It seems that in looking around for amplifiers and integrated amps that double their power as the impedance is halved (high current), they seem to be in a minority. Is it just more costly to build good-sounding high current electronics and the market demand for them just isn't there, or what?
Yeah, we've had this discussion before. Same old same old. Lots of assertions, but no supporting data. Negative feedback is bad because it causes time-domain distortion, distortions we can measure aren't important
Of course there is plenty of supporting data, and the distortions we are talking about *can* be measured, as well as heard.
high output impedance doesn't really affect frequency response linearity.
I don't know where you got that but you did not hear that from me. In fact the whole point of that paper (which now I am guessing you did not read) is that you have to **pay attention** to these things to **prevent** errors in 'frequency response linearity'.
so very high current amps are mostly for people that have more money than sense (like me).
Tube amps are for people even more skewed towards money than sense. ;-)
So, are you saying here that you have a tube amp in your future?? :)
One can and sometimes does hear in excess of 110 dB. It's not just the volume, but the duration and the frequency that one hears these peaks that are of concern. When it's appropriate, it's nice to have the capability. Some speaker can handle it without significant distortion.
Not sure how this thread deteriorated into a philosophical argument. Typical example of the audiophile niche market.
"High current" has faded as marketing buzz word. That's all. Still continues as a design philosophy. Don't make me name names. Doubling down, well that requires, along with adequate power supplies, a specific kind of circuit and feedback, which happens to be the new buzz word.
There's one brand, to remain nameless but with unusual sincerity, that only tests the amp into 4 ohm power resistors, and only at 1 kHz. They divide that by 2 for the rating into 8 ohms. They also claim stability into 2 ohms. It's a good brand and an impressive amp so I'm not disputing. Just saying that advertised ratings are not real-life, reactive loads.
Irv, thank you for offering the words of reconciliation to Grant.
03-16-11: Irvrobinson For a good voltage-source amp with 100w into 8ohms, if the speaker has a peak impedance of 16 ohms into 4KHz the amp will clip at 50w, and if the lowest impedance occurs at 40Hz with 4ohms the amp will clip at 200w, but the frequency response at 50W will still be flat (within the amp's spec) across the entire spectrum up to 50w.
Trick question - what happens if the speaker is reproducing 4KHz and 40Hz *at the same time*?
Well, since one frequency is far higher than the other, there will be instants of time at which their peak amplitudes will simply sum together. If both frequency components have the same amplitude (which is highly unlikely with music), the amp could provide half of its maximum output voltage at each frequency, without clipping. Since for a given impedance power is proportional to volts squared, power delivery at each frequency at the clipping point would be 1/4 of the numbers you cited above: 12.5W at 4kHz, and 50W at 40Hz.
Why would I want less power? I think the better question is why would I accept less. My reasons:
1. Even 110db peaks are really, really loud. I'd like to hear for a lifetime. 2. Most audiophile speakers will have significant distortion at these volume levels. Why listen to so much distortion? 3. Most stereo solid state amps will need well over 20amps at 120v from the wall power outlet to produce 600w/ch. What are you plugging the amp into? ;-)
Oh yeah, and a correction of my multitasking math, assuming a speaker with 89db sensitivity at 2.83v, and assuming a 4 ohm impedance, 600w/ch does not give you clip-free 120db+ peaks, you'd get about only 114db peaks or so.
Well, Tvad, since I assume I'm the root of your urge to leave, I think you're over-reacting. For one thing, in the interest of full disclosure, I was multitasking when I typed in that response, and while (I think) everything I said was correct I actually *misread* your post in my haste! Yes, IMO, you still have a misunderstanding about ss amps work, but I'm actually feeling pretty stupid at the moment for explaining some behavior related to what you were talking about, not the specific effect you were actually describing! Sigh.
I also admit to enjoying banter like this entirely too much, and it was never intention to chase you (or anyone else) away. So how about you stay, and I'll try to cool my responses a bit, and I'll also try to improve my focus before I type!
I think some people, especially those running ss amps, are comforted by the idea that there is nice margin of available power away from clipping. Others claim that some distortion is audible from stressed amps before full clipping occurs. Some times the extra power is not that much more expensive. Some amp manufactures claim that their Class AB amps slide from Class A to Class B at a ratio of power, e.g. 20% of rated ouput. Some amp manufactures claim that their Class A amps are only capable of sustaining full Class A output at their 8 Ohm rating, as the impedance drops so does the ability to maintain Class A output, e.g. at 4 Ohms those amps are only capable of producing half their typically rated output into 8 Ohms in Class A. If that's the case, the higher powered amp(s) might sustain higher quality sound further into power demands, though not quite up to full available power output.
