Thanks. I was reffering to this, but I incorrectly assumed it applied to NcoreThe Ncore design is fundamentally a self oscillating PWM amplifer, which makes it intrinsically difficult to see how it could work with a fixed period sampled digital input. Not impossible, you can, in principle, shift any part of the topology into the digital domain, but within the bandwidths and computation limits, pretty difficult. I'm not sure how they might use an ADC in the comparator except that in some sense a comparator is a 1 bit ADC, although the comparator in the Ncore amplifier is a zero crossing detector, which is not quite the same thing as a simple level comparator. There are other places in the amplifier where some digital control is useful, most certainly in the protection circuitry, and maybe control of the forward filter could be effected, which would be central to the Ncore design.
The basic Ncore patent is well written and worth a read.
Combined DAC/PWM devices certainly exist. Of note for ASR denizens is the beloved JBL LSR 30x family, that uses the STA 305B for the entire digital chain, from digital in, DSP, and power amp. Not exactly a high end chip, but the end result in the loudspeaker does not seem to generate complaints about fidelity. There is no definable DAC in this chip that is separate to the power amplifier, and one might indeed characterise it as a power DAC. But an Ncore it certainly isn't.
The Ncore plate amplifiers are available with DSP, they include a conventional DAC feeding an analog signal to the amplifiers.
Oooh. That one is way cool. I had not seen that paper before. That actually is effectively a digital input Ncore in many ways. But very clever. I wonder why we haven't seen it as a product. Maybe it isn't cost effective.Thanks. I was reffering to this, but I incorrectly assumed it applied to Ncore
https://www.researchgate.net/public..._PWM_Switching_Amplifier_with_Global_Feedback
Plus, you all have the broadest distribution of poisonous species in the world. Up here, pretty much nothing that will actually kill you (without good reason, at any rate).So you've got moles, deer and groundhogs. We've got possums, wallabies, bandicoots and cockatoos. We've just given up trying to grow anything. Even herbs. You go out one day and you have a nice big basil plant. Next morning, nothing but dirt in the pot. And that was 30ft above the forest floor on our back deck.
The main differences between the four XLS models. As features are added they move up to the next model. And of course power ramps up.Are you saying there's a difference between the 1002 and 1502 other than the power output level? Cost-wise is $60-$100 upgrade.
I’ve been using the xls1502 to power a JBL B460 sub (2245 driver). My only comment is some hiss. I sit fairly close to it and the driver sensitivity I believe is 90 both which makes things a little worse. I will probably replace it and see if I can eliminate it at some point.seems a fine amp for subwoofers, you get plenty of power and between -110db and -120db up until 90 hz
I’ve been using the xls1502 to power a JBL B460 sub (2245 driver). My only comment is some hiss. I sit fairly close to it and the driver sensitivity I believe is 90 both which makes things a little worse. I will probably replace it and see if I can eliminate it at some point.
Using balanced out of a Minidsp SHD. Low pass filter did help for sure reduce some of the noise. I’ll have to check to see what happens when I remove the connection. It is capable of some tremendous output though and isn’t an issue too often, but on quite passages of music it is audible.What type of connection are you using?
If you remove it, does the hiss stop? Mine does this with an rca connection but when removed its silent. I also found that if I set a low pass filter on the crown amp, the hiss is greatly reduced, even if I set the low pass to its max 3000hz (iirc that is the max)
I ordered some better rca cables that are grounded only at one end to shield. (Worlds best cables on amazon)
I noticed this distortion chart is at 45kHz bandwidth. What is the purpose of using this bandwidth? If I implement the low pass DSP at 20kHz will that simplify the amplifier’s job and reduce the distortion?
What do you mean setting the low pass at 3000 Hz, a low pass with a 3000 Hz bandwidth would remove all the highs. You meant 300 kHz maybe?What type of connection are you using?
If you remove it, does the hiss stop? Mine does this with an rca connection but when removed its silent. I also found that if I set a low pass filter on the crown amp, the hiss is greatly reduced, even if I set the low pass to its max 3000hz (iirc that is the max)
I ordered some better rca cables that are grounded only at one end to shield. (Worlds best cables on amazon)
Horrible amplifier. And, as usual, the recommended one.
Conclusions
Competent pro amplifiers target for good enough noise and distortion. The Crown XLS 1002 falls in that category so if you were expecting to have anything better for so little money and so much power, you would be disappointed. But otherwise the amp does what it targets to do.
I am going to put the Crown XLS1002 on my recommended list for non-critical applications or for driving subwoofers and such.
What’s the purpose of measuring anything above 20kHz? (Assuming it’s not a broken AM transmitter, of course), especially in combination with the audible frequency range and metrics?That won't help. The frequency response is already limited to 20KHz by the ADC. The higher distortion at higher frequencies is because the 45KHz bandwidth of the test includes ultrasonic harmonics.
What is horrible about it? Apparently it is audibly transparent.Horrible amplifier. And, as usual, the recommended one.
He is using it on a subwoofer (as am I). So you don’t want highs in that. My point was that setting a low pass (no matter it’s value, but not too low that it interferes with other crossover settings and create phase issues) helps with the noise.What do you mean setting the low pass at 3000 Hz, a low pass with a 3000 Hz bandwidth would remove all the highs. You meant 300 kHz maybe?