One thing to say and I think it also involves switch-mode PSU's ? If a very powerful amp the power is drawn from the exact part we call ripple ( sine wave upper 15 % , the crest ) . The lovely sides of the mains sine wave ignored . This causes problems with noise pollution regulations with big amps . Increasingly the companies use switch-mode as this helps side steps the problems as the certificate comes with the power supply . To my way of thinking it seems unlikely that the switch-mode makes it better inside the amp . Surely compounding ripple of 50 or 60 Hz origin with the switching residuals ? What also applies is the size of the high voltage switch-mode caps . The average modestly equipped amplifier has 50 - 0 - 50 V and 2 x 22 000 uF . Looking at a Hypex switch-mode it is 0 - 165 - 330 and 2 x 680 uF ( had to measure as best I could as numbers obscured . looks about right ) . Taking the CV value 50 x 22000 = 1 100 000 165 x 680 = 165680 . Lets imagine the values are affected by a square law ( doubt it is a simple as that ) . 165/50 = 1 221 858 . If so it is parity . Never seen anyone state it . As the current is reduced I guess a square law would apply ?
Hypex are bad boys . The 180 watts turns out to be a realistic 22.5 watts if reading carefully ( It is a sort of cover story of the device , a Japanese company was told off for this years ago when a 40 watt amp limited itself to 17 watts after a few minutes of sine wave testing ) . The reason being that just like any amp getting rid of the heat is not optimum when so small . They say if using real music the RMS will be 1/8 at clipping . Fair enough , others using class AB try hard to make it reality . A watt being a watt . Also the 400 watt PSU just described can not sustain full power . In both cases transients will be to the peak power . I will be carefully testing the Hypex . I have said to it's owner I will say it is 2 x 40 to 50 watts until I know better . For want of a better test , that will be when my fingers say the T bar is too hot . From memory the Hypex can supply 22 amps peak . Maybe Hypex are right and that is the same as an AB amp running 180 watts ? Fear will take over when my Magneplanars will be used . Maybe I should get my baffle speakers finished , Still can't make up my mind where to put the holes ? Top third , bottom third is my best guess . Offset top is a ,I have no knowledge decision . Looks right , but . Which gives best bass / baffle ripple / Plenty of work recently so that has come first . 4 x 2 wood 15 inch bass and 12 inch upper bass mid .
Hypex are bad boys . The 180 watts turns out to be a realistic 22.5 watts if reading carefully ( It is a sort of cover story of the device , a Japanese company was told off for this years ago when a 40 watt amp limited itself to 17 watts after a few minutes of sine wave testing ) . The reason being that just like any amp getting rid of the heat is not optimum when so small . They say if using real music the RMS will be 1/8 at clipping . Fair enough , others using class AB try hard to make it reality . A watt being a watt . Also the 400 watt PSU just described can not sustain full power . In both cases transients will be to the peak power . I will be carefully testing the Hypex . I have said to it's owner I will say it is 2 x 40 to 50 watts until I know better . For want of a better test , that will be when my fingers say the T bar is too hot . From memory the Hypex can supply 22 amps peak . Maybe Hypex are right and that is the same as an AB amp running 180 watts ? Fear will take over when my Magneplanars will be used . Maybe I should get my baffle speakers finished , Still can't make up my mind where to put the holes ? Top third , bottom third is my best guess . Offset top is a ,I have no knowledge decision . Looks right , but . Which gives best bass / baffle ripple / Plenty of work recently so that has come first . 4 x 2 wood 15 inch bass and 12 inch upper bass mid .
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First tests of a Hypex UCD 180 on a conventional 500 VA PSU of +/- 38 V . 2 x 22 000 uF . The upper graphs 10 kHz , the lower 1 kHz .
1 kHz is OK and running 20 Vrms gets the T bar hot after 15 minutes . I must say if my class AB amps did this I would be unhappy . 10 kHz already seems a struggle . Hypex say something about THD not being easy to measure at the limit of usual audio . Perhaps a tidy up required of the amp . The PSU is well laid out so I doubt it . I have the Hypex switch-mode so these are to get some facts about the modules I wanted before saying too much .
