I so far haven't experienced these drop outs on anything but pure tone sines, which makes me wonder if it is some kind of protect/instability detect mode that (incorrectly) kicks in.
Sure we can work around it - but i'd rather the rootcause is eliminated in the modules
It does not impact the DSP filter. The voltage gain is up +6dB.
What that actually corresponds to in SPL on a given module in the actual impedance I would measure
The filter stay the same, I know.
Do I understand it correctly though, that due to voltage gain of +6dB when I run CH1+CH2 in BTL-mode, the filter function that was used with CH1 is still the same, but SPL for combined CH1+CH2 is higher than with CH1 due to the voltage gain of BTL?
I don't own a plate amp yet, I can only assume. BTL doubles the load voltage swing vs single ended so theoretically the power is x4 not x2. If Hypex employs the same (single) LF filter for a BTL config, no attenuation along the predrive, then you'll see a quadruple of power which translates to +6dB SPL.
In any case, highly advised to test your LF with a calibrated mic at 1m and verify the assumptions pre/post BTL. I'm guessing that a BTL config might add some distortion and artifacts.
Thank you for the mathematical explanation. I have found in my measurements that the woofer channels in BTL mode had an elevated output of about 6 dB. This supports your calculation.
Somehow, the crossover is not summing up as smooth as before, it shows a small dip now. I wonder if what could influence this.
Somehow, the crossover is not summing up as smooth as before, it shows a small dip now. I wonder if what could influence this.
Hmm, if you see a dip then maybe tweak phase alignment? If you have a 2-ch scope you'd want to check both amp outputs at the crossover frequency with a sine wave, before and after BTL with 6dB att. Look for amplitude and phase of each HP and LP channels. Good luck
This is only possible with digital S/PDIF. For RCA, you must input to both of the separate plate amps.
It will work, but with the Fusion amps it is worth to go all the way with jitter reduction measures IMHO. I am currently experimenting with a JCAT USB -> JCAT USB isolator (optionally, can be left out) -> JL sounds I2S over USB vIII (SP/DIF) output solution with UltraBib v1.3 supply which gives good results...
I guess Jitter is an issue with practically every DAC, except for perhaps a few very high end ones with more extreme counter measures. Having galvanic isolation and local reclocking does not do enough by far at least. But (assumably) given the asychronous resampling in Fusion amp it is at least very audible there. I hoped it would have been different, but it is like it is...
Have you actually measured the jitter of the Fusion? What level of jitter do you think is audible?
The asynchronous sample rate conversion (common in many modern DACs) and reclocking does actually reduce source- and cable-related jitter to the extent that it is mostly non-issue.
No, I have no means to measure this regrettably. I heard you need to go very low in jitter level to not affect audio quality (somewhere between fs and ps level). What exactly causes the audibility of jitter I do not know, but I presume it should not only be taken from a THD perspective. Though I also understand recordings may also have a high instrinsic jitter.
From my ("non scientific") experiments at home, at least changes in the digital chain are easily and clearly audible. This includes OS reconfigurations, reduction of active processes/applications/services and the choice in audio players on PC side. Apart from effects on jitter, it will also affect noise levels.
From my ("non scientific") experiments at home, at least changes in the digital chain are easily and clearly audible. This includes OS reconfigurations, reduction of active processes/applications/services and the choice in audio players on PC side. Apart from effects on jitter, it will also affect noise levels.
I am curious what your source for that is. It contradicts all I have read and experienced.
Have you verified that objectively, or is it subjective perception?
Don't remember where. At least something is mentioned here:
https://www.thewelltemperedcomputer.com/KB/BitPerfectJitter.htm
There are references to 10-20ns from scientific studies and 50-200ps from John Swenson.
I have only verified it subjectively.
https://www.thewelltemperedcomputer.com/KB/BitPerfectJitter.htm
There are references to 10-20ns from scientific studies and 50-200ps from John Swenson.
I have only verified it subjectively.
Yes. It also references this study:
OK, so it might or might not have been actual. Anyway, as I wrote, the asynchronous sample rate conversion (common in many modern DACs) and reclocking does actually reduce source- and cable-related jitter to the extent that it is mostly non-issue, so I don't understand your statement that "(assumably) given the asychronous resampling in Fusion amp it is at least very audible there".