Measuring Amplifiers - Page 22 - AVS Forum
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post #631 of 1917 Old 04-24-2008, 06:53 PM
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Measured power output: 512 watts RMS into 8 ohms @ 0.09% THD,
1,024 watts RMS into 4 ohms @ 0.15% THD

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I too was wondering what kind of Hokus Pokus they were using to justify Peak power (assuming the dayton can even produce its rated power in peak bursts) into RMS power. It must be that hi-tech math to go along with the hi-tech amp.
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post #632 of 1917 Old 04-24-2008, 08:09 PM
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Thylantyr,

I will agree but the tests done are still great general info. I bet most amps tested from cheapie Behringer A500 to ubber esoteric monster monoblocks will go POUF! when pushed to meet the output specified at the lowest safe load(specified in the manual) for even ONE HOUR.The least that will happen the amp will be under life shortening load.

And this will not be realistic use of any amp,anyone who buys an amp to fully use the "rated" max output (watts)is disturbed and should find another hobby.
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Ask yourself mortal , do you have as much displacement as me ? The answer is no unless you have a Windmere fan sub.
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post #633 of 1917 Old 04-24-2008, 08:15 PM
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OK, so my buttkicker is on the block. What is the cheapest way to get an actual 1000 watts of clean juice?
RMX? (I need the cliff notes!!!!)

Lot's of low rent stuff stacked up into a medium rent pile.
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post #634 of 1917 Old 04-24-2008, 08:18 PM
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I am entirely willing and eager to see test results provided by Dayton supporting there published spec. I welcome such an outcome to this situation. I don't begin to understand all the science behind amplifier technology and testing.

That being said it is difficult to square what we have found here. I am on the edge of my seat on this one.

Also I must apologizes to the staff at Dayton Audio for moving directly to the conclusion that the amp is defective. As a lay person in the field of electronic amplification the results did and do seem conclusive. Still more exploration of what is going on here is warranted on my part before getting so worked up about it.

"There is no greater mistake than the hasty conclusion that opinions are worthless because they are badly argued."
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post #635 of 1917 Old 04-24-2008, 08:34 PM
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And this will not be realistic use of any amp,anyone who buys an amp to fully use the "rated" max output (watts)is disturbed and should find another hobby.

I am planing on connecting this amp to a set of 4 15" drivers capable of over 2" of linear excursion. These driver will be put into a set of cabinets that at 250rms per driver allow the drivers to reach there (near) max excursion. Its gonna be a lot of work and a lot of fun. But in the end those drivers better be making ever bit of clear undistorted bass they can.

I didn't buy a 1000 watt amp to almost make a lot of bass (yeah I know I'm sick but many of us are. 600watts or 1000watts it would still be load).

I put parts together based on what I know and what I can discern from the information I have. My design says it ok to have some friends over and turn the volume to 10 if I'd like.

So simple put 10 better be 10.

"There is no greater mistake than the hasty conclusion that opinions are worthless because they are badly argued."
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post #636 of 1917 Old 04-24-2008, 08:45 PM
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Quote:
Originally Posted by DaytonAudio View Post

As a follow-up, I'd like to say I'm concerned by some here that immediately assume this amplifier is bad, especially in light of the fact that this is a tracking amplifier that's designed to deliver high voltage into reactive loads (ie, loudspeakers). They are not optimized for fully resistive load banks. So much of this talk in this thread is not relevant to driving woofers. These hi-tech amps can put a ton of power into the actual woofer and cannot be fully tested using standard non-inductive resistant loads. That being said, we'll post additional information as soon as we complete our internal testing.

Our ultimate goal here at Dayton Audio is to provide audio enthusiasts with products that meet and exceed expectation, and we apply that to our customer service as well. Thanks again.