On idle the oscillation frequency gives about 26 mV rms . This changes to 176 mV with a muted preamp output connected . The > 230 kHz output reference 20 V rms 10 kHz is - 52 dB and > 8 peaks of about equal amplitude . Took my eye off the ball as the 1 kHz is at about 17 V rms ( 10 : 1 probe ) . Same outcome .
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Yes. There are those who see a power amp a nothing more than a fancy regulated power supply.In a normal power amp you are really listening to the PSU ....
Not arguing here, but I would like to point out something I consider to be important.
All this testing with steady state sine waves is nice and fine, but is not in my view very realistic or representative at all. IT IS SIMPLY NOT POSSIBLE TO EVER USE ANY AMP IN THIS MANNER, as this leaves almost zero dynamic reserve. Since music is a hodge-podge of varying signals, both by amplitude and in time, sine wave testing merely lets us know how much do we have in reserve should we need it. If we want to know what the amp will do under reasl world conditions, we would need to test it steady state at lease 6 dB below its rated mximum, to take into account at least some dynamic events.
This also applies to power dissipation. Who knows anyone who sits in their room listening all day to full power sine waves? I've met many kinds of people in my life, but never such a person. Not even Nige and I do it. Oh, what the hell, not even Wayne does it!
Also, odd accidents can and will happen, by default in the least opportune moment. For example, Dan d'Agostino's latest mammoth amp failed dismally on the IHF 20 (or 30?) minute test of having to work at 1/3 nominal power before testing for full power. Like or dislike Krell products, I don't think anyone half serious would question Dan's prowess in designing high power amps. Anyway, that particular sample was sent back to the factory and the problem was located to an incorrectly labelled thermal switch, which siad it would switch off at 65 deg C, but it consistently switched off at 45 deg C, or some such, not sure about the actual numbers.
I would give 10 years of my life to see some HT 5.1 receivers actually tested like that, you know the ones, those with flimsy butterfly wings soldered to a simple aluminium plate, always of modest thickness, because it's a lot cheaper than buying real heat sinks. It hasn't been once that I've seen them switch on their dinky little fans for additional cooling even after working half an hour under rather favorable room conditions.
My point is, it's high time to rethink the whole system of standards, and especially those related to power output testing, to bring them more in line with what we have learnt over the last sa 15 years, and to bring them, in my view, more towards reality rather then theory. Time to forget only lab 8 or 4 Ohm resistors only as loads, but to add say power delivery at 10 kHz in parallel with say 1 uF (obviously, this can be discussed).
I firmly believe this by now very lacking system of outdated measerement creates an equally faulty public. What is a layman to think, when the current standards teach him to think in a certain way?
All this testing with steady state sine waves is nice and fine, but is not in my view very realistic or representative at all. IT IS SIMPLY NOT POSSIBLE TO EVER USE ANY AMP IN THIS MANNER, as this leaves almost zero dynamic reserve. Since music is a hodge-podge of varying signals, both by amplitude and in time, sine wave testing merely lets us know how much do we have in reserve should we need it. If we want to know what the amp will do under reasl world conditions, we would need to test it steady state at lease 6 dB below its rated mximum, to take into account at least some dynamic events.
This also applies to power dissipation. Who knows anyone who sits in their room listening all day to full power sine waves? I've met many kinds of people in my life, but never such a person. Not even Nige and I do it. Oh, what the hell, not even Wayne does it!
Also, odd accidents can and will happen, by default in the least opportune moment. For example, Dan d'Agostino's latest mammoth amp failed dismally on the IHF 20 (or 30?) minute test of having to work at 1/3 nominal power before testing for full power. Like or dislike Krell products, I don't think anyone half serious would question Dan's prowess in designing high power amps. Anyway, that particular sample was sent back to the factory and the problem was located to an incorrectly labelled thermal switch, which siad it would switch off at 65 deg C, but it consistently switched off at 45 deg C, or some such, not sure about the actual numbers.
I would give 10 years of my life to see some HT 5.1 receivers actually tested like that, you know the ones, those with flimsy butterfly wings soldered to a simple aluminium plate, always of modest thickness, because it's a lot cheaper than buying real heat sinks. It hasn't been once that I've seen them switch on their dinky little fans for additional cooling even after working half an hour under rather favorable room conditions.