"Actually, my experience is that most audiophile speakers sound like crap at very loud levels. There are notable exceptions like Legacys, big Wilsons, and the top-of-the-line Revels, to list a few, but most don't, so I'm wondering what people think they need so much power for? "
Add OHM Walsh (omni) speakers to the list of exceptions.
These shine at lifelike levels but also require the power and juice to do it best. Part of this is the Walsh driver and teh omni design that fills the room with sound more like a live acoustic performance rather than directing all its energy at you and making you want to leave the room, like speakers at a rock concert.
Most people who have owned the over the years run them off more commonplace amplification and probably have never likely heard what they are capable of. That included myself as well until recently.
My Dynaudio monitors do not mind the power and current, but can also get by better without it, though they will never deliver the meat on the bones at higher levels like a pair of large, robust suitably powered full rangers.
Isn't clipping an even worse consequence than unbalanced frequency response alone?
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Yes, absolutely. But unless you listen at *very* high levels (like averaging higher than 95db) most audiophile amps (100w+ per channel) with most speakers (89db sensitivity at 2.83v) probably won't clip. If you are clipping there are lots of 200w+ amps into 8ohms that will likely do you or your speakers harm before they clip.
Actually, my experience is that most audiophile speakers sound like crap at very loud levels. There are notable exceptions like Legacys, big Wilsons, and the top-of-the-line Revels, to list a few, but most don't, so I'm wondering what people think they need so much power for? I know people think they need 600w/channel into 4 ohms, and if they're willing to pay for it I say: go for it, but the math looks like you'd be producing 120db+ peaks, and I can't believe people are listening at those levels. Or am I naive? :-)
Yes- audio equipment does not care what kind of music you play on it.
An amp with a low output impedance does not have a frequency response that varies with a speaker's impedance.
That depends on how the speaker is designed. Take a look at http://www.atma-sphere.com/papers/paradigm_paper2.html
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Yeah, we've had this discussion before. Same old same old. Lots of assertions, but no supporting data. Negative feedback is bad because it causes time-domain distortion, distortions we can measure aren't important, and high output impedance doesn't really affect frequency response linearity. Frankly Atmasphere, your assertions remind me of Audioquest's argument that skin-effect really does matter at audio frequencies, even though all of the measurements say it's inconsequential.
I think it has been well-said previously in this thread that we don't see more high-current amps because they're very expensive to build, and because most people don't need anywhere near as much power as they think they do at low impedance levels, so very high current amps are mostly for people that have more money than sense (like me).
Tube amps are for people even more skewed towards money than sense. ;-)
03-16-11: Unsound Tvad, I for one would hate to lose you, and your valued balanced contributions to this forum. This particular thread doesn't seem that contentious to me. I do hope you'll reconsider.
I strongly second these thoughts. Grant, as I indicated earlier I have nothing but the highest respect for your innumerable contributions to this forum, from which I and countless others have benefited greatly. I too very much hope that you will reconsider.
Tvad, I for one would hate to lose you, and your valued balanced contributions to this forum. This particular thread doesn't seem that contentious to me. I do hope you'll reconsider.
An excellent example is a Sound Lab ESL, but by no means the only example. You can also run into frequency response variation with highly reactive speakers (high efficiency). You have to look at the intention of the designer of the speaker.
"But if you're not listening to acoustic music, and are of the RR family, then quality of sound isn't what you're after as much as volume of sound."
That's a very biased perspective.
There is high quality and lesser quality non acoustic music as well. Volume is part of it because that is the nature of the beast but not the whole story by a longshot.
I would argue that it is more costly and difficult to reproduce music that is meant to be loud and powerful accurately and convincingly than it is to reproduce acoustic music that you liten to normally at lower SPLs.
It's a mistake to discount music forms that one does not care for just because one does not care about them. They are forms of music people listen to as much or even more so in practice than others.
That kind of attitude is one way how audiophiles get a bad name.
As a former owner of VK1000 mono's and many other Pass 600 sized monster blocks I for one don't miss having to place amps of that size any more.
95dB and above speakers driven by an 8 watt 300B SET is as good as it gets for truly refined sound. But if you're not listening to acoustic music, and are of the RR family, then quality of sound isn't what you're after as much as volume of sound. Dare I say it...acoustic rules!
Well, I'm of the opinion that it matters based on what I've experienced in my system using speakers that had an uneven impedance curve.
