Does it make sense to pay for a more powerful amp when one has "enough" power?
default -- Sat, 12/12/2009 - 20:27
Personally, I find the specs speaker manufacturers provide quite useless. With amps, I like more power than less as more power sounds more real to me.
In mating amps and speakers, if one stays within the same brand family, does it make sense to spend more $$$$ to get more power when one already has seemingly enough power? For example, if one gets great sound from a pass xa30.5, does one get better sound with xa160.5? If one loves the xa160.5, would getting xa200.5 give better sound? Is the ARC 610 that much better than ARC 210? I imagine the sonic signature stays the same, but do better parts (and more parts) improve the sound, or do they hurt the sound?
Unfortunately, most dealers don't carry multiple models of amps. Thus, comparisons are hard to come by. What are the diminishing returns? Are the more expensive amp the better amps? What are all of the factors to consider?
Looking forward to your responses as I'm running out to hear some live jazz. Thanks!
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How efficient are your speakers and what kind/s of music do you listen to?
There's a theory (and some evidence) that lower-powered amplifiers sound better than the same circuit in a higher-powered model. Often, the more powerful amplifier in a line has the same input stage, but more output transistors, more heatsink area, and a larger power supply. All those output transistors have to work together, and no two transistors are perfectly identical. The low-powered amplifiers tend to be sweeter in the midrange and treble.
I have driven a variety of loudspeakers with the 100W Pass XA100.5 amplifiers and only on a couple of occasions (lasting seconds, cumulatively) have I wished for more power.
As SundayNiagara points out, loudspeaker sensitivity is key. You can drive a 105dB-sensitive horn speaker full full volume with 5W. At a CES a number of years ago, I saw a new speaker being demonstrated. The playback level was at that of background music, but the meters on the 300W McIntosh amplifiers were constantly pegged; the speaker was that inefficient.
Is the ARC 610 that much better than ARC 210?
On a pair of Magico Mini 2s, absolutely! Depends on the speaker really, but most can use more power than their rating suggests.
I recently switched from a 200+ watt integrated (BAT) to a 75 watt McIntosh to drive a pair of not very sensitive Sonus Faber Auditors. Much happier with the 75 watt-er.
Many different factors come into play -- circuit design, components, build quality, etc.
More power is needed if:
1. your speakers are inefficient
2. you like to listen loudly
3. your room is large
4. your speakers have excessively low impedance
Otherwise, Mr. Harley has it right - the theory (true in my experience) that less power = better sound is justified. Want proof? Listen to an OLD Pioneer SA-5100A integrated amp (10 WPC) with some high-quality, high-efficiency speakers; magic! Now listen to the same speakers with any other Japanese higher-powered amp of the same era; garbage! This one example is insufficient to prove the theory, but listen for yourself...
I'd also mention that above a certain power rating (typically 30-50 watts, in my experience) there is no sonic penalty for going on up the power ladder in the same make of electronics. In other words, once multiple, parallel output devices are required, there is no (noticeable) sonic penalty for adding more. The difference between a 30-WPC tube amp and a 100-WPC tube amp will be MUCH greater than the difference between the 100-WPC amp and a 300-WPC one. Of course, there are always exceptions to the rule...
A good sense of humor makes it ALL sound better!
Yes, I agree. You need more power if you listen loud enough that your amp can't deliver the power you need for dynamics and peaks.
Do you want to listen to orchestral peaks at a realistic sound level of 105-110 dbl? If so, you'll need about 300-400WPC for a typical speaker of 87dbl sensitivity, at a typical listening position of 10 feet away or so.
If not, and you listen at lower levels then you don't need all that power and you'll probably do fine with a 100WPC or so.
No substitute for lots of good power. The problem is finding a good powerful amp, at a reasonable price.
I think that even efficient speakers, work better with more power. We have once switched from a SET 300B based, about 8W I believe, to 50W SS on a pair of Zinngali horns. I was blown away by the dynamics improvement. That speaker are about 100 dB sensitive.