My point is, it's high time to rethink the whole system of standards, and especially those related to power output testing, to bring them more in line with what we have learnt over the last sa 15 years, and to bring them, in my view, more towards reality rather then theory. Time to forget only lab 8 or 4 Ohm resistors only as loads, but to add say power delivery at 10 kHz in parallel with say 1 uF (obviously, this can be discussed).
I firmly believe this by now very lacking system of outdated measerement creates an equally faulty public. What is a layman to think, when the current standards teach him to think in a certain way?
Wayne, this isn't the first time you mention that 1/3 power. While I'm not disputing the basic thought, I now seriously wonder if you have any idea of how loud say 1/3 of just 100 Watts is in a room? Even with less than usual efficient speakers, not to even mention those in the trend, rated at say 92 or more dB/2.83V/1m?
To put it mildly, it's a level of loudness you can't stand for longer than a few minutes, assuming that the average power level is 33W/8 Ohms, or 16.25V/8 Ohms. On a continuous basis, unless your house is moved away from your neighbors' houses, it likely to have the cops ringig at your door fairly soon (not that you'd ever hear them ringing).
Look at the distortion spectra , vs power output you will see it falls right in that range and you can hear it, nelson jokingly calls it the clunk 
, this became noticable to me decades ago when doing speaker developement , we measure voltage output when listening and exceeding this amt had a significant sonic character change it avg out at approx 33%. Looking at a list of amps on stereophile suggested this was true with rising distortion , completely diffrrent for toobs , where in subjective listening test we could access its full power rating before becoming subjectively offensive , I'm in belief this phenom is why toob lovers claim 100 watts toob sounds as powerful as 300 SS...
Lower imps changes everything where true current delivery is the key , for eg on the Bembehs the 1.3 ohm nom from 250-22k sounds best on the PS Audio for eg at no more than 5-6 volt rms , 15 volts peak , above this the sound gets strained and thins out , much different on the Krell where you dont use as much to sound fuller and larger and never sounds strained right up to the blasted relay trips at 20v peak..
Simple test , 2 ohm bench load 10 volt rms if overtemp after 10 mins then baby amp ..
Also its easy to exceed the 33% i suspect you listen to loud electronic music with no dynamics , live recordings like opera , stage , chior , etc will have you easily exceeding those numbers . These rediculous dynamic testing typically are too short and trlls you nothing give it a 1-2 second pulse and call me in the morning
, this became noticable to me decades ago when doing speaker developement , we measure voltage output when listening and exceeding this amt had a significant sonic character change it avg out at approx 33%. Looking at a list of amps on stereophile suggested this was true with rising distortion , completely diffrrent for toobs , where in subjective listening test we could access its full power rating before becoming subjectively offensive , I'm in belief this phenom is why toob lovers claim 100 watts toob sounds as powerful as 300 SS...Lower imps changes everything where true current delivery is the key , for eg on the Bembehs the 1.3 ohm nom from 250-22k sounds best on the PS Audio for eg at no more than 5-6 volt rms , 15 volts peak , above this the sound gets strained and thins out , much different on the Krell where you dont use as much to sound fuller and larger and never sounds strained right up to the blasted relay trips at 20v peak..
Simple test , 2 ohm bench load 10 volt rms if overtemp after 10 mins then baby amp ..
Also its easy to exceed the 33% i suspect you listen to loud electronic music with no dynamics , live recordings like opera , stage , chior , etc will have you easily exceeding those numbers . These rediculous dynamic testing typically are too short and trlls you nothing give it a 1-2 second pulse and call me in the morning
I looked back at a Flying Mole class D amp I tested in 2007. The Hypex is miles better . Still troubles me to see the junk coming out of it . If it was harmonics we would say no way . When class D residuals it is OK . Surely worse as unrelated to the original . Someone said FET amps sound OK because similar things happen . Could be mildly true . I will post if it gets interesting . Liked that it didn't get hot . That was true . Hypex sell themselves short on that . I understand as people can be brutal with amps . TO 220 = 22 amps ? The highside devices on PA class H are so maybe if switching SOA is not exceeded and it is OK ? 1.3 mm wire = 22 amp at a pinch ( 2.5 mm 27 A in the wall of a house , 1 mm 14 amps fused at 6 amps ) . Even TO3 is puny compared with wire . Fuse wire more like .
