freeDSP - an open source 2-in 4-out digital crossover board

[basreflex]

Cyberpit-san
nice, here is an example of turn-on mute. the PNP emitter net is connected to the input voltage before the regulator. upon connection of the supply, the PNP -NPN pair acts as a triac and latches on, until the line MUTEDRIVE is pulled low.
the mutedrive net can be driven by the MPx port, when programmed as a timer delay when the DSP starts executing. monitoring the voltage across the regulator could also warn for turn-off and trigger the mute again.
for example by monitoring a voltage generated by a pnp transistor across the regulator and converted by the AUX adc..

 

[CyberPit]

New Muting Tr. Driver Circuit

Hi basreflex-San,


Thanks a lot.

Well, there are many ways to detect the power issues.
My DSP code is not so reliable, so I would go with HW solution rather than SW.
Additionally reason is keeping free limited ADAU1701HW(MPxx) resources .



Here is my current muting driver circuit.

 

[CyberPit]

2way Amp Installation

Hi all,

Current Status is still in evaluation...
DIY DSP PROCESSOR PROJECT PAGE

HILO

 

[basreflex]

nice chassis,where did you buy that ?

 

[CyberPit]

nice chassis,where did you buy that ?

That's recycled junk chassis.
Originally used in MP3 paging player. Not in sale now...

 

[CyberPit]

192kHz Sampling Crossover Project Evaluated

Hi there?
I have tested 192kHz Sampling 2way Crossover project with my ADAU1701 board.
It works fine, Analog I/O but it's a HI-Res Audio Crossover.

DIY DSP PROCESSOR PROJECT PAGE



(fs=48kHz) (fs=192kHz)

 

[emilvv]

Hello,

I have FreeDSP classic with arduino nano programmer.

When I am uploading HEX file to eprom do I need to power FreeDSP board by its 12V too ?

Thank you,
Emil

 

[CyberPit]

Hi emilvv-San,

When I am uploading HEX file to eprom do I need to power FreeDSP board by its 12V too ?

Yes, EEPROM power pin8 should be stable during the data write operation.

 

[emilvv]

Thank you

Thank you CyberPit,

I hope soon to test programmed DSP 🙂

Regards,

Emil

 

[Piersma]

Stereo imaging

I am using a single FreeDSP board for one audio channel (left) in an active speaker.
Another FreeDSP board is fitted in the other active speaker and is serving the other (right) audio channel.

The imaging in a stereo setup is (almost) totally lost.

Here's my question:
which clock(s) do i have to synchronise? Is it only the master clock which is available on the expension header? Or do I also need other clocks to synchronise? likewise LRCLK, BCLK..

 

[CyberPit]

Hi Piersma-San,

Another FreeDSP board is fitted in the other active speaker and is serving the other (right) audio channel.

If your Right-channel sound via Left-channel DSP, It will takes some time to receiving I2S, DSP data handling and sending I2S in the serializer. As a result of this, the Right-channel sound will be delayed some.
So you need to add some delays into the Left-channel.

In case of your I2S bus signal distributed to both channel (in parallel), I guess the received data will be latched into the DSP synchronized with the LRCK transition. Remember to set the I2S ports should set to the Slave(Follower)-mode.

 

[Piersma]

Extending I2S

Hi Cyberpit,

I think your proposed method would work but
I looked into the issues of propagating I2S over serveral meters and came to the conclusion a buffer would defenitely be needed.
For now I will leave the idea of extending the I2S signals.

Thanks for your support !

 

[CyberPit]

Hi Piersma-San,

I looked into the issues of propagating I2S over serveral meters and came to the conclusion a buffer would defenitely be needed.
For now I will leave the idea of extending the I2S signals.

Well, It's difficult to extend MCLK and I2S signal path with copper cables.

DS90LV047ATM(LVDS Driver)
DS90LV048ATM(LVDS Receiver)
And using with quad twisted-pair cable (such as CAT5 or HDMI-Cable...) will be fit for your needs.

 

[Piersma]

external DAC PCM5102A

Decided to extend the FreeDSP with an external DAC. Advantage is the increased voltage output capabilities and dynamic range of the PCM5102A.
Note that you have to change the polarity of the I2S bitclock.
The bitclock polarity is set from negative to positive.

 

[CyberPit]

Hi Piersma-San,

I agree with you, It's an important point using with embedded DAC with external DACs...

Note that you have to change the polarity of the I2S bitclock.
The bitclock polarity is set from negative to positive.

Well, most of ADAU1701 based FreeDSP board has phase inverted 0.9V output except my designs.
FreeDSP Classic SMD A/B and the FreeDSP Classic SMD A/B plus II has 2V phase corrected outputs.
They don't need to care those things.😀