Indeed. I have been told that the first ones were built using 2 KEFkits per box.
When I calculate mathematically with 26 dB gain 2 Vrms should become ~ 40 Vrms, and 40^2 / 8 is about 200 which sounds about right.
EDIT: I checked an answer by Bruno and 2 Vrms it is for full power, at least into 8 ohm.
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As OllBoll says - 2Vrms is the upper limit for input amplitude/voltage (not power), unless you modify or remove R141.
Even 4 V is too much (doesn't matter if it is on an xlr, rca or whatever connector). If you want to drive it with 8V, you have to remove or replace R141.
Paul McGowan:
"Far more transparent" then Ncore? That's strong words and difficult to take seriously.
Going against the grain | PS Audio
"Far more transparent" then Ncore? That's strong words and difficult to take seriously.
There was no comparison to Ncore mentioned in PM's post. The amplifier Mr McGowan is working on uses a proprietary input stage, coupled to a uCD output stage. Hopefully the new 0 NFB input stage will bring this amp to the next level, and I am interested in hearing it.
Sure - it will be interesting to compare Paul's "less feedback" approach with Bruno's "there is no such thing as too much feedback" approach. But if you are against strong feedback out of principle, the nc400 isn't for you...
Feedback might apply differently on input and output stage. (From what I have understood) Paul seems to be very happy with Bruno's latest UCD400OEM output stage -but with Paul's own class A input stage of course.
In what way would it be different in an input stage? The function of feedback is precisely the same in both cases - to linearize the amplifier, and remove errors. The only difference is that it is somewhat easier to get an input stage reasonably linear without applying feedback.
Paul's own class A input stage might be great, but that doesn't really say anything about whether feedback is a good or a bad idea.
I have a small question about the NC400.
The amplification is said to be 26dB (20xVoltage) and 2V is said to drive it to clipping.
2Vrms conforms to the regular 5.6Vpp, now for the question.
Is this total differential input voltage? I.e. 2.8Vpp for each of the + & - for a balanced signal? (1Vrms for each)
The amplification is said to be 26dB (20xVoltage) and 2V is said to drive it to clipping.
2Vrms conforms to the regular 5.6Vpp, now for the question.
Is this total differential input voltage? I.e. 2.8Vpp for each of the + & - for a balanced signal? (1Vrms for each)
A balanced signal isn't 1 half signal on each side, it is a full signal in between the + and the -. The NCore is a real balanced amp so there is no ground as input.
So it is 2 Vrms single ended from hot to ground or 2 Vrms balanced from hot to cold.
Yeah, that's exactly what I was saying, 2Vrms is the differential voltage between the hot and the cold. Since they are out of phase 180 degrees the hot and cold need to be 1Vrms each combining to 5.6Vpp differentially.
Having a pre with 3.3Vpp on both hot and cold respectively will drive it to clipping.
Having a pre with 3.3Vpp on both hot and cold respectively will drive it to clipping.
On a differential input, the only thing that matters is the voltage difference between the + and - inputs, so you can't really talk about the signal of one of them in isolation.
The data sheets don't specify a maximum voltage as such, but the SNR is specified against 2.8 Vrms that corresponds to a peak value of +- 4 V (8 V peak-to-peak) for a sine wave.
As you say, the voltage gain is 26 dB (a factor of 20). Looking at the rated output power (THD=1%) figures, we get a max output voltage of 40 Vrms at 4 and 8 ohm, and 34 Vrms at 2 ohms, corresponding to 2 Vrms (+- 2.8 V peak, 5.6 V peak-to-peak) and 1.7 Vrms (+- 2.4 V peak. 4.8 V peak-to-peak) respectively.
When you say "3.3Vpp on both hot and cold respectively", what would that be referenced to? A differential input is not referenced to ground.
A 2 V rms signal is 2.8 V peak and 5.6 V peak-to-peak. It does not matter if it is a differential/balanced or unbalanced input.
Yes, 2 V rms is 5.6 V peak-to-peak, but there is no "1 V rms each", as there is no magical reference point in the middle to refer to. A differential signal is the voltage between the two inputs, not the sum of the difference between the inputs and some ground reference - the ground (and hypothetical "halfway" reference point) doesn't enter the picture at all.
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