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Look at the distortion spectra , vs power output you will see it falls right in that range and you can hear it, nelson jokingly calls it the clunk
Lower imps changes everything where true current delivery is the key , for eg on the Bembehs the 1.3 ohm nom from 250-22k sounds best on the PS Audio for eg at no more than 5-6 volt rms , 15 volts peak , above this the sound gets strained and thins out , much different on the Krell where you dont use as much to sound fuller and larger and never sounds strained right up to the blasted relay trips at 20v peak..
Simple test , 2 ohm bench load 10 volt rms if overtemp after 10 mins then baby amp ..
Also its easy to exceed the 33% i suspect you listen to loud electronic music with no dynamics , live recordings like opera , stage , chior , etc will have you easily exceeding those numbers . These rediculous dynamic testing typically are too short and trlls you nothing give it a 1-2 second pulse and call me in the morning
Whoa there, Big Fella!
Reread my comment - I made it quite clear that I do not object to the notion and/or the claim that SS amps tend to sound at their best at 1/3 of their power. In fact, I tend to agree, at least in most cases.
The problem is that the more powerful an amp is, the higher the level of the sound in the room, and above a certain point, that same level becomes unbearably loud. All pleasure gone, all pain in.
Not to even try to look at 200+ WRMS/8 Ohms amps, even a moderate power 100 WRMS should go to at least 30 Watts of continuously dissipated power to get to its "sweet spot". In my case, given that my speakers do 92 dB/2.83V/1m, this implies effectively at least 50 WRMS (as it doesn't even start to clip before 170+ W/8 Ohms), which is 17 dBW. Since my speakers are just a bit further away from me than 3 m (10 ft), I would be producing something like 103 dB SPL at 3 m.
Worse yet, a say JBL 4312 monitor would be producing 106 dB!
Wayne, these are, quite literally, deafening levels. Not to even mention what would happen when a transient in the midrange should pass by, adding another say 6 dB just for kicks.
And, believe it or not, after an hour of that kind of regime, I do believe something like at least 80% of all SS class AB amps would start to cook, simply because most of them were made for home use, not PA.
Lastly, a technical point. That logic is most probably quite true for the majority of home orientated SS amps, but still, not all are the same. Most of these amps use a small number of output devices (or, specifically, as few as possible to get away with the specs). This is to say their bias currents for the output stage will be 50-200 mA. I use what is known as class AAB, meaning it is set to above average quiescent current. This in turn means the amp is spending more time in pure class A, thus introducing a new variable into the 1/3 power scheme.
Statistically, specifically I (and I believe most people) spend around 98% of my listening time at power levels below the 1 Watt mark. Hence, I spend 98% of my time in pure class A, given that my speakers are an easy and always a load of at least 6.5 Ohms.
You really want to hear what that 1 Watt sounds like in my room - loud, baby.
As for my music taste, you got it absolutely right, only the wrong way around. I thrive on melodic usic, and that usually rules out typical electronic music. I go for Simon & Garfunkle, Gordon Lightfoot, Leonard Cohen, Joan Baez, Joni Mitchell, but I also do a lot of Enya, Loreena McKennitt and other Irish artists, Scots like Bert Jansch, and the pop music from the 1960 to 1980 period. I do not have many albums of what is today considered as "electronic music", one Blue Man Group CD (the first one) and Enigma - that's it. Instead, I buy John Denver, The Marshall Tucker Band, Waylon Jennings and the like. Some movie music, and of course, lots of locals. Plus the classics and some variations on that theme (Waldo de los Rios, Gregorians, etc).
Sorry Wayne, but that is just a tad too simplistic an explanation, all the more so as about the same thing happens with my JBL Ti600 floorstanders (rated at 91 dB/2.83V/1m), and with my AR94s, although with them because of their lesser sensitivity, the noise level is reduced to slightly more bearable. All bad speakers, eh?
BTW, my primary speakers have a net volume of 2 ft3 and weigh in at 63 lbs each - though not giants, not small fry either. Their maximum SPL is a tad above 110 dB. Again, while setting no records, hardly miniscule, and I do have the amp guts to back them up.
You are now mixing signals. First you talk about 1/3 power levels, which on my Karan works out to about 60W/8 Ohms, or 33W/8 Ohms with the Citation 24, and now you say you listen at around 88 dB. So, what does that 1/3 power apply to, continuous or regarding peaks?
