New Wondom ADAU1701 DSP Unit

[FrankV]

@FrankV thank you! I’ll definitely test with a variety of loads, but if 6k is spec then I won’t mark it down for issues below that . I’ll see what I can do about measuring coil whine as well.

Well it is the spec of the PT2259 but not the spec of the Wondom because they do not give a load spec! Also, Topping and many others do not often quote input impedance.

You might trigger the PSU issue by setting the PSU nominal 5V input voltage at 4.75V, as the Wondom is supposed to work with a USB PSU. From the user manual: "DC5V/1A USB Type-C"

 

[mcdn]

Well it is the spec of the PT2259 but not the spec of the Wondom because they do not give a load spec! Also, Topping and many others do not often quote input impedance.

You might trigger the PSU issue by setting the PSU nominal 5V input voltage at 4.75V, as the Wondom is supposed to work with a USB PSU. From the user manual: "DC5V/1A USB Type-C"

If it’s specced at 5V why would I test it at 4.75V? Maybe I’ve misunderstood what you’re asking for?

 

[FrankV]

If it’s specced at 5V why would I test it at 4.75V? Maybe I’ve misunderstood what you’re asking for?

It implies it is supposed to work with a USB adaptor. The USB specification is 5V +/- 5%, hence an adaptor could supply just 4.75V and be within spec.

 

[mcdn]

Ah, I think they mean 5V 1A over a USB-C connector. Not a negotiated USB power delivery. 5V has been the accepted minimum since forever, I can’t ever recall a power supply delivering less, and if it did you’d blame the supply not the powered device surely?

 

[mcdn]

Looks like the baseline has been 5.5V since 2014: https://en.wikipedia.org/wiki/USB_hardware

 

[mcdn]

Hi all! I bought one of the Wondom units to use in my garage (just basic main/sub splitting and some PEQ), but I'm going to give it a thorough test first. Some of my reviews have got onto the front page so I wanted to ask in advance to see what interested people would like me to measure/check.

After mucking around for a bit I've realised the issues with the gain structure and underpowered outputs mean it's basically unusable except as a toy, so I won't be bothering with a full review Yes I know I could have figured that out from the thread but my enthusiasm for cheap AliExpress imports got the better of me

In summary:

• Persistent 1kHz -60dB tone
• Heavy distortion above 800mV input
• Heavy distortion above 125mV output
• Non-defeatable volume control with a daft law that means only the top quarter of its range is usable
• Utterly pointless default/demo programming - they should at least make it usable as a sub crossover by default
• Requires the staggeringly bad Sigma Studio software to program it (how the hell do you make software that visibly fails to draw a screen smoothly on a 4GHz CPU with 16GB RAM and an SSD?)

On the plus side my younger son wants to practice soldering so we can use it for that and see if some of the mods proposed here work.

So the search for a reasonable MinisDSP 2x4 (or 2x4HD) alternative continues...

 

[FrankV]

Ah, I think they mean 5V 1A over a USB-C connector. Not a negotiated USB power delivery. 5V has been the accepted minimum since forever, I can’t ever recall a power supply delivering less, and if it did you’d blame the supply not the powered device surely?

I have a fairly new USB 3.0 hub with it's own PSU which gives out 5.126V. Without the PSU It only puts out 4.66V from a USB 3.0 port on my PC, which is rather low! In the latter case I would not complain about the Wondom, but even with 5.126V input the Wondom does not regulate properly.

After mucking around for a bit I've realised the issues with the gain structure and underpowered outputs mean it's basically unusable except as a toy, so I won't be bothering with a full review Yes I know I could have figured that out from the thread but my enthusiasm for cheap AliExpress imports got the better of me

In summary:

• Persistent 1kHz -60dB tone
• Heavy distortion above 800mV input
• Heavy distortion above 125mV output
• Non-defeatable volume control with a daft law that means only the top quarter of its range is usable
• Utterly pointless default/demo programming - they should at least make it usable as a sub crossover by default
• Requires the staggeringly bad Sigma Studio software to program it (how the hell do you make software that visibly fails to draw a screen smoothly on a 4GHz CPU with 16GB RAM and an SSD?)

On the plus side my younger son wants to practice soldering so we can use it for that and see if some of the mods proposed here work.

So the search for a reasonable MinisDSP 2x4 (or 2x4HD) alternative continues...

With a high impedance load (>47k), I did not see distortion up to 900mV output, but that was with an ADC-DAC straight-through test project and the volume control backed off. Input up to around 1.3V did not cause an issue. However, the DSP input will allow up to 2V (=900mV at the ADAU1701 ADC input) but due to the +3.5dB gain after the DAC and the severe signal handling limitations of the volume control, any signal greater than around 800mV out of the ADAU1701 DAC gets distorted by the volume control.

Not seen the performance problems you are describing for SigmaStudio. Have used for a few years and even on my laptop it is ok.

If your son needs further guidance for the mods, let me know. The results will be at least as good as the original miniDSP 2x4.

