Introducing DSPi | A powerful, user friendly and open source DSP for less than a cup of coffee

[bogdansrb]

Exactly what I was beginning to mull. Which codec were you thinking of? I was pondering stereo DACs, either AK4493S, which is cheap and capable of very good performance, certainly better than most codecs I'm aware of, or ES9039QN, which is still reasonably priced, has I2S and SPDIF in and excellent performance, better even than the 8 channel 9039PRO, which has an issue with 10 kHz THD according to @IVX.

I've used the AD1938 in another project and it's quite nice. A bit pricy but 4AD and 8DA and it can operate in "hardware" mode (it doesn't need an MCU for programming).
Another option would be AK4619.

 

[giubeppe]

Thanks, I'll check that out. BTW, I don't know if it was a problem on my side or else, but I had issues with 96kHz 24bit and had to make some changes to make it work. Not sure that is related or not.

Reply to self, I was able to get 96/24 to work correctly for my i2s version. Binary are always at link

 

[BossBunos]

Very impressed with this project so far! I will definitely keep following this. Would be nice to see it evolve into some sort of DIY fusion amp/dsp solution in the end with 3 or 4 channels. Maybe combined with a wiim streaming chip

 

[Wesseling Audio Lab]

That solution is up to end user configuration decision
One of my plans is one chassis, DSPi , DACs, 4 channels class D, usb in, 2 spdif inputs with front panel input select and 4 gang analogue volume
LDAC streaming will be possible with PICO W

 

[Kingsnake]

That solution is up to end user configuration decision
One of my plans is one chassis, DSPi and 4 channels class D, usb in, 2 spdif inputs with front panel input select and 4 gang analogue volume
LDAC streaming will be possible with PICO W

My current plan is:
DSP > mid-range DAC > TPA3255 power amp.
I’m mainly considering the TPA3255 because I already have a spare Mean Well 48 V / 600 W PSU, so it makes sense to build around that.
I’ve also got an SMSL M6 sitting unused, it uses the AK4390EF DAC chip — so I may repurpose it for the DAC stage rather than buying something new. I'm on the fence with this because I like the idea of a little separate unit - DSP > mid-range DAC with rotary encoder with included push button (push button toggles inputs)

 

[Sonic-Wall]

Ok @Sonic-Wall I merged Weeb Labs' changes into the code and with the help of my AI intern I enabled 24 bit on I2S.
Binary here: https://github.com/giubeppe/DSPi/blob/refactor/Binaries/rp2350-24bit.uf2

Please note, I'm not checking if the other SPIDF outputs are still working and neither I can validate if the output is really 24 bit. Would you be able to on your side, please let me know.

@giubeppe Thanks a lot for adding the I2S outputs again! Even the I2S signal is now 24 bit, it doesn‘t work with my I2S-to SPDIF output board. I measured the I2S output voltage, and it shows 1.3 - 1.7V. Unfortunately, I do not have an Oscilloscope. However, when I just convert it to HDMI-I2S, my DAC shows DSD64 2.8MHz, but I can only hear a very noisy signal with music in the background.

 

[giubeppe]

@giubeppe Thanks a lot for adding the I2S outputs again! Even the I2S signal is now 24 bit, it doesn‘t work with my I2S-to SPDIF output board. I measured the I2S output voltage, and it shows 1.3 - 1.7V. Unfortunately, I do not have an Oscilloscope. However, when I just convert it to HDMI-I2S, my DAC shows DSD64 2.8MHz, but I can only hear a very noisy signal with music in the background.

Let me check when I’m back home. Can you also tell me the sampling rate as well?

 

[capslock]

I've used the AD1938 in another project and it's quite nice. A bit pricy but 4AD and 8DA and it can operate in "hardware" mode (it doesn't need an MCU for programming).
Another option would be AK4619.

Ok, full codecs with analog in. Even the DAC section is mid-fi at best, especially in the AK4619: 91 dB SINAD typ., 80 dB min at 48 kHz, worse at 96 kHz. Commercial gear with those kind of codecs is never audibly transparent in my experience. How about AK4458? It plays in a different league at 107 dB SINAD per spec sheet. I have seen distortion measurements of the Aurora DSP, harmonics AFAIR were all in the < - 100 dB range, and that is with output stages that were not particularly optimized. This is also the family of DACs used in the Hypex plate amps. You would need to use a AK5552 or 5558 ADC, depending on number of input channels needed, that plays in the same league as the DAC.

