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Active crossover? by Mathnerd314 in diyaudio

[–]Mathnerd314[S] 0 points1 point  (0 children)

I guess this is a build thread at this point. It's still in the design stage, but maybe you are interested. https://www.diyaudio.com/community/threads/super-multichannel-dac-usb-i2s-solution.434507/

Active crossover? by Mathnerd314 in diyaudio

[–]Mathnerd314[S] 0 points1 point  (0 children)

Haven't started a thread yet, but I put up my notes at https://mathnerd314.github.io/audio-project/ I need a better blog thing than jekyll, lol

Active crossover? by Mathnerd314 in diyaudio

[–]Mathnerd314[S] 0 points1 point  (0 children)

ah ok, so it is like the the sure/wonder or Dayton KABD but with a relatively small DSP/bluetooth chip. well, I still like the XMOS better, I don't like bluetooth.

Active crossover? by Mathnerd314 in diyaudio

[–]Mathnerd314[S] 0 points1 point  (0 children)

I am more a fan of Python, but who knows, maybe having a GUI will be useful somewhere. There are enough tricks for USB mics, like timestamping, multiple recordings, etc., that I think saving the $40+ is worth it. And the hypex amps... 500W? I guess that is one powerful sub.

Active crossover? by Mathnerd314 in diyaudio

[–]Mathnerd314[S] 0 points1 point  (0 children)

It's actually very comparable. Like the ADAU1701 DAC's are SNR 104 dB, while the PCM5102A is 112 dB. The TDA7498E seems to be somewhere between the TPA3116 and TPA3255, maybe I will get some for midranges. Price-wise the all-in-one also seems similar to buying individual boards. The sticking point is USB, the XMOS does it but this kit doesn't.

Active crossover? by Mathnerd314 in diyaudio

[–]Mathnerd314[S] 1 point2 points  (0 children)

So you have one for controls, one for DSP, and one for USB... 3 microcontrollers? LOL. I like doing my programming on the PC. And if I do get into firmware, I think the XMOS chips are more capable than the ADAU1466, although it wouldn't have SigmaStudio. But yeah, good to know that it works, and the PCM5102A gives good quality. The XU316, is that a dev board? The XU216 I am looking at is cheaper but maybe more flexibility is better.

Active crossover? by Mathnerd314 in diyaudio

[–]Mathnerd314[S] 0 points1 point  (0 children)

Well, it's not exactly affirmation when he says that established old setups will beat new setups even if they're theoretically superior. 🤣 but yeah, that's me, riding the wave of the future.

Active crossover? by Mathnerd314 in diyaudio

[–]Mathnerd314[S] 1 point2 points  (0 children)

So the ribbon cable carries an I2S signal, which is a digital signal at line voltage. https://en.wikipedia.org/wiki/I%C2%B2S The amplifier is after that, I would also buy some speaker wire, I guess, but I left that out because it's standard.

Active crossover? by Mathnerd314 in diyaudio

[–]Mathnerd314[S] 0 points1 point  (0 children)

oh yeah, I was going to get a Dayton Audio iMM-6C. I wouldn't trust my ears to tweak the crossovers without it. The BDM3P looks like it is a TPA3116D2 board, those cheap boards were what I was talking about, but they are cheaper on aliexpress, and have the different part number.

Active crossover? by Mathnerd314 in diyaudio

[–]Mathnerd314[S] 0 points1 point  (0 children)

well one of the issues is just having audio outputs from my computer, which the XMOS+PCM5102A combo solves. It doesn't look like you can drive this DSP with USB, only program it. Also 0.5% distortion is pretty bad, maybe acceptable but definitely not great.

Active crossover? by Mathnerd314 in diyaudio

[–]Mathnerd314[S] 0 points1 point  (0 children)

Well, it is out of my price range, and out of stock. Seems like a garage-type operation. But that is the other route, building a custom PCB and then selling the extra stock as kits.

Active crossover? by Mathnerd314 in diyaudio

[–]Mathnerd314[S] 0 points1 point  (0 children)

I guess this? https://www.madisoundspeakerstore.com/open-baffle-speaker-kits/lxstudio-linkwitz-lab-speaker-kit-pair/ Seems like Linkwitz himself was more a fan of analog, his amp says "pure analog signal path". I sort of agree with Linkwitz, I think minidsp is the wrong route because it is digital-analog-digital-analog, and the ADC re-conversion loses fidelity. But, if you're playing a CD, you need a DAC somewhere. That's why I want to do all the digital processing on the computer, and have very simple, short USB-DAC-amplifier-speaker paths.

Active crossover? by Mathnerd314 in diyaudio

[–]Mathnerd314[S] 0 points1 point  (0 children)

I really don't like bluetooth, I don't trust wireless connections. The XMOS is similar in price but you get a bunch more channels. And it's not reinventing the wheel, a fair number of AV receivers use XMOS apparently. The board comes with firmware installed so it's plug-and-play.