No substitute for lots of good power. The problem is finding a good powerful amp, at a reasonable price.
I think that even efficient speakers work better with more power. We have once switched from a SET 300B based, about 8W I believe, to 50W SS on a pair of Zinngali horns. I was blown away by the dynamics improvement. That speaker was about 100 dB sensitive.
I had the opportunity to compare side-by-side the Adcom GFA-535, GFA-545, and GFA-555 back in the early 1990s. The lower-powered GFA-535 was definitely the sweetest sounding of the group. The amplifiers were the same except that the higher-powered units had output stages that were scaled up in size.
It's not always the case that the lower-powed units sound better. In many instances, a company's higher-powered amplifiers get better parts, more elaborate circuit, and an improved power supply.
Robert it was so good to read your sensible replies. I used to sell hifi at store which had the same name as your magazine. We spent many an hour comparing Threshold 400A's to 4000's, Gas Ampzilla's to the Son of Ampzilla and the Bryston 4B to the 2B--- in all cases the lower powered amp sounded much better. There was one glaring example to the contrary --- the english amps. The larger naim and linn amps were always substantially better than the babies.
That said, one of the better salesmen at a well respected store recently reccomended in a forum that his client should use a 600 watt Mcintosh amp with his Kilpschorns to extract the very last bit of head room....Go figure.
Hold on, guys, you're likely to have some novice readers immediately dismissing more powerful amplifiers for smaller ones out of hand. It's incorrect, IMHO, to generalize and say that "every" small amplifier will sound better than "every" large amplifier. Just ain't so! While it may be true, in some instances, that a given manufacturer's lower powered amp may outperform their higher powered siblings (e.g. Robert's evaluation of the three Adcom amps), it is totally off base to suggest that a low powered design from manufacturer A will sound better than a high wattage product from manufacturer B, simply because of the power rating. You simply must know the two specific amplifiers being compared to make a call as to which is better (in the context of a given system and a given listener).
As any seasoned audiophile knows, the performance of an amplifier is dependant on many factors other than power, that making a decision on this criteria alone is a huge mistake.
This may be oversimplifying things, but I've always found that it's best when I buy the combinations that sound good to me. If you are an educated audio consumer (and it seems like most of the people that post here are) you already know quality. When I first started buyng better audio products in the late 70's, I had a 25 wpc Japanese integrated amp that was paired with some custom made speakers (Phillips drivers and crossovers). While it didn't peel the wallpaper with volume, that combo had a wonderful soundstage, balanced sound, excellent detail and separation. Years later when the time came to add more power, I purchased a 80wpc Japanese amp (different company). What a mistake! It made my speakers sound like somebody had put 10 layers of canvas in front of them. I learned my lesson and returned it that day! When choosing between power levels of a similar product line or competing products, go with the ones that reproduce sound the way you like it. Was one Adcom better than another? It's a matter of taste when you get to a high level of quality. Don't nit-pick too much and make sure that you are the one happy with the sound, not your friends or some experts. Everybody has a different "ear"
I believe that there is another factor besides amplifier output power, and that the ability to deliver current can be equally, if not more, important. This is particularly true when using loudspeakers with low impedance - either overall or with dips. The issue here lies in the amplifier's power supply and it's ability to react rapidly to changes in level in the program material and, at the same time, to drive whatever impedance is presented by the loudspeakers also based on the frequency-mix of the program material.
A power supply that cannot react rapidly enough or lacks current delivery capacity will have a significant effect on the sound produced.
I run a pair of loudspeakers that have a quoted sensitivity of 93dB and a 'nominal impedance' of 6ohms, but their impedance curve dips to around 3ohms at one point. I run them using four different amplifiers ranging from 60wpc (Audiolab 8000A), to 100wpc (Audiolab 8000P and then Classe' CA-100) and finally to 250wpc (Jeff Rowland 201s) and each change in amplification has seen the speakers' performance enhanced. This I attribute to a variety of factors: power output, current delivery and damping factor.