 

[john61ct]

I want analog multi-channel input to my convolver computer not just digital. Echo Audiofire 12 seems to be very good value these days, probably because most folk don't want to mess with FireWire conversion.

But this PCIe card apparently works fine with some rPi hosts

Add StarTech.com 3 Port 2b 1a 1394 Mini PCI Express FireWire Card Adapter · Issue #752 · geerlingguy/raspberry-pi-pcie-devices

The StarTech IEEE 1394 3-port Mini PCIe FireWire adapter slots into a mini PCIe slot, and supplies two FireWire 800 ports, and a single FireWire 400. User @RobertMCortese built Open MRU, a Raspberr...

github.com

I wonder if there would be a way to integrate with this project, rather than having to dedicate a full-fledged PC?

Sorry if this is wildly off topic, please explain why, and maybe post responses that would be diversionary here

As good value for PC I/O as Echo Audiofire 12 ?

Total interface noob here, please ELI5 I don't need to record or mix music in the creative sense, just looking to get multi-channel analog in and out of HTPC type hardware. Primary use case is DIY convolving, loudness contour, bass management, room correction PEQ. The Echo Audiofire 12 unit...

www.audiosciencereview.com

to keep this thread clean

Echo Audiofire 12

Echo are the latest soundcard manufacturer to move into the market for Firewire interfaces, and the flagship of their range promises 12-channel analogue I/O with pristine sound quality.

www.soundonsound.com

 

[Weeb Labs]

This may be an unpopular perspective but I have never seen the practical need for exceptionally performant DACs (SINAD >80dB) so long as they are limited by distortion rather than noise.

In principle, I always want to achieve the best possible performance. This informs both my purchase and engineering decisions but to my knowledge, there has yet to be a DBT study demonstrating the practical need for distortion performance below -70dB.

 

[yewneek]

So if I have a good audio interface and a good software eq I don't need this? I thought the clever thing was to use it standalone?

That's the word I was looking for! Standalone!

All the other DSP's I'm aware of that are used with hifi are programmed, disconnected, and used, standalone. Like a DAC, or the WiimPro or a phono preamp.

Once the software is on, you just plug and play.

It's a bit more cost than a cup of coffee, to be fair, and a bit more time, which has value in its own right. It's still in Alpha stage IMO.

MiniDSP is complete, which may well be what many seek, just something that works.

Credit to the developer but it's a LOT of effort if you don't have a RaspberryPi of *any* flavour set up. I don't.

I just want something that works!

GB

 

[yewneek]

- Currently it is a USB audio device. So you connect it to a computer to set the filter parameters, then you can use it with the computer or with any other USB audio device. For example, I am using mine with a Nintendo Switch as input and a JDS Atom DAC on the output.

- You need to have a Raspberry Pi Pico ( can be any of the original/W/2/2W, but 2 or 2W is more powerful). You need to be able to connect it to an output SPDIF connector with the correct output resistors/capacitors. This means either soldering or using a Pico and a SPDIF output with headers. Then you need to connect this to a DAC with SPDIF input (can be coax or optical). The device supports up to four SPDIF outputs.

- Optionally, an RCA and a couple of resistors and capacitors can be used to add a subwoofer output.

- If you get a Pico with headers and a motherboard SPDIF connector with headers, then no soldering is needed, otherwise soldering would be needed.

Amazon.com: Pico 2 with Pre-Soldered Color-Coded Header Compatible with Raspberry Pi Pico 2 Microcontroller, Based on RP2350, Dual-Core ARM Cortex-M33 and Dual-Core Hazard3 RISC-V Processor 4MB Flash, 3 Items : Electronics

Amazon.com: Pico 2 with Pre-Soldered Color-Coded Header Compatible with Raspberry Pi Pico 2 Microcontroller, Based on RP2350, Dual-Core ARM Cortex-M33 and Dual-Core Hazard3 RISC-V Processor 4MB Flash, 3 Items : Electronics

www.amazon.com

Amazon.com: Acxico 1 pcs SPDIF Optical and RCA Out Plate Cable Bracket for ASUS MSI Gigabyte Motherboard : Electronics

Buy Acxico 1 pcs SPDIF Optical and RCA Out Plate Cable Bracket for ASUS MSI Gigabyte Motherboard: Laptop Replacement Parts - Amazon.com ✓ FREE DELIVERY possible on eligible purchases

www.amazon.com

It's a computer USB-audio device, by effect, it's not standalone, sadly.