Rich Taylor
Dayton Audio

Bravo Dayton for a timely and informative response. i have purchased your products in the past and will now continue to do so feeling secure in my purchases. Your RS series subs are too often overlooked and i find them to be "gems" amongst other DIY drivers in the same price point. Consumer support on a HT forum........Priceless !
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post #637 of 1917 Old 04-24-2008, 10:48 PM
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Am I wrong in my understanding that an RMS rating was/is supposed to be roughly equivalent of what a device can do in continuous operation? There seems to be a general consensus forming that since nearly all companies overstate thier product, this makes it generally acceptable? If this is the case and we generally have had enough of such nonsense, doesn't it make sense to go after the worst perpetraitors first? Bear in mind Dayton called in question the method of testing, however did they in doing so share with us the methods they used to achieve thier ratings? Of course not. Its the same ol same ol, if you don't like the message.........you know the rest.
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post #638 of 1917 Old 04-24-2008, 11:11 PM
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Root mean square ( RMS ) is a term applied to an averaging of peak levels, meant to represent the average heating levels of an ac sine wave as compared to a DC current of the same level. ( someone correct me if I missed something )

RMS does not actually mean continuous.... in any way shape or form. It's mathematical expression is .707 of peak.

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post #639 of 1917 Old 04-24-2008, 11:37 PM
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yeah, rms can mean anything really, you can even do high crest noise test to derive your RMS value.
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post #640 of 1917 Old 04-25-2008, 01:55 AM
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Uh so no debate on whether or not load banks are a good approximation of a sub?

The way I saw it, it's a shootout between amps - ie, how they stack up to each other regardless of what the heck they were tested on... But it would have been cooler if the 'load bank' was actually an array of 18 inchers.
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post #641 of 1917 Old 04-25-2008, 05:32 AM
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Root mean square ( RMS ) is a term applied to an averaging of peak levels, meant to represent the average heating levels of an ac sine wave as compared to a DC current of the same level. ( someone correct me if I missed something )

RMS does not actually mean continuous.... in any way shape or form. It's mathematical expression is .707 of peak.

Yes I understand all this. Seems to me alot of times in the past I saw something like this on spec sheets .............250 watts @ 4 ohms RMS (continuous)
..................................400 watts @ 4 ohms peak

At any rate if we cannot assume that an amp can output its RMS rating in continuous mode, Should we then make the same assumption that our drivers can not handle continuous power input at there RMS rating as well? And in the long run, if all this is true what good is an RMS rating? After all it would appear they are just picking a number out of the blue for marketing purposes. Soon everything will be marketed much like the 3000 Watt White Van speakers.......Shouldn't we as the consumer demand that retailors at the very least show us THIER testing methodolgy?
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post #642 of 1917 Old 04-25-2008, 05:39 AM
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I have an array of subs......some one post a test on how to use drivers to test an amplifier. I have 2 good friends that are electrical engineers, one of whom works for a MAJOR audio company. I am curtain we could perform the "proper" test to see what this amp could do.

This test would then be done on a dynamic load and there for put the whole argument to rest.

So if anyone has such a test detailed email or pm me.....or better yet just post it up. I am sure whatever test will put the current findings into prospective as being rock solid or not.

"There is no greater mistake than the hasty conclusion that opinions are worthless because they are badly argued."
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post #643 of 1917 Old 04-25-2008, 05:59 AM
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As a follow-up, I'd like to say I’m concerned by some here that immediately assume this amplifier is “bad”, especially in light of the fact that this is a tracking amplifier that's designed to deliver high voltage into reactive loads (ie, loudspeakers). They are not optimized for fully resistive load banks. So much of this talk in this thread is not relevant to driving woofers. These hi-tech amps can put a ton of power into the actual woofer and cannot be fully tested using standard non-inductive resistant loads. That being said, we'll post additional information as soon as we complete our internal testing.

Our ultimate goal here at Dayton Audio is to provide audio enthusiasts with products that meet and exceed expectation, and we apply that to our customer service as well. Thanks again.

Rich Taylor
Dayton Audio

So we have many forms of testing?

I agree that if the testing isnt applicable to the real world then its going to give numbers that are meaningless.

Im one of those who said "WOW" to the 4 ohm numbers but I have also posted that I still thought the Dayton put out good power since I had it up against the eD LT/1300, the EP2500, the QSC RMX 1850. It didnt act like a amp that was giving only 600 Watts either but the tests do worry me.

Im just a reader in this and I have little knowledge about the different tests, I dont even care to learn the details I just want to know if tests being done are truely reflect what the amp will give us on a day to day basis.

What it sounds like is that Chuck is testing the raw power of the amps through hard core, brute force testing in which is kind of meaningless to the power the amp will give my 2 Q18s. The confusion continues.......

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post #644 of 1917 Old 04-25-2008, 06:02 AM
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The way I saw it, it's a shootout between amps - ie, how they stack up to each other regardless of what the heck they were tested on... But it would have been cooler if the 'load bank' was actually an array of 18 inchers.