Relating back to what Unsound stated in his previous post, the reduced power output into higher loads (lower impedances if I'm reading Unsound correctly) from an amp that does not double down (double power as impedance is halved) resulted in a sound that was always "bright" because less power was being delivered by into the mids and bass frequencies than the treble frequencies. Therefore, there was a higher decibel level in the highs than in the mids and bass. The difference was not large, and it probably wasn't noticeably measurable on a Radio Shack decibel meter, but the results were clearly audible on my speakers that had an uneven impedance curve.
Once I drove them with an amp that doubled down, the sound was evened out and the speakers no longer sounded "bright".
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Sorry, but this is pretty basic misunderstanding of how amplifiers work. An amp with a low output impedance does not have a frequency response that varies with a speaker's impedance. The key parameter that varies is potential current delivery by frequency before clipping occurs. So for a good voltage-source amp with 100w into 8ohms, if the speaker has a peak impedance of 16 ohms into 4KHz the amp will clip at 50w, and if the lowest impedance occurs at 40Hz with 4ohms the amp will clip at 200w, but the frequency response at 50W will still be flat (within the amp's spec) across the entire spectrum up to 50w.
Trick question - what happens if the speaker is reproducing 4KHz and 40Hz *at the same time*?
The Class D/icepower BC ref1000m monoblocks I am using meet all your criteria except for price and power exceeds your stated range at 500w/ch into 8 ohms, which is generally more of a boon than a problem with most large full range speakers built to run all out at higher volumes.
The bass is absolute top notch in my opinion with any kind of music, have not heard anything better in terms of proper weight along with refinement/articulation, at least in my two well tuned rooms (one larger and one smaller). In the sunroom, anything I use that sounds balanced and right in those two rooms tend to go a bit boomy and bass heavy, which clearly indicates that the room is the thing that brings the performance level of an otherwise nicely balanced rig down a notch or two, at least in my case.
I think this is one of the amps that Tvad mentioned above that he has tried and found to deliver properly balanced sound.
I've tried every "good" speaker and amp combo I've owned current and past in that room and always similar results, OK but not great.
I haven't tried my realistic Minimus 7s taht I use over the summer on the deck though! THat might be worth trying! Smaller may be better in a case like this with overzealous room acoustics!
In a tough room like my wife's sun room, options to achieve "perfect" sound are limited.
1) minimize the imperfections through tweaking and learn to live with it 2) have the room professionally analyzed and based on findings, do some combination of treatments and/or signal processing using a graphic or parametric equalizer 3) rely on near field listening 4) headphones
For 2, a newer possible variation these days that might prove effective is doing the needed signal processing in the digital rather than analog domain. That provides more flexibility and precision in whatever processing might be needed.
Ironically, directly below my wife's sunroom is my office where my gear lives and often serves as my main listening room. This is also 12X12, however I have not had problems getting whatever speakers I put in there to sound spot on.
There are other differences that I suppose help account for this:
1) I had the ceiling and walls in that room insulated when the house was built so as to have a place to liten without disturbing anyone. It also has a solid wood rather than hollow door for same purpose
2) standard 7' whatever drywall ceiling, actually lower towards rear where there is a conduit so ceiling is not flat
3) rigid concrete foundation floor with very thin but dense industrial grade carpet and padding
So I guess my point is that there is a lot of factors that go into how a room "sounds" and it can be hard to predict without actually hearing it.
Mapman, thanks for the sentiments. The beat goes on. I'm still looking for the high current amp in the used market that better matches my speakers and fits my amplifier profile:
clarity with bass weight and refinement Not extremely heavy: 50-90lbs at most- bad back amp w/higher input impedance is required for my Cary SLP 05 high current - doubles down - 100-300 wpc not over $2k known for quality sonics Mirage OMD28 speakers
Current matters when you're driving difficult loads, and as Tvad mentioned, there's no real drawback. I value systems as follows: source=>preamp=>amp=>speakers. There's a ton of excellent speakers that are hard to drive (I've owned Apogee's, Eminent Technology, Celestion 700's, etc)and of course many excellent speakers I'd like to fool with at some point. I don't want my speakers telling me what amp I should use... I'm not sure why anyone would think this is not a sensible approach.
Wow, Map, That would appear to be an awful space. Headphones, anyone? I had some MG-1s in a 10x10 room with an 8' flat ceiling. now THAT was terrible. I had to swap the speakers L/R (they are marked) to make is sound right.
Sorry to hear your still fighting bass and other issues. Your case is a tough one to get a handle on because I know you've tried so many things, including subs, and still have not yet scored completely.
