Trying to understand your test here, were you comparing the EVAL1, bypassed, directly, versus adding the Neurochrome at unity gain? And you found 10dB noise reduction? I don't see how that is possible - I must not be understanding the test, properly. How/why was gain matched, if both were operating with 0dB gain?
Nice "breadboard"!mocenigo said:
I asked and that picture was taken when they came fresh out of the reflow oven. Out of 200 regulators, it was the only one that had a bit too much solder paste, so slid a bit off centre. He noticed it right away and moved it over with his heat gun, before soldering on the headers.. Anyways you don't get cold solder joints in a reflow oven of the caliber that made those regulators. But it's possible (0.5% in this case) to have a single component move slightly off centre. The resistor above it is in parallel anyways. So it was a purely cosmetic flaw.
Hope this helps.
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Trying to understand your test here, were you comparing the EVAL1, bypassed, directly, versus adding the Neurochrome at unity gain? And you found 10dB noise reduction? I don't see how that is possible - I must not be understanding the test, properly. How/why was gain matched, if both were operating with 0dB gain?
Nice "breadboard"!
No, it was with the Purifi buffer NOT bypassed ONLY VS the Purifi bypassed and with the neurochrome (configured for 13Db gain) in front of it.
However I settled for 7.3Db gain on the Neurochrome board.
You wanted to leave three times, Mike, it would be glorious if we had our “mikexit” at last
PRaT is audiophile subjectivist speak. Stands for Pace, Rhythm And Timing. As to what it actually means, your guess is as good as mine.
I wonder whether this was originally meant as a joke, since the term was born in the English audio world and "prat" means also buttocks and "an incompetent or stupid person; an idiot."
"Technically" (note the quotation marks) one can refer to this 1992 Stereophile article, and I would say it applies mostly to amps that have a generous power supply, designed for speed more than finesse (so quite a bit of ripple, large caps but no inductors) in order to get a very well marked and tight bass. Think classic olive fascia NAIM NAPs. When you have that "foot tapping inducing" bass line, then you get PRaT. We are talking very unrefined amplifiers here, but more enjoyable than many other products at the time when they were first introduced.
I am always wondering what "speed" means in this context - clearly not something measured in km/h, m/s or miles/h.
I received a Connex SMPS 800 the other day (with custom +65/-65 raiLS). Nice looking supply, mine has Samwha caps at the input side, but nicer UCC caps for the output and Nichicons elsewhere. Very compact supply for how much power it produces.
I managed to replace one of the 7815 IC regulators with a Belleson for the 15 VDC supply for VDR. It was a very tight fit, and I do not recommend trying this for those who are not certain they can do it. I removed the input capacitor to the regulator first, to get access, then unscrewed the 7815 from the heat sink, then removed first the heatsink, followed by the regulator. I had to grind off a bit of the heatsink to fit the Belleson, then I loosely mounted the Belleson to the sink, put it in place, and soldered the legs of the heat sink, then tightened the screw, and soldered the legs of the Belleson. Then soldered the input capacitor back in place. I am also going to add a .1 µF ceramic cap across the input of the Belleson on the underside of the board, but did not have the needed 0805 size part at hand.
Anyway, I fired up the supply and everything works as expected with 14.97 VDC from the Belleson.
Waiting on the Purifi stuff to arrive now, and have to build the +/- 18 VDC linear supply.
I managed to replace one of the 7815 IC regulators with a Belleson for the 15 VDC supply for VDR. It was a very tight fit, and I do not recommend trying this for those who are not certain they can do it. I removed the input capacitor to the regulator first, to get access, then unscrewed the 7815 from the heat sink, then removed first the heatsink, followed by the regulator. I had to grind off a bit of the heatsink to fit the Belleson, then I loosely mounted the Belleson to the sink, put it in place, and soldered the legs of the heat sink, then tightened the screw, and soldered the legs of the Belleson. Then soldered the input capacitor back in place. I am also going to add a .1 µF ceramic cap across the input of the Belleson on the underside of the board, but did not have the needed 0805 size part at hand.
Anyway, I fired up the supply and everything works as expected with 14.97 VDC from the Belleson.
Waiting on the Purifi stuff to arrive now, and have to build the +/- 18 VDC linear supply.
The power supply, i.e. having a large reservoir of energy for transients - underdesigned supplies will result in sagging dynamics. I do not know either what “speed” as a property of sound means.
Ok so it is the same as for amps: large reservoir of energy for transients, not sagging, i.e. "good transient response" in my convoluted speak.
Correct - also, stored energy (perhaps more related to drivers) is a big cause for sloppy & weak performance. Accuracy is very much related to transient response (step or impulse response), an aspect of music reproduction that gets a bit less focus than THD and IMD. I don't want to favor anyone of does as they all matter. For amplifiers, you are right, its the ability to deliver enough current when asked for, hence the answer to how many watts do I need, is "probably more than you think"... lol.
- also, stored energy (perhaps more related to drivers) is a big cause for sloppy & weak performance. Accuracy is very much related to transient response (step or impulse response), an aspect of music reproduction that gets a bit less focus than THD and IMD. I don't want to favor anyone of does as they all matter. For amplifiers, you are right, its the ability to deliver enough current when asked for, hence the answer to how many watts do I need, is "probably more than you think"... lol.