The problem with it just being a shootout, some amps are not design to do that whatsoever. I think the pro amps will win the shootout probably every time if this is the case. Kind of like running a 1/4 mile horse vs a 1 mile horse in a mile race.


People who are like me shouldnt need to know all the different tests available and we are going to read these threads taking away numbers and believing that they represent real world usage since most posts suggest this is the case. If the tests do not reflect real world usage then why do they have so much importance?

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post #645 of 1917 Old 04-25-2008, 06:49 AM - Thread Starter
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Here is an excerpt from a well regarded amplifier manufacturer. The first are the specifications (in detail) about one of the amplifiers that they manufacture. The second is a power FAQ explaing/selling about the way these amplifiers work and the testing that goes into them. Note the RMS vs. Peak vs. Avg levels.

SPECIFICATIONS

Configuration: Mono Input:
RCA (Ref 8) or True balance XLR (Ref 8b)
Power output (see Power FAQ)

Power/Load 8 ohm 4 ohm 2 ohm
Peak Power
(20 msec hold time) 288W 576W 1152W
Avg. Power per Cycle 144W 288W 576W
RMS Power 100W 100W 100W


RMS power is the maximum continuous power of the power supply and it is constant. Avg. and peak power provide the required instantaneous power boost.
THD+N < 0.05% from 20 Hz to 20 kHz, 8 ohm load, 10 W.
Damping factor > 4000 at any audio frequencies, output (source) impedance is near zero for the entire frequency response
Input impedance: 47K ohm
Gain: 26 db
SNR = 100 db at 100W
Cardas connector & patented rhodium over copper binding post
Chassis is completely made of high grade brush and anodized aluminum to reduce audio resonance
Dimension: 6.5" x 10.5" x 1.75"
Worldwide AC voltage (84VAC to 264VAC). No need for AC regulator if the AC voltage falls within the specified range.
Weight: 3 lb
Reference 8 uses a 100W SMPS and the power output spec. reflects the limitation of the SMPS.


POWER FAQ

Q: XXXXXX's amplifier is so small and light. Does it provide adequate power?
A: Don't be deceived by the XXXXXX's amplifier's size. Our technology utilizes high-performance switch-mode power supplies (SMPS).
As opposed to traditional linear power supplies, which are always large and bulky, SMPS offers what at first looks like a
contradiction: smaller size and higher efficiency. More significantly, SMPS operates at much higher frequencies -- thousands of
times faster than linear power supplies operating at 50/60Hz. SMPS responds faster, thus providing the instantaneous power
high-performance music reproduction requires. Even a very small SMPS is several times more capable than a 50/60Hz linear power
supply. SMPS also offers sophisticated over-current and short circuit protection in addition to meeting industry safety and
reliability standards. XXXXX's cool-running SMPS provides an unequalled regulated output without the 100/120 Hz ripple voltage
found in linear power supplies, even when huge cans of filter capacitors are employed, as is normally the case with high-end amplifiers.

Q: What are Peak and RMS (Root Mean Square) power ratings? What's the effect on audio output?
A: RMS power is the continuous power an amplifier is capable of outputting over long periods. Peak power is the short-term power an
amplifier outputs when faced with sudden, high-energy signals. Another important measurement is the sine wave's Average Power Per Cycle.

Vpeak = Peak output voltage of amplifier
R = Speaker load in Ohm
Peak Power = (Vpeak)2 / R
RMS Power = Power supply's RMS power
Max Power Per Cycle = (Vpeak)2 / 2R
Headroom refers to an amplifier's ability to go beyond its rated average power (RMS or continuous power) for a short time, in the
recreation, for example, of loud, fast-rising audio signals. In order to achieve ample headroom, i.e., the ability to produce loud
peak levels without distorting, an amplifier must have a stiff power supply with a good amount of reserve energy. The ability of the
power supply to quickly recharge its capacitors is critical. An explosive low-frequency sound, e.g., at 50Hz, consists of an attack
followed by a series of rapidly decaying lobes of a 50Hz sine wave. An amplifier with 140W peak power with 20ms hold-time is capable
of providing 140W power to the 50Hz musical note (full cycle of 50 Hz is 20ms). For example, a series of explosive sounds seem to occur
in close succession, yet their base notes are far enough apart (1 second = 1000 ms) for the amplifier to provide the required peak
power. For typical home listening, more than 20W of power is rarely consumed. Even so, when demand exceeds 20W, a good amplifier should
provide RMS power and high-peak power with consistently low distortion. XXXXX's amplifier is capable of generating peak power at less
than 0.05% THD+N).

