Exact this is the reason, why technican guys still mißunderstand the claims of the advertising department guys that are mostly lawyers, who know how to move perfectly at the borderline between truth and untruth.
If you read datasheets of commercial audio products, please think still to the super sound computer high-end loudspeaker or car hifi speaker datas with 1000 watts PMPO and 5 euros/pc.
If such claims as "40W in ClassA" not mentioned, were also sold far fewer devices, independed of the brand. And making money today's top priority
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Exactly!
And this is the reason why it is illegal to do so.
It is in some way understandable that some designers do not have the skills to design good electronics, but that does not justify faked ratings.
If you bought a new car with 200 KW @ 6000 rpm, then you would be somewhat disappointed finding out, that only 100 KW was present.
To me it is repulsive to see manufacturers state things like that, knowing that it is not true at all. One will indeed know when 40 watts of class A is present, the heat is the messenger.
Ratings are used as eyecatchers, and if untrue the manufacturer gains marketshares which are unjustly taken from the honest manufacturers.
I think one should do ones best to make products superior to others, and tell the truth about them, rather than faking it.
the company "Ultrasound Design Group" claims a lot of interest regarded perfect sonic transmission of their 400.000 US-$ Parsec amp: Please open the URLs about
http://www.diyaudio.com/forums/pass...s-basic-description-italians-400-000-amp.html
for read the details
http://www.diyaudio.com/forums/pass...s-basic-description-italians-400-000-amp.html
for read the details
There seems to be a small mistake in the schematic from lumanauw. The 80.6ohm resistor going to the base of the B1186 driver should be connected to the emitter of the preceding transistor, not the collector, which is equal to the -35V supply. Just in case someone wants to simulate (or build!) the circuit
As I note by creating the simulation results in circuitmaker, you are right. Two other devices are not the right value: the 100 pF capacitor parallel at one of the two 100K NFB resistors and the resistor in parallel to the NFB capacitors.
now I have simulated the Densen Circuit from lumanauw
supply voltage: 72V (+/-36V, floating GND, thus DC protection)
open loop gain, first gain stage: unity gain 2x1,1mA idle current
open loop gain, second voltage gain stage: 1400 times, 2,2mA idle current
closed loop gain stage: 58 times
Output Buffer: super-ß triple
Input/Output: 170mVss/10Vss
Idle current, Output Buffer 4/33/1500mA (Class A)
THD 10KHz: H2: 4mV, H3: 1mV, H4: 50uV, H5: 15uV H6 and higher: <2uV
Idle current, Output Buffer 2,6/16/30mA (Class AB)
THD 10KHz: H2: 4mV, H3: 15mV, H4: 400uV, H5: 7mV H7: 3mV, H9: 2mV
Idle current, Output Buffer 4/33/1500mA (Class A)
THD 100KHz: H2: 34mV, H3: 7,5mV, H4: 300uV, H5: 60uV H6 and higher: <25uV
Idle current, Output Buffer 2,6/16/30mA (Class AB)
THD 100KHz: H2: 38mV, H3: 13mV, H4: 2mV, H5: 5,3mV H7: 2,5mV, H9: 1,2mV
More results and the diagrams I will post in the next time, but the schematic I don't post, because it would be removed as already happen by lumanauw
Exactly!
It cannot be said any clearer.
But in my experience this is mostly done by "high enders". Maybe I´m naive, bit I don´t think that engineers from the larger coorporations will do such a thing. Look at this i.e.
Output power 8 ohm: 2 x 80 W (20-20.000Hz, THD 0,07%)
Output power 4 ohm: 2 x 160 W (1 kHz, THD 0,7%)
They do want it to look as if the amp does double the power, which it will not do, but they actually provide the correct data.
The example is a Denon PMA 2010AE
You're entitled to your own opinion, but in mine, this is junk:
please read this report regarded "Perception &Thresholds of Nonlinear Distortion" from Institute of Electronic Systems, Aalborg University, complete:
http://projekter.aau.dk/projekter/fbspretrieve/9852082/07gr1061_Thesis.pdf
Then you get another view to some preconceived opinions
Hmm!
Are you suggesting that distortion does not matter
The measurement GK refers to must be regarded as a best case, since it is a purely linear and resistive load. IRL it is not so.
