Cat5 is an example of a high-speed, (relatively) long-distance connection that is susceptible to interference. While "all multi-core unshielded cables should be twisted" is a good rule of thumb as a first approximation, it should not be taken as an absolute commandment. Low-impedance, slow-speed control connections (such as nAMPON) are pretty immune from interference, so twisting is not required.
Just like the mythical battery with just one pole
If nampon would need to be twisted, it should be twisted with a ground lead. But it doesn't.
I've found interesting post in the history of this loooonng thread related to "dragons" beyond 20kHz:
They are nonsense. I know the game. Someone has a case to make (e.g. for the existence of supernatural beings, telepathy, etc) and they try to prove this by pointing at evidence which perchance hasn't been collected yet but which will surely vindicate their beliefs when provided. And when you say "bollocks" they'll then proceed to challenge you to disprove them, thereby suggesting that by default their theory holds. And by accepting to play their game you accept their terms. Well, before doing so, be aware of what follows: you do the hard work to do the experiment of which they claim to know the answer without bothering to try. You provide evidence which flatly refutes their claim. What happens? Instead of saying "you're right and I was wrong" they'll just invent another story for you to disprove. That tactic is called "moving the goalposts". It is one of a range of techniques nitwits use to give the impression that they are in a position to take on actual experts. I haven't the foggiest whose claims you are referring to but I'm imagining some forum discussion where someone says "oh THD is nothing, it's IMD that matters" and someone else says "go and check out the IMD plot then, it's all there" followed by the first speaker replying "yes but their plot stops at 20kHz and beyond that be dragons". It just keeps going, there's no telling what they'll come up with next.
Now, to answer your question technically. Ncore's loop gain is plotted in the white paper. Unlike linear amplifiers, open loop distortion is fully independent of frequency so the distribution of various harmonics is the same for all frequencies. You can take that as a given. You can read the distortion spectrum either from the 30W plot I posted earlier or you can glean a good indication from the IMD plot done at even higher output powers. So you look up how much lower loop gain is at various harmonics of 10kHz, you look up the amplitude of the matching harmonics from a known spectrum and from there you can work out what the HD would be at 10kHz. Since loop gain includes the output filter, be sure to scale the calculated HD back down 40dB/dec after 35kHz.
In short, the information is already there. Querulants often rely on their inability to read in order to make a point
Ah, thanks for the reminder - I am sure we have all come across people like the ones Bruno talks about...
Every few days it seems there is someone that needs reminding of that. hey Julf?
I did save it too, I do think it might come in handy
I am constructing an amp with two NCORE 400s, intended to drive 2 ohm loads on each output (4 x 8 ohm drivers in parallel for each channel). This is for my home stereo system, where the average power will be a few watts at most. Is one SMPS600 supply still sufficient, or should I use one per channel for best performance? And, would constructing the amps as monoblocks result in better performance?
Thanks in advance,
Francis
Thanks in advance,
Francis
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got my ncores rebuilt into a different chassis, and i swear i hear a difference, don't know if its the isolation of the ncore/smps modules or something
Post some more pics of the chassis
Depends on how much current/power you will need to drive the woofer, but I would assume you'd be OK with just one shared SMPS600.
I'll want the current available on peaks of course, but I don't listen at concert levels, so the average power will be a watt or two. Are monoblocks better? I have the room for two chassis in my rack, so it's certainly not out of the question.
That may not be practical because of room constraints; but I do plan to have four outputs on each amp channel, with separate 10AWG wires to each driver.
The average is very low it's true, but with the 2 ohm loads I wondered if peaks would suffer. As it turns out, I think I'll just build monoblocks, so each amp gets its own supply in any event.
In the SMPS600 they spec that it can handle 575 W with 2 NC400 with a 4 ohm load @ 90 seconds. So one SMPS should at least be able to handle enough current for bursts of ~ 140 W on each 2 ohm speaker, and ~ 68 W continously. (275 W on 2 NC400 @ 4 ohm)
68-140 is still a lot more than a few watts
I'd say let the cabling situation decide if you want another SMPS, if you build your own speaker you could integrate the amp into the speaker and get everything more neat. If not then I'd stay with a single one.
That is 575 W of amp output (not PS output). The specs of output power as function of load impedance shows that it is not current-limited, so gives even more power into 2 ohm.
I agree.
Post some more pics of the chassis
you can find more pics of the chassis from a thread the guy that made them started
http://emotivalounge.proboards.com/thread/30640
he only made 7 of this chassis and another 2 customs for someone else, he might or might not be willing to make more chassis.
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