Q: Is XXXXXX's 300W amplifier less or more powerful than a linear solid state or tube amplifier rated for 300W?
A: In terms of reproducing music's dynamics, the more power the better. The commonly accepted measurement rates the output when the
amplifier clips at 1% THD. What is clipping? Clipping occurs in a linear amplifier when its output signal tries to exceed the limits
of its power supply voltage. In a linear amplifier using transistors and a bulky transformer/rectifier, the storage capacitor is recharged
once every 8.33 milliseconds, with its voltage only slightly above the maximum output voltage, a situation in which the amp could quite
easily clip. Simply put, the amp has very little headroom. With tube amplifiers, the supply voltage is very high, typically 300-600V.
Even though tube amplifiers have higher overall distortion, subjectively, they sound more powerful. XXXXXX's amplifier is a switching
design with ample headroom. It will not clip at its rated 300W. Even at this extraordinarily high output level, it will sound subjectively
better than a 300W linear amplifier.
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post #646 of 1917 Old 04-25-2008, 08:18 AM
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Quote:
Originally Posted by TheEAR View Post

I will agree but the tests done are still great general info. I bet most amps tested from cheapie Behringer A500 to ubber esoteric monster monoblocks will go POUF! when pushed to meet the output specified at the lowest safe load(specified in the manual) for even ONE HOUR.

I never said the tests aren't useful

Would be bet big money that a Pass Labs amp won't
run all day doing a sine wave test ?



The storm was gone, but dark clouds still hung around
The perfect setting for things to come......

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post #647 of 1917 Old 04-25-2008, 08:28 AM
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Why is everyone coming out of the closet with pitchforks crying foul
just because the Dayton amp didn't do so well on a sine wave test
and this isn't big news as I have linked Binks tests on this forum for over
a year showing the same fact and few raised their pitchforks.

http://home.pacbell.net/lordpk/bink/bink.jpg

If you are going to pick on Dayton, you might as well pick on
those other manufacturers too.

The reason you shouldn't pick on these reputable manufacturers
is that there are a million ways you can test an amplifier and you
have to dig to find out what method was used.

That's why most electronics people prefer to use the rms test method because
it's simple to do, it's the worse case scenario, and it's easier to correlation data
from different amplifier tests. But not all rms tests may use the same references
so you have to know the test conditions.

Don't let people confuse you, this is actually very simple stuff, you know,
AC and DC theory, two entry level electronics classes.



The storm was gone, but dark clouds still hung around
The perfect setting for things to come......

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post #648 of 1917 Old 04-25-2008, 12:33 PM
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Quote:
Originally Posted by penngray View Post

The problem with it just being a shootout, some amps are not design to do that whatsoever. I think the pro amps will win the shootout probably every time if this is the case. Kind of like running a 1/4 mile horse vs a 1 mile horse in a mile race.


People who are like me shouldnt need to know all the different tests available and we are going to read these threads taking away numbers and believing that they represent real world usage since most posts suggest this is the case. If the tests do not reflect real world usage then why do they have so much importance?

Well they don't have to reflect 'real world usage' IMO. If you're wondering exactly WHAT the difference between the ep1500 and the 2500 are, this test is fine. That or how they stack up to a crown blah blah model. You're right the fancier stuff will usually win but that does not make the rest worthless or undesireable. I know better subs exist but I went with two 12s because I think it's enough for my room/set up. Same with amps. So the cheap one didn't do as well as the expensive one - at least it did something without dying, so it's still positive publicity IMO. DaytonAudio shouldn't take this to heart because we're not all dumb and rich, buying only the one amp that did best and has a four digit price tag.

As for how much these will put into real drivers, it's something between the load bank numbers and the OEM RMS rating so it's easy enough to ballpark it if and when you go out for an amp using any of this data. I say the tests are fine and I want to see more amps tested even if the numbers come out lower than those that can be achieved with a driver and random signals (ie music/movies, not sine waves).