Even if everything is matched well electronically, room acoustics and individual preferences still come into play in determining what sounds good.
Maybe a near field setup of some sort might be the best approach if you can get to that kind of setup in your room.
My best guess is the thing you need new most is a new room. Unfortunately, that is one of the hardest things to have to deal with.
My wife's very lively sun room, 12X12 with a cathedral ceiling, lots of windows and a hard tile floor is that way. What sounds spot on other rooms never quite gels completely in there. Generally there is too much bass and imaging and soundstage is not totally up to snuff. Fortunately for me that is only an auxiliary listening location so I am able to live with what I get there, though I have not given up on trying to get it perfect.
Hack, remember that a high current amp will decrease power into higher loads. There are limitations in either case. Choose your speakers and amplify them appropriately.
Although I always have the greatest respect for opinions expressed by Ralph (Atmasphere) and Grant (Tvad), and I almost always find myself in agreement with both of them, in this case I think that their posts are commingling two separate issues.
ANY amp having negligibly small output impedance, such as most solid state amps, WILL double the amount of power that is delivered into a halved load impedance, PROVIDED that it is operated within the limits of its maximum voltage, current, power, and thermal capabilities. That is a matter of basic electrical engineering principles. If in fact Harley disagrees with that he is wrong.
Most, and perhaps nearly all, tube amps will not do that, BECAUSE their output impedance is not negligibly small.
All of that is essentially a separate issue from the one I believe Emerson (Foster_9) was asking about, which I believe concerns whether or not the MAXIMUM power ratings of a solid state amp are twice as much for a 4 ohm load as compared to an 8 ohm load.
03-15-11: Tmsorosk ...there may be other reason's it doesn't sound bright other than just the double down aspect.
Tvad , you may be comparing apples to oranges . The new amp is likely quit different in design , there may be other reason's it dosn't sound bright other than just the double down aspect . Is the output the same on both amps into an 8ohm load . Size of transformers can have a great effect too . I guess if an amp is well under powered for the situation doubling into 4ohm would likely help . Glad your happy with your new amp though .
So far the efficient Class D amps I've tried have not presented the clarity, bass weight, and refinement with the (somewhat difficult load) speakers I own now. (I need some power and current damn it!). So I continue to look at Class AB designs. But I'm not interested in a 125 lb behemoth either; just a reasonably priced high current amp(less than 3k ) that doesn't take 2 people to lift and isn't old as the hills and in line to be re-capped soon. An amp with good sonics too.
I just did a quick search to see what amps double down and found the following do , Ayre , Classe , Edge ,luxman , Marantz , Simaudio , Tenor and some Levinson and Parasound , probably lots of others . As others above have said I don't think that aspect is very important , even in a large room and at lease braking levels .
Hack, remember that a high current amp will decrease power into higher loads. There are limitations in either case. Choose your speakers and amplify them appropriately.
Well, in my experience I haven't come across high current amplifiers that double down and sound anything less than stellar. If an amp cannot double down I'll pass on it...why limit your choice of speakers due to challenging impedance loads and such?
Atmasphere, You stated basically that you think the goal of any high end audio system is to have the equipment sound like real music. I think many would agree with this approach. However, given the great variety of recording quality, doesn't this imply that the system will impart some level of coloration to make one's whole collection sound like real music? What do you think of the approach that equipment should be as true or faithful to the recording as possible, ie, as neutral and transparent as possible? Great recordings will sound great but lesser recordings, not as good.
Another reason that there may not be as many high current electronics as you might think could be that they are only of concern to "audiophiles" looking to max out performance of there system. Most people get by fine with less than industrial strength SS amplifiers in whatever gear they happen to listen to.
It's only the audiophile camp, a small niche itself, that is concerned with things like high current, high efficiency, tube amps, etc.
I will say though that within that niche, tube gear and high efficiency speakers to go along seem to be experiencing a renaissance and cutting into the high current SS amp/lower efficiency speakers domain compared to the recent past, so that would have to have some effect on how much of any particular design one sees.
I think Atmasphere is a big force behind this, at least on this site. He apparently makes some very nice gear, believes strongly in what he does and is a verbal champion of the approach, so kudos to him and the others who have helped breath some life back into the paradigm!
Unsound, Well what can I say? We just have different taste and hear differently. most of the very best natural sounding systems I`ve ever heard were comprised of high quality but low powered amplifiers with very efficient speakers. Utterly natural/organic music reproduction with disarming realism and presence. That`s my personal experience ,if your ears have led you in a different direction then by all means continue to follow it. Ijust know what`s been better to me that` all. Best Regards,
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