Recent content by p-we

ddude003, thanks for responding. When looking at various Class D reviews, including Hypex, while not perfectly linear above 20kHz, do not replicate this kind of huge resonance with a big peak. Looking at the curves I made with Liberty Instruments Praxis using their proprietary audio interface...

This was supposed to be about the comparisons of amplifier FR under different Z loads, but now also includes understanding how to get the probes done right in REW. Regarding the variability of amplifier FR, I think there is merit in doing real time calibrations even if the effect size is small...

Did some searching online. Found systems using much lower shunt resistance +/- 1kohm and the 1:10 ratio. Have now tried with 9kOhm series with 1k shunt. Distortion measurements now look to be based on true amp spec's, previously quite high. This is the TDA7498 connected to a real speaker

Investigating the HF attenuation issue, I opened up the Liberty Instruments 'Audpod' hardware interface to find both external probe inputs are indeed shunted by a 4.7k resistor immediately at the junction as you said it would have to be. Since they recommend 47 to 50k series resistors, a +/-...

The measurements were done using the 50kohm balanced probe to the speaker outputs as discussed above with a soundcard cal file and without a loopback. Also 8.2 ohm is a mistake, It was a 3.3 ohm resistor, so overall closer in nominal impedance to the real speaker

I've compared the output of two Class D amps: Hypex UcD180HG vs.TDA7489E. Each graph has 2 plots with 8.2 ohm resistive load and a 4 ohm bass reflex speaker. The measurements a were done with a +/- 5 watt stimulus. There is a difference but indeed, not huge. What I don't understand is what is...

John, I've been thinking about your response and how back EMF figures into it. I think back EMF phenomena, which is Z load dependent, is always present to some degree and the main reason why amplifier outputs as a general rule do not have consistent linearity in the audible FR range. I'm...

John, I find it to be special when the developer is the first to reply. REW is amazing and quite the achievement. My gratitude to you for making it easily accessible. I'm trying to see if I can migrate to REW. Probing the speaker output is quite common, probably ubiquitous, in dedicated speaker...

Hello REW community, I have been a faithful customer of Biil Wazlo's Liberty instruments products through the years but Praxis is 32 bit, getting fussy with new hardware and constant changes in the Windows environments. So trying REW and it looks cool. I have also searched this topic and...