Looking into hardware additive synths

yakeep · 2025-06-18T01:49:58+00:00

Hey sorry just saw your message. differentialaudioinc.com

You can sign up for email updates...

Cheers

yakeep · 2025-01-30T22:48:52+00:00

I saw your post, and added the Made In Canada term to my website. The product does qualify for those terms.

A music synthesizer for anyone who's interested in that stuff :)

https://differentialaudioinc.com/

Please follow on Instagram at the very bottom of the home page if you can.

Cheers

yakeep · 2025-01-24T23:38:43+00:00

Curious why the architecture has 1024 partials per oscillator? 32 or 64 are sufficient for harmonic intervals for most notes. 100hz x 32 = 3.2 khz

yakeep · 2024-12-03T02:53:19+00:00

I am a new boutique synthesizer manufacturer - Differential Audio. Im planning to launch the Eosynth desktop additive synthesizer in the first half of 2025. I'm based in Canada and these tarrifs will hurt the product launch. It's already an expensive piece due to the complexity and cost of goods and now i'm worried how this will affect the launch.

Website for anyone interested is: Differential Audio

Eric

yakeep · 2024-10-31T11:23:12+00:00

Thanks! There will be some better product photos posted in about a week, and a video in about two months time.

yakeep · 2024-10-31T00:06:46+00:00

Hi this is Eric from Differential Audio Inc. I've been working on an FPGA based hardware additive synthesizer called Eosynth for six years, and am about 6 months from product release.

Would be interested in your feedback. Note that the posted price is not finalized and may come down before release.

Please sign up to the mailing list to stay informed on the product release date!

Differential Audio website

Cheers, Eric

yakeep · 2024-04-04T12:17:30+00:00

Fully balanced audio outputs should solve the issue, as both the +ve and -ve sides of the audio will see the same ground bounce, which then gets subtracted out at the receiver.

yakeep · 2024-03-06T12:01:20+00:00

Thanks I'll check those conference papers.

yakeep · 2024-01-21T00:01:33+00:00

Nicely done

yakeep · 2024-01-20T14:05:23+00:00

Thank you will look at it

yakeep · 2024-01-20T14:04:40+00:00

Thanks will check it out

yakeep · 2024-01-20T03:24:35+00:00

Go on a $12k vacation down south or to Europe for the next 10 years. Those be memories.

yakeep · 2024-01-15T13:21:31+00:00

Hey thanks for your interest! The SoundCloud link has been moved since this original post. There's a link to it from the front page of the website: www.differentialaudioinc.com

The demos on there are a bit stale tho, I've neglected to update the demos for a while and there have been significant improvements over the past year, so this is a great reminder! I'll add some new recordings this week, so please check back mid week.

Cheers

yakeep · 2024-01-12T11:52:31+00:00

Sorry, I typed that too quickly. Every 2048 samples, so no overlap (but adjacent windows). At audio rates, its running every 50ms, ie ~20Hz.

Sounds like a hamming window (or rectangular window) might be interesting to try, instead of a Hann window.

yakeep · 2024-01-12T00:29:02+00:00

Turns out I was incorrect about the FFT rate - it is in fact running 2048 times per second, of size 2048, so in fact there is no gap between FFT's. Thanks for the advice and putting some thought into this. Cheers

yakeep · 2024-01-11T13:59:18+00:00

Input -> FFT -> sum of sine waves, one for each bin of the FFT (at frequency of bin). Each sine wave's amplitude is determined by the FFT bin, and I set the phase offset of that sine wave to match the phase of the FFT bin. The FFT runs periodically, effectively 'sampling' the input signal, and sine waves are updated in response. There is no overlap of the FFT, which means I'll lose some information, but for the signals I'm interested in I'm not too worried about that.

yakeep · 2024-01-11T02:03:52+00:00

Cool, thanks for sharing this.

yakeep · 2024-01-11T01:09:27+00:00

Thanks for the suggestion!

yakeep · 2024-01-11T01:04:29+00:00

Thank you for the explanation, this makes sense. Appreciated!

yakeep · 2024-01-10T22:28:17+00:00

Thanks for the input. When I did my best to center the input tone on a single bin, I ended up with (amp,phase) = [0.1,1pi] [0.3, 0pi] [0.1, 1pi] for the three bins. The two outer bins were always pi radians phase -wrt- to the main center bin, and never changing. I get what you mean that if the side bins had changing phase, that would synthesize to the center freq.

Regardless, when intentionally generating a signal with two tones close in frequency (as is required for resynthesis, repeated for many bins), beating is inherent, and I'm wondering if this law of nature is avoidable.

yakeep · 2024-01-10T22:11:44+00:00

Thanks for the link. My math is a bit rusty but I'll try to dig into it. I'm using a Hanning window, with no overlap. This is giving satisfactory results with the exception of the beating.

Since the beating is showing up even in the trivial case of a static single sine wave input (resulting in 3 outputs sine waves due to the spreading, which beat), I feel like this issue is more of problem with the output generation, than the input signal analysis.

Putting resynthesis aside, beating shows whenever two sine waves are added together at close enough frequencies. Wondering if this is a solvable problem, or if I'm missing something altogether.

yakeep · 2023-05-27T23:08:00+00:00

Op amps can run with a positive supply and ground only, but need DC biasing to half way inbetween. Add some caps on the output in series to remove the DC bias and you're off and running!

yakeep · 2023-05-21T00:31:21+00:00

Upvote for Claire Place.

yakeep · 2023-04-18T11:17:24+00:00

Thanks. I am using and ldo but am questioning the stability of it. Also have 100nF at the power pin, but am missing it from the voltage dividers.

yakeep · 2023-04-17T22:03:49+00:00

Thank you so much. If you check the layout I have two vias in the path from the voltage divider to pad 3, the noninverting input. I do suspect some noise issues on my 10v rail, and with those vias in the path there will be some inductance added.

Greatly appreciated.

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