100W will drive the speakers already past their MaxSPL spec, so no, I would not worry.
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Hypex Nilai500DIY Amplifier Review
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terryforsythe
Major Contributor
Here is a link to a Google Docs spreadsheet to calculate amplifier power needed:
Amplifier Power Requirement
Read and consider the notes to the right of some of the input parameters when selecting a value for those parameters.
Luvchampagne
Active Member
Thank you. Great reference especially for people that keep preaching that 300wpc is enough especially for sub 87db efficient speakers.Here is a link to a Google Docs spreadsheet to calculate amplifier power needed:
Amplifier Power Requirement
docs.google.com
Read and consider the notes to the right of some of the input parameters when selecting a value for those parameters.
Another issue to consider - as I understand it, hypex and purifi design amplifiers are rated at peak output. In other words, there is no headroom beyond the rating, without forcing the amp into clipping. Whereas more traditional SS amps have headroom allowing for reasonable transients without clipping. Ymmv depending on amp.
? The rating is for all amps the same: after clipping they do not nothing good, or in other words: right behind the knee is nogo (graphically speaking)..
Go look at the ASR reviews for the Hypex and Purifi amps you're considering. The reviews will give you the actual measured max wattage at clipping, etc. you can use the measured values as the "real world max" or however you would like to reference it.
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Applies for 102dB SPL full-range spec, although for the 106dB SPL over 100Hz you'd need around 210W.
Luvchampagne
Active Member
Already done that
Was looking to upgrade from an older SS amp to one of the newer Purifi amps.
Actual measured max wattage is often less than stated and no more than low single digit % different than stated. Dropping impedance usually shows less than stated.
Traditionally SS amps were measured not at clipping but at some thd like 0.001%. More recently, amps are stated at 1% thd so more of a red delicious to fuji apple comparison between hypex/purifi and SS amps.
Older SS amps, as long as well built, will have lower sinad than the hypex/purifi amps but under actual conditions, probably inaudible, but will have the headroom I stated above.
Nope, not in a real room:
And even then, both amps will have no issues delivering 210W.
And yes, it’s at 1m. That’s also how the maxSPL is defined. At that level you’ll probably reach the woofer Xmax.
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I don't think the max SPL rating takes 6dB of room gain into account. Going by that logic, in a "real room" the max SPL rating of the speaker would be 111dB.
That might be correct. You’re then lucky you can make up for the lower maxSPL below 100 Hz. Still, either amp can drive this speaker to destruction.
I beg to differ: My NAD 2200 is rated at 100 watts a channel and was tested here:
It is power measurements where the magic of this amplifier comes to life so let's look at that with 4 ohm load first:
We can see a kink in distortion when we hit 200 watts as the unit sails past that to produce whopping 337 watts per channel, both driven! Per design characteristics, you can have much more during momentary peaks:
Wow, we have one kilowatt of power coming out of this amp in short duration!
And signal to noise ratio:
Conclusions
Nice to see innovation like this from equipment that is over 30 years old! Shame on manufacturers that produce amplifiers for much less power, more distortion and higher prices these days. No, you don't get a fancy case here and sheet metal is strictly budget category. But you are not going to sit on the amp. The guts are where it matters and NAD 2200 delivers.
NOTE: the output relay on stock 2200 gets corroded and fails over time. There are videos and DIY threads on how to upgrade the relay there to fix the problem. The unit tested here has that fix. Other than that, there are not reports of many other reliability issues even though NAD products are often said to be less reliable than other brands.
Overall, I am happy to recommend the NAD 2200. I almost gave it the highest honors but given the upgraded nature of the test unit, and the fact that used amps may have issues, I avoided that. But you could have easily pushed me to give it the golfing panther.
Here is who & why:Well, everyone can makeup a magic number for rated power, and then make an amp that is actually way more powerful. Let’s slap a 50W rating on the Purify, and be amazed at how much more powerful it really is.
Not just any Yaa-Hoo: but a truly intelligent one from the Netherlands:
A person from the Netherlands (Bjørn-Erik Edvardsen [1945-2018] {Chief Engineer of NAD from the early 1970's until his death}), while not inventing the idea, sure did a good job of perfecting it: It's called headroom:
Its most famous product is the late-1970s NAD 3020, an integrated amplifier designed by Bjørn Erik Edvardsen, which was highly regarded by various magazines in Britain.
