Some reading on how many bits we need:
Second-Order Digital Filters Done Right
The main reason is when doing filtering to reduce noise induced by quantization errors.
Hi Gerhard.
Is there any update on this topic? Will there be new firmware soon? Were other points found in the firmware were precision is lost?
Fedde
My ever present wish:
Current source amp modules. It's so sad great amps like the NCore that perform so well in the midrange and above stick to low output impedance when it could reduce driver distortion so much by having higher output impedance. It is an active DSP plate amp where each driver has its own DSP channel and amp. It would be so easy to compensate for the change in frequency response by the high output impedance.
Even better would be if the modules were switchable from low / high output impedance so the low woofer could be low output impedance and the midrange and tweeter could have high output impedance. Or even better yet such that we could input say fs and have it transition from low output impedance to high if we have say a midwoofer instead of a separate midrange.
Current source amp modules. It's so sad great amps like the NCore that perform so well in the midrange and above stick to low output impedance when it could reduce driver distortion so much by having higher output impedance. It is an active DSP plate amp where each driver has its own DSP channel and amp. It would be so easy to compensate for the change in frequency response by the high output impedance.
Even better would be if the modules were switchable from low / high output impedance so the low woofer could be low output impedance and the midrange and tweeter could have high output impedance. Or even better yet such that we could input say fs and have it transition from low output impedance to high if we have say a midwoofer instead of a separate midrange.
It's slightly off-topic, but how a high output impedance help to reduce driver distortion? Anyway, high output impedance is a loss, more power into heat and a loss of control, causing coloration, which is a type of distortion. You want high output impedance? Put a series resistor (or more) between the amp and the driver. End of story.
I would like a feature to configure the volume step of the RC, e.g. one, two or three dB steps. I think the steps are too small now. Also, the HPD GUI could be a bit improved regarding volume control. A larger slider and buttons for +- 1 and 3 dB. By the way, an open software interface to control volume would be even better.
Fedde
Fedde
The output impedance doesn't generate more heat in the driver, it just interacts with it in another way. If you (with say DSP) correct the input such that the same amount of sound is created from the driver then the same power goes into the driver. The magic about high output impedance though is that the amplifier makes the current, not the voltage match the input. A lot of distortion in the drivers (driven by voltage amplifiers) are because the impedance of the driver is just slightly different on the inward or outward stroke. Not by a lot but this imbalance creates distortion since it causes different amount of power to go into the speaker. A current amplifier will deliver the same amount of current, thus nullifing this type of distortion. Within about 2 octaves of fs this is not the major cause of distortion so within that region a voltage source is a better performer.
In this post I show some measurements where I compared output with a 6ND430 amplified by a NCore (voltage source) and a high distortion tube-like (but current source) F2J. The fs of the driver is ~ 70 hz and you can see at ~ 200 hz and above the 3rd and higher harmonics gets reduced by a lot with the current source amplifier.
I mean, even Bruno Putzeys himself used current source amplifiers in the Grimm LS1. (he even made the midwoofer amp fancy by having it a voltage source at fs and then transitioning into a current source to avoid that distortion increase on the low end)
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Interesting, thanks for that info and measurements! But more interesting is that I use the 6ND430 driver as midrange right now in my own speakers and with a Hypex FA253 I cannot be able to produce a distortion profile like you posted with a Ncore amp, where the 3rd harmonic distortion is at the same level as the 2nd in the midband.
The 6ND430 may have had it's own problems in that range in the past, because Eighteen Sound has changed this driver since it released and I use the newest version of this driver and your measurements is from 2012.
As fedde said, seems like some drivers have more benefit from current drive than others.
Yes, and I forgot a pretty important fact: I used two of them nude in a dipole configuration where one of the drivers was inverted, thus lowering 2nd order distortion although 3rd should be a bit higher.
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I got a bug with a pair of Speaker equipped with FA253 and the Global (Pre) EQ. Everytime I boost/cut in the Low Frequencies and load this setting to the DSP, the Woofer gets a DC Offset. Then the membrane turns outward/inward and stays there for a while and then begin to oscillate. The lower the frequency the stronger the Offset. It doesn't change by playing music.
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An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
try to open them in a new tabbtw is there a easier way to upload a picture here? maybe without link?
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