I disagree with your disagreement. Dither was only one overlooked problem. At the time, people were adamant that CD sounded (had to) better than LP simply because it was newer technology and the manufacturers told them it sounded better and came up with feasible but naive technical justifications. This is the problem I am highlighting: it's a sort of bigoted hubris, to put it too strongly perhaps.
Very self-aggrandizing but I reckon you lot just couldn't get a regular job.
What else is new they had something to sell, folks are prostituting their engineering knowledge to push MQA right now.
I meant demonstrate that Shannon's information theory and the seminal texts on digital signal processing (such as Oppenheim) were inadequate for describing digital audio.
As isolation between channels is easy to measure did you measure before and after? That would be useful information, otherwise it's another case of glom for victory.
I have no doubt that many DIY projects suffer from this as circuits with near zero PSRR are often praised for their wonderful sound in some corners so an amplifier project inevitably becomes a power supply project.
The irony of course is that headphones suffer due to isolation and so many people add a cross feed circuit in as they are annoyed by the 'three blobs' imaging thus reducing channel seperation.
Replace specialised with 'generic' and I might agree with that statement.
I think you glossed over an important word.... the entire system.
And, many here love their TT and phono carts.
Even analog tape machines.
These do not all have -100+ dB isolation or cross-talk between channels to 20KHz.
Nice if they did.
Not even considering far field listening and what that does to isolation and separation between channels.
THx-RNMarsh
Last edited:
Preamps can have out-of-phase crosstalk, which some might hear as an improvement.
Dual triodes shared between channels, or pickup from large coupling capacitors, can cause this.
Counterpoint used grounded shields over coupling capacitors in some models to reduce this effect.
Last edited:
I did not. However, I hope to have a good set of measurements available soon for the current state of the project. Depending on the results I may find there is more to do.
While it would be great to document measurements after each change, it would be hard to do here for various reasons. I have limited bench space for one thing. I have to rearrange the work space for hardware construction, software development, measurements, etc. In addition, I have very limited test equipment for doing high-end audio stuff where small differences can matter. Just figuring out methods to build small circuits, hold down SMD devices, use hot air at times, troubleshoot, listen, sleep, eat, work on DACs, debug Arduino/Windows interactions, etc., ends up being a lot more demanding that I imagined when I started on this journey. I still don't even have a good enough 1kHz notch filter here, but the parts to make one are around here in one of these boxes.
In the end, all you get is what I have. Right now what I have is what I have been describing. Again, measurements are coming soon, I hope.
EDIT: At least there is a DAC-3 and an AHB2 to keep me grounded in what good means. You may recall the reason the old Bryston 4B had to go was because the DAC/HPA project was beginning to sound better than the reference system. AHB2 sure fixed that though.
Last edited:
I asked what was missing that would say the original concept could not work. Nothing in theory says that I can't make an analog anti-aliasing 20kHz brickwall filter -120dB at 22.1kHz the same goes for an anti-imaging filter. The sinc amplitude correction for first order sampling was well known. No up sampling no digital filters at all involved. BTW Apogee was founded making just such filters out of lots of 5532's.
I'm not sure what you mean most applications literature still states the standard approximation as if it was exact (with frequency warping exact at fs/2). If you restrict yourself to matching a single z to s pole it can't be exact except at one frequency, but a standard bi-quad filter has some free parameters you can fiddle with to make a better fit. AFAIK this remains a fairly obscure topic not really text book stuff and not relevant to the original issue.
Shame. You've missed a chance to really learn something about both cross talk and PSRR there which may have helped others, or at least moved the discussion here beyond woo and foo.
I understand that, which is why Engineers need labs, to get all the stuff in. What I would give* to still have a large garage with a 6 ft workbench in (ex-production including the hangers for the calibrated electric screwdrivers). Which is why I have huge admiration for those who find time to do all the measurements who are not doing them as homers at work. I still have great admiration for those who do it at work just to help us out mind
.You have a DAC and ADC, that is more than good enough to pump a frequency sweep at FS into one channel and measure what comes out the other. You don't even need to set anything up as you have your DAW all ready.
*Still being married to the ex is not a price I would have paid to keep the workspace tho
.Haha, you missed my rant, probably because it wasn't clearly stated. My rant was towards, "I heard cross talk is important for differentiating systems", but no sort of refining what you meant by that. Did you mean it starts being important to have whole system channel isolation of 60 dB, 100 dB? At what frequencies? That's also why I mention 0 dB means you're running mono, which obviously sounds different to stereo!
Last edited:
- Status
- Not open for further replies.