wpc is the biggest you can get from Pass Labs. The muscle of flagship amps in those mfgs has been virtually halved. I mean, was 1,000 wpc, 900 wpc, or a 750 wpc amplifier ever necessary? If they were, why are they no longer necessary? What has changed in audio or speaker technology to cause the dwindling of 'muscle' amps?
Bf85b117 4590 4be7 a756 d05f898cdaf9mitch4t
Interesting question. I would say that 1000 wpc was never necessary. What I have noticed with Krell amps is that they double power all the way down. 400 wpc @ 8 ohms, 800 wpc @ 4 ohms, 1600 wpc @ 2 ohms. Their flagship amps are a bottomless pit of power. Is it possible that the older amps were rated differently? It may have been the result of marketing because the audiophile thought of the day was more power was always better. Just some thoughts...
Maybe Krell and Pass gave up the Wattage Wars when this fella came along:
Class D amps are taking over for traditional big heavy Class A/B amps.

I think some go up to 1000 watts into 8 ohm, but I find 500 w/ch Class D to never break a sweat in my application.

That's still way more juice than most people would have ever been able to apply practically prior.
No, Big Iron always been for people with Big house, Big room, Big speaker and Big wallet.
Maybe in the USA. AnalogDomain still offers their Apollo amp at 4000 watts 8 ohms and 8000 watts 4 ohms.
I would assume that demand has been off for such high wattage stuff. Due to the economy? Saturation? Dunno.

Practically speaking, the big power was really only useful for bass content in big inefficient woofers.

Nowadays, many speaker manufacturers have moved away from very inefficient acoustic suspension designs and are using more efficient bass reflex variants and even some really efficient horn-loaded configurations.

In addition, many audiophiles are opting for separate powered-subwoofers, taking a load off the "full range" speakers and therefore also their amplifiers.

Personally, I would be intrigued by a really big acoustic suspension woofer powered by some gazonga amp -- back to the old days. (But isn't this just what a lot of subwoofers are?)
"Nowadays, many speaker manufacturers have moved away from very inefficient acoustic suspension designs and are using more efficient bass reflex variants and even some really efficient horn-loaded configurations."

Maybe, but most "quality" speakers you see these days are small to fit mot peoples lifestyles better and go for an extended low end to boot, which means they are inherently inefficient and benefit from watts and current.

Flip side is many with these speakers don't realize the shortcomings they may be living with in lieu of 250w/ch or more often needed to realize full potential and/or they don't care all that much even if they do.
The difference in attainable SPLs from a 1,000 watt amp and a 600 watt amp is just over 2dB. It's not a big deal.
I think there was an escalating contest among "big iron" manufacturers of the day. Consumers tend to latch onto categorical assets, real or otherwise, and when makers get that scent they run with it. In the case of the amps in question, momentum carried them well beyond anything sane or useful before common sense among consumers signaled a cease and desist to Krell and their competitors.

As an aside, does anyone else think that Krell looked like what the army would create if they were designing amplifiers.
Onhwy61 maybe it's not big deal on 1kHz, but bigger on other frequencies depending on speaker. If you plan to install Meyer Sound arrays in your listening room, than probably you'll feel difference.
For average home rooms and speakers It's not big deal anyways.
I think that megawatt power amps were necessary if you could afford them + you had a big enough room for them to perform to their max to create outdoor concert-level SPLs.

I seem to also think that megawatt power amps are dwindling due to the economy. These amps require huge power transformers & just the weight of these power xformers necessitates the use of thick metal for the chassis & huge heatsinks. That's a lot of machined metal that costs a pretty penny. Many people are not going to spend that kind of money anymore given the way the economy turned in 2008.
Big Iron may just become a collectors item. I used to peruse the 'for sale' items here on the 'Gon for Big Iron just to see what was available. There used to be much more of it available. Now you don't see much of it here any more in the 'for sale' listings. I think the owners may be holding on to it. I have a big room and big speakers, but I do plan to give Class D a shot to see what all the fuss is about.
I'm into monster Class A amps instead of A/B; Accuphase, Pass Labs, etc. Class A just sounds better. :D
@mitch4t, I think you may like what you hear from class D. I used to have what, to me, was "big iron" ATI1506 6x150 amp. Not huge power output like you guys are talking about, but man I hated having to move that thing. Threw off a lot of heat, and was just onerous. Felt like it weighed 75 pounds - maybe it actually did. I bridged it to put out 450wpc into my home theater fronts, but had to sell it when my business turned down in 2008. I did regret selling it, and wished I hadn't for a long while - it just looked so cool (when I wasn't trying to relocate it).