Another famous product was based on Erik's NAD focuses on the concept of effective power, potentially enabling delivery of dynamic power bursts far in excess of their rated RMS power. The key to this feature requires use of a flexible power supply which stores significant reserve current for quick release at moments of high musical load. Originally developed at NAD by Phill Marshall, NAD's various incarnations of his design have been associated with different names over the years including Power Envelope and recently PowerDrive.
Additional benefits of this approach include the fact that amplifiers using this technology can handle complex, real-life, lower-impedance loudspeaker loads as compared with the simple 8-ohm resistor typically used to calculate advertised power ratings and the fact that the circuitry in this approach requires less cooling, while maintaining ability to handle complex impedance loads as low as 2 ohms.
NAD chose to design the 2200 as an inherently powerful amplifier, with the size, weight, and heat-dissipating ability (as well as the price) of a typical 100-watt unit. Because of its conservative design, its clipping power output, even in the “low power” mode, is about 140 watts per channel. Since the switch to a higher supply voltage occurs at the 140-watt level, any switching transients are masked by the high acoustic level.
Despite its conventional appearance, the NAD 2200 is radically different from other stereo power amplifiers in its design and performance, some aspects of which border on the spectacular. It carries a relatively moderate power rating of 100 watts per channel into 8-ohm loads from 20 to 20,000 Hz with no more than 0.03 percent distortion. In size, weight, and price, it is similar to a number of other good 100-watt amplifiers. Not surprisingly, it follows the NAD tradition of giving its amplifiers conservative power ratings and the ability to drive low-impedance speaker loads without difficulty (the clipping power output is specified as 140 watts into 8 ohms or 200 watts into 4 ohms).
Despite its conventional appearance, the NAD 2200 is radically different from other stereo power amplifiers in its design and performance, some aspects of which border on the spectacular. It carries a relatively moderate power rating of 100 watts per channel into 8-ohm loads from 20 to 20,000 Hz with no more than 0.03 percent distortion. In size, weight, and price, it is similar to a number of other good 100-watt amplifiers. Not surprisingly, it follows the NAD tradition of giving its amplifiers conservative power ratings and the ability to drive low-impedance speaker loads without difficulty (the clipping power output is specified as 140 watts into 8 ohms or 200 watts into 4 ohms).
However, the NAD 2200—which the manufacturer calls the “Power Tracker”—has some remarkable dynamic power capabilities. Its dynamic headroom is rated at 6 dB, which means that it can deliver—in 20-millisecond bursts, twice per second—400 watts per channel to 8 ohms, 600 watts to 4 ohms, and 800 watts to 2-ohm loads. If that is not enough, the amplifier can also be operated in a bridged (mono) mode, in which it is rated to deliver up to 400 watts of continuous output into 8 ohms—or, in terms of dynamic power, 1,200 watts into 8 ohms and 1,600 watts into 4 ohms! It is also said to have a wide “dynamic power envelope,” which means that it can maintain these high levels for longer than the standard 20-ms bursts.
The importance of high dynamic power output for realistic music reproduction has been widely recognized for some years. One way to achieve it is by using a signal-controlled, or “smart,” power supply, in which the output voltage is controlled by the instantaneous signal level and automatically adjusts itself to accommodate the brief high peak levels found in most musical and vocal waveforms. Since the average power requirement is usually one-tenth or less of the peak power demand, the switched-voltage design approach offers the attractive possibility of doing without a large, expensive, heavy-duty power supply whose full output will be needed for only a small fraction of the time. Instead, the amplifier can use a relatively compact, inexpensive, low-voltage power supply almost 100 percent of the time, augmented by a second, higher-voltage supply that comes into action only as needed.
The output transistors of the NAD 2200 amplifier are high-powered, fast-switching devices capable of delivering some 60 amperes of peak current for brief periods. One key difference between the 2200 and most other switched-voltage amplifiers is the choice of the power level at which the changeover occurs. In some amplifiers it occurs at a fairly low power output, such as 15 watts. This arrangement offers economies in manufacture, since most of the time the amplifier generates little heat and requires a small heat-dissipating surface. On the other hand, the switching often produces a transient “glitch” on the waveform, which could conceivably be audible, at the point where the supply voltage increases.