The Rowland 201s are capable of delivering 250w into 8ohms, 500w into 4ohms and a peak current output of 35amps. This is significantly higher than any of the predecessors and the amplifiers are usually operating well within their performance parameters, which is obvious from the loudspeakers' performance.
So, I believe that to just look at amplifier in terms of it's power rating can be potentially misleading. Do consider other aspects - particularly current delivery capability.
To add to the sensible opinion posted by Robert Harley above regarding the Adcom amplifiers, I have to say that years ago I worked for a brazilian manufacturer that produced several integrated amplifiers whose circuit topologies were loosely based on previous designs by Japan Victor Company (soon to be called "JVC" then...)
Gradiente made those amplifiers on two different quality levels, which had three and two power levels each one.
In both quality lines, the lower power model always sound noticeably better than the more powerful one. In the case of the higher quality line, the heavier amp (65 wrms/ch) had twice the number of output transistors, and the power supply had about 10-15 more volts between rails. The preamp section was exactly the same. But the cleanest sounding one was the 40 Watt per channel version.
Only when going to great pains to hand select every output transistor (the old 2N3055) to match their gain at at least four points by using a cumbersome manual curve tracer, which meant at least three to four hours of dedicated work, was that the 65 Watt per channel model was able to match its simpler 40 Watt small brother! AND you also had to raise the Bias current significantly, making the larger model much hotter than the smaller one, which had much larger heatsinks. (This was performed only in a very limited number of showroom units and units directed to be used by special clients and factory friends)
I still have one "Gradiente PRO-1200" integrated amp made in Brazil in 1974, still working perfectly after all these years. While it is an old design that is only "quasi-complementary, all NPN devices", it has a sweetness and clarity in the midrange that rivals many present day designs. My experience is very similar to the one superfalcon describes with his 25 Watt amp in regards to the sounstage, separation and detail.
While I echo all of the comments posted re room size,efficiency,impedance etc.,I don't believe readers should assume that the lower power version of a manufacturer's line will sound better in every case.My experience suggests otherwise.The mcormack dna 500 sounded significantly better than it's lower powered brother.Similarily,the Bryston amps seem to be in a much higher league than their lower powered brothers.My personal belief is that more power is better,certainly with the bulk of today's great speakers,most of which like lots of power.
More dynamic headroom from more power should be a guideline for buyers but power should be looked at in terms of high current amperage not Watts. Unfortunately many manufactures don't seem to list the Amperage current capabilities of there products the way they do the Watts. In the early 80's I purchased a Harmon Kardon PM665 integrated amp which I loved for twenty years(student loan well spent). It really is what got me hooked in this hobby. HK rated it at 110 watts/side but proudly posted that it had 45 amps continuous high current. When it died my first effort to replace it was a 100 watt Rotel that had 20 amp current capability. With half the current capablilty it was not even close, the bass slam, dynamics and envolvement was gone. I was a bit shocked at the difference and returned the Rotel. The amperage is what grips the speakers not the watts. So to get to the question of wether a higher priced higher watt power amp is worth it, I would suggest investigating the increase in amperage between the units, not just the watts. I also believe that larger amps can become over kill in a normal listening environment and that with the increased complexity of the larger amp you can lose some magic. I owned a Bryston 3BSST, I later sold it and purchased a Bryston 4BSST thinking that more watts means better sound. Well in hindsight I felt the 3BSST @ 165 watts sounded better than the 4BSST at double the watts. I am betting that the Amp current capabilty between the two Brystons is pretty close.
I currently own a pair of Mark Levinson ML-2's, putatively 25 watts per channel into eight ohms, or 50 watts into the nominal four-ohm load which are reputedly my Martin-Logan reQuests. While I have never felt the need to push the sound levels into ear-bleeding territory, I have pushed the sound levels seriously on more than one occasion and never ONCE have I ever heard the 2's clip, nor have I thought they lacked the means of properly reproducing my source material in terms of sonic impact or dynamic range. Whether this is a case of the ML-2's being underrated or not, I do not know. I CAN tell you that I once auditioned them against a Levinson 332.5 and the supposedly lower-powered 2's held their own in all respects in a room measuring 22' x 14'.