Fast forward, and I now have a Peachtree Grand Integrated running a pair of WB Arcs - power overkill for sure, but I've got 440wpc on tap, it's the size of a small stereo receiver, and barely gets warm. And the sound is absolutely luscious. It's amazing that so much power can come from something with such a nice footprint, without much heat thrown off. I admit - I still think "big iron" amps look so cool, but there's something to be said for one's audio equipment not dominating your living space - before I bought the Peachtree I almost bought a Bel Canto, so nice looking with such a small footprint. I like that trend.
Class D is basically high efficiency amp technology that is newer than traditional Class A or B, but has come into its own these days when power and current is still needed but not the size, bulk, and cost.

I love my Class D amps and will likely never look back from here. That includes tube amps as well.
I had a Class D amp. I didn't care for it and it ran out of gas early and overheated. To be fair, it was a mass produced Onkyo, and it's probably not the ultimate in Class D design. Right now, I have an A/B amp; the sound is good, but not phenomenal. It is a bit restricted dynamically. It doesn't breathe like a great Class A amp will. But it doesn't really run out of gas and overheat like the Onkyo did. Anyway, those are my thoughts at the moment on Class D and amps in general.
If "big iron" has gone out of fashion, it seems that McIntosh and Musical Fidelity haven't heard about it.
@Mapman, it's interesting that you mention not going back from Class D, including to tube amps.

In addition to the Peachtree Grand, I have an ARC VSi55 that I run in the winter when the heat isn't an issue here in AZ, and I swap them out between my two rooms just for fun. I consider the ARC to be a nice amp, nice sound, nothing to sneeze at. And we've done just casual A/B tests between the Peachtree and the ARC, and at measured equal sound levels I honestly can't tell them apart. They sound equally enjoyable, except that the Peachtree can play much louder effortlessly. Which sort of highlights how far Class D has get tons of power, in a nice footprint, low weight, without all the heat, and at least in my case it just happens to sound as sweet and balanced as my Audio Research tube amp.
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Manley NEO 250s that I use certainly have some big iron in them and they sound better than the Krell 400cx they replaced.
you can call me crazy!, In 2012, I bought a used Krell 700cx, took me two years to get the amp modded, renewed cosmetics too, this was because of the lack of money, however, The amp is Brand new inside and out, sounds incredibly better than before by alot!, I bought this amp because I knew the good ole days of Big Iron were Over, I cannot justify buying an amp for alot of money and my step son of 14 can pick it up by himself, At the cost of High-end, I feel like at 180 pounds and extreme heat of a rocket engine of pure class A, I got my $11,500.00 worth that I have into this amp, I have no regrets, it has 2014 caps that were not available in 2005, and a huge amount of other parts were replaced, you should see the bag of parts that was sent back to me, The sound is like a much more exspensive amp that is not a krell, incredible treble, grainless pure Bliss, NOT ever brittle!, Never heard a krell amp do this, I have heard alot of amps out there, tube or solid state that cost in the stratiesphere, I believe I am very satiesfied compaired to those more exspensive other amps.,, cheers.
Big iron....more than 100lbs??....140lbs??

I love big iron and if your going to leave it on 24/7 because some sales manager says to ..then pay the power $$$$

I love big speakers (and I dont mean girly ones like Wilson's maxx or Peak Consultant. .etc)
To me anything less than twin 15" per speaker(ATC 300..Rockport Arrakis..etc) is not big...l use the Maxx as a example because of their drivers not cabinet.
A Krell fpb 600/700 will make those big boys dance..
I believe that double the woofer power is the best...
For example. .if you have 2 fifteen inch rated at 400w each at 8ohms which equals 800w at 8ohms then I want 1600w at 4ohms so that the headroom equation comes into play...this means BIG IRON..