An IRL speaker will with ease be able to modify the frequency response of an amp like this. Especially if you turn up the volume a bit.
This is of course correct. I will not deny that the Densen amplifiers can be better constructed. On the other hand, one must also see that there are a lot of amps (especially with tubes, but also "solid state" amplifiers like "ZEN/ALEPH" series of master Nelson Pass), the THD values are not particularly good, but still have a very high sonic transmission quality . And vice versa - there are a lot of amplifiers with excellent THD values, however, unsatisfactory results of the playback because the high order products and the large sense to complex load resistances.
If we have all amplifiers in the world from same price class together with Densen's B-350 for an audible quality check, Densen B-350 would be not the best, but one of the best, despite the high THD values, because basicly no high values of higher-order distortion products occur (mainly because of the small open loop gain and the chooised NFB connection in front of the pp output power buffer darlington). I am shure, if there the NFB point on the speaker output, THD values would be better, but sound bader though more high order THD.
However, my opinion is to avoid even too high values of low order THD values. Therefore Bonsai think right.
If we have all amplifiers in the world from same price class together with Densen's B-350 for an audible quality check, Densen B-350 would be not the best, but one of the best, despite the high THD values, because basicly no high values of higher-order distortion products occur (mainly because of the small open loop gain and the chooised NFB connection in front of the pp output power buffer darlington). I am shure, if there the NFB point on the speaker output, THD values would be better, but sound bader though more high order THD.
However, my opinion is to avoid even too high values of low order THD values. Therefore Bonsai think right.
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When the outside loop power darlington leaves class A, at the same moment it starts to produce huge amount of higher harmonics. I know what I am speaking about, as I have been designing class A output stages for 7 years. Compared to this, properly designed global NFB amp would have much lower amplitude of higher harmonics.
There is a way how to design low distortion, class A out-of-the-loop output stage. CFP, high idle current and multiple output devices. Then, one needs a proper heatsink, which is not the Densen case. This Densen amplifier is really poorly designed.
There is a way how to design low distortion, class A out-of-the-loop output stage. CFP, high idle current and multiple output devices. Then, one needs a proper heatsink, which is not the Densen case. This Densen amplifier is really poorly designed.
@tiefbassuebertr
First of all, if you look at the price for the B350 it is €7.500 pair.
Which should be sufficient to engineer well what so ever.
The story about good sounding high distortion amps, I do not believe in.
I´ve heard a lot of amps with both a lot of distortion and with very little.
To my experience the ones with high distortions are not good reproducers, but it is right that they are more likely to be fancied, if the harmonics are linear and tube like, which means equal order.
But they do not at all reproduce the signal from the input. They reproduce with huge colouration, which some audiophooles like a lot.
Amplifiers measuring very good, does to my experience not necessarily sound good. But when distortion is well controlled, linear and smooth, there is a good chance for good sound.
Any amplifier incl. the B350 would be reproducing a lot better without the large amounts of distortion. And that is what high fidelity sound is al about.
The Densen seems to be a result of some idiosyncratic design philosophy, which probably is the origin of their "airguitar factor". So for music needing a bit of extra distortion, it might work out.
Btw. it also lacks the ability to deliver power when the load becomes harder.
First of all, if you look at the price for the B350 it is €7.500 pair.
Which should be sufficient to engineer well what so ever.
The story about good sounding high distortion amps, I do not believe in.
I´ve heard a lot of amps with both a lot of distortion and with very little.
To my experience the ones with high distortions are not good reproducers, but it is right that they are more likely to be fancied, if the harmonics are linear and tube like, which means equal order.
But they do not at all reproduce the signal from the input. They reproduce with huge colouration, which some audiophooles like a lot.
Amplifiers measuring very good, does to my experience not necessarily sound good. But when distortion is well controlled, linear and smooth, there is a good chance for good sound.
Any amplifier incl. the B350 would be reproducing a lot better without the large amounts of distortion. And that is what high fidelity sound is al about.
The Densen seems to be a result of some idiosyncratic design philosophy, which probably is the origin of their "airguitar factor". So for music needing a bit of extra distortion, it might work out.
Btw. it also lacks the ability to deliver power when the load becomes harder.
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