I cited a Goldmund (generally) as an example of high-end amplification. Pick any successful, high priced boutique stereo or monobloc amp. with >0.03% THD and you have another potential example.
Regarding distortionless amplifiers, if you followed any threads with discussions of Edmond Stuart's TMC amplifier designs, you'd see he was quoting down to 1ppm/20kHz distortion. That is blameless, if not effectively distortionless. How about a Halcro if you want a commercial example?
Of course, if you are being pedantic, there is no device that could ever escape the laws of physics and meet that or any other infinitessimally precise criteria completely - hence the term "blameless" as defined by Douglas Self. However, the point is, that we could safely claim that the amplifier was distortionless for all practical purposes.
Yes , women only complain when the sound is bad not loud ..🙂
50watt rms/ ch = 400 va...
400 watt/ch = 3200 va
Less would work and Andrew's 2 times would prove inadequate for building a true voltage source , admittedly far superior to what you would like to do, nothing worse than having an undersized PSU, in reality regardless of amp choosen you are really listening to the psu ...
Low is not distortionless , low is not blameless and the Halcro as well as others have Issues a lot more than looking at thd PPM values, like a weak psu to begin with and what the hell is a "boutique" amplifier ! Something your wife takes with her when getting her hair done ...
🙂
May i suggest we pick one amp actually bench tested and then discuss why its blameless or not and why many consider their gray scale sonics poor..
With all due respect, all amplifiers have a sonic signature , because they all have differing Distortion spectra, even when having the same THD Numbers, there is no blameless , you can identify them when listening ...
Regards
How about if I built my Dx Blame as a 50wpc amp with 70v rails, 5 output pairs and a 500VA supply? If I write "50w stereo amplifier" on the front panel it would then meet your rule 🙂
Hi Andrew!
Missed this one. Yes - so true
Why can loudspeaker designers get away with stupid impedance characteristics and us EEs must always 'clean up after them'. (Reminds me of the days where churches were architect-designed with the most awful acoustics, and one had to try clean up the mess afterwards with electronics. Even these days .... sorry.)
It means in fact that "100W into 8 ohms" becomes meaningless. It has to be an expensive "100W into 2 ohms", for the odd occasion that a frequency comes along where the loudspeaker designer did not care to equalise the dip out - or worse: equalised the dip in (but realising that ES loudspeakers have special requirements).
Nightmare, that is 😱
with that traffo is was able to test my super leach amp,
with both channels driven to 45volts ac output into an 8 ohm dummy load, as per FTC....
i did not have a camera 20 years ago....
this is an even bigger traffo i made about the same time...
it has a 2 1/4 center leg and stacked to about 5 1/2 inches..
good for 4800 volt-amperes,
4m from your floorstanders has just reduced your sensitivity to 79db/w and then add in power requirements for 12 db peaks , women are very sensitive to PSU noise ..
🙂
Hi Andrew!
Missed this one. Yes - so true
Why can loudspeaker designers get away with stupid impedance characteristics and us EEs must always 'clean up after them'. (Reminds me of the days where churches were architect-designed with the most awful acoustics, and one had to try clean up the mess afterwards with electronics. Even these days .... sorry.)
It means in fact that "100W into 8 ohms" becomes meaningless. It has to be an expensive "100W into 2 ohms", for the odd occasion that a frequency comes along where the loudspeaker designer did not care to equalise the dip out - or worse: equalised the dip in (but realising that ES loudspeakers have special requirements).
Nightmare, that is 😱
What about the EE nutcase who doesnt try to build a true voltage source amplifier , so the poor speaker designer has to compromise sonics to work with his dinky toy 500va 70v psu amplfier ...
🙂
for the record i never insisted that large values of sag is acceptable, show me in what thread did i said that....
i am merely pointed out that such an amp exist and that there could be others...
the ideal traffo will have zero sag, but we live in a real world, so sag is inevitable....
that is the reason i build my own traffos that are huge as i am fully aware of the importance of the psu in any amp...
you give instructions to members as if they are your pupils....
but i will never listen to you unless you can demonstrate by way of showing us your completed amps....as simple as that...
You are then, in fact, saying that human hearing is capable of discerning artifacts way below threshold of hearing - or you are simply disputing that there is a threshold of hearing....? You are thus contesting hundreds of hours of tests proving what is and is not audible, done by dozens of prestigeous research bodies, and reams of reports to that effect over decades?
Care to justify such a stance with some proof/reports? Where can I read about that?
AJT, where can I buy a beautiful transformer like yours? All they sell in my part of the world are ugly toroidals that look like big fat donuts.
Not the way I would put it............Missed this one. Yes - so true
...................It means in fact that "100W into 8 ohms" becomes meaningless. It has to be an expensive "100W into 2 ohms",...............
100W into 8r0 is equivalent to 28.3Vac into 8r0.
That can be quoted as +29dBV into 8r0.
If you change the load to 4r0, one would expect the voltage to hold up to somewhere near the 8ohms voltage.
for me >= +28.5dBV would be acceptable as indicating a good current ability into 4r0 test load.
Now change to 2r0 test load. This would require a further small drop in voltage to indicate good current delivery.
>=28dBV into 2r0 would be acceptable.
I work with voltages most of the time. They are so telling of performance.
Convert those dBV back to power if you need numbers.
28.5dBV into 4r0 is 26.6Vac is 177W into 4r0
28dBV into 2r0 is 25.1Vac is 315W into 2r0. (not 100W into 2r0, which would indicate a current crippled amplifier)
Cordell specifies at least 180% power into a halving of load resistance as an indicator of adequate performance. You can see that -0.5dBV does not quite meet Cordell's standard.
-0.4dBV for each halving of test load resistance would slightly exceed Cordell's minimum standard indicator.
BTW,
I can exceed Cordell's (180%) standard with transformers of less than 2times maximum output power into the lower of the test loads.
i.e. a 625VA transformer for a single channel for 311W (+30.95dBV) into 4r0 and 170W (+31.3dBV) into 8r0 using quiescent rails of +-58.5Vdc, shows a loss of -0.34dBV on halving the test load impedance from the nominal rated amplifier capability.
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then don't call it 250 watt into 8 ohms but something else...
no law against that...
a 500 watt traffo will not stop delivering power at 501 watts...
you can draw substantially more short term...
and the nature of music, compared to pure sine waves, energy content is smaller...
Are you saying you cannot hear the difference or there is no sonic difference because you can cite research papers?
If scientific research shows after eating corndogs 100 testers could not tell the difference between amplfiers , can we then conclude corndogs are bad for your hearing ...
🙂
Research = results or is it results = research ..?
My personal research and experiences have shown there is a difference and its audible, its why there is no one amplifier, the bar keeps moving ...
Regards
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😀😀😀😀!
What about him? If his amplifier is poor (define poor), fully agreed!
But going OT (apology Mods) - I am not a loudspeaker designer, but I have difficulty seeing how a speaker designer necessarily needs to 'compromise sonics' in order to achieve a reasonable impedance-frequency characteristic. Again then: Are you saying that all those excellent loudspeakers on the marketplace with 'good' impedance graphs, are inferior to the few that are unable to return such?
But I must not lure you OT - this is another subject. I am going to stand off for a while now to watch a rugby match (local national sport); success to you doing 'your thing'! ..... night/early morning there?
There is a big difference in the sonics , he is not driving a pure resistor with a static frequency , yes his amp will work, but his wife will complain ...🙂
Why compromise the Psu , its Diy , if its cost, better to buy use from Ebay look at Rotels you can buy them for 300.00 and get a higher quality amplifier....
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