Recent content by Shadders

Hi, I did a quick check on the LM3886, and it has an open loop gain of 115dB (typical). For the low gain mode of 9.5dB for the peak output, then that infers 105.5dB of feedback. That is quite a lot of feedback. Regards, Shadders.

Hi, CD is restricted to 22kHz based on the limitations of CD using a sampling frequency of 44.1kHz. The measuring equipment such as Audio Precision will still use 80kHz measurement bandwidth. Regards, Shadders.

Hi, Agree on the consistency approach. The problem is that only Hifi News uses a measuring bandwidth of 80kHz for both class AB and class D, since they do not use Audio Precision. As such, using 45kHz for the measurement bandwidth by this site, somewhat addresses the inconsistency, and hence...

Hi, Here is a link to the Philips UcD amplifier from a third party document : http://www.handsontec.com/pdf_files/UM10155_2_Discrete_ClassD_Amp.pdf The patent referenced in section 7.3 is by Bruno Putzey. Isn't what you describe already implemented by Hypex/Purifi, the high level of feedback to...

Hi, Here is a link to Hifi News Nad M23 power amplifier that uses the Purifi module implemented in their own Nad design. https://www.hifinews.com/content/nad-m23-class-d-power-amp-lab-report Hifi News use their own proprietary equipment which uses a measurement bandwidth of 80kHz, since the...

Hi, The distortion above 20kHz is not heard, so the degradation of THD+N is not an issue. The test here for the 1kHz i believe used the 22kHz filter, and the result probably reflects the datasheet values. Regards, Shadders.

Hi, Thanks - i was unsure what number of harmonics were used to produce THD. 10 seems OK for 2kHz, but for 1kHz and an amplifier that has high order harmonic distortion, which may be heard from 10kHz to 20kHz, then maybe more is a benefit ? The blog from AP indicates that THD+N may measure all...

Hi, Probably it is a remnant from how it has always been done, given the capability of the equipment, but then measuring the extra 180kHz has no real benefit apart from presenting those amplifiers that excel at linearity. Regards, Shadders.

Hi, I think you have copied the wrong graph - you have pasted the AHB2 by mistake ? Yes, the extra 23kHz (from 22kHz to 45kHz) can add the extra noise which is summed by the AP equipment. Regards, Shadders.

Hi, It depends on who is doing the testing. In general, the class D amplifier testing uses a 22kHz bandwidth due to the switching frequency causing issues with the Audio Precision measuring equipment ...

Hi, My interpretation is that the ballooning is based on the amplifier characteristics and that the measurement bandwidth is set to 45kHz, as opposed to the usual 22kHz, so more of the harmonics are captured. I am assuming that the other measurements were implemented using the 22kHz bandwidth...

Hi, No they don't. Cyrus class D amplifiers use linear power supplies. Regards, Shadders.

Hi, You missed the point completely. Class AB amplifiers consume more power at idle, and as per my example more than 2x. In fact the Nad seems to be consuming much more than expected for some reason for a class D amplifier. Given todays cost of energy, 61watts for a class AB stereo amplifier...

Hi, I read a review of the Nad C 298 class D amplifier and its idle power consumption is 25watts (https://www.hifinews.com/content/nad-c-298-class-d-power-amp-lab-report) Another report on a class AB amplifier Rotel RA6000 has an idle power consumption of 61watts...

Hi, We have seen this type of thing before with MQA. No evidence of there being a problem, and yet MQA was a solution to that problem (without evidence). Same for Chord aspects. Without evidence of transient or timing problems, then those without an inquiring mind could easily be fooled, and...