Draw what conclusions you will, but watts ain't always watts from where I sit.
An important factor in how well an amplifier can drive a loudspeaker is the amplifier's performance when the impedance drops. We'll assume for the moment that the 8-ohm rating is legitimate—measured full-bandwidth and within a reasonable distortion figure (not in clipping).
Think of a seven-channel AV receiver rated at 100Wpc into 8 ohms that has one pair of output transistors per channel, a power transformer for all seven channels that weighs 8 pounds, heat-sink area for each channel that's about the size of a deck of cards, and costs $499.
Now think of the Pass Labs XA100.5, a 100W into 8 ohm amplifier that I'm currently using. These two amplifiers look as though they are equally powerful—100Wpc into 8 ohms. But the Pass has 40 output transistors, a power transformer that weighs at least 50 pounds (my estimate) for just one channel, and heat sinks (again for one channel) that have perhaps 100 times the surface area and mass of the AVR's heat sinks.
Put them both on the bench and the both deliver 100W into 8 ohms, although it's likely that the Pass is conservatively rated and can deliver a bit more. Drop the load impedance to 4 ohms and the AVR might output 150W, while the Pass will output 200W. Leave them both on the bench and the AVR will probably shut down due to overheating in a matter of minutes. The Pass is just cruising along and could run in that condition indefinitely.
Now drop the impedance to 2 ohms. The AVR might output 180W for a few seconds and then shut down. The Pass could probably deliver at least 350W and do so comfortably and indefinitely.
The Pass can deliver current through the speakers' voice coils when called upon; the AVR cannot. It is current flow through the speakers' voice coils that caused them to move back and forth. If the current is restricted, the sound wil be as well.
Remember, these two amplifiers carry the identical power rating of 100W into 8 ohms.
This is one reason why power amplifiers sound and perform so differently in the real world.
Robert,
In your opinion, would the Magico Mini II benefit from the added power/current (320 watts/36 amps vs. 200watts/20amps into a 4 ohm load) that the Pass XA160.5 has over the XA100.5? Thanks. Peter
I have been thinking of "upgrading" my current setup from two pair of B&K 200-wpc monos bi-amping my speakers to one pair, possibly of higher power. It's beginning to seem like I should leave the idea alone. The potential replacements so far are the Odyssey Stratus monos, B&K's own 200.1 Reference monos, and Cambridge Audio's 840 (bi-amping with 2 of them). I've pretty much eliminated the Emotiva XPA-1 monos (500 wpc) because of size and weight concerns. While listening to the Return to Forever Live at Montreaux blu-ray recently, I remember thinking, "I don't need to replace or upgrade anything; this sounds pretty good." My speakers have a nominal impedance of 6 ohms and a minimum of 4, according to the specs. Volume isn't an issue, but I was wondering about improvement in sound with a power upgrade. Of those amps still in the running, only the B&Ks are above 200wpc (250). Aside from watts, all these amps have enough "amps" so that they won't work that hard at all.
Maybe I should go for better parts and not more watts, if I do indeed decide to change.
Hi Prepress!
What a dilemma - If your current setup is satisfying, I'd leave it alone. On the other hand, my experience has been that monos tend to sound better than stereo amps. Personally, I'm not convinced that the circuitry has anything to do with it; I believe, rather, that the shorter speaker wires make the bigger difference.
When you have a preamp connected to a power amp via a long interconnect, the source and destination impedances are generally closer to stable, and there is little impedance change with frequency. When you have the power amp connected to the speakers by long speaker cables, however, the speaker impedance changes (often wildly) with frequency as does the electrical phase angle. Because of the impedance mismatch and variation between the power amp & speakers, it seems (theoretically) that speaker cable should have significantly more impact on sound than interconnect cable.
