By habit, when you increase the slew-rate (and reduce HF distortion) of a power amp, the first thing you notice is sharper basses. Then you discover little details in instruments that you never heard before. Like nails or mediators on the guitar strings, noise of pedal and feeling of the hammers on pianos, hits of the strings on drums, metal and weight on cymbals, more space between instruments, better separation...
The only thing you don't notice is an increase of trebles. On the contrary, you have a feeling of less level, while they are more 'fluid' or easy. Less 'noticeable'.
The only thing you don't notice is an increase of trebles. On the contrary, you have a feeling of less level, while they are more 'fluid' or easy. Less 'noticeable'.
Sounds a bit like the concentric vs concave tendency of high motor strength speaker drivers with over hung motor structures compared to under hung motor systems in speaker drivers...
Congested and aggressive vs open and refined sound.
When I bodged around with both UCD and aussie amp implementations I found the speaker return routing critical. Routing back to the boards opposed to directly to the PS ground resulted in "controlled", somewhat congested and closed sound while directly to PS ground gave extension and "life" if somehow also a bit unruly sound in some cases.
However I eventually preferring UCD with speaker return to the boards when everything settled down in a system with some very small bookshelf speakers. The aussie never really worked and was directly terrible with speaker return to the boards... Was told it shouldn't matter, but boy it made a difference!
I guess high feedback amps are quite sensitive to how the return current is routed. The distance between the feedback reference point and the current routing is probably the thing...
From what you describe, if you haven't tried both returning speaker to PS and directly to the UCD boards, you might like to try out both options and hear whether it affects what you dislike about the UCD amp ....
Cheers,
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...It is possible to choose PS ground 1 or 2 cm from board ground. I always choose that the last 5 years.
That might work with the UcD, but seems like a bad idea with the nCore.
Haven't tried it due to my linear PS typically demands some 10cm or so.
I am inclined to believe that even a few cm's can be enough to screw with the operation of the nfb loop -especially since you remove it from the ground plane and thereby form a path that has to go through ground plane and through the wire to the PS ground. I believe this to be the reason for why Bruno placed both speaker terminals on the ncore boards and as close as possible...
I also tried to route speaker return back to both PS ground and the UCD boards in order to ensure low R and maintain voltage reference on the boards, but this sounded sort of "in between" the other options and clearly less refined than routing the current through the boards.
If you built ncore without routing speaker return back to the boards terminal I am quite sure that they wont perform as intended -and in a quite audible manner too.
With the aussie modules I couldn't stand the sound when routing speaker return back through the boards, so i might change like the UCDs when run in, but that "sound" made me too impatient. It was simply unbearable for music or tv listening.
It is a good idea for most amps . Tighter bass is the result. A Bus for Ground work better then star ground .
If you talk about connecting the nc400 ground and the smps ground, then perhaps. But not for "returning" the connection to the speaker.
I heard many other effects (good And bad ones) both on the UCDs and the aussie amps.
Think about it like this; if the amp's operation is governed by its feedback loop (high damping factor is a sure sign...)
- then what you essentially do when moving the speaker return is to "tweak" the feedback circuitry because you move what it is designed to steer the amp operation after away from the reference point it has been designed to work according to.
I see, thanks.
well, I guess it's fair to look at the both sides of the coin, I think some people see this is class D bashing. the guy who sold me the Audio Refinement switched to a Jeff Rowland Concerto. B&O modules with SMPS, not linear PS. yes, it's 6 times more expensive but it's as class D as it gets. from his words, the JR is a superior amp. I really believe it's a matter of implementation.
I sold my JRDG Model 2 to actively biamp (with servo on the low end) my speakers with UcD modules...
The proto-types still get much better replies from listeners. Having a hard time justifying the price of swapping the UcD's for Ncores but I assume that would be the next step....
(edit) So that is why I am STILL monitoring this thread...
The implementation is better. I could find NO FAULTS with the JRDG Model 2. Well it was heavier than a boat anchor. But sonicaly paired with the JRDG Consonance it was extremely musical.
WAS:
Analog XO and "old" Erath Electronic suspension unit in a "center" enclosure feeding "external" the JRDG Model 2 for B&W 805s and Bryston 4B on the 15's sealed 1.24 cft enclosure flat to 20Hz.
IS:
Analog XO, "new" Erath Electronic suspension unit AND the UcD modules in a single center enclosure driving new tops (Scan Speak Revelator tweet, Same B&W Kevlar mid) and new dual 10" aluminum cone woofers on bottom. Again, small sealed cabinet flat to 20Hz.
FUTURE: 1) all electronics AT the speakers in full mono mode. 2) Digital feeds to the active speakers. 3) Digital XO / DSP at the speakers. 4) "eventually" digital DSP "servo" and retire the Erath unit...
So as you can see, it was not a one for one swap of amplification... MANY other factors contribute to the better replies.
so nothing fancy. that's weird.
in my book anyone owning that kind of gear (call it audio snobbery, whatever) is not the type that just falls for hype so I trust your opinion.
I'm trying to find an explanation for what I'm experiencing. maybe it's the Dynaudios that are known to be hard loads for amps. still, all the objective facts don't expose obvious phenomena indicating that there's current limiting, clipping or something of the kind. and actually my Dyns are an exception, the impedance is equalized and the impedance magnitude has a minimum of about 3.8 ohms if I recall correctly. and there's the mysterious back EMF phenomena, pretty much unsupported by objective data. AND that should (well, should it?) be even less of a problem with the UCDs.
but in the end the Audio Refinement sounds better.
FWIW, here's the ARC schematic + some more measurements: http://www.klausmobile.narod.ru/industrial/in_01_arcomplete_e.htm
in my book anyone owning that kind of gear (call it audio snobbery, whatever) is not the type that just falls for hype so I trust your opinion.
I'm trying to find an explanation for what I'm experiencing. maybe it's the Dynaudios that are known to be hard loads for amps. still, all the objective facts don't expose obvious phenomena indicating that there's current limiting, clipping or something of the kind. and actually my Dyns are an exception, the impedance is equalized and the impedance magnitude has a minimum of about 3.8 ohms if I recall correctly. and there's the mysterious back EMF phenomena, pretty much unsupported by objective data. AND that should (well, should it?) be even less of a problem with the UCDs.
but in the end the Audio Refinement sounds better.
FWIW, here's the ARC schematic + some more measurements: http://www.klausmobile.narod.ru/industrial/in_01_arcomplete_e.htm
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