Lab Tests (when new)
Preconditioning the NAD 2200 for 1 hour at 33 watts output into 8-ohm loads left its top cover (over the internal heat sinks) only moderately warm. With both channels driven at 1,000 Hz, one channel clipped at 158 watts output. Into 4 ohms, the power at clipping was 240 watts, and into 2 ohms it was 365 watts (the last measurement was made with only one channel being driven, since an internal D.C. fuse blew when we drove both channels to clipping with 2-ohm loads).
The 1,000-Hz distortion into 8 ohms was about 0.005 percent at very low power (0.1 watt). It decreased to 0.0035 percent at 10 watts and reached 0.0082 percent at 150 watts, just before clipping occurred. With 4-ohm loads the distortion was very similar at most power outputs and reached 0.0071 percent at 200 watts. The 2-ohm distortion was also very low at most power levels, reaching 0.0225 percent at 300 watts. Into 8 ohms, the distortion was lowest, between 0.001 and 0.002 percent, from 30 to 100 Hz; it rose into the 0.01 to 0.02 percent range from 1,000 to 20,000 Hz at power outputs of 100, 50, and 10 watts.
Dynamic power measurements were somewhat complicated by the thermal feedback system of the amplifier. As it heated up the maximum power decreased, so we were never able to repeat our measurements exactly on successive attempts. Nonetheless, the results were very impressive. With the standard 20-millisecond test signal, the maximum output was 450 watts into 8 ohms (for a dynamic headroom of 6.5 dB), 685 watts into 4 ohms, and 870 watts into 2 ohms. We repeated these measurements with 4-ohm loads and with longer-duration tone bursts.
The output of 700 watts did not change for bursts in the 20- to 50-ms range, but it decreased slightly to 570 watts with 100- and 200-ms bursts and to 285 watts with bursts of 300 ms and longer. (The output did not drop significantly with a 1-second burst, and, in fact, it remained at 240 watts in a “continuous” measurement lasting perhaps 30 seconds.) We repeated this test (in part) using the bridged mode, reading outputs of 1,100 watts for 20 milliseconds, 800 watts for 50 milliseconds, and 700 watts for 100 milliseconds.
The frequency response of the NAD 2200, measured through its “normal” inputs, was down 3 dB at 12.5 and 45,000 Hz, and it was flat within +0, —0.3 dB from below 20 Hz up to 20,000 Hz. Through these inputs the bandwidth of the amplifier is limited by internal filters.
Using the “lab” inputs, the lower — 3-dB frequency was below our 5-Hz measurement limit, and the upper — 3-dB frequency was 135 kHz. The A-weighted noise of the amplifier was 93 dB below 1 watt, or 113 dB below its rated output. The amplifier was stable when driving simulated reactive speaker loads, and its reactive load factor was 1.6 dB at 63 Hz. The slew factor exceeded our measurement limit of 25.
Comments
Our measurements speak eloquently about the performance of the NAD 2200. We also used it as the power source for some of our pulse-power tests of loudspeakers (1 cycle of a sine wave followed by 128 cycles off) and found that its bridged-mode output was just short of 2,000 watts into a 2-ohm impedance! For listening to music in a home environment, the NAD 2200 may well be the most powerful amplifier you can buy, especially if you use a pair of them in the bridged mode (which probably would be a case of “overkill” for most people). If ever an amplifier could be said to be “digital ready,” this one can. Its readiness is not merely a matter of being louder than other amplifiers, although not many others could match it in sheer decibel level, but of its virtual immunity to overload with whatever program peaks an amplifier might encounter, even on Compact Discs.
The Soft Clipping circuit works well, although the chances that anyone will drive the NAD, 2200 to within 0.5 dB of its clipping point are slim indeed. The circuit has no measurable effect on the amplifier’s distortion or other characteristics, so it can be left on at all times. We found that the overload light did not flash until the output waveform was heavily clipped, but this is a minor matter. No matter how you look at it, the NAD 2200 is a superb amplifier and an outstanding value.
terryforsythe
Major Contributor
I believe you are thinking of tube amplifiers. SS class AB amps may clip a little more gently than a class D, but they still clip pretty hard (some amps may include clipping protection, though). My suggestion is make sure you know how loud you will be listening and have adequate power to avoid clipping. See the note for the second input parameter, "Desired Maximum SPL at Listening Position", in the spreadsheet to which I posted the link, which states "Increase SPL to account for transients, e.g., add an additional 15-20dB over listening volume (Lmax), or a bit higher if listening to a lot of uncompressed music."