Unless you are active
I have a fully recapped (214 caps)Krell FPB 600 and a 700cx that are in mint shape and only need one pickup or shipping in Canada only..
These actually will almost put out 1000w/ch
The rest are Mark Levinson. .ML 333...332..331..&..335
I believe I will accept your invitation and say you are certainly crazy to invest that much in that amp. However, I give you credit for putting your money (lots of it) where your mouth is. You sound very happy and for all I know, in the long run, you may prove to be the smartest guy on this forum. Crazy people always think everyone else is crazy.
If your 14 year old can easily lift 180 lbs. he's one damn strong kid.
I cannot see why people would ever need more then 250WPC. Most speakers do not require more then 50wpc continuously. Top power can by much much greater.

The Passlabs XA series sound better then the X series even though the XA is less powerful.
Always wanted one of the big Krells, but their amps weighed over 100 lbs and I could not see myself trying to move one and always needing help. I think many folks who would have considered some of these big amps passed for similar reasons and the smaller market for these amps shrank even more as time went on. It may have caused all the manufacturers to pause.
. are correct about weight being a big issue with Big Iron. I have four big Pass Labs monoblocs and I seriously injured my back trying to move them around. They weigh 150 pounds each. It took several years for my back to heal. They are pretty much in a permanent spot until I sell them. Should I ever need to move them around the room, I'd have to pay someone to do it.
@ Macrojack, Im sorry, I was tring to say, that if my 14 year old step son could pick up my amp, He cannot!, cannot even budge it!, LOL!, I was saying that because of the weight of the amp, I feel like I got Big Iron of a amp, and am satiesfied with NO regrets of the money me and the wife has spent on this Krell 700cx, the up-graded caps made a profound difference!, we both are very happy with the sound, cheers.
Hi Mitch4t, concerning your amps, I have found wood to be a good resonace control, I went to lowes, bought a flat dolly with wheels, filled in the middle with plywood, painted it all black, put the Krell 700cx on it, I can litterally roll the amp right out the house, and any where in the room with no problems, the amp stays on this self made amp stand, sounds very good to us doing so, maybe you should try this, looks great, matches the amps colour, the wheel trim is silver, so it's a good cosmetic fit.
I had a Class D amp. I didn't care for it and it ran out of gas early and overheated. To be fair, it was a mass produced Onkyo, and it's probably not the ultimate in Class D design. Right now, I have an A/B amp; the sound is good, but not phenomenal. It is a bit restricted dynamically. It doesn't breathe like a great Class A amp will. But it doesn't really run out of gas and overheat like the Onkyo did. Anyway, those are my thoughts at the moment on Class D and amps in general.

Dave_72 --

Class D amps span many varieties, but I guess I may just share your overall view on Class A amps. I was very happy with my NuForce Stereo 8.5V3 for years, specified at 150 watt with 8 ohm resistance, and through my moderately sensitive speakers (a measured 93dB) and acoustically relatively live 20 square meter listening room never appeared to run out of steam - which, in lieu of the circumstances and different needs put aside, it shouldn't.

Then I got to hear my setup via the pure Class A Belles SA-30 poweramp, specified at 30 watt/8 ohm, and my initial concerns that the sonic imprinting would loose some of its effortless quality at higher volumes with complex music and ditto soundtracks from my Blu-ray collection vaporized immediately; in fact the on-paper less proficient Belles amp, at least watt-wise, turned out to deliver gains in all respects, having never heard my music and Blu-ray collection with as much naturalness and unrestricted, effortless power. The music simply flows unhindered with a simplicity and presence that is very fulfilling - indeed addictive. Here, in comparison, the NuForce appears somewhat congested, rather pale and, in a sense, stifled.

Whether indicative of the true potential and/or possible sonic "signature" of one amplifying principle over the other, it certainly had me revise the need for wattage - in my setup, that is - and also a beginning investment in the Class D segment of amplifiers. It's not that I'm oblivious to other factors that are important when speaking of power delivery (if we're to limit the aspects evaluated, and not go deeper into sound quality per se), not least the "bodily" feel of it, but I guess it just surprised me in above named case.

