I am Danish, so I know what 88 means. Had two friends who was sent to 'camps' and survived - they have passed away now.
Scott, no disrespect to your work, I honestly would be the last one, but may I suggest this:
I know, the filter is not OOB (code for 20KHz as we all know), but if this was used as a USB DAC and source was JRiver with its inbuilt 64 bit parametric equalizer, then I can furnish the right numbers to plug in and voila, OOB rule restored.
Also, most DACs use two I/Vs and then summed afterward, the first series resistors after the I/V is driven by low Z, so two small bypass caps can also restore flat response. I have modeled the response in SoundEasy and can predict the values even before I make the circuit.
It comes down to, not flat response at the final output, but any benefit that can be arrived at putting the response where it sounds best (and getting the best) out of the DAC. Then add any correction needed.
Hypothetically, we can put that 1st pole anywhere and correct for it.
Cheers, Joe
Hmm, if this is practical with MC carts, perhaps Stu and I could do a little comparo between this setup and a famous-maker phono amp that he has at his place currently. I've always been a fan of the cost effective solution.
They hand speed limits and you can only drive fast in designated sections of the autobahn
The A380 program is struggling . . . It's a fine piece of engineering but orders are not at the planned level (see a number of reports over the last six months). It seems the travel market really does require more medium haul ultra efficient aircraft. I have a friend who works for Boeing here in Shanghai and many of the regional airlines here are buying 787.
(The A380 story by the way did not come from my Boeing acquaintance - just google it).
Back to amplifiers - I've built both VFA's (e-Amp, and another big 250W) and 3 CFA's over the last 8 years. My personal opinions aside, they all sound very good to my ears.
I don't understand, since the first day I subscribed to this forum, the position of some people here about CFAs and some other things. They seems to act like members of some Inquisition court.
No, LTP is not the only way to design an input stage of a Power amp. More than this, applying retroaction the the anode of a tube was the most common way to reduce distortion at the beginning of the HIFI story , nothing exotic ...
CFAs and VFAs (LTP) have inherent pro and cons. While, knowing them, you can adress with more or less success the cons of each topology. OS had demonstrated you can achieve very low distortion numbers with both topologies, and get very close results. And, yes, CFAs are a little better for slew rate and high frequencies (phase margins, bandwidth, PSRR rejection at HF) while VFAs are better at Low frequencies (PSRR).
Yes, everything has a 'character' in hifi. a power supply or even a Cascode. You can call-it a signature.
Magical ? Not at all and we can measure the differences.
Now, if some are unable to hear them, happy they are: They just have to buy any amp on catalog that reach what they consider as the distortion thresholds and keep-it plugged for the next 10 years.
On my side, I had to test a lot of power amps for my recording studios in my life. I realized the ones i preferred were CFAs most of the time, not knowing what they were. For this crime, I'm on the ignore list of very open minded people here like jan.didden (In good and large company ;-).
Yes. We can readily show the contradiction, just by considering energy lost in electrical load versus energy required for mechanical damping. It's way short.
Ignoring aircraft, which are such a long term thing with no much national ego involved most of us can't get our heads around it (concorde, the space shuttle of the airways) I think we are in violent agreement on this
I should start by noting you put me on your ignore list some 6 months ago
If we accept
-both are valid approaches
-both can measure well below understood human thresholds of hearing
And ignore 'Engineering constraints' such as complexity and setup costs so all the 'but I get the same performance with fewer devices' arguments are pushed away, then it's really down to if you can hear any differences and if so what is causing that. And that will only cause a fight if the true believers keep forcing sighted listening results at everyone. Once you read that VFA has better bass that information is lodged there forever to bias you!
He isn't but there are some acolytes on the forum that are. OS is one of the most balanced here in his views and I have utmost respect for him.
http://www.desordre.net/bloc/images/lama.jpgI should start by noting you put me on your ignore list some 6 months ago
I cannot accept because I don't know where are the :"understood human thresholds of hearing".
- Why the hell are-we measuring high order harmonic distortion components above 20KHz ?
- Where is the accuracy between measurements made with constant level sinusoidal signals and musical reproduction made of complex transients ?
- Where is the accuracy of such measurements, made on resistive loads, when we use our amplifiers to drive very imperfect and complex electro-acoustic transducers ?
- etc...
About superiority of VFA basses, any argument to justify this, apart the attention can be less kept by the better transient reproduction of a CFA (if any ) in a full range system ?
Is the comparison fair enough ? (Same power supply, same dumping factor, same phase behaviors at low frequencies). On my two way system (FC: 1kHz), I cannot make the difference between a Class D amp, a CFA and a VFA , powered by the same PSU, dumping factors equalized, when they drive the boomer.
It is so easy to amplify low frequencies up to 1 - 5KHz with actual components on the shelves.
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I love tintin
OK, so under a few KHz you are happy that no real difference. So far so good. As for the rest I don't know. I agree with you that more measurements should be made into realistic loads, but what that load should even be will cause arguments.
I have my chosen speakers so can optimise for those.
But to be very clear I have no problem with 'I prefer'. Audio is an undemanding electrical problem after all.
OK, so under a few KHz you are happy that no real difference. So far so good. As for the rest I don't know. I agree with you that more measurements should be made into realistic loads, but what that load should even be will cause arguments.
I have my chosen speakers so can optimise for those.
But to be very clear I have no problem with 'I prefer'. Audio is an undemanding electrical problem after all.
In order-
These components can indicate other circuit problems, can cause further audible distortion further down the signal chain, and can intermodulate. These are reasons why some of us are uninterested in achieving ultra-high bandwidth, far beyond what is necessary to achieve the task of amplified audible signals.
Fourier theorem. And typically, measurements are made at several different levels. Some of us even measure distortion versus power and distortion versus frequency. Imagine that!
Indeed, reactive loads should absolutely be used as part of a measurement regime. Resistive loads are necessary but not sufficient. Ditto for characterizing amplifier drive capability- the PowerCube measurements used by Audio Critic were exemplary.
(Not as much as a shipping guy in Greece. http://www.ponentevarazzino.com/wp-content/uploads/tintin1.jpg )
Do we realy need 24/192 playback system?
24/192 Music Downloads
...and why they make no sense
https://xiph.org/~xiphmont/demo/neil-young.html
24/192 Music Downloads
...and why they make no sense
https://xiph.org/~xiphmont/demo/neil-young.html
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