That being the case, it makes sense to minimize the effect of speaker cables by keeping them as short as possible, thus effectively "direct-coupling" the power amplifier to the speaker. This is possible with mono amps (which can be placed adjacent to the speakers) but generally not possible with stereo amps which must be "centrally located" between the speakers.
Of course, I could be wrong...
A good sense of humor makes it ALL sound better!
Boomzilla,
I have Kimber 8TC running in twin 6-foot pairs to the speakers; I could get away with 4-ft pairs, but why go there? And based on my experience, I agree that speaker cables make a bigger difference than interconnects. The Kimber was a noticeable step up from the Tara Labs RSC it replaced. Of course, the 8TC is a heavier gauge and that had a lot to do with it. More information coming off the discs these days.
I'll have to think about this some more. Upgrading would be nice, but since it isn't a necessity I can take my time. So, you think that more power doesn't necessarily translate into more control over the speaker, especially in better bass? What about a beefier power supply or reserve, as opposed to more watts?
Hi prepress -
More power generally controls the bass better, but not always. Beefier power supplies generally control the bass better, but not always. A major factor in bass control (as I understand it) is damping factor. I believe that this is a ratio calculated by dividing the speaker's impedance by the output impedance of the amplifier. In the damping factor sweepstakes, a bigger damping factor number is generally better in terms of woofer control. You haven't much control over the speaker's impedance (though, from a damping factor aspect, higher-impedance speakers are better). The amplifier's impedance is generally determined by the number of output transistors in parallel - more transistors = lower output impedance & better damping factor. Generally, the output transformers of tube amps give them a worse damping factor ratio than for transistor amps that lack the transformers' impedance. This is why muscular transistor amps with no output transformers (think Krell...) are reputed to have greater bass control than other amps.
Of course, the previous paragraph is all theoretical. In practice, some amps even with poor damping factor ratios seem to have perfectly good bass control. If I were you, just for the fun of it, I'd get some 12-ga. zip cord (heavy-duty "contractors' extension cords" are a cheap source) and wire myself some 4-foot runs in parallel. The cost is minimal, and since it is an experiment, you don't even need to tin the wire-tips - just cut & strip. Plug those puppies in between your amps & speakers and (ignoring the remainder of the frequency spectrum) just listen to the bass. Is it noticeably tighter? If so, larger ga. speaker wires (Kimber 12TC?) might be a cheaper fix than swapping amps. If you hear no difference, then you've lost the cost of an extension cord & some time AND you've found out that speaker cables are NOT the weak link in your system so far as bass control goes.
Of course, feel free to value this suggestion at the exact amount that you've paid for it... My advice isn't sterling in any way, shape, or form. If what you seek is better bass control, though, the experiment is one that I'd try.
A good sense of humor makes it ALL sound better!
The 8TC is the equivalent of 9-gauge cable. The 12TC would be even heavier than that. I will continue to consider the possibilities (including cable), but must remind myself there's no rush. What I really should do is make time for some real listening sessions (not as easy as it sounds) and see how I think after that. I may "hear" myself out of buying anything. The idea was to replace the performance of 4 monos with two, which probably means better amps. I could simply remove one pair of the B&Ks, but that will thin out the bass a bit, most evidently on recordings that are light on bass to start with.
Maybe I need to stay away from these forums too...at least, temporarily.
Two good amps? Better than B&K? Good bass control? Odyssey Stratos monoblocks!
A good sense of humor makes it ALL sound better!
Well, they are on the list. They offer no more power than my current amps, though; the special edition Stratos is only the same (200w), and the regular ones a bit less at 180. The other question is, would the extra 50w the B&K 200.1 offers result in any difference, at least in theory? I like the B&K sound, and the Odysseys will require more break-in time.