With much larger and more heavily damped listening rooms, greater listening distances and less sensitive/more problematically driven speakers, one can easily imagine the need for many hundreds of watts where 30 Class A dittos would've come up short, and the need for live-like SPL's could even demand more. Striving for the simpler amp construction/topology however seems desirable though, and thus more sensitive speakers are called for than the general general market can accommodate, despite what looks like an upward swing in general speaker sensitivity.
I ment, decked the dolly with ply wood over the complete top of it, not to high or low, cheers.
Class D amps span many varieties, but I guess I may just share your overall view on Class A amps.

Thanks Phusis, I appreciate that. Meaning your thorough explanation. Basically, I have high efficiency speakers, so Class A should be no problem. I'm currently looking at; Accuphase, Pass Labs, and Luxman. I'm sure I'll find the right one for me, the one that'll make me content for several years instead of a months or 2.

I am always looking at what I would buy next for whatever reason. I always find so many great options that I think will sound really good that it makes it hard to decide. In the end, I find I save money as a result of indecision.

if the stuff I have were not doing well for whatever reason, then that adds a sense of urgency. If it ain't broke, I tend to not fix it. But it is also fun sometimes just to play and try different things.
Basically, I have high efficiency speakers, so Class A should be no problem.

Dave, those speakers are also an easy load for tube amps, which work quite well on them- several of our customers use similar JBLs (the export version).
Seems as though big power offerings are having something of a resurgence of late.
Unsound...who's got the big power offerings that you speak of?
Jeff Rowland's new Daemon integrated provides 1500 watts per channel. Big enough?
I imagine Unsound is referring to the prodigious output of many new class D designs. While they certainly deliver the juice, they are not the massive, back breaking monster blobs of metal that I took as the object of the thread title.
OTOH, the above mentioned Daemon does weigh 99 lbs.
^ Classe, Naim and Rowland.
Unsound, do you know price tag on the totl Naim combo?
Saw the price of the amps; let me just say I'm not bothering with an audition.:-)
Have PASS 350.8 350 ch its plenty and sounds wonderful.
Higher efficiency class d amps up the ante in terms of power available when needed. Very "green" as well.
Tube amp freaks are mostly not in this discussion as few bother with the extreme high horsepower versions as they just generate too much heat...the ones who do bother with those must have great ventilation or no clothing. Class D ain't going away, but might be kicked around by Class G or whatever's next among the switching amp crowd. I own a Class D bass amp (Ampeg PF) that sounds fine, so at least I'm on board the train so to speak.
I had a Rogue ST90 with KT120`s (100 Watt), sounded very VERY nice but I felt as though I needed more power for 'Those Occasions' and my Revel F52`s certainly can use up some power. But I was leery of pushing the tube amp too far.

I sold the Rogue and put a Class D Audio SDS-470 in its place (300/600 Watt) for the $$ the Class D 470 reminds me of the NAD 3020 I bought when it first came out.
I Used that 3020 with DCM Time Windows in a small room at the time and the combo was crazy good sounding !

This Class D Audio amp is crazy good too !! Plenty of power, runs cool, looks cool (silver w/blue leds) has great left-right imaging and nice depth and has bass power too.

But I`m realizing 'Those Occasions' don`t happen as often as I thought and I miss the small detailed subtleties, like the cymbals as they fade off/decay and other things that tubes are good at.

Anyway...Now I`m looking for a Rogue Atlas and I`ll keep the Class D here for those other occasions :)
lass g is older technology. I had a hitachi sr 804 once. Nice piece but pretty average sound.

Class. D is much more sophisticated modern technology that makes sense to me. When I read about class g it does not sound like such a great idea anymore.

I'd be more interested in tube amps if class d did not turn out to float my boat so well. Class d offers some good attributes of both ss and tube sound.

Two extreme ways to go these days it seems to me. More efficient amps to get the most out of popular smaller less efficient speakers or power hungry low output tube amps with very large efficient speakers. At least if we are talking full range in larger rooms.
I went from 100wpc tube amps to a pair of D-Sonic 600w mono amps after my power regenerator murdered them one fine morning. At the time, I was running 86db Snell speakers that I had bought with the amps back in 1991. I expected the new cheap class-d monos to be a serious setback compared to the Atma-Spheres, but elated when they turned out to be good as their generally HT customer base rave about, but it took me a long time and a lot of tweaking to get them to really fit well in my 2 channel system. But, with the right power cords and some reasonably good support under them, they can sound superb. These amps weigh about 10# each and are the same size and shape as a shoe box yet are capable of great things when the upstream system is singing sweetly.

