Mainly it comes down to headroom. Many amps can cleanly play short term peaks higher and sometimes much higher than their continuous power ratings .... Except pure Class A which are limited to their rated power.
Mainly it is a factor of power supply capacitance, regulation and sometime feedback (that can negate power supply ripple). How beefy the output stage is can come into play as well.
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Tube-amps sometimes "seem" more powerful as their distortion is typically more pleasant when they clip, but they are still clipping.
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100w pure class A into 2 Ohm ... Means 100W is all you get , no headroom. Now you are trying to change the measure because your anemic claim was fantasy? That's not too honest now is it?
Your selective cut and paste and your mention of phase angle shows you neither understand my post nor amplifier specs. You are making a claim about an amps potential performance that is impossible to make with only continuous power specs. |
27 amps is 1500 watts into 2 ohms. 60amps is 7200 watts. 60amps would require a bus voltage of 120V at 2ohms, phase-angle aside. I think the number of speakers that drop below 1.5 ohm approaches a handful and even the number that drop much below 2 ohms are uber expensive and won't be matched with a $1,500 amplifier. 60 amps at 1.5 ohms requires a 90V bus voltage (approx). Odd of the odyssey amplifier having a 90V bus supply are pretty much 0. Given it's power rating, it is much more likely to be close to 35-40V. That 60A specification is pretty meaningless ..... not to mention 60A would drag down the power supply capacitors pretty seriously, further limiting the practicality of delivering this much current.
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There are few variables and they are easy to understand if you take the time to do it. Some people want it to be complex because THEY do not understand it and wish that others do not, so that keeps them on level ground. |
Most tube amps don't have "guts" in the bass due to low damping factor. You may prefer that or you may not and that will be room / speaker dependent.
That dip in impedance is a factor of woofer electro-electromechanical properties and sometimes a 2.5/3.5 way folding in another driver. Crossover may shunt current from woofer to tame a peak. |
Miller as usual puts a lot of words down that mean exactly nothing. Actually your last post said absolutely nothing. Lots of snark and veiled insults but no actual info.
Tube amps may hit above their weight because they can often be driven into clipping without sounding awful and YES people with low power tube amps do this.
Other than that, looks at watts at the low of your speakers impedance. One amp that does 100 watts and 4 ohms and 200 at 2 ohms is not the same rating as 100 at 4 and 150 at 2 if your speaker dips to 2 ohms.
Other than that, mainly comes down to headroom provided by the power suppl both the voltage and capacitance and a beefy enough output stage to deliver short term peaks. There is no magic, no ethereal effects ... Just basic low level engineering. Flowery words are meaningless. |
erik_squires,
Did you look into resonances? It is not uncommon to use the "cross-over" to damp a resonance. Your assumption is that the cross-over designer was competent as well. Especially in boutique audio, my experience is that is often not the case. Thank you for the post. Always good to have a reasoned discussion.
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The Behringer is 1500 watts into 2 ohms, which is about the lowest impedance of the Wilson. There will be absolutely nothing anemic about it compared to the ML2, and that is obviously spouting uninformed nonsense, nothing actually related to reality.
1500 watts into 2 ohms is 27 amps. The ML2 is 100 watts into 2 ohms ... or 7 amps.
"Current" is nothing more than watts at a given impedance.
1500 watts into 2ohm is always more than 100 into 2 ohms, especially when the lowest impedance is 2 ohms. I get it, you don't like Class-D, but don't make up facts.
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sejodiren, Your post is welcome, as it illustrates quite well this concept of "doubling into 4, doubling again into 2" is just a "lazy mans" spec. It sounds impressive, but only if the design is conventional, and even then, the only specification that matters is how many watts at your speakers lowest impedance. 300 watts into 2 ohms, and 150 into 8, is still better than 200 into 2 ohms, and 50 into 8. The Proton, which does not increase that much into 4 / 2 ohms, has a design methodology based around real world music where peaks are short in length, and for those peaks, it can deliver significantly more power (headroom). It's this headroom that makes an amplifier deliver above its rated continuous wattage (which you can only compare at the same impedance). sejodiren102 posts12-21-2019 9:39pmRead
the review for this Proton that I own. A lowly 40wpc but 6db of
headroom. It makes my DQ 10's just sing compared to the Yamaha SS
receiver I was previously using at 95wpc in 2 channel mode. I don't
know a whole lot about the 'techy' stuff but I believe it's a class
g/h? Incredible sounding 'little' amp for sure.....
