This blog may provide interest to some newbie looking for low cost, easy to build class d amp source tuned to their listening taste. I have already tried this circuit on the breadboard and it sounds surprisingly good but I’m sure it will work much better on PCB of course. The timer chip I used is the CMOS LMC555 because it’s a lot faster than bipolar counterpart such as 15 ns rise and fall times and can oscillate up to 3 MHz @ 5V. Of course you can use bipolar 555 timer as well.
About the circuit:
The circuit consist of 2 classical yet popular configurations; The master wired as “astable multibivrator” and the slave as “one shot” monostable.

https://geekcircuits.com/wp-content/u...ive-filter.png
Figure 1.
Slave A is an active band pass filter tuned to 20 Hz with +/-7 Hz bandwidth serving as “mega bass enhancer” while slave B is a simple high pass filter with -3db roll-off at 7 KHz for the treble. Slave C will fill-in...

https://www.diyaudio.com/forums/parts...-resistor.html

Motorola used one on their first cell phone.

Chauser eleptical low pass with nulls at 4.5k and 9k iirc.

Now I am wondering if I could create a "passive line level" with this, avoiding inductors.

Here is a link to a design article:
https://electronicdesign.com/article/...sband6366.aspx

Reflektor Notes: https://www.diyaudio.com/forums/power...ml#post2724088 post 4287

B1 with Shunt https://www.diyaudio.com/forums/pass-labs/145201-building-symmetrical-psu-b1-buffer-2.html#post1854512

https://www.diyaudio.com/forums/power...ml#post2223856

schematics #1983 https://www.diyaudio.com/forums/power...ml#post2103465

Transformer R-Core EBAyhttps://www.ebay.com/itm/110V-50W-R-c...item4ab0dbf733

V1.2R schematics

https://www.diyaudio.com/forums/power...lator-320.html

board design starts 2384

Sense wire: Use RG58 on all your shunts for...

https://www.diyaudio.com/forums/digit...ification.html

more on setting up sound card for measurementshttps://www.diyaudio.com/forums/solid...rements-9.html

Lets start by examining a few popular connectors available for the DIY enthusiast.

Here is one of Home Grown Audio's rhodium plated silver connectors. Very simple morphology. Some may find these "cheap" looking. Well...they are designed with simplicity in mind, and the cost is very reasonable. Acoustically, I really like the sound. High frequency extension is great, though with very resolving equipment, a tad to "bright". Still, a great buy. As far a durability goes, they are quite tough. But, with the stress testing that I do, after completing the cable, there is a tendency for the crimped-on negative portion to disassociate from the head. Keep in mind that I apply way more tension than would be encountered under normal operating circumstances. Overall, a very nice, inexpensive connector.

Next shown is the Audio Note RCA connector. This is a very well built RCA. Acoustically, a little more tamed in the upper frequencies compared to the HGA....

Here's a pic of the underside of the DAC before I started hacking tracks. Bottom left area is where the digital circuits are, with ground plane. Top left are the analogue output filters. Right is the caps, rectifiers and regs of the power supplies - digital at the bottom and analogue at the top.

The AD1955 sits about the centre of this pic, and if you look closely you'll notice two small holes I drilled in the groundplane either side of it where I will later install the 10uF decouplers.

The second pic shows the component side, prior to any hacks - the 'virgin board' if you like, although sullied by the two small holes near the DAC chip. The analog supply is pin15, that's at top left.

Third, here's the meat of the digital circuitry and I've already added one decoupler to the AVDD (analogue positive supply). To the right of the 24.576 XTAL (not required) is the DIR9001 SPDIF receiver. The DIL chip is a multiplexer allowing both USB and SPDIF input...

I didn't get it. There are gifted design engineers on this forum. They get involved in threads. BUT, in most cases, eventually an 'issue' develops and the engineering guy gets binned or banned or asks to be banned. Why why why? Happened to me a few times. Not that I got banned, thank Ohm, but I got close to leaving because I too got enough of it.
Of what?
Let me explain. Most engineering types like to explain things, to tell others with less experience and knowledge what they are doing wrong and how they can do it better. They inundate you with facts, figures, links to engineering papers etc, and expect that the other guy flows over with gratitude. But, funny enough, it doesn't happen that way. The 'other guy' gets pissed off from being corrected all the time. Hell, he didn't come here for that, he came to have fun, discuss his hobby and his latest creation.

[flashback] At the time Al Gore's An inconvenient Truth came out, the same director (!) also made Too...

So I am going to write some details down about the DCB1 Hynotize Hot-Rod buffer. The current production board is black, 2 oz copper and 2mm thickness. (See below) The below blue pictures are prototype boards and are not representative of the product.

Here are some of the specifics to help understand ordering parts for it etc. This is not a detailed build guide, but there is a link to one below from another forum member.




They can handle 10mm pitch snap-in capacitors 25mm width capacitors.



There are positions for smaller MUR120 type diodes OR MUR820 style TO-220 style diodes. Not both!

The vRef LEDS can now be bypassed with a 25mm Film cap or a 100uf electrolytic. The film cap by consensus is best at .22uf.

...

Hello,

Click here is my project blog. There is some information about my headphone amplifier products.

Thank you.

Doug Self's comprehensive work on power amplifiers has been an inspiration to me over a number of years. In it, he coined the notion of the 'blameless amp' as one which was beyond reproach, measurements-wise. So I pondered over running with the notion of 'blameless DAC' along the same lines. Initially this sounded attractive, even though not entirely original. Google found a reference to it already here on diyaudio but could not show me the actual posting.

I decided on reflection that the 'blameless DAC' would be not such a good idea. That's partly because for me, measurements are not the goal of audio design. Enjoyable sound is what does it for me, not vanishingly low THD figures. So a 'blameless DAC' could only be blameless if measurements are God, so to speak. For someone like me for whom auditory experience is all, I decided I'd need another term for my DAC project.

I've settled instead on the term 'highly evolved converter' or HEC for short. This recognises...