I have no intention of comparing them with the Atma-spheres at the time. I have made scores of changes to the system since then, many of which would also have improved the sound of the OTLs as well, and if I ever find a few thousand "extra" dollars to have them repaired, I may put them back in service during the Winter months, but in the mean time, I'm not missing anything.

Just one last thought about the efficiency of the class-d amps. I calculated the energy cost savings for the 2 years following the change from tube amps. It was costing about $80/month for electricity to power the amps and another $50/month to run the air conditioning in the not-winter season here in Wisconsin.
Mcbuddah, what is wrong with your Atma-Sphere amps? Bad tubes?

A simple and inexpensive means of dealing with hot amplifiers, tube or solid state, is to install ceiling ventilation with ductwork to move the warmed air out of the building. This is very cheap to install and costs very little operate and is very effective! Air conditioning is rather brute-force.
"A simple and inexpensive means of dealing with hot amplifiers, tube or solid state, is to install ceiling ventilation with ductwork to move the warmed air out of the building. "

Installing new duct work is simple?

I guess its all relative.
Mapman, letting the heat coming off amplifiers escape to the outdoors can be extremely effective. Whether that requires ductwork depends upon the construction and what systems are in place. In other words if you are able to remove the heat there is no need to cool it, but you will need to make up the volume of air removed somehow.

My room with the big Sound Labs is pretty large. The Atma-Sphere MA-1s or MA-2s are perhaps fifteen feet away from the listening area, so the heat has some distance to travel, in which it blends with the room air. Although it is noticeable it's not bad. The HVAC system is generously oversized, so even with the big amps going and a dozen people listening, it's all good.

Mcbuddah, since you're in Wisconsin you might want to stop by one day for a visit. I have the M-60s in the downstairs system (essentially the system we showed at AXPONA a few weeks ago) in the much smaller room, and it's a very liveable, cozy and relaxed listening room.
Ralph, I actually retired as a HVAC technician and so did learn to calculate room heat gain/loss as well as measuring current draw. When the amps were in service for the last few years, they were located too close to the house's only thermostat and routinely caused it to read up to 10 degrees(f) higher than ambient temperature only fifteen feet farther away. The whole issue would be moot if they were still working, as I have just finished a major remodeling project in which my wife agreed to let me swap locations with the HT system and now have quadrupled the room square footage far away from the thermostat.

As to the problem with the amps, they both went bad within minutes of each other. I suspect that they were murdered by a malfunctioning PPP regenerator unit that also died that day. I believe that its AC output stage went bad and created some kind of uncontrolled, clipped signal instead of the nice rounded waves it is designed for. The fireworks happened shortly after powering up the system normally. After 20 years with them I had a routine for startup and put them in standby for an hour while warming up the Thor phono stage. The preamp was a Classe DR-6 that was always left on, so there could not have been a problem with a failure to turn the gear on in the right sequence. After cueing up the first record of the day, I noticed that only one channel was playing so I moved behind the errant speaker and reached for the amp's off switch while the good side played on normally. Before I could switch it off, several of the power tubes went bright orange and one exploded. About a minute after switching it off, the other side started the same fireworks show and there the PPP shut down, dead as a stone.

The reason I decided to replace them with the class-d amps rather than sending them back to you was purely economic. I loved those amps since I bought them from Bruce Jacobs 25 years ago. But, my income has gone down with retirement and I hoped they might not be too bad for the money I had. I figured that repairs would need at least $600 worth of new tubes, $100 for new packaging to ship, $$300 for 2-way shipping, I would need more than a grand just to get started. I guestimated that each amp would need at least $1500 to fix and that put the repair out of my reach. Fortunately, the D-Sonic amps have proven to be over achievers for their price.

Now, a few years down the line, I have a bit more income and have made scores of changes to my system and hope to someday have the Atma-Spheres fixed. I know in my heart that they would glorious in the configuration I am putting together.