 

[mcdn]

I have a fairly new USB 3.0 hub with it's own PSU which gives out 5.126V. Without the PSU It only puts out 4.66V from a USB 3.0 port on my PC, which is rather low! In the latter case I would not complain about the Wondom, but even with 5.126V input the Wondom does not regulate properly.



With a high impedance load (>47k), I did not see distortion up to 900mV output, but that was with an ADC-DAC straight-through test project and the volume control backed off. Input up to around 1.3V did not cause an issue. However, the DSP input will allow up to 2V (=900mV at the ADAU1701 ADC input) but due to the +3.5dB gain after the DAC and the severe signal handling limitations of the volume control, any signal greater than around 800mV out of the ADAU1701 DAC gets distorted by the volume control.

Not seen the performance problems you are describing for SigmaStudio. Have used for a few years and even on my laptop it is ok.

If your son needs further guidance for the mods, let me know. The results will be at least as good as the original miniDSP 2x4.

True my testing was into a slightly low impedance of about 2kOhm. It might do better into a higher load, but 2k is still only 1mW at 2V. The frustration is that fixing these issues wouldn't increase the BOM at all, it's simply poor design.

 

[FrankV]

Yes, is stands no chance into a 2k load.

Poor design indeed although if the output volume control is a must then a different circuit would be required which would push up the BoM cost.

 

[Audiomaniac3]

Well,updated unit on same adau1701:

'BDSP2.4U Adau1701 DSP review'

Aug 23, 2025

Hello everyone,in this video:

I got a BDSP2.4U DSP processor for review, based on the adau1701 chip with two inputs and four outputs.

Thanks to Sigma studio,you can make many corrections and changes to the audio signal,adjust the delay,signal level,equalization, crossover and much more.

BDSP2.4U is perfect for adjusting and setting up the LFE channel in a home theater.

To programm this unit ICP1 or ICP5 is necessary.

BDSP2.4U:

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Sure Electronics is a professional audio amplifier supplier that provides electronics hobbyists and business partners the middleware which can help reduce customers' development difficulties and save their precious time-to-market by making the products directly released in the market.

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ICP5...

• Audiomaniac3
• adau1701 dsp equalization home theater
• Replies: 2
• Forum: Audio Electronics and Hardware

 

[Audiomaniac3]

Internals comparesment.

 

[FrankV]

Can you tell me what these two ic's are? If they are the same as the Wondom then it is a doomed product in the same way as the Wondom.

 

[FrankV]

The PT2259 used in the Wondom has poor load driving capability so will not drive a Topping amp for a start without severe clipping or having to use reduced signal levels, resulting in low DNR and poor noise performance. The ic is specified to drive 6k minimum load and they mean it.

 

[Audiomaniac3]

what these two ic's are?

 

[FrankV]

And I'm guessing these will be SGM8904:

If so, this is a copy of the Wondom, or the other way around and will be just as bad.
I managed to make mine half decent by bypassing the PT2259 ics, remove these 8 capacitors:

Then bridge each lower pad of the four lower capacitors to the upper pad of the upper capacitors with 100uF/6.3V electrolytics, +ve on the lower side.


Optionally reduce the gain around the SGM8904 ic by 3.5dB by lowering the feedback resistor value in each channel, details further back in this thread: https://www.audiosciencereview.com/...w-wondom-adau1701-dsp-unit.46656/post-2289541

 

[Audiomaniac3]

Wondom

Do you know how to make i2s input work?
I soldered pins to j106 and configured my project,I have little bit better adc to i2s unit,but can't get it to work.

 

[FrankV]

Do you know how to make i2s input work?
I soldered pins to j106 and configured my project,I have little bit better adc to i2s unit,but can't get it to work.

Not tried it with this incarnation. I assume you configured the registers in the Hardware Configuration window? As the pins are multipurpose, need to check they have not hung something else like a Pot or LED on the I2S pins.

 

[Audiomaniac3]

Not tried it with this incarnation. I assume you configured the registers in the Hardware Configuration window? As the pins are multipurpose, need to check they have not hung something else like a Pot or LED on the I2S pins.

That way it worked fine from this adc to jab5 over i2s.

But I am not sure how to make it work on adau1701.Board gets unresponsive as soon as I connect adc to it.

 

[FrankV]

My guess is that the MCLK pin is not buffered on the board. The ADAU1701 oscillator circuit does not have enough drive for external circuits. If you disconnect MCLK does the ADAU1701 board continue to work?

 

[flangefrog]

Pics of my BerryBak BDSP2.4U Pro

WONDOM OFFICIAL SHOP - Bluetooth Amplifier Board - Sure Electronics - BCPB - 18650 charger - T-AMP - Volume Control

Sure Electronics is a professional audio amplifier supplier that provides electronics hobbyists and business partners the middleware which can help reduce customers' development difficulties and save their precious time-to-market by making the products directly released in the market.

store.sure-electronics.com

Edit: The ADAU1701, PCM1822 and PCM5122 sections had shields which I removed for the pics