Recent content by Rob Watts

My research into transient timing whilst developing Quartet M scaler, demonstrated the huge importance of transient timing; indeed, the tiniest error has perceivable consequences. Fortunately, research into the brain's timing accuracy at the cellular level has shown that as we get older, the...

Oops, corrected my spelling. I suspect a Freudian slip here, as I have been suffering badly with a chest infection, and the subsequently the tiniest of tinnitus! My doctor gave me antibiotics yesterday, and am feeling a great deal better today. I had known about the quote "music is the silence...

Debussy's once said ”Music is the space between the notes“ and in my view there is some truth in the quote; it certainly highlights the fact that transients are essential, for without transients there would be no spaces between the notes. But the timing of transients is absolutely vital from...

Yes that will work (or use a splitter). The benefit of a splitter is both sets of cables are screened. I do watch this thread but you are much more likely to get me to post if @Rob Watts is used, as most of the time people post great replies - before I have had a chance to read the original!

Absolutely no change at all, nor to the FPGA code. The last change was in 2020, with a minor component package update on one part, so there have been no significant changes since production started.

TT2 doesn't run twice as fast as Dave, that's not how pulse array works. In fact, the full explanation of how pulse array works is considerably more complex - the devil's in the details - and unfortunately those details are propriety. And if I was inclined to fully disclose it, the vast majority...

Rather than talking about reversibility, it's more accurate to talk about the requirements to have full sinc function coefficients, as that's the important issue. The issue is sinc reconstruction, not whether it's symmetric FIR or not. It's only full sinc that will perfectly reconstruct. You...

Just to re-cap there are broadly two forms of filters - causal filters (where the output depends solely on the current and past values) and symmetric acausal filters (where the output depends upon future and past values, and when the coefficients for samples offset into the past or the future...

Hmm - so a symmetric FIR filter (like the WTA filter) is time invariant, that is the impulse response is identical for when time is running forwards or backwards. But there are some filters, such as all the analogue ones and some digital ones (EQ and HF filters) which give different outputs...

Just to clarify, the HF filters implemented before Mojo 2 was a 2nd order simple filter - equivalent to two RC type filters - and so it had a significant drop at 20kHz of around -0.9dB. Measurement people could complain about that drop, so I made it switchable. With Mojo 2's UHD DSP I can have...

No, the FPGA to element flip-flop path is irrelevant - so long as there are no setup and hold violations - as the OP from the flip flop is re-timed by the master clock (the 104MHz), so any delays on the input to the flip-flop has zero effect on the output.

That sounds fine, as it's lowest impedance is the same as my 803D3.

It was designed for the B&W 803 D3, which has the lowest impedance of 3 ohms. So it will be fine so long as it doesn't fall below 4 ohms nominal and 3 ohms minimum.

You will need to reduce it by some dB's - I would suggest +7dB as the limit with Hugo M scaler.

At the moment the intent is to get the pulse array ADC working - and I am getting much closer to that prospect, with assembled boards arriving in the next few months. The earlier unit worked perfectly up to -20dB, and the next board should fix this final issue. Then we need to turn that into a...