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Luvchampagne
Active Member
"Go look at the ASR reviews for the Hypex and Purifi amps you're considering"
"I believe you thinking of tube amplifiers."
No. Not what I was saying.
Take a Mcintosh Mc462. Current production amp.
MC462 (rated 450 Wpc, 3.0 dB headroom)
450wpc rated at 2, 4, or 8 ohm loads with <0.005% THD.
1. Not rated at clipping. Rated at 450wpc. Almost everyone refers to the MC462 as a 450wpc amp.
2. According to Erin's audio, not Mcintosh published spec,
https://www.erinsaudiocorner.com/electronics/mcintosh_mc462/
My understanding is that hypex /purifi amps are rated at Peak Power.
If you talk with a Mcintosh fan, very few quote this Peak Power spec.
If you talk with Purifi/Hypex makers and fans, they all quote the Peak Power spec.
So we're not discussing apples vs. apples.
Not saying one amp is better than the other amp.
Just saying a little due diligence clarifies quite a bit.
"I believe you thinking of tube amplifiers."
No. Not what I was saying.
Take a Mcintosh Mc462. Current production amp.
MC462 (rated 450 Wpc, 3.0 dB headroom)
450wpc rated at 2, 4, or 8 ohm loads with <0.005% THD.
1. Not rated at clipping. Rated at 450wpc. Almost everyone refers to the MC462 as a 450wpc amp.
2. According to Erin's audio, not Mcintosh published spec,
https://www.erinsaudiocorner.com/electronics/mcintosh_mc462/
My understanding is that hypex /purifi amps are rated at Peak Power.
If you talk with a Mcintosh fan, very few quote this Peak Power spec.
If you talk with Purifi/Hypex makers and fans, they all quote the Peak Power spec.
So we're not discussing apples vs. apples.
Not saying one amp is better than the other amp.
Just saying a little due diligence clarifies quite a bit.
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The Power Supply will have limited impact on the rated power.... however, a more powerful PSU, will provide more current, and the amps ability to handle low impedance and/or reactive loads will thereby increase.
The abilities of the amp to drive 2ohm loads will in almost all cases be limited not by the amp circuits but by the power supply circuits.
So you can do all sorts of calculations as to how much power is required, but your "power" figure is based on an impedance and an assumption of a resistive load - which most speakers are NOT.
Both the Hypex and Purifi modules are fully specified by the manufacturers, and are capable of handling low impedance loads - GIVEN SUFFICIENT CURRENT from the power supply.
So if you want to calculate how much power you need, find a calculator that explicitly uses the impedance as a variable, and set it to the Ascilab A6 minimum impedance of around 3 ohm - and try to find out what the power rating of the amps you are comparing, is at that load ( easy to find what the amp modules are capable of at 2ohm... use that as worst case - but they are dependent on power supplies with sufficient current - you can potentially calculate max power output by the current capabilities of the PSU, it is a bit more complicated though!)
You are quite right to call out the power supply as an important variable / difference - however it is only a difference for low impedance loads... for those people with speakers that do not descend below 4ohm, it is pretty much a non issue.
terryforsythe
Major Contributor
I now see what you are saying. Yes, certain amps like Mcintosh have some headroom built in. I would not assume that is the case for all class A/B amps.
Luvchampagne
Active Member
100% agree.
I remember talking with other car audio and home theater hobbyist and debating the power figures given by most manufacturers. Imho, more fiction than fact, especially multi channel AVRs.
Also many amps with fully regulated switch mode power supplies, have very little headroom, whereas traditional non switching power supplies often can provide additional power for short term peaks....
Swings and roundabouts - your rated continuous power from a switch mode power supply tends to be higher at any price point, but little or no headroom, whereas your traditional power supply will have substantial "headroom" but a much lower continuous rating at the same pricepoint.
Often the difference comes down to power supply design rather than amplifier class! Nowadays you can find Class AB amps with SMPS's.... there are even some Class D's with "linear" power supplies (although less of those).
terryforsythe
Major Contributor
It depends on whether the amplifier is voltage limited or current limited at the target load impedance.
According to the Nilai's specifications, with a 4 ohm load the output power increases from 300 W/ch to 525 W/ch going from a single power supply powering both channels to two power supplies, one per channel. Thus, the Nilai is current limited at a 4 ohm load using a single power supply for both channels. With an 8 ohm load, the output power is the same regardless of whether one or two power supplies are used, meaning that the Nilai is voltage limited at 8 ohms.
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