 

[Weeb Labs]

It's a computer USB-audio device, by effect, it's not standalone, sadly.

It is standalone in the sense that it can be connected to any device with support for USB audio. This would include PCs, phones, tablets, gaming consoles and many TVs.

SPDIF input is also on the way.

 

[Salt]

That's the word I was looking for! Standalone!

All the other DSP's I'm aware of that are used with hifi are programmed, disconnected, and used, standalone. Like a DAC, or the WiimPro or a phono preamp.

Once the software is on, you just plug and play.

It's a bit more cost than a cup of coffee, to be fair, and a bit more time, which has value in its own right. It's still in Alpha stage IMO.

MiniDSP is complete, which may well be what many seek, just something that works.

Credit to the developer but it's a LOT of effort if you don't have a RaspberryPi of *any* flavour set up. I don't.

I just want something that works!

GB

This project is not for 'go for it and buy', but a serious, documented, science based approach to a technical device.
Based on an idea on the flue fly, it was very fast extended and now some additional experts are involved.
That is technical expertise and science at its best.

You do not need to appreciate this, not understand what it is about, and can buy whatever you want.

 

[Rocky Maine]

On Windows, connected a Pico 2 and flashed v1.1.0.
Console is also v1.1.0.
Console is showing "No USB devices visible to LibUsbDotNet"

Launched Zadig and chose the option from a previous post (Weeb Labs DSPi Interface 2).

It's prompting to downgrade? Is this correct?

There's also an Interface 0 in the dropdown with different drivers.

Device Manager

Not sure how to proceed.

 

[Grooved]

Ok, full codecs with analog in. Even the DAC section is mid-fi at best, especially in the AK4619: 91 dB SINAD typ., 80 dB min at 48 kHz, worse at 96 kHz. Commercial gear with those kind of codecs is never audibly transparent in my experience. How about AK4458? It plays in a different league at 107 dB SINAD per spec sheet. I have seen distortion measurements of the Aurora DSP, harmonics AFAIR were all in the < - 100 dB range, and that is with output stages that were not particularly optimized. This is also the family of DACs used in the Hypex plate amps. You would need to use a AK5552 or 5558 ADC, depending on number of input channels needed, that plays in the same league as the DAC.

If the project is using a Codec (not separated DACs and ADCs), but with better performance, you also have these two:
ES9290: https://www.mouser.fr/datasheet/3/3763/1/ES9290_Datasheet_v0.3.2.pdf
AK4458: https://www.mouser.com/datasheet/2/1431/ak4458vn_en_datasheet-3010057.pdf

 

[Jumpybah]

Congratulations on this project.
I'm eagerly awaiting the SPDIF input.
It would be nice to be able to control the DSP remotely, perhaps via Wi-Fi with an ESP32.
What do you think?

 

[Weeb Labs]

On Windows, connected a Pico 2 and flashed v1.1.0.
Console is also v1.1.0.
Console is showing "No USB devices visible to LibUsbDotNet"

Launched Zadig and chose the option from a previous post (Weeb Labs DSPi Interface 2).

It's prompting to downgrade? Is this correct?

There's also an Interface 0 in the dropdown with different drivers.

View attachment 513998

View attachment 514001

Device Manager

View attachment 514000

Not sure how to proceed.

You need to proceed with the downgrade.

 

[capslock]

If the project is using a Codec (not separated DACs and ADCs), but with better performance, you also have these two:
ES9290: https://www.mouser.fr/datasheet/3/3763/1/ES9290_Datasheet_v0.3.2.pdf
AK4458: https://www.mouser.com/datasheet/2/1431/ak4458vn_en_datasheet-3010057.pdf

The 4458 is what I recommended above but it is an 8x DAC, not a codec. Maybe you meant another part number?

 

[Rocky Maine]

You need to proceed with the downgrade.

Thanks.

I ran the downgrade, shows successful:

The console still shows the 'no usb devices' message.

I checked Device Manager and the DSPi USB driver remains at the previous version.

What am I doing wrong?