[sdiy] Low voltage synthesis?

Mike Bryant mbryant at futurehorizons.com
Fri Jan 14 12:37:52 CET 2022


Yeah :-)

Not really sure what people have against digital nowadays as you can model any sound you want accurately in digital.  If you want a particular distortion, just model it.   Far easier than playing with random biases on obsolete transistors trying to get a particular nuance to the sound.

Cost is usually always lower as well.  Somebody showed a design with the STM32H750 the other day which I often use, and if you need about ten times that processing power the Pi CM4 range (when available) gives you almost 10 billion 64 bit instructions/second.

I guess it’s just the maths that scares people off.



From: Tom Wiltshire [mailto:tom at electricdruid.net]
Sent: 14 January 2022 11:28
To: Mike Bryant
Cc: cheater cheater; cheater cheater via Synth-diy
Subject: Re: [sdiy] Low voltage synthesis?

Fantastic! Even less chance of any noise!

So Cheater is looking for ways to do low voltage audio with low noise and distortion, and all the examples we're finding are...digital!?! It's not really a surprise, is it?


On 14 Jan 2022, at 11:19, Mike Bryant <mbryant at futurehorizons.com<mailto:mbryant at futurehorizons.com>> wrote:

Cut out the middle bit :-)

BD28623MUV<https://www.rohm.com/products/audio-video/audio-amplifiers/speaker-amplifiers/bd28623muv-product>

These modulate the PDM directly from the I2S input, so there’s no analogue on-chip at all.

TI, ST, NXP and Infineon have similar parts for different power levels.


From: Tom Wiltshire [mailto:tom at electricdruid.net]
Sent: 14 January 2022 10:27
To: cheater cheater; cheater cheater via Synth-diy
Cc: Mike Bryant
Subject: Re: [sdiy] Low voltage synthesis?

I'd guess:

DAC -> Class D amp -> Outside world.

Not a lot of scope for noise in that very short signal chain.




On 13 Jan 2022, at 23:45, cheater cheater via Synth-diy <synth-diy at synth-diy.org<mailto:synth-diy at synth-diy.org>> wrote:

I wonder what's being used in places like
mobile phones or wireless earbuds for example, they can't be running
+/-5V op amps or LV op amps with major crossover distortion.

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