http://www.hifi-classic.net/review/proton-d540-410.html
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Optimize, yes we do know what you are asking if say they give a spec into 8, 4 and 2 ohms which many do.. |
You mean like statements like this that ONLY apply to pure-class-A and make assumptions about heat-sink materials, power supply architecture, etc. that are not a given in all designs. One pound of weight for every 2 watts is a good litmus test for
evaluating Class A amplifiers. An amplifier weighing less might not be
pure Class A. It might be almost Class A, or it might be one of the many
products which achieve a Class A designation through trick circuitry. What's funny is that people will quote the likes of Pass when it suits them, but ignore the other things he writes when it suits him, like Large inductors in series with the transformer primaries and secondaries
can be used to stretch the duration of the charge pulse to the power
supply capacitors, improving regulation and reducing noise. ... those large inductors negate heavy gauge power cords. Of course, not everything that Nelson pass says/rights is entirely accurate either: Also, it helps if the power supply capacitors before and after the
switcher are very substantial. This is typically not the case, since one
of the primary motivations to use switchers is to save money. Power supply capacitors before the switcher are not "substantial", as small values are essential to achieve good power factor and THD, a typical design goal of AC\DC switching supplies. As a matter of fact, substantial capacitance on the front end of an AC\DC switching supply will reduce the requirement for output capacitance to achieve the same performance and will reduce the overall cost to achieve the same performance. |
Define "read the most correctly". Are you am amplifier design/EE? If you don't exceed the rated continuous or peak wattage at a given impedance, then you have enough current (and voltage). Georgehifi is making assumptions about performance that are not supportable with the data on hand ... namely wattage at a given impedance. I won't claim a 1500 watt $500 amplifier is going to have the overall sonic performance of a high end class-A amplifier, even at 100W, but with a speaker that drop to 2 ohms (approx), an amplifier that can deliver 1500 watts at 2 ohms, is not going to sound "anemic" as long as you don't drive it into clipping. Watts, or power, is equal to voltage multiplied by current. But an
individual speaker may want more voltage at some frequencies, versus
more current at other frequencies. And if your amplifier is limited in
one of those dimensions, it will have trouble driving the speaker. |
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I will guarantee something you have not done ... listen to the Alexia with the Behringer. They may not be fancy, and they may not be what we traditionally think of as "hi-fi" but they are designed to drive loads every bit as harsh as the Alexia, and to do it continuously in harsh environments.
georgehifi6,476 posts12-22-2019 2:33pm
Like said listen to the Alexia driver by the 3000w Behringer then with the 25w ML2's
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No, you are wrong Georghifi , and I see you have made this wrong claim many times on this forum and even though many people have told you you are wrong, you keep making it. Phase-angle w.r.t. load impedance is only "harsh" in that it places significant thermal stress on the output devices of linear amplifiers and additional loading on the power supply. That does not impact Class-D amplifiers. It is a transient condition in real world music. In continuous power measurement, it is NOT a factor of current delivery as maximum dissipation DOES NOT occur at the peak current / lowest impedance. That goes back to my original post above w.r.t. the importance of the power supply, which can support transient peaks with capacitance, but if you want "nice" continuous measurements, you need a beefier transformer/switching supply. Again, you are making a leap w.r.t. amplifier performance that you are NOT able to make with the limited information available. 2 amplifiers each able to deliver 100 watts cleanly at 2 ohms, can each supply the same current no matter what they may do at 4 or 8 ohms. Without knowing what the inherent limitation is of the design, you cannot make conclusions, only assumptions ... and you know what they say about assumptions. Being able to deliver 1500 watts into 2 ohms, cleanly, does show the ability to deliver 27 amps. Being able to deliver 100 watts into 2 ohms, shows the ability to deliver 7 amps. Any other conclusions you want to attempt to come to are just conjecture. -phase angle plus low impedance can look a very much harsher load to the amp than just the low impedance alone. |
Georgehifi, Here is the difference between me and you. Your posts are all conjecture and hand-waving. Conjecture and hand waving is ..... well just that. Again, let's look at facts: - 1500 watts into 2 ohms is 27 amps
- 100 watts into 2 ohms is 7 amps
- Maximum dissipation in a LINEAR amplifier with a real speaker load DOES NOT happen at the spot on the speaker impedance curve where the current delivery is highest.