Of course, there could be nothing wrong with the set up I have. This is as much about creating rack space as it is sound improvements. I still need to do some serious listening and start comparing specs. and since volume isn't an issue (I can't turn the system up much more lest it be too loud, hence the idea that more power would grant improvement at lower levels [so I thought]). Do you own the Stratos monos?
Do you own or have experience with the Stratos?
I've become a bit enamored with the McIntosh 501 monos, and wouldn't mind having them, but it's difficult to justify them given their size, weight and price. Plus, I don't truly need 500 watts; it would be about sound quality, if anything.
What we are really dancing around several topics here amplifier power/need and system matching.
I've found it useful to find out what brand of electronic the speaker manufacturer uses when he or she is developing their speakers when I'm considering a new speaker purchase.
Most are willing to tell you or make recommendations.
And, amp manufacturers are willing to make recommendations or tell you what brand of speakers they use to test their products based on my experience.
It doesn't hurt to go to your local high end dealer and listen to the speakers and amps you're interested in purchasing.
My local dealer lets me take equipment home when I'm close to a purchase. They just take an impression of my credit card and away I go. Of course there is an understanding if you don't come back within a specfied time your card gets charged!!
Just my thoughts on the subject of amp power and how much is enough.
Watts alone aren't the whole story, of course. Some of the amps on my short list offer more than the 100–300 recommended watts for my speakers, which are also a not-that-efficient 83dB sensitivity. In fact, only two (the B&Ks and Odysseys) fall within that recommended range. What all have in common, though, is heavy-duty current peak-to-peak and will definitely take control of my speakers. Even though my current 2 pair of monos give me more than adequate listening levels, I note they don't work at all to achieve that. The power meter on my line conditioner shows that they're loafing. It's more than likely anything I buy will be loafing. But that's okay. I'm looking at all the specs, reviews and reports I can find regarding the amps I'm considering (the list changes, depending on the results of the process). In the end, the most powerful amp may not win the day, but the one that I think is the best overall fit.
Meters lie! The amp that sounds the best with your speakers may not be the one that has the recommended power, the one that has the current capability, or the one that "reads the best." I've had a 60-watt stereo receiver that sounded more dynamic than my 350-watt, TAS-recommended power amp! Unfortunately, synergy can't be measured or predicted - only heard. You may have to just keep trying till you find the amps that do what you think they should, and those amps are likely NEVER the ones you expect them to be. I know that this is a disappointing comment to read if you're hoping to make an intelligent choice sans audition, but I believe that this is a factual comment. Happy auditioning!
Boomzilla
A good sense of humor makes it ALL sound better!
Boomzilla,
That's why output wattage isn't the only criterion to consider. I use my current amps as a guidepost in this. They are 200wpc and offer 40A peak as I recall. Volume isn't an issue in a 14.5 x 18.5 room. The dynamics are lacking a bit perhaps, and the amps seem to congest a bit during full-bore orchestra music. B&K's latest monos offer 250wpc and 150A current, and the specs say max power consumption is 875W; they'll NEVER work that hard in my setup. The B&K tech I spoke to says their current monos have better parts, will be cleaner (especially in the midrange) and go deeper in the bass than my Sonatas. That sounds good to me and I'm familiar with and like the basic B&K sound; it would be easy to just get a pair. Plus, at $2998 they're cheaper than some of the other alternatives. The Parasound JC 1s have snuck onto my list even though beyond my budget, and have less peak current than the B&Ks (according to the specs), yet I have no doubt they'd sound good also. These may be the only amps I can audition before buying.
The 800-lb gorilla for me is power consumption, not output. All of the amps on my list will drive my speakers easily. But the'yll need to work within the context of a regular household line. Parasound assures me the JC 1 will. The Emotivas will. They all will. But how much impact on my electrical bill? There are practical considerations which are as important as sonic ones. So no, your comment isn't disappointing; in fact I think we agree. Reviews, specs and such are part of the research process and i have some basic criteria for any prospective candidate to meet. Other than that, I'll keep digging until I get what I believe is the overall best choice.