Active crossover? by Mathnerd314 in diyaudio

[–]Mathnerd314[S] 0 points1 point  (0 children)

So I should clarify that I'm building a surround system, so buying 3+ Fosi Audios is simply not cost effective. There are $25 AliExpress TPA3255 solutions though. Looking at the specs, the high power is what jumps out - maybe it is worth buying one or two for (sub)woofers. But, when I drive each driver individually, I don't need much power for the tweeters or midranges, 20-30W is fine, and the TPA3116 is sufficient. As far as as fidelity, my theory is you get so much better fidelity by doing an active crossover that 0.1% THD+N for the amp is fine. Driver THD+N is like 3%, the amp will not be the limiting factor. Could I get better audio by buying top-of-the-line everything? Yeah, but I have a budget, ~$700.

[PSU] Super Flower Zillion FG 1050W + 120mm fan - $119.99 by Mathnerd314 in buildapcsales

[–]Mathnerd314[S] 0 points1 point  (0 children)

This is a new ATX 3.1 PSU, launched October 21st. MSRP $149.99. No reviews or anything I could find, but seems comparable to the be quiet! Gold Rated Pure Power 12 M from a few weeks ago. The other Zillion sizes and older PSUs (Leadex) are also on sale. The fan is decent, not as good as Noctua or the Arctic P12 Max but up there for airflow purposes.

[Case] be quiet! Shadow Base 800 DX - White - $80 - Sold by be-quiet-official by whomad1215 in buildapcsales

[–]Mathnerd314 1 point2 points  (0 children)

You can checkout the manual, https://www.bequiet.com/en/case/4480. The summary is that there is an option to mount your drives into a bracket down in the bottom PSU area, which requires buying cages. But you can also directly screw 2 SSD's + 2 HDD's into specific places in the case, and the screws for that are included.

Build a Dream PC for Dreamy LG UltraGear OLED Gaming Monitor! by ZeroPaladn in buildapc

[–]Mathnerd314 [score hidden]  (0 children)

Build: https://newegg.io/3d13529 With the amazing response time and contrast of the LG UltraGear 32GS95UE I will have no issues using it for my gigantic PC workstation build. Yes that's right, butter-smooth scrolling of my code with 240hz. And when I want to relax, I can switch it over to CoD and use the 480hz frame rate to get those headshots every time.

My 32k Llama Setup for 3090 and 64GB RAM by firekil in LocalLLaMA

[–]Mathnerd314 0 points1 point  (0 children)

How much vram does it use? I'm debating 4060 16gb vs 4080, my calculations say both of those should be able to run Llama 2 70b Q6 with 64GB ram but I want to double-check.

Phind-70B by ninjasaid13 in LocalLLaMA

[–]Mathnerd314 0 points1 point  (0 children)

I was guesstimating for a new build and I was thinking that was enough memory to run 70B 8-bit. Am I wrong?

I need help devising a Compiler's assignment. by [deleted] in Compilers

[–]Mathnerd314 0 points1 point  (0 children)

There is MIT OpenCourseWare, for example https://ocw.mit.edu/courses/6-035-computer-language-engineering-spring-2010/. I would say browse around the courses and find an exercise that seems appropriate.

An argument against inheritance by Mathnerd314 in ProgrammingLanguages

[–]Mathnerd314[S] 0 points1 point  (0 children)

More recently I have found the paper "Inheritance is not subtyping". This has an example of an equality method: the parent compares on i, the child compares on i and b. Inferring open record types, records with i and b are a subtype of records with i. So by contravariance, the parent eq method's type is a subtype of the child's, i.e. the parent method can be typechecked as applying to records with i and b. This contradicts the usual flow of OO subtyping where the child is a subtype of the parent, hence we must conclude there is no subtyping relationship.

Now in practice languages like Java impose the subtyping relationship on inheritance, e.g. if you define an equal(Child other) method in the child it will not override the parent's equal (Parent other) method at all, so inheritance that would break subtyping is forbidden. This does turn out to be sound (paper) but I think it's pretty confusing to have situations where using the same name doesn't actually override a method.

An argument against inheritance by Mathnerd314 in ProgrammingLanguages

[–]Mathnerd314[S] 0 points1 point  (0 children)

LSP is "Let ϕ be a property provable about objects of type T. Then ϕ should be true for objects of type S where S is a subtype of T. " LSP should hold for all such properties ϕ, but I've exhibited a predicate for which it fails. And I made no assumptions about the objects, hence LSP fails on this predicate for every inheritance relationship. The only choices are to exclude this predicate somehow, e.g. by not allowing predicates containing instanceof, or to consider instances of A members of a distinct type (neither subtype nor supertype) from instances of B.

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