All this can be said for benchmarks on computers. 3dmark has been acused of being irrelevant to real life gaming, but regardless it does use the latest tricks and shows how different video cards/CPUs stack up against one another.

This is a forum full of bright and capable people; I'm betting before long we'll have both kinds of testing covered. We already have a volunteer with a sub array
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post #649 of 1917 Old 04-25-2008, 01:06 PM
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I agree. Chucks test results are very good to make an informed decision. This forum is all about leading people to their respective goals. I have 2 x EP2500s and am planning to buy a RMX 1850HD - why? I just want to own one. Reality is, thats all I can afford though I know (from this forum) there are more superior amps out there.
The computer example goes for fast cars too ...just because a car that can make 0 to 60 in 4 secs - that does not make it better than an ordinary family car unless you drive 0 - 60 in 4 secs every other day. It all depends on driving conditions and needs (listening content and driving conditions in this case).
Lets be realistic, how long can one listen to a sub/mains more than 100 watts anyways (in a home) continously...I am sure I will get beaten up here.
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post #650 of 1917 Old 04-25-2008, 01:41 PM
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I like how they put RMS as long term.... exactly how long?? A peak can last what 30-40 msec or maybe more?

I would say long term power output as maximum output before amplifier shutting down for thermal or other fault @ specified load. Even that will vary as some speakers are a lot more reactive than others. Of course this will vary with mode of operation ( stereo or bridged ) and impedance.

What good is saying an amp does x amount of power RMS for 10 seconds then goes into thermal protection.... ?

"You take the blue pill - the story ends, you wake up in your bed and believe whatever you want to believe. You take the red pill - you stay in Wonderland and I show you how deep the rabbit-hole goes."
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post #651 of 1917 Old 04-25-2008, 02:14 PM
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Quote:
Originally Posted by michael hurd View Post

What good is saying an amp does x amount of power RMS for 10 seconds then goes into thermal protection.... ?


Post #7



The storm was gone, but dark clouds still hung around
The perfect setting for things to come......

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post #652 of 1917 Old 04-25-2008, 02:32 PM
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Here is an example impedance from a simulation. TC 3000 15" QVC in a 6 cu ft vented box, with a couple of peq's.



This shows that the actual impedance ( sim of in-box ) ranges from a low of 6.487 ohms to a high of 57 ohms at 33 hz.

It is good to know what an amp will do into a resistive load, but to correlate the acutal voltage and current levels into a speaker ( reactive load ) would be best. Some amps will do MUCH better than others in these real world situations.

"You take the blue pill - the story ends, you wake up in your bed and believe whatever you want to believe. You take the red pill - you stay in Wonderland and I show you how deep the rabbit-hole goes."
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post #653 of 1917 Old 04-26-2008, 03:49 AM
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Quote:
Originally Posted by stickshift View Post

Lets be realistic, how long can one listen to a sub/mains more than 100 watts anyways (in a home) continously...I am sure I will get beaten up here.

My receiver is 110 WPC and I get close to clipping even with my little monitor 3's (2ch with LFE into mains)

Meybe my hearing sucks
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post #654 of 1917 Old 04-26-2008, 07:54 AM
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People most of the amps you own if not all will miss the spec. SO keep your plastic knives in your pockets and relax.

Buy amps with twice the rating,this way you are sure to get the minimum you want.

Ask yourself mortal , do you have as much displacement as me ? The answer is no unless you have a Windmere fan sub.
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post #655 of 1917 Old 04-26-2008, 08:43 AM
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Quote:
Originally Posted by AlexE View Post

My receiver is 110 WPC and I get close to clipping even with my little monitor 3's (2ch with LFE into mains)

Meybe my hearing sucks

Alex,
smaller less efficient speakers would need more power to get loud. The next time you are looking at speakers check out the the 2.83v sensitivity. If you had speakers that were 3dB more efficient that would be like having double the amp power.

Regards,
Dan
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post #656 of 1917 Old 04-26-2008, 11:37 AM
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Hey Chuck,

I have used and worked with these and very similar amps. Long term power delivered probably won't meet the spec, but that could even be intentional by way of limiting or other related methods. I'm in not intending to defend the amp, as most amplifiers are rated in rather rosy conditions. The marketeers dis-information puts the honest guys at a gross disadvantage in the general market, and they have to usually find a point of compromise.