- Class-D is not impacted by phase w.r.t. power delivery in the same way a linear amplifier is, either in device dissipation or power supply loading.
- Other than knowing an amplifier can deliver 100 watts into 2 ohms, you have no data that shows the power supply is any more capable of supporting continuous additional power delivery and the dissipation peak of the speaker load
- You have not heard the Alexia with the Behringer, but you are making many claims that you don't have the requisite data to support.
- You are deflecting bringing up OTL amplifiers
- There are many reasons why power may not double with every 1/2ing of the impedance, and without knowing what that reason is, you can't made factual conclusions about an amplifier beyond that it will clip at a given wattage and load impedance (as stated in the specs). If the 2 ohm wattage is stated (and distortion components), and given that impedance doesn't drop below 2 ohms for almost all speakers, then beyond knowing where clipping will occur for 2 amplifiers, you really don't know much else. Any other conclusion you arrive at is purely assumption.
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Oh come on George, I don’t know any amplifier vendor that publishes independent data, only reviewer data. Your comment about MOSFETs is ignorant. It’s easy to drive into 2 ohms with complimentary MOSFETs. Purely an architecture thing. I don’t know why you insist on this repeated ignorant. Please learn more about amplifier design before posting on this. You know the Behringer is rated into 2 Ohm ... Why would you say what you do? Optimize, - P = v * I
- P = v^2 / R
- P = i^2 * R
If you know P and R, then you can calculate I and V. I am not aware of any commerical audio amps designed as current sources ... Not practical as it would not work with off the shelf speakers as it would screw up the crossover operation. |
Oh George, maybe someone will give you a new record for Christmas. Yours appears to be broken.
You have never actually designed an amplifier. That much seems obvious to me. Guessing you don't know much about speaker performance versus damping factor either.
Your holy grail wrt power doubling from 4 to 2 ohms ... Says more about the power supply AND feedback level than the output devices. An amplifier designer would know this.
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I guess you didn't get a new record for Christmas. Ghi, I think you would be surprised what can be built for a $150 in parts when you purchase in volume. |
Did my research. Stand by my post. You don't seem to have actual amplifier architecture design experience. You adapted the compression circuit from mixers to make a pre-amp billed as passive, though technically not passive. No obvious experience with any serious design of BJT or FET amps. |
Oh come on Clearthink. You can do better than that. I am not sure that rant is even worthy of inclusion in my book, "Clearthink's Practical book of Impractical Rants". I have come to expect much more of you. |
Georgehifi,
So let me get this right. You design with Cadmium Photocells but you don’t know they are ACTIVE semiconductor devices? That’s right, active semiconductor devices. Period. End of story. Not debatable even.
My gosh. You don’t even know how a CdS photocell works. It does not change its chemical properties when exposed to light. It is a doped semiconductor. Exposing it to light increases the availability of free electrons for conduction.
Teletronix limiting amplifiers, first released in late 1950’s, early 1960’s used CDS Photocells to control audio level. That was later built into other equipment. YOU absolutely did not introduce photocells to audio for level control. |
Nice try ghi, but if anyone is stalking, you are stalking me. I posted 6 times in this thread before you did. You are free to post whatever you want, but if you post erroneous information that you can’t back up, people like me are quite warranted, perhaps even morally obligated to call it out.
You make many claims about amplifier performance that are not founded and would not be made by someone with a somewhat deep understanding of amplifier topologies and what drives their performance limitations.
That you don’t even understand the operation of the underlying technology of the product you sell further calls into question your technical abilities which you appear to use to justify the validity of your other statements, since you don’t justify them from a circuit design / architecture standpoint.