As you put it, 88 dBa I get to with about 1 Watt. The power meters on my Philips Black Tulip amp are said to comply with DIN standards, which Bob Cordell informs me is the de facto standard for serious meters, although in studios, they have better yet; they may have been that when new in 1982, but today, I don't put too much faith in them. Still, for loud to very loud in my room, which is fairly alive (no drapes, no carpet, etc), the needle never goes past the 6 W mark.
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+10 Charles ,
D @ your listening distance you are at approx 82db/w / ch , Unfortunately dynamic compression happens with speakers as much as amplifiers, small speakers more so than large. When speaker and amplification is correct you have to catch yourself going with the volume , theres an unrestricted feel to everything , you will wiz pass 100db without concern ....
On large scale recordings it is not unusual to see peaks pass 100db , if he system gets hard you will reach for the volume, on simple recordings you can get away with alot ...
D @ your listening distance you are at approx 82db/w / ch , Unfortunately dynamic compression happens with speakers as much as amplifiers, small speakers more so than large. When speaker and amplification is correct you have to catch yourself going with the volume , theres an unrestricted feel to everything , you will wiz pass 100db without concern ....
On large scale recordings it is not unusual to see peaks pass 100db , if he system gets hard you will reach for the volume, on simple recordings you can get away with alot ...
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No, actually that was a 20 LED peak meter, with some solid response times. By no means the best there is, but much better than one sees in your typical home product range.
Nevertheless, I agree it probably underreads at least a bit, something like -2 or -3 dB in peak mode, so what was shown as 6 Watts was probably more like 15-18 Watts or so. But nowhere near 120W, I guarantee that, simply because the amp it was reading won't do more than 70W/8 Ohms in peaks.
Damn it Wayne, how many times do I have to repeat this before you catch it?
My room is SMALL, 4.5 by 3.5 m (app. 15 by 10 feet), has no carpet, no drapes and one wall is 80% window area. It is very much alive, there's nothing to dampen the sound - hardly ideal, I know, but for various reasons, this has to be so.
My problem are neither the speakers, nor the electronics, my problem is a very small overall room volume.
Or do you suggest the room has nothing to do with anything?
Nice. To even get them into the room, I'd have to kick out my bed. To give them sopace behind to work with, I'd have to kick everything else out from the room, and then I'd end up with the speaker just 6 feet from me.
But, since they would be so near me, think of the amp power money I could save ...
Wayne, Serbia was first demolished by an early morning attacken by the Germans on 6 April 1941, by an undeclared war air strike. That knocked down well over 50% of the city's housing.
Then, after the victory of 1945, the communists who snatched power and effectively hijacked the entire country, started building small flats and apartments simply because with the same money they could build more of them. In 1945, Belgrade's population was around 350,000; today, it is estimated at around 2 million.
The key indication is Marshall Tito's comment to lawyers: "You lawyers, do you really always want to have it by law?" This communist logic shut the door to even their own existing rules and regulations, so I live in an apartment with a total area of 62.5 m2, when the current regulation at the time had it that a three room apartment had to have at least 70 m2.
Latest developments led to another absurdity - modern apartments are being built with much larger areas, even up to 600 m2 (app. 6,500 ft2), but the price of 1 m2 varies from 1,500 to 2,200 euros ($2k to $2.9k per m2 or app 11 ft2). Thus, a typical apartment currently costs, for say 70 m2, something like $140k to $200k, an abnormaity in a country where the average monthly salary is less than $500 - if you are lucky to be employed, and 42% of the population is not that lucky.
So, small rooms like mine are very common, and their sheer size makes large speakers, really large, simply not possible, or absurd.
Hope you caught it this time, Wayne.
This is in Watts, right? dB = 10log(ratio). 3 dB is a factor 2. To get a factor of 3 (18 Watts), it would have to have been off by about 4.8 dB, not 3 dB. Also, 2 dB is a factor of about 1.6. So your 6 Watts, when higher by 2 dB or 3 dB, could have been 9.5 to 12 Watts, not 15 to 18 Watts. If it was 15 to 18 Watts, i.e. a factor of 2.5 to 3, to then your meter would have been reading low by 4 dB to 4.8 dB.
Sorry. The 3 dB caught my eye so I knew it couldn't be more than 12 Watts instead of 6 Watts.
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