A few quick questions on the Dayton testing as I haven't kept up with the methods and what you are able to test. What sort of duration was the test you ran on the Dayton? Where did you have the input level on the amp? Did you try to further increase the drive signal into 4 Ohms? I'd be curious at what point the amp hits 1% and 10% THD.

Of course all amplifiers design types clip a little differently. It's ironic that we are still looking for the most zeros to the right of the decimal point rather than focusing on audible distortion.

I generally listen to the output with a very high impedance speaker connected to correlate at what point the numbers really become audible.

Finally, I believe it was Bob Lee or someone else I knew in the pro audio community who had on a few occasions made the clarification that most engineers won't use the term "RMS Power." You can measure RMS Voltage, and you can measure RMS Current. The product of the two result in average power. There is no continuous power waveform from which to take the Root Mean Square. If that was measured over a sufficiently long period of time, it make sense to call it continuous average power.

I know it's a bit of a nitpick, but it is also something that should be clarified when anyone starts trying to pin anyone down for specifications. "RMS Power" is a coloquial term that has been largely created by the audio marketing departments where the engineers didn't have the opportunity to catch it.

Mark Seaton
Seaton Sound, Inc.
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post #657 of 1917 Old 04-26-2008, 11:59 AM
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"Lets be realistic, how long can one listen to a sub/mains more than 100 watts anyways (in a home) continously...I am sure I will get beaten up here."

Realistically, it's not that hard to clip a >1000 W amp at less than earsplitting levels with today's soundtracks; I've done it with a Crown K2 driving a pair of Ava 18's.

Noah
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post #658 of 1917 Old 04-26-2008, 12:06 PM
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Re: Michael and TC3000. Well all you're asking is they test an amp with different resistive loads. It doesn't even have to be dynamic. Test it at a few freq's at 4ohm, 8ohm, 16ohm and 32ohm. Bingo bango. There's enough data.

However, if an amp (like the Dayton that's creating all the fuss) does an excellent job at 32ohms, but wont keep increasing power below 8ohms, will fail to power 4 ohm subs with authority until their resistance values increase to a more friendly level. Those frequencies will then either be played at a reduced output and/or the distortion is going to sore. So maybe, that amp shouldn't be rated to 4ohm, but instead, 6ohms?

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post #659 of 1917 Old 04-26-2008, 12:57 PM
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Dayton Test:
In fairness to the other amps tested (all in the same manner) at least they did not fall on their a** at 4 ohm loads this badly and most pro's good to 2 ohm...

Let's face it, if I am a consumer and I need an amp to drive a 4 ohm subwoofer load and I have a choice of products - this $400 Dayton amp barely matches the performance of a $220 O-audio 500W plate amp, and would be a huge disappointment versus a Behringer EP2500. With the Behringer, I can get two channels at 650W (4 ohm) for less than the Dayton.

For $300, I can have the Behringer EP2500 that can compete with a Crown K2at more than double the price - now that's value.

So at the end of the day to me the consumer, what is the better deal?
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post #660 of 1917 Old 04-26-2008, 01:27 PM
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Quote:
Originally Posted by Mark Seaton View Post

It's ironic that we are still looking for the most zeros to the right of the decimal point rather than focusing on audible distortion.

It's been discussed. Chuck has his testing goals defined at the beginning
of this thread.


Quote:


Finally, I believe it was Bob Lee or someone else I knew in the pro audio community who had on a few occasions made the clarification that most engineers won't use the term "RMS Power." You can measure RMS Voltage, and you can measure RMS Current. The product of the two result in average power. There is no continuous power waveform from which to take the Root Mean Square. If that was measured over a sufficiently long period of time, it make sense to call it continuous average power.

I know it's a bit of a nitpick, but it is also something that should be clarified when anyone starts trying to pin anyone down for specifications. "RMS Power" is a coloquial term that has been largely created by the audio marketing departments where the engineers didn't have the opportunity to catch it.


Because audio forums are generally not electronics engineering forums,
people tend to speaker 'consumer' so everyone knows what is going on.
I try to use the term 'rms test method' to describe what you said.
Watts RMS is fine too, ie 1000W RMS. Continuous is another animal that has
time as the missing variable in product specs, ie 1000W RMS continuous is
pretty vague. 1000W RMS continous for 1 hour before going thermal is more specific. .. even that has missing variables as what is ambient temperature.

A million ways to test amplifiers.



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