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When you keep sticking your foot in your mouth and showing lack of knowledge, even about the things you claim to be the expert on, are you surprised I would expect you lack knowledge in amplifiers , things of which you keep making erroneous statements on? |
Optimize, amplifier power tests, right or wrong are made into constant resistance loads. The equations I posted are simple extensions of ohms law. All that is required is to use RMS values. They work.
With inductive and capacitive loads there may be other thermal limits placed on the available power, at least with non switching amplifiers.
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JerryBJ,
No to belabor a point, but someone that accuses others of trolling I understand has even sent private messages to people asking them to report threads they did not like. |
Class D and linear amps have the exact same rail voltage limitations. They often have the same linear power supply front ends. Certainly audiophile Class D amps. They also get more oomph out of the same sized capacitor bank for real music.
It's torque at the wheels that moves a car, not engine torque. I can always convert more horsepower to more wheel torque with gearing.
Many consumer brand receivers have poor ability to drive difficult loads and poor damping factor. The more audiophile brands even though rated lower watts at 8 Ohm tend to be much better.
Everything is designed to a price point. Not doubling in power into 2 ohms (continuous) is often just a factor of the limitation of the transformer. It can only transfer so much power. A nice capacitor bank can give you much of the benefit for real music (not simple sine wave power tests). |
The impedance curve of a speaker takes into account the reactance already and hence the current. Few speakers dip below 2 Ohm. Some do, but they are rare. If your speaker doesn’t dip below 2 ohms than having an amp that doubles in power into 1 ohms is likely paying for something you are never going to use. Their is more to doubling into 1 ohm than just beefing up the supply, and there is no guarantee that the trade-offs , like higher feedback, are going to sonically pleasing. This is why "rules of thumb", like doubling of power into 1/2 the resistance is "better", should be taken with a grain of salt.
If your speaker does not dip to low ohm, then a so called beefy amp will not sound any beefier, but one with higher voltage rails and more capacitance will, even though it can't double into 2 ohms or 1 ohm or whatever artificial metric you want to use that may not apply to your system. |
1) I have never made any claims about the SQ of the amplifier. 2) Do you have proof it cannot deliver the required current into 2 ohms to achieve 1500W? 3) What does "residue of current starvation" mean? Are you implying they are selling an 8000W amplifier for < $400 now? Please explain in some detail, as you keep avoiding this, why you believe it is impossible for a Class-D amplifier to work properly into 2 ohms. If it existed it would be PA, junk and it wouldn’t be getting it’s 1500w
from a well designed amp with great current ability that can double
down from 325w @ 8ohm and 750w @ 4ohms.
No, the 1500w would be the
result of residue from current starvation from an amp that was
originally 6000w or 8000w at 8 or 4ohms, and it would sound like junk |
P = I*I*R. Alexia's lowest impedance is 2 ohms. That means 80*80*2 = 12,800 watts (minimum) during that peak.
V = I * R = 80 * 2 = 160 volts minimum (to achieve 80 amps).
The Antileon is 175 watts into 8 ohms suggesting a maximum rail voltage of something probably a few volts over 37.5V. Even if current and voltage were 180 degrees out of phase at the impedance peak, you only have 75 volts (not the 160 needed to drive 80 amps into 2 ohms).
You will excuse me if I consider your 80 amp measurement suspect. What were you using for a current probe?
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EPDR is not a measure of impedance, nor does it represent what the maximum current will be for a given voltage. EPDR is used as a measure for amplifier dissipation loading (not delivered power either). EPDR is a measure of the maximum loading point of the output devices of a linear power amplifier. It is the point where the (current * voltage drop, rail to output) in the amplifier is at a maximum, hence where the dissipation is at a maximum within the amplifier. That is all it means. It is not a direct relationship to what the maximum current draw is of an amplifier. EPDR does not occur at the impedance minimum in a reactive load, which means it also does not occur where the maximum current is delivered for a practical speaker. Note my statement below. I specifically used 2 ohms as a minimum as that is the impedance minimum, and hence represents where the current peak would occur for any given voltage. You did not indicate what you used for the a current probe. P = I*I*R. Alexia's lowest impedance is 2 ohms. That means 80*80*2 = 12,800 watts (minimum) during that peak. |
EPDR does not impact Class-D amplifiers. I do not understand why you will not communicate what you used as a current probe to measure 80 amps peaks?
Generally I would expect an amplifier that costs literally 100 times more (per channel) than another amplifier to be "superior". However, your comment about "seriously current starved" cannot be backed up with facts. It does not go backwards into 2W, it has about 75% more power into 2W than it does into 4W. Do I have any illusions it can do 1500W into 2 ohms, even IEC bursts? Not really. But then again, you don't have proof it doesn't. I do know for a fact it puts out 75% more power into 2 ohms than it does into 4 ohms.
The Gryphon is a claimed 350W into 4 ohms continuous. The Behringer claims 750 (2x, not 17x). It also claims 3000W into 4 ohms. Will it? Doubt it, but maybe for IEC bursts. Will it do >1500W in long enough bursts to support real music at those levels? Yes it will, and yes, that is quite a bit more than the ~100 times more expensive Gryphon.
The primary limitation of it at 2 ohms, is the same as it is at 4 ohms, thermal, not current.
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Layman’s terms:
It all comes down to "rated" power of your amplifier across the impedance of your speakers, with high emphasis over the bottom KHz or so.
Note I said across impedance, and not just at the lowest impedance as is often brought up. While a 4 ohm speaker may drop to 2 ohms (or less), it may also go up to 10 or 12 ohms (or higher) and do that over a relatively narrow frequency range. At a given volume level, not being able to deliver the required voltage at the impedance peaks or the current at impedance minimums will both cause issues in sound.
We next get into continuous ratings and peaks ratings. There are US and international standards for peak ratings. Are they good enough? Questionable, but nothing is stopping anyone from over designing beyond the standards with oversized transformers and/or large capacitor banks (or an architecture that allow more power supply droop). Of course you need high enough power supply voltages and beefy enough power supply to support the music peaks at the impedance peaks (which can be where heavy bass occurs), and a beefy enough output stage (and power supply) to support the current peaks and the minimum impedance, which are pretty much always bass.
From above .... beefy supply is the first need independent of the speaker requirements, and if your speaker dips low in impedance, you need a beefy output stage too, .... and there are many architectures that have been created to allow higher short term power bursts as is required for real music, but does not improve continuous power ratings.
So can you tell the "power" from the specs .... maybe. Depend on whether the amplifier vendor provides you enough details and you know enough about your speakers. That is about as easy as one can make it.
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There are two types of people: - Those who know how to use Google (and other references), can sift through results using sufficient knowledge to reach accurate conclusions and consult industry friends to cross-reference.
- Those who insult others, but cannot back up their insults.
I don't know any audiophile who would make putting 75% more power into 2 ohms than 4 ohms their defining criteria for purchasing an amplifier. Do you? |
It couldn't possibly have anything to do with amplifier architecture and pleasant soft-clipping. Nope, it couldn't possibly be that. It probably has nothing to do with the rated power at your speakers lowest impedance either. 2 watts of SS power to equal 1 watt of tube power |
listening99, Unfortunately, I could not find much in the way of testing of the STA200, and as you probably know, the marketing literature is very sparse w.r.t. details. There is this test on AudioScience https://www.audiosciencereview.com/forum/index.php?threads/review-and-measurements-of-nuforce-sta-20...... which is all done into 4 ohms, and other than fairly high mains noise, nothing looks off. Since you have not mentioned an issue with your likely highly efficient horn loaded speakers, that does not appear to be a problem, but if the Tekton Moab's are a lot more efficient than what you have now, that could be a problem. Take the comments made by the "reviewer", AMIRM, with a grain of salt. He is the type of "measurements" person, that gives other people who believe in measurements a bad name. His comment "Looking at the power rating versus distortion, the STA-200 doesn't bring much to the party over the much cheaper Topping TP60 ($199)" ... shows a lack of knowledge/experience w.r.t. what is important. At low power levels, where almost all music is, the STA200 has much lower THD than the Topping TP60, and considerably lower IMD. The STA200 though clips really hard w.r.t. IMD. With the really efficient speakers, hopefully you won't run into that issue. Tekton is usually conservative in their impedance ratings. When they say 4 ohms, it usually will not dip much below 4 ohms. I would say you have